Topics

Power supply adjustments

Bob McGraw - K4TAX
 

Why not get Alexa to adjust the voltage for you?   "Alexa, turn the supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.   Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed the 4 screws holding then cover, plugged in the cord and turned the supply on.   I picked up my light in one hand and my plastic adjustment tool in the other {you do have and use a plastic adjustment tool don't you?} and made the adjustment. Nowhere at any time did my hands or fingers come close to any voltage.    I did put my Fluke DMV on the output terminals first to monitor the voltage.  At 14.49 indicated,  I stopped.   Turned the supply off, put the cover on and secured it with the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
And for some stupid reason, when they could have put that pot on the underside of the circuit board (which ends up on the top) for simpler access, they didn't.  So you're reaching in around open hot high voltage OR turning it on/off a lot of times to get it set right.  Plan B could have been to put the pot on the edge or board flush with a hole for a plastic tool to access...

I maintain that if the design engineers (of ANY field) EVER had to work on, fix, adjust their product, the design would be far different and techs would bless them instead of using 'adult language' curses...  ;-)

I hold that Elecraft 'gets' this, their designs are modular and except cable routing and some panel connecting, is boringly simple.

Rick NK7I


On 11/6/2019 10:32 AM, Rob Sherwood wrote:
The Astron power supplies I own have an internal pot to set the voltage. I would adjust it with nothing connected.  The can likely go over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some reason removing the top covers are a pain.  Rob, NC0B

dalej
 

Remember to take into account the voltage drop to your Fluke DMV ( I use Fluke 77). The best is to use the K3 onboard meter, that should show you the real voltage the K3 is seeing.

Dale, K9VUJ

On 06, Nov 2019, at 16:18, Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you? "Alexa, turn the supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type. Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon. I put it on the desk, removed the 4 screws holding then cover, plugged in the cord and turned the supply on. I picked up my light in one hand and my plastic adjustment tool in the other {you do have and use a plastic adjustment tool don't you?} and made the adjustment. Nowhere at any time did my hands or fingers come close to any voltage. I did put my Fluke DMV on the output terminals first to monitor the voltage. At 14.49 indicated, I stopped. Turned the supply off, put the cover on and secured it with the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
And for some stupid reason, when they could have put that pot on the underside of the circuit board (which ends up on the top) for simpler access, they didn't. So you're reaching in around open hot high voltage OR turning it on/off a lot of times to get it set right. Plan B could have been to put the pot on the edge or board flush with a hole for a plastic tool to access...

I maintain that if the design engineers (of ANY field) EVER had to work on, fix, adjust their product, the design would be far different and techs would bless them instead of using 'adult language' curses... ;-)

I hold that Elecraft 'gets' this, their designs are modular and except cable routing and some panel connecting, is boringly simple.

Rick NK7I


On 11/6/2019 10:32 AM, Rob Sherwood wrote:
The Astron power supplies I own have an internal pot to set the voltage. I would adjust it with nothing connected. The can likely go over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some reason removing the top covers are a pain. Rob, NC0B

Bob McGraw - K4TAX
 

The Fluke was used only to determine the voltage while setting the power supply voltage.  I'm not about to tweak the supply voltage with the radio turned on!   The Fluke  is more accurate than the analog meters on the power supply.    Then with the radio connected and turned on, the Fluke at the power supply indicated 14.49 while the voltage indication on the K3S was 14.4.   I'd say 0.09 volts difference would be acceptable.    Oh what is the accuracy of the voltage indication in the K3S?

Please explain "voltage drop to your Fluke"?

73

Bob, K4TAX

On 11/6/2019 5:04 PM, dalej via Groups.Io wrote:
Remember to take into account the voltage drop to your Fluke DMV ( I use Fluke 77). The best is to use the K3 onboard meter, that should show you the real voltage the K3 is seeing.

Dale, K9VUJ


On 06, Nov 2019, at 16:18, Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you? "Alexa, turn the supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type. Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon. I put it on the desk, removed the 4 screws holding then cover, plugged in the cord and turned the supply on. I picked up my light in one hand and my plastic adjustment tool in the other {you do have and use a plastic adjustment tool don't you?} and made the adjustment. Nowhere at any time did my hands or fingers come close to any voltage. I did put my Fluke DMV on the output terminals first to monitor the voltage. At 14.49 indicated, I stopped. Turned the supply off, put the cover on and secured it with the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
And for some stupid reason, when they could have put that pot on the underside of the circuit board (which ends up on the top) for simpler access, they didn't. So you're reaching in around open hot high voltage OR turning it on/off a lot of times to get it set right. Plan B could have been to put the pot on the edge or board flush with a hole for a plastic tool to access...

I maintain that if the design engineers (of ANY field) EVER had to work on, fix, adjust their product, the design would be far different and techs would bless them instead of using 'adult language' curses... ;-)

I hold that Elecraft 'gets' this, their designs are modular and except cable routing and some panel connecting, is boringly simple.

Rick NK7I


On 11/6/2019 10:32 AM, Rob Sherwood wrote:
The Astron power supplies I own have an internal pot to set the voltage. I would adjust it with nothing connected. The can likely go over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some reason removing the top covers are a pain. Rob, NC0B





dalej
 

A few tenths of a volt. I was in jest with you Bob…All this volt stuff is really not very significant. Keep the K3 output at 25 to 40 watts and the IMD will be at minimum. I’ve looked at the IMD specs on these transistors and at about 40 watts or so they are the cleanest as I think you already know. I would not trade a 12 volt rig for a 40 or what ever final which requires a special PS. If I have a PS failure (which I have had in the past) I simply go to the shop, grab another and I’m back on the air. With these rigs with built in supplies at 40 volts something the whole rig goes back unless the ham is good at repairing switching supplies which for me I am not. I just grab my spare and be gone. Example the Icom 7800 PS, not even a schematic avaliable for it and I hear the cost for replacement is somewhere South of one kilobuck…can you believe it. I’m just a poor old ham and having a spare PS fits my needs just fine.

Dale, K9VUJ

On 06, Nov 2019, at 17:14, Bob McGraw - K4TAX <rmcgraw@...> wrote:

The Fluke was used only to determine the voltage while setting the power supply voltage. I'm not about to tweak the supply voltage with the radio turned on! The Fluke is more accurate than the analog meters on the power supply. Then with the radio connected and turned on, the Fluke at the power supply indicated 14.49 while the voltage indication on the K3S was 14.4. I'd say 0.09 volts difference would be acceptable. Oh what is the accuracy of the voltage indication in the K3S?

Please explain "voltage drop to your Fluke"?

73

Bob, K4TAX


On 11/6/2019 5:04 PM, dalej via Groups.Io wrote:
Remember to take into account the voltage drop to your Fluke DMV ( I use Fluke 77). The best is to use the K3 onboard meter, that should show you the real voltage the K3 is seeing.

Dale, K9VUJ


On 06, Nov 2019, at 16:18, Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you? "Alexa, turn the supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type. Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon. I put it on the desk, removed the 4 screws holding then cover, plugged in the cord and turned the supply on. I picked up my light in one hand and my plastic adjustment tool in the other {you do have and use a plastic adjustment tool don't you?} and made the adjustment. Nowhere at any time did my hands or fingers come close to any voltage. I did put my Fluke DMV on the output terminals first to monitor the voltage. At 14.49 indicated, I stopped. Turned the supply off, put the cover on and secured it with the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
And for some stupid reason, when they could have put that pot on the underside of the circuit board (which ends up on the top) for simpler access, they didn't. So you're reaching in around open hot high voltage OR turning it on/off a lot of times to get it set right. Plan B could have been to put the pot on the edge or board flush with a hole for a plastic tool to access...

I maintain that if the design engineers (of ANY field) EVER had to work on, fix, adjust their product, the design would be far different and techs would bless them instead of using 'adult language' curses... ;-)

I hold that Elecraft 'gets' this, their designs are modular and except cable routing and some panel connecting, is boringly simple.

Rick NK7I


On 11/6/2019 10:32 AM, Rob Sherwood wrote:
The Astron power supplies I own have an internal pot to set the voltage. I would adjust it with nothing connected. The can likely go over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some reason removing the top covers are a pain. Rob, NC0B





Bill K9YEQ
 

The simplest solution, operate at 20-30 watts output and if not good enough, turn on the KPA500 or KPA1500 and be clean. That is my shack and I really don't need to struggle with supply voltage so much. I am upgrading to #10 wires even though....

73,
Bill
K9YEQ

https://wrj-tech.com/

-----Original Message-----
From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of dalej via Groups.Io
Sent: Wednesday, November 6, 2019 6:02 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

A few tenths of a volt. I was in jest with you Bob…All this volt stuff is really not very significant. Keep the K3 output at 25 to 40 watts and the IMD will be at minimum. I’ve looked at the IMD specs on these transistors and at about 40 watts or so they are the cleanest as I think you already know. I would not trade a 12 volt rig for a 40 or what ever final which requires a special PS. If I have a PS failure (which I have had in the past) I simply go to the shop, grab another and I’m back on the air. With these rigs with built in supplies at 40 volts something the whole rig goes back unless the ham is good at repairing switching supplies which for me I am not. I just grab my spare and be gone. Example the Icom 7800 PS, not even a schematic avaliable for it and I hear the cost for replacement is somewhere South of one kilobuck…can you believe it. I’m just a poor old ham and having a spare PS fits my needs just fine.

Dale, K9VUJ



On 06, Nov 2019, at 17:14, Bob McGraw - K4TAX <rmcgraw@...> wrote:

The Fluke was used only to determine the voltage while setting the power supply voltage. I'm not about to tweak the supply voltage with the radio turned on! The Fluke is more accurate than the analog meters on the power supply. Then with the radio connected and turned on, the Fluke at the power supply indicated 14.49 while the voltage indication on the K3S was 14.4. I'd say 0.09 volts difference would be acceptable. Oh what is the accuracy of the voltage indication in the K3S?

Please explain "voltage drop to your Fluke"?

73

Bob, K4TAX


On 11/6/2019 5:04 PM, dalej via Groups.Io wrote:
Remember to take into account the voltage drop to your Fluke DMV ( I use Fluke 77). The best is to use the K3 onboard meter, that should show you the real voltage the K3 is seeing.

Dale, K9VUJ


On 06, Nov 2019, at 16:18, Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you? "Alexa, turn the supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type. Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon. I put it on the desk, removed the 4 screws holding then cover, plugged in the cord and turned the supply on. I picked up my light in one hand and my plastic adjustment tool in the other {you do have and use a plastic adjustment tool don't you?} and made the adjustment. Nowhere at any time did my hands or fingers come close to any voltage. I did put my Fluke DMV on the output terminals first to monitor the voltage. At 14.49 indicated, I stopped. Turned the supply off, put the cover on and secured it with the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
And for some stupid reason, when they could have put that pot on the underside of the circuit board (which ends up on the top) for simpler access, they didn't. So you're reaching in around open hot high voltage OR turning it on/off a lot of times to get it set right. Plan B could have been to put the pot on the edge or board flush with a hole for a plastic tool to access...

I maintain that if the design engineers (of ANY field) EVER had to work on, fix, adjust their product, the design would be far different and techs would bless them instead of using 'adult language' curses... ;-)

I hold that Elecraft 'gets' this, their designs are modular and except cable routing and some panel connecting, is boringly simple.

Rick NK7I


On 11/6/2019 10:32 AM, Rob Sherwood wrote:
The Astron power supplies I own have an internal pot to set the voltage. I would adjust it with nothing connected. The can likely go over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some reason removing the top covers are a pain. Rob, NC0B





Michael Mickelson
 

Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

Thanks to all who contributed.  Mike  KD8DZ

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:
Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>






--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M
 

Dennis Ashworth
 

Are the supply voltage differences powering the K3 really material to IMD numbers? I’ve not seen data to answer the question either way ... just curious.
Dennis, K7FL

On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:


Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

Thanks to all who contributed.  Mike  KD8DZ

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:
Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>






--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M
 

Edward McCann
 

Mike-

Which 30 Amp Astron power supply?

Let us know the results!

73,

AG6CX


On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:

Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

Thanks to all who contributed.  Mike  KD8DZ

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:
Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>






--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M
 

Rob Sherwood
 

This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering.  The pattern I measured was linear, the higher the voltage, the lower the third-order IMD.  At really low voltages the much higher odd-order products degrade significantly.  Test was on 20 meters, at a nominal 100 watts as per the K3 power setting.  Two equal tones were generated within the K3.  Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts.  At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

 

Voltage                IMD in dBc   Note: Add 6 dB for PEP method

11.5                        -14.1 dBc

12.0                        -16.9 dBc

12.5                        -17.9 dBc

13.0                        -19.0 dBc

13.4                        -20.0 dBc

13.8                        -21.1 dBc

14.2                        -22.4 dBc

14.6                        -23.7 dBc

14.8                        -24.0 dBc

 

Rob, NC0B

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Dennis Ashworth
Sent: Thursday, November 07, 2019 11:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

 

Are the supply voltage differences powering the K3 really material to IMD numbers? I’ve not seen data to answer the question either way ... just curious.

Dennis, K7FL



On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:



Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

 

Thanks to all who contributed.  Mike  KD8DZ

 

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>





--

Michael Mickelson

J. Reid Anderson Professor of Physics and Astronomy, emeritus

Denison University

740-587-0687 H

740-644-1238 M

 

 

Rob,

K3s are tested for -30 dBc or better 3rd-order IMD at 13.8 V at 100 W (ARRL method, 6 dB higher than your table). Average across all bands is typically -35 dBc. The one you measured may not be correctly biased, or not up to the latest rev. 

Further improvements have been made to both the 10 and 100 W modules in the K4. 

73,
Wayne
N6KR

On Nov 7, 2019, at 11:50 AM, Rob Sherwood <rob@...> wrote:

This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering.  The pattern I measured was linear, the higher the voltage, the lower the third-order IMD.  At really low voltages the much higher odd-order products degrade significantly.  Test was on 20 meters, at a nominal 100 watts as per the K3 power setting.  Two equal tones were generated within the K3.  Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts.  At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

 

Voltage                IMD in dBc   Note: Add 6 dB for PEP method

11.5                        -14.1 dBc

12.0                        -16.9 dBc

12.5                        -17.9 dBc

13.0                        -19.0 dBc

13.4                        -20.0 dBc

13.8                        -21.1 dBc

14.2                        -22.4 dBc

14.6                        -23.7 dBc

14.8                        -24.0 dBc

 

Rob, NC0B

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Dennis Ashworth
Sent: Thursday, November 07, 2019 11:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

 

Are the supply voltage differences powering the K3 really material to IMD numbers? I’ve not seen data to answer the question either way ... just curious.

Dennis, K7FL



On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:



Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

 

Thanks to all who contributed.  Mike  KD8DZ

 

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>





--

Michael Mickelson

J. Reid Anderson Professor of Physics and Astronomy, emeritus

Denison University

740-587-0687 H

740-644-1238 M

 

dalej
 

wondering what the IMD is with power set to 35 watts and the PS set to 13.8

Dale k9vuj




On 07, Nov 2019, at 13:50, Rob Sherwood <rob@...> wrote:

This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering.  The pattern I measured was linear, the higher the voltage, the lower the third-order IMD.  At really low voltages the much higher odd-order products degrade significantly.  Test was on 20 meters, at a nominal 100 watts as per the K3 power setting.  Two equal tones were generated within the K3.  Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts.  At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.
 
Voltage                IMD in dBc   Note: Add 6 dB for PEP method
11.5                        -14.1 dBc
12.0                        -16.9 dBc
12.5                        -17.9 dBc
13.0                        -19.0 dBc
13.4                        -20.0 dBc
13.8                        -21.1 dBc
14.2                        -22.4 dBc
14.6                        -23.7 dBc
14.8                        -24.0 dBc
 
Rob, NC0B
 
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Dennis Ashworth
Sent: Thursday, November 07, 2019 11:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments
 
Are the supply voltage differences powering the K3 really material to IMD numbers? I’ve not seen data to answer the question either way ... just curious.
Dennis, K7FL


On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:


Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.
 
Thanks to all who contributed.  Mike  KD8DZ
 
On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you?   "Alexa, turn the 
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.   
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed 
the 4 screws holding then cover, plugged in the cord and turned the 
supply on.   I picked up my light in one hand and my plastic adjustment 
tool in the other {you do have and use a plastic adjustment tool don't 
you?} and made the adjustment. Nowhere at any time did my hands or 
fingers come close to any voltage.    I did put my Fluke DMV on the 
output terminals first to monitor the voltage.  At 14.49 indicated,  I 
stopped.   Turned the supply off, put the cover on and secured it with 
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the 
> underside of the circuit board (which ends up on the top) for simpler 
> access, they didn't.  So you're reaching in around open hot high 
> voltage OR turning it on/off a lot of times to get it set right.  Plan 
> B could have been to put the pot on the edge or board flush with a 
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to 
> work on, fix, adjust their product, the design would be far different 
> and techs would bless them instead of using 'adult language' 
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except 
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the 
>> voltage. I would adjust it with nothing connected.  The can likely go 
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some 
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
> 
>
>





-- 
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M
 


 

On average, IMD will be much better at 35 W than at 100 W. And as with all class AB amps using MOSFETs, the IMD will vary per-band.

Wayne
N6KR

On Nov 7, 2019, at 12:37 PM, dalej via Groups.Io <dalej2=mac.com@groups.io> wrote:

wondering what the IMD is with power set to 35 watts and the PS set to 13.8

Dale k9vuj




On 07, Nov 2019, at 13:50, Rob Sherwood <rob@...> wrote:

This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering. The pattern I measured was linear, the higher the voltage, the lower the third-order IMD. At really low voltages the much higher odd-order products degrade significantly. Test was on 20 meters, at a nominal 100 watts as per the K3 power setting. Two equal tones were generated within the K3. Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts. At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

Voltage IMD in dBc Note: Add 6 dB for PEP method
11.5 -14.1 dBc
12.0 -16.9 dBc
12.5 -17.9 dBc
13.0 -19.0 dBc
13.4 -20.0 dBc
13.8 -21.1 dBc
14.2 -22.4 dBc
14.6 -23.7 dBc
14.8 -24.0 dBc

Rob, NC0B

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Dennis Ashworth
Sent: Thursday, November 07, 2019 11:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

Are the supply voltage differences powering the K3 really material to IMD numbers? I’ve not seen data to answer the question either way ... just curious.
Dennis, K7FL


On Nov 7, 2019, at 10:22 AM, Michael Mickelson <@KD8DZ> wrote:


Bob, thanks for that information. I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting. The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

Thanks to all who contributed. Mike KD8DZ

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:
Why not get Alexa to adjust the voltage for you? "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon. I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on. I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage. I did put my Fluke DMV on the
output terminals first to monitor the voltage. At 14.49 indicated, I
stopped. Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
And for some stupid reason, when they could have put that pot on the
underside of the circuit board (which ends up on the top) for simpler
access, they didn't. So you're reaching in around open hot high
voltage OR turning it on/off a lot of times to get it set right. Plan
B could have been to put the pot on the edge or board flush with a
hole for a plastic tool to access...

I maintain that if the design engineers (of ANY field) EVER had to
work on, fix, adjust their product, the design would be far different
and techs would bless them instead of using 'adult language'
curses... ;-)

I hold that Elecraft 'gets' this, their designs are modular and except
cable routing and some panel connecting, is boringly simple.

Rick NK7I


On 11/6/2019 10:32 AM, Rob Sherwood wrote:
The Astron power supplies I own have an internal pot to set the
voltage. I would adjust it with nothing connected. The can likely go
over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
reason removing the top covers are a pain. Rob, NC0B







--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M


Joe Subich, W4TV
 

On 2019-11-07 2:50 PM, Rob Sherwood wrote:

The pattern I measured was linear, the higher the voltage, the lower the third-order IMD.
Given the rate of change, I would not call the slope linear.

There is a terrible 2.8 dB worsening of IMD when the voltage drops from
12.0 to 11.5 volts. In addition, you change from 0.5V steps below 13.0
V to 0.4V steps above which hides an improvement in dB/V between 13.0
and 14.6V (1.0, 1.1, 1.3, 1.3 dB/0.4V). The improvement "flattens out"
again above 14.6V (only 0.3 dB/.02V).

It does make one wonder if the K3/K3S could achieve -36 dB/PEP at
50-60 W with a 14.5V supply <G> (particularly if the LPA were set up
for better IMD at that level).

73,

... Joe, W4TV


On 2019-11-07 2:50 PM, Rob Sherwood wrote:
This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering. The pattern I measured was linear, the higher the voltage, the lower the third-order IMD. At really low voltages the much higher odd-order products degrade significantly. Test was on 20 meters, at a nominal 100 watts as per the K3 power setting. Two equal tones were generated within the K3. Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts. At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.
Voltage IMD in dBc Note: Add 6 dB for PEP method
11.5 -14.1 dBc
12.0 -16.9 dBc
12.5 -17.9 dBc
13.0 -19.0 dBc
13.4 -20.0 dBc
13.8 -21.1 dBc
14.2 -22.4 dBc
14.6 -23.7 dBc
14.8 -24.0 dBc
Rob, NC0B

Rob Sherwood
 

Hi Wayne,

 

It is an older K3, but with a much newer rev power amp replaced a few years ago. 

 

The PA power pins have been replaced after they overheated. 

 

It is one sample, but the reason for the test was to confirm past measurements that IMD gets better as the voltage goes up, even past 14.2 volts.

 

I am not implying that all K3 or K3S test this way, only this one sample that I tested.

 

Many rigs of multiple brands do not meet -30 dBc at 100 watts (or maximum output).  In 2010 a K3 tested at -27 dBc.  A K3S I had access to was a 10 watt rig and I didn’t measure it.  Dennis, K7FL, asked a question, and I answered it.  Yes, voltage materially matters, particularly at lower voltages.      

 

Rob

NC0B

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of N6KR
Sent: Thursday, November 07, 2019 1:22 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

 

Rob,

 

K3s are tested for -30 dBc or better 3rd-order IMD at 13.8 V at 100 W (ARRL method, 6 dB higher than your table). Average across all bands is typically -35 dBc. The one you measured may not be correctly biased, or not up to the latest rev. 

 

Further improvements have been made to both the 10 and 100 W modules in the K4. 

 

73,

Wayne

N6KR

 


On Nov 7, 2019, at 11:50 AM, Rob Sherwood <rob@...> wrote:

This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering.  The pattern I measured was linear, the higher the voltage, the lower the third-order IMD.  At really low voltages the much higher odd-order products degrade significantly.  Test was on 20 meters, at a nominal 100 watts as per the K3 power setting.  Two equal tones were generated within the K3.  Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts.  At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

 

Voltage                IMD in dBc   Note: Add 6 dB for PEP method

11.5                        -14.1 dBc

12.0                        -16.9 dBc

12.5                        -17.9 dBc

13.0                        -19.0 dBc

13.4                        -20.0 dBc

13.8                        -21.1 dBc

14.2                        -22.4 dBc

14.6                        -23.7 dBc

14.8                        -24.0 dBc

 

Rob, NC0B

 

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Dennis Ashworth
Sent: Thursday, November 07, 2019 11:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

 

Are the supply voltage differences powering the K3 really material to IMD numbers? I’ve not seen data to answer the question either way ... just curious.

Dennis, K7FL




On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:



Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

 

Thanks to all who contributed.  Mike  KD8DZ

 

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:

Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>






--

Michael Mickelson

J. Reid Anderson Professor of Physics and Astronomy, emeritus

Denison University

740-587-0687 H

740-644-1238 M

 

Rob Sherwood
 

There is no question the K3 is better at 35 watts. I can make some measurements at different power levels. Rob, NC0B

-----Original Message-----
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of N6KR
Sent: Thursday, November 07, 2019 1:42 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

On average, IMD will be much better at 35 W than at 100 W. And as with all class AB amps using MOSFETs, the IMD will vary per-band.

Wayne
N6KR


On Nov 7, 2019, at 12:37 PM, dalej via Groups.Io <dalej2=mac.com@groups.io> wrote:

wondering what the IMD is with power set to 35 watts and the PS set to 13.8

Dale k9vuj




On 07, Nov 2019, at 13:50, Rob Sherwood <rob@...> wrote:

This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering. The pattern I measured was linear, the higher the voltage, the lower the third-order IMD. At really low voltages the much higher odd-order products degrade significantly. Test was on 20 meters, at a nominal 100 watts as per the K3 power setting. Two equal tones were generated within the K3. Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts. At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

Voltage IMD in dBc Note: Add 6 dB for PEP method
11.5 -14.1 dBc
12.0 -16.9 dBc
12.5 -17.9 dBc
13.0 -19.0 dBc
13.4 -20.0 dBc
13.8 -21.1 dBc
14.2 -22.4 dBc
14.6 -23.7 dBc
14.8 -24.0 dBc

Rob, NC0B

From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Dennis Ashworth
Sent: Thursday, November 07, 2019 11:28 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

Are the supply voltage differences powering the K3 really material to IMD numbers? I’ve not seen data to answer the question either way ... just curious.
Dennis, K7FL


On Nov 7, 2019, at 10:22 AM, Michael Mickelson <@KD8DZ> wrote:


Bob, thanks for that information. I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting. The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

Thanks to all who contributed. Mike KD8DZ

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:
Why not get Alexa to adjust the voltage for you? "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon. I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on. I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage. I did put my Fluke DMV on the
output terminals first to monitor the voltage. At 14.49 indicated, I
stopped. Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
And for some stupid reason, when they could have put that pot on the
underside of the circuit board (which ends up on the top) for simpler
access, they didn't. So you're reaching in around open hot high
voltage OR turning it on/off a lot of times to get it set right. Plan
B could have been to put the pot on the edge or board flush with a
hole for a plastic tool to access...

I maintain that if the design engineers (of ANY field) EVER had to
work on, fix, adjust their product, the design would be far different
and techs would bless them instead of using 'adult language'
curses... ;-)

I hold that Elecraft 'gets' this, their designs are modular and except
cable routing and some panel connecting, is boringly simple.

Rick NK7I


On 11/6/2019 10:32 AM, Rob Sherwood wrote:
The Astron power supplies I own have an internal pot to set the
voltage. I would adjust it with nothing connected. The can likely go
over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
reason removing the top covers are a pain. Rob, NC0B







--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M


Rob Sherwood
 

Ok, it isn't a straight line, but what I was trying to imply was it consistently improved with higher voltage.
It didn't plateau and then get worse.
Approximately a 10 dB difference from 10.5 to 14.8 volts, and approximately 3 d difference between 13.8 and 14.8 volts.
Rob, NC0B

-----Original Message-----
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Joe Subich, W4TV
Sent: Thursday, November 07, 2019 1:50 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

On 2019-11-07 2:50 PM, Rob Sherwood wrote:

The pattern I measured was linear, the higher the voltage, the lower
> the third-order IMD.

Given the rate of change, I would not call the slope linear.

There is a terrible 2.8 dB worsening of IMD when the voltage drops from
12.0 to 11.5 volts. In addition, you change from 0.5V steps below 13.0
V to 0.4V steps above which hides an improvement in dB/V between 13.0
and 14.6V (1.0, 1.1, 1.3, 1.3 dB/0.4V). The improvement "flattens out"
again above 14.6V (only 0.3 dB/.02V).

It does make one wonder if the K3/K3S could achieve -36 dB/PEP at
50-60 W with a 14.5V supply <G> (particularly if the LPA were set up
for better IMD at that level).

73,

... Joe, W4TV


On 2019-11-07 2:50 PM, Rob Sherwood wrote:
This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering. The pattern I measured was linear, the higher the voltage, the lower the third-order IMD. At really low voltages the much higher odd-order products degrade significantly. Test was on 20 meters, at a nominal 100 watts as per the K3 power setting. Two equal tones were generated within the K3. Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts. At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

Voltage IMD in dBc Note: Add 6 dB for PEP method
11.5 -14.1 dBc
12.0 -16.9 dBc
12.5 -17.9 dBc
13.0 -19.0 dBc
13.4 -20.0 dBc
13.8 -21.1 dBc
14.2 -22.4 dBc
14.6 -23.7 dBc
14.8 -24.0 dBc

Rob, NC0B

Bill K9YEQ
 

That is significant. I checked my voltage at the K3S and need to make some changes real soon. I generally only run < 30 watts into my KPA1500, but need to improve voltage at the radio for those few times I run barefoot at 60+ watts.

73,
Bill
K9YEQ

https://wrj-tech.com/

-----Original Message-----
From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of Rob Sherwood
Sent: Thursday, November 7, 2019 3:54 PM
To: 'Elecraft-K3@groups.io' <Elecraft-K3@groups.io>
Subject: Re: [Elecraft-K3] Power supply adjustments

Ok, it isn't a straight line, but what I was trying to imply was it consistently improved with higher voltage.
It didn't plateau and then get worse.
Approximately a 10 dB difference from 10.5 to 14.8 volts, and approximately 3 d difference between 13.8 and 14.8 volts.
Rob, NC0B

-----Original Message-----
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Joe Subich, W4TV
Sent: Thursday, November 07, 2019 1:50 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

On 2019-11-07 2:50 PM, Rob Sherwood wrote:

The pattern I measured was linear, the higher the voltage, the lower
> the third-order IMD.

Given the rate of change, I would not call the slope linear.

There is a terrible 2.8 dB worsening of IMD when the voltage drops from
12.0 to 11.5 volts. In addition, you change from 0.5V steps below 13.0
V to 0.4V steps above which hides an improvement in dB/V between 13.0
and 14.6V (1.0, 1.1, 1.3, 1.3 dB/0.4V). The improvement "flattens out"
again above 14.6V (only 0.3 dB/.02V).

It does make one wonder if the K3/K3S could achieve -36 dB/PEP at
50-60 W with a 14.5V supply <G> (particularly if the LPA were set up
for better IMD at that level).

73,

... Joe, W4TV


On 2019-11-07 2:50 PM, Rob Sherwood wrote:
This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering. The pattern I measured was linear, the higher the voltage, the lower the third-order IMD. At really low voltages the much higher odd-order products degrade significantly. Test was on 20 meters, at a nominal 100 watts as per the K3 power setting. Two equal tones were generated within the K3. Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts. At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

Voltage IMD in dBc Note: Add 6 dB for PEP method
11.5 -14.1 dBc
12.0 -16.9 dBc
12.5 -17.9 dBc
13.0 -19.0 dBc
13.4 -20.0 dBc
13.8 -21.1 dBc
14.2 -22.4 dBc
14.6 -23.7 dBc
14.8 -24.0 dBc

Rob, NC0B

Bob McGraw - K4TAX
 

Any of the Astron supplies and likely others should be adjusted {usually internally} to 14.5 volts at the supply terminals with NO load or nothing connected to the supply.     Mine are SS-30M supplies and one RM-30 supply.   

If you have SS-30M supplies, the voltage adjust pot is on the front right of the PC board as viewed from the front of the supply.   The pot that is hanging in the air behind the Volt meter is for the meter calibration.   Likewise, the pot that is hanging in the air behind the Amp meter is for the calibration of that meter.

Then, with the radio in CW mode, transmit at 100 watts, key closed, you should see 13.5 to 14.0 volts on the K3/K3S voltage display.    If your voltage indicated is lower than this, check the voltage at the supply to confirm it is not dropping under load.  If it is not, then suspect the connections on the power cables from the supply to the radio.    If you use a power distribution strip, I suggest not connecting the radio to the power strip but connect the radio direct to the power supply.   Every added connection and plug in the DC path does adds resistance and thus voltage drop.   E = I x R   Therefore 20 amps and 0.05 ohms equals 1 volt drop between the supply and the radio.   That 0.5 ohms is the total combined resistance of the DC Pos and the DC Neg and the fuse and any other connections in the path.

PLEASE read the article in QST, November 2019, by Rob Sherwood.  "It's Time to Clean Up our Transmitters"   pp 38 -41

73

Bob, K4TAX

On 11/7/2019 1:37 PM, Edward McCann wrote:
Mike-

Which 30 Amp Astron power supply?

Let us know the results!

73,

AG6CX


On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:

Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

Thanks to all who contributed.  Mike  KD8DZ

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:
Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>






--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M
 

Michael Mickelson
 

Ed, I have two linear supplies, an RS-35A and RS-35M.  Both are over 30 years old and continue to work well.  

Mike kd8dz

On Thu, Nov 7, 2019 at 2:37 PM Edward McCann <Ag6cx1@...> wrote:
Mike-

Which 30 Amp Astron power supply?

Let us know the results!

73,

AG6CX


On Nov 7, 2019, at 10:22 AM, Michael Mickelson <mickelson@...> wrote:

Bob, thanks for that information.  I have two of the 30Amp Astron supplies and will make an adjustment to a higher setting.  The discussion on the effects of supply voltage on the K3/K3S tranSmitter performance has been very inStructive.

Thanks to all who contributed.  Mike  KD8DZ

On Wed, Nov 6, 2019 at 5:18 PM Bob McGraw - K4TAX <rmcgraw@...> wrote:
Why not get Alexa to adjust the voltage for you?   "Alexa, turn the
supply on and set the voltage for 14.5."

The supplies are usually in the category of the "set and forget" type.  
Thus the caution of "no user serviceable parts inside".

I adjusted one of mine this afternoon.  I put it on the desk, removed
the 4 screws holding then cover, plugged in the cord and turned the
supply on.   I picked up my light in one hand and my plastic adjustment
tool in the other {you do have and use a plastic adjustment tool don't
you?} and made the adjustment. Nowhere at any time did my hands or
fingers come close to any voltage.    I did put my Fluke DMV on the
output terminals first to monitor the voltage.  At 14.49 indicated,  I
stopped.   Turned the supply off, put the cover on and secured it with
the 4 screws.


73

Bob, K4TAX

On 11/6/2019 3:54 PM, Rick Bates, NK7I wrote:
> And for some stupid reason, when they could have put that pot on the
> underside of the circuit board (which ends up on the top) for simpler
> access, they didn't.  So you're reaching in around open hot high
> voltage OR turning it on/off a lot of times to get it set right.  Plan
> B could have been to put the pot on the edge or board flush with a
> hole for a plastic tool to access...
>
> I maintain that if the design engineers (of ANY field) EVER had to
> work on, fix, adjust their product, the design would be far different
> and techs would bless them instead of using 'adult language'
> curses...  ;-)
>
> I hold that Elecraft 'gets' this, their designs are modular and except
> cable routing and some panel connecting, is boringly simple.
>
> Rick NK7I
>
>
> On 11/6/2019 10:32 AM, Rob Sherwood wrote:
>> The Astron power supplies I own have an internal pot to set the
>> voltage. I would adjust it with nothing connected.  The can likely go
>> over 16 volts. I have 3 RS-35Ms, but have never used a 50. For some
>> reason removing the top covers are a pain.  Rob, NC0B
>>
>
>
>
>






--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M
 



--
Michael Mickelson
J. Reid Anderson Professor of Physics and Astronomy, emeritus
Denison University
740-587-0687 H
740-644-1238 M
 

Rob Sherwood
 

In general with factory supplied power cables, particularly very long Icom cables, the voltage drop in the cable is 0.5 volts, if not significantly more. I cut my Icom cables in half, which also removes the fuses and fuse holders and their associated poor connection issues.

My Astron power supplies are over voltage and over current protected. An Icom PS-125 or PS-126 doesn't have any fuses in the short power lead, so I feel comfortable removing the fuses. My TS-890S runs on an Astron RS-35M with a shortened cable with no fuses.

In any case, as asked for, here is some more data all taken at 13.8 volts in transmit mode as read by the K3 LCD.
Also the PA in this K3 is Rev C.

Wattage 3rd order IMD
100 watts -21.1 dBc
75 watts -27.8 dBc
50 watts -33.7 dBc
35 watts -36.7 dBc
12 watts -23.4 dBc
10 watts -29.2 dBc

Note at 12 watts and below the driver is providing the RF output. The PA is out of the circuit.

Rob, NC0B

-----Original Message-----
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Bill K9YEQ
Sent: Thursday, November 07, 2019 2:56 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

That is significant. I checked my voltage at the K3S and need to make some changes real soon. I generally only run < 30 watts into my KPA1500, but need to improve voltage at the radio for those few times I run barefoot at 60+ watts.

73,
Bill
K9YEQ

https://wrj-tech.com/

-----Original Message-----
From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of Rob Sherwood
Sent: Thursday, November 7, 2019 3:54 PM
To: 'Elecraft-K3@groups.io' <Elecraft-K3@groups.io>
Subject: Re: [Elecraft-K3] Power supply adjustments

Ok, it isn't a straight line, but what I was trying to imply was it consistently improved with higher voltage.
It didn't plateau and then get worse.
Approximately a 10 dB difference from 10.5 to 14.8 volts, and approximately 3 d difference between 13.8 and 14.8 volts.
Rob, NC0B

-----Original Message-----
From: Elecraft-K3@groups.io [mailto:Elecraft-K3@groups.io] On Behalf Of Joe Subich, W4TV
Sent: Thursday, November 07, 2019 1:50 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Power supply adjustments

On 2019-11-07 2:50 PM, Rob Sherwood wrote:

The pattern I measured was linear, the higher the voltage, the lower
> the third-order IMD.

Given the rate of change, I would not call the slope linear.

There is a terrible 2.8 dB worsening of IMD when the voltage drops from
12.0 to 11.5 volts. In addition, you change from 0.5V steps below 13.0
V to 0.4V steps above which hides an improvement in dB/V between 13.0
and 14.6V (1.0, 1.1, 1.3, 1.3 dB/0.4V). The improvement "flattens out"
again above 14.6V (only 0.3 dB/.02V).

It does make one wonder if the K3/K3S could achieve -36 dB/PEP at
50-60 W with a 14.5V supply <G> (particularly if the LPA were set up
for better IMD at that level).

73,

... Joe, W4TV


On 2019-11-07 2:50 PM, Rob Sherwood wrote:
This morning I decided to measure a K3 in respect to third-order IMD vs. power supply voltage as read on the K3 metering. The pattern I measured was linear, the higher the voltage, the lower the third-order IMD. At really low voltages the much higher odd-order products degrade significantly. Test was on 20 meters, at a nominal 100 watts as per the K3 power setting. Two equal tones were generated within the K3. Note: at 14.8 volts on TX, the voltage on RX was 15.1 volts. At 13.8 volts on TX, the voltage on RX was 14.0. The power supply was an Astron VS-35M, and the length of PowerPole cable was 16 inches.

Voltage IMD in dBc Note: Add 6 dB for PEP method
11.5 -14.1 dBc
12.0 -16.9 dBc
12.5 -17.9 dBc
13.0 -19.0 dBc
13.4 -20.0 dBc
13.8 -21.1 dBc
14.2 -22.4 dBc
14.6 -23.7 dBc
14.8 -24.0 dBc

Rob, NC0B