Date   

KPA1500 AC Power Hiccup

Jim Denneny
 

We have occasional, very rare, AC power hiccups (blips).  These are momentary events. I have UPS on 115VAC lines to radios and pc's. When these "burps" occur, the KPA1500 220VAC power turns on. I am uncertain if these events are serious to the health of the amp.  I do not detect any issues.  Should I be concerned?  Power company has not been able to pinpoint the source even with a recorder on our power meter. If this is dangerous to the health of amp, I will disconnect power to amp.  These events are rare and disconnecting amp AC plug daily would be a royal PITA.

Jim K7EG


Re: K3 transmitter power woes

Alan Baker - G4GNX
 

A better and more professional approach is to run the rig and gently heat the inside, using a hair dryer. Observe any adverse changes.
Use a freezer spray on parts that are under suspicion and again watch for changes.
This technique can be narrowed down to really small areas, then a jeweller's loupe may reveal a cracked trace.
Do not just bridge any cracked traces with solder alone - bridge with fine wire then solder in place.

73,

Alan. G4GNX


------ Original Message ------
From: "southdaleus via groups.io" <dalej2@...>
Sent: 14/09/2021 06:36:40
Subject: Re: [Elecraft-K3] K3 transmitter power woes

Magnifying glass or jewelers eye loupe and a close inspection for cracked solder joint.  That's what I would do before sending it away.  

Dale, K9VUJ


Re: K3 transmitter power woes

Charlie T, k3ICH
 

Be careful, of necessity, "dielectric" (silicone) grease is an insulator and will not enhance conductivity although it MAY inhibit corrosion.

73, Charlie k3ICH

-----Original Message-----
From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of Chet, N8RA
Sent: Monday, September 13, 2021 8:39 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3 transmitter power woes

Thanks Bob,

Would some dielectric grease on the pins then prevent future problems by blocking environmental degradation?
Same question for the little coaxes.

Chet, N8RA


Re: K3 transmitter power woes

g4abx
 

Chet -- good morning

I've had a few issues with my K3 and my K3S output power over the years.
All of them now resolved
They included: 
  • Failed TX/RX diode on K3 PA
  • Failed pre-drive transistors on K3S PA (Not the 12 watt stage but the driver transistors on the same board)
  • Gold pins added to the K3 PA (Did the mod myself)
  • broken connection to Low Pass filter toroid (Probably did that myself when fitting the 100 watt PA)
In my experience its rare to get failed electronics -- and I wouldn't 'adjust' stuff like trimmers to try and 'tweak' the output.
However I have had both electromechanical (connectors) and failed electronics on my K3/K3S over the years.

If you have an oscilloscope then my advice would be to trace the signal levels back from the PA through the rig until you get something that is stable -- that doesn't vary intermittently -- otherwise you will continually chase your tail.

You need to find the root cause and that will take time and some test kit. No amount of 'twiddling' stuff and hoping it gets better will solve your problem.
If you haven't got a scope I bet you know someone who has?

Its not difficult to trace signals on the K3 but -- if like mine, I suggest you remove any second RX, and any other accessories. Remove the PA module and start from as 'bare bones' a rig as you can get to. I also suggest you put a dummy load on the Low Power PA output to ensure you are loading that module correctly when you do any tests.

Its frustrating to find intermittent faults but I guarantee, there is a root cause!

73
Bruce G4ABX


Re: K3 transmitter power woes

southdaleus
 

Magnifying glass or jewelers eye loupe and a close inspection for cracked solder joint.  That's what I would do before sending it away.  

Dale, K9VUJ


Re: K3 transmitter power woes

Bob McGraw - K4TAX
 

Having never used that for sensitive electronics and low level signals, I can't say.  Frankly I would not put that on any contacts internal to my radios or amplifiers.  From my experience in power systems, it is OK.  But when, and I didn't say if, clean-up i necessary, it is a bitch to remove.

De-Oxit is a good contact cleaner.  The rule is least is best. If you can find such, a lint free cloth or lent free swab is preferred.  We use these in TV to clean video drum heads.    I have no clue if they are still available as video drums are basically obsolete.

73

Bob, K4TAX

On 9/13/2021 7:38 PM, Chet, N8RA wrote:
Thanks Bob,

Would some dielectric grease on the pins then prevent future problems by blocking environmental degradation?
Same question for the little coaxes.

Chet, N8RA



-----Original Message-----
From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of Bob McGraw - K4TAX
Sent: Monday, September 13, 2021 5:54 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3 transmitter power woes

Sounds suspiciously like dirty connectors inside the radio. Which one? All of them. Your guess is as good as mine.

I use a good contact cleaner which I apply to a Q-Tip swab. You'll need several. Unplug a cable and scrub the male pins. Then work that connector on and off a couple of times to clean the female pins. Be sure the cable is correctly aligned and fully seated. Likewise for edge connectors and the one to the KPA100a power amp. Pull the filters in the receiver and clean those pins as well. Same process.

NEVER spray anything into the radio. You'll really be sorry for doing so.

It doesn't sound like a serious issue to me. It is time and patience consuming however.

73

Bob, K4TAX



On 9/13/2021 2:49 PM, Chet, N8RA wrote:
My K3 transmitter has been struggling for months to behave. I've heard
the service dept turnaround in CA is very long so I might not see it
the rest of the year if I sent it in and wanted to avoid that if
possible. I've followed advice suggested here with no lasting success.

Especially on 6M the power sometimes takes a long time deciding to
reach the setpoint. Sometimes it will be OK, but a few hours later
after just sitting there, it again won't, and drops to a low output level.

I've run the transmitter gain calibration routine again and again and
it fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W
calibration shows errtxg as it runs but the utility says the
calibration had succeeded.

I've checked that the bandpass filters are OK by using an antenna
analyzer with an attenuator to check receiver sensitivity- all bands
seem pretty close.

I've rechecked if the LPA FET's are ok (I changed two last year), and
set their bias current levels again and all seems well with them.

I've upped the supply voltage- that seems to work for a day or two but
then same old problems come back

I've replaced the fwd and rev power meter Schottky diodes, no fix.

Sometimes when the transmitter fails to reach the set power level, I
can tweak the pwr knob and it will reach the changed level, but
sometimes not and it falls back to a lower value. On 6M, while in
"tune" if the power does not reach the setpoint (e.g. 30W) and I turn
the pwr knob down below 12 where the 100w amp is bypassed and then
turn it back up to reengage the 100w amp, the power will sometimes
reach and stay at the setpoint (30W). But that condition does not stay Ok too long.

The transverter output also exhibits similar power problems

I've reloaded the firmware. The utility initially reported "checksum
reconciliation value" and I have no idea what that means.

And finally, this weekend, when I set the receive mode to data-a, the
audio output had shifted to a higher freq spectrum width (e.g.
500-3300) on the WSJT spectrum display with clearly more hiss in the
speaker. Cycling the xtal filters, normalling the shifts and widths
had no effect. Changed the mode to USB and the audio spectrum was
normal, change back to data-a and it was shifted. So I operated WSJT-X
in USB. Hours later, data-a was back to normal. First time I've
observed that. Today it is AOK. GOK what happened Saturday.

Any other suggestions before I bit the bullet and prepare to send it
to Elecraft? Thanks for any ideas.

Chet, N8RA















Re: K3 transmitter power woes

Chet, N8RA
 

Thanks Bob,

Would some dielectric grease on the pins then prevent future problems by blocking environmental degradation?
Same question for the little coaxes.

Chet, N8RA

-----Original Message-----
From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of Bob McGraw - K4TAX
Sent: Monday, September 13, 2021 5:54 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3 transmitter power woes

Sounds suspiciously like dirty connectors inside the radio. Which one? All of them. Your guess is as good as mine.

I use a good contact cleaner which I apply to a Q-Tip swab. You'll need several. Unplug a cable and scrub the male pins. Then work that connector on and off a couple of times to clean the female pins. Be sure the cable is correctly aligned and fully seated. Likewise for edge connectors and the one to the KPA100a power amp. Pull the filters in the receiver and clean those pins as well. Same process.

NEVER spray anything into the radio. You'll really be sorry for doing so.

It doesn't sound like a serious issue to me. It is time and patience consuming however.

73

Bob, K4TAX



On 9/13/2021 2:49 PM, Chet, N8RA wrote:
My K3 transmitter has been struggling for months to behave. I've heard
the service dept turnaround in CA is very long so I might not see it
the rest of the year if I sent it in and wanted to avoid that if
possible. I've followed advice suggested here with no lasting success.

Especially on 6M the power sometimes takes a long time deciding to
reach the setpoint. Sometimes it will be OK, but a few hours later
after just sitting there, it again won't, and drops to a low output level.

I've run the transmitter gain calibration routine again and again and
it fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W
calibration shows errtxg as it runs but the utility says the
calibration had succeeded.

I've checked that the bandpass filters are OK by using an antenna
analyzer with an attenuator to check receiver sensitivity- all bands
seem pretty close.

I've rechecked if the LPA FET's are ok (I changed two last year), and
set their bias current levels again and all seems well with them.

I've upped the supply voltage- that seems to work for a day or two but
then same old problems come back

I've replaced the fwd and rev power meter Schottky diodes, no fix.

Sometimes when the transmitter fails to reach the set power level, I
can tweak the pwr knob and it will reach the changed level, but
sometimes not and it falls back to a lower value. On 6M, while in
"tune" if the power does not reach the setpoint (e.g. 30W) and I turn
the pwr knob down below 12 where the 100w amp is bypassed and then
turn it back up to reengage the 100w amp, the power will sometimes
reach and stay at the setpoint (30W). But that condition does not stay Ok too long.

The transverter output also exhibits similar power problems

I've reloaded the firmware. The utility initially reported "checksum
reconciliation value" and I have no idea what that means.

And finally, this weekend, when I set the receive mode to data-a, the
audio output had shifted to a higher freq spectrum width (e.g.
500-3300) on the WSJT spectrum display with clearly more hiss in the
speaker. Cycling the xtal filters, normalling the shifts and widths
had no effect. Changed the mode to USB and the audio spectrum was
normal, change back to data-a and it was shifted. So I operated WSJT-X
in USB. Hours later, data-a was back to normal. First time I've
observed that. Today it is AOK. GOK what happened Saturday.

Any other suggestions before I bit the bullet and prepare to send it
to Elecraft? Thanks for any ideas.

Chet, N8RA







Re: K3 transmitter power woes

Chet, N8RA
 

Radio was back to Elecraft many years ago and they did the gold pins upgrade.

 

Chet, N8RA

 

From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of mikerodgerske5gbc via groups.io
Sent: Monday, September 13, 2021 7:05 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3 transmitter power woes

 

Serial number/gold pins?

7!

Absolutely Awesome 



On Sep 13, 2021, at 4:56 PM, radio@... wrote:

Great tip.

Thanks Bob

Sherman
w8hi





On Sep 13, 2021, at 5:53 PM, Bob McGraw - K4TAX <rmcgraw@...> wrote:

Sounds suspiciously like dirty connectors inside the radio. Which one?   All of them.  Your guess is as good as mine.

I use a good contact cleaner which I apply to a Q-Tip swab. You'll need several.    Unplug a cable and scrub the male pins. Then work that connector on and off a couple of times to clean the female pins.  Be sure the cable is correctly aligned and fully seated.     Likewise for edge connectors and the one to the KPA100a power amp.  Pull the filters in the receiver and clean those pins as well.   Same process.

NEVER spray anything into the radio.   You'll really be sorry for doing so.

It doesn't sound like a serious issue to me.   It is time and patience consuming however.

73

Bob, K4TAX



On 9/13/2021 2:49 PM, Chet, N8RA wrote:

My K3 transmitter has been struggling for months to behave. I've heard the

service dept turnaround in CA is very long so I might not see it the rest of

the year if I sent it in and wanted to avoid that if possible. I've followed

advice suggested here with no lasting success.

 

Especially on 6M the power sometimes takes a long time deciding to reach the

setpoint. Sometimes it will be OK, but a few hours later after just sitting

there, it again won't, and drops to a low output level.

 

I've run the transmitter gain calibration routine again and again and it

fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W

calibration shows errtxg as it runs but the utility says the calibration had

succeeded.

 

I've checked that the bandpass filters are OK by using an antenna analyzer

with an attenuator to check receiver sensitivity- all bands seem pretty

close.

 

I've rechecked if the LPA FET's are ok (I changed two last year), and set

their bias current levels again and all seems well with them.

 

I've upped the supply voltage- that seems to work for a day or two but then

same old problems come back

 

I've replaced the fwd and rev power meter Schottky diodes, no fix.

 

Sometimes when the transmitter fails to reach the set power level, I can

tweak the pwr knob and it will reach the changed level, but sometimes not

and it falls back to a lower value. On 6M, while in "tune" if the power does

not reach the setpoint (e.g. 30W) and I turn the pwr knob down below 12

where the 100w amp is bypassed and then turn it back up to reengage the 100w

amp, the power will sometimes reach and stay at the setpoint (30W). But that

condition does not stay Ok too long.

 

The transverter output also exhibits similar power problems

 

I've reloaded the firmware. The utility initially reported  "checksum

reconciliation value" and I have no idea what that means.

 

And finally, this weekend, when I set the  receive mode to data-a, the audio

output had shifted to a higher freq spectrum width (e.g. 500-3300) on the

WSJT spectrum display with clearly more hiss in the speaker. Cycling the

xtal filters, normalling the shifts and widths had no effect. Changed the

mode to USB and the audio spectrum was normal, change back to data-a and it

was shifted. So I operated WSJT-X in USB. Hours later, data-a was back to

normal. First time I've observed that. Today it is AOK. GOK what happened

Saturday.

 

Any other suggestions before I bit the bullet and prepare to send it to

Elecraft? Thanks for any ideas.

 

Chet, N8RA

 

 

 

 

 

 













Re: Small hiccup on K3

Bob McGraw - K4TAX
 

Common mode current is the portion of conductor currents not matched by exactly opposite and equal magnitude currents. This is the portion of total current responsible for a feedline behaving like a single wire line. Common mode current is most commonly caused by improper feedline installation or antenna design.

http://www.k0bg.com/common.html

Comments by W8JI; 

https://www.dxengineering.com/techarticles/balunsandfeedlinechokes/balun-basics-common-mode-vs-differential-mode


73

Bob, K4TAX


On 9/13/2021 7:01 PM, Bob McGraw wrote:
I say one can not ground common mode current.

73

Bob, K4TAX



On 9/13/2021 4:47 PM, Jim Brown wrote:
On 9/13/2021 2:41 PM, Bob McGraw - K4TAX wrote:
No, not missing anything.........except some common mode choke(s).   Either on the coax between the KPA500 and KAT500

No good reason for this.

and/or on the USB cable
between the radio and computer.

Maybe on interconnecting cables, but more important, implement proper grounding and bonding. Study N0AX's ARRL book on the topic, and/or
http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC








Re: Small hiccup on K3

Bob McGraw - K4TAX
 

I say one can not ground common mode current.

73

Bob, K4TAX

On 9/13/2021 4:47 PM, Jim Brown wrote:
On 9/13/2021 2:41 PM, Bob McGraw - K4TAX wrote:
No, not missing anything.........except some common mode choke(s).   Either on the coax between the KPA500 and KAT500
No good reason for this.

and/or on the USB cable
between the radio and computer.
Maybe on interconnecting cables, but more important, implement proper grounding and bonding. Study N0AX's ARRL book on the topic, and/or
http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC






Re: K3 transmitter power woes

mikerodgerske5gbc
 

Serial number/gold pins?

7!
Absolutely Awesome 

On Sep 13, 2021, at 4:56 PM, radio@... wrote:

Great tip.

Thanks Bob

Sherman
w8hi





On Sep 13, 2021, at 5:53 PM, Bob McGraw - K4TAX <rmcgraw@...> wrote:

Sounds suspiciously like dirty connectors inside the radio. Which one?   All of them.  Your guess is as good as mine.

I use a good contact cleaner which I apply to a Q-Tip swab. You'll need several.    Unplug a cable and scrub the male pins. Then work that connector on and off a couple of times to clean the female pins.  Be sure the cable is correctly aligned and fully seated.     Likewise for edge connectors and the one to the KPA100a power amp.  Pull the filters in the receiver and clean those pins as well.   Same process.

NEVER spray anything into the radio.   You'll really be sorry for doing so.

It doesn't sound like a serious issue to me.   It is time and patience consuming however.

73

Bob, K4TAX



On 9/13/2021 2:49 PM, Chet, N8RA wrote:
My K3 transmitter has been struggling for months to behave. I've heard the
service dept turnaround in CA is very long so I might not see it the rest of
the year if I sent it in and wanted to avoid that if possible. I've followed
advice suggested here with no lasting success.

Especially on 6M the power sometimes takes a long time deciding to reach the
setpoint. Sometimes it will be OK, but a few hours later after just sitting
there, it again won't, and drops to a low output level.

I've run the transmitter gain calibration routine again and again and it
fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W
calibration shows errtxg as it runs but the utility says the calibration had
succeeded.

I've checked that the bandpass filters are OK by using an antenna analyzer
with an attenuator to check receiver sensitivity- all bands seem pretty
close.

I've rechecked if the LPA FET's are ok (I changed two last year), and set
their bias current levels again and all seems well with them.

I've upped the supply voltage- that seems to work for a day or two but then
same old problems come back

I've replaced the fwd and rev power meter Schottky diodes, no fix.

Sometimes when the transmitter fails to reach the set power level, I can
tweak the pwr knob and it will reach the changed level, but sometimes not
and it falls back to a lower value. On 6M, while in "tune" if the power does
not reach the setpoint (e.g. 30W) and I turn the pwr knob down below 12
where the 100w amp is bypassed and then turn it back up to reengage the 100w
amp, the power will sometimes reach and stay at the setpoint (30W). But that
condition does not stay Ok too long.

The transverter output also exhibits similar power problems

I've reloaded the firmware. The utility initially reported  "checksum
reconciliation value" and I have no idea what that means.

And finally, this weekend, when I set the  receive mode to data-a, the audio
output had shifted to a higher freq spectrum width (e.g. 500-3300) on the
WSJT spectrum display with clearly more hiss in the speaker. Cycling the
xtal filters, normalling the shifts and widths had no effect. Changed the
mode to USB and the audio spectrum was normal, change back to data-a and it
was shifted. So I operated WSJT-X in USB. Hours later, data-a was back to
normal. First time I've observed that. Today it is AOK. GOK what happened
Saturday.

Any other suggestions before I bit the bullet and prepare to send it to
Elecraft? Thanks for any ideas.

Chet, N8RA



















Re: K3 transmitter power woes

radio@ebillsharp.com
 

Great tip.

Thanks Bob

Sherman
w8hi

On Sep 13, 2021, at 5:53 PM, Bob McGraw - K4TAX <rmcgraw@benlomand.net> wrote:

Sounds suspiciously like dirty connectors inside the radio. Which one? All of them. Your guess is as good as mine.

I use a good contact cleaner which I apply to a Q-Tip swab. You'll need several. Unplug a cable and scrub the male pins. Then work that connector on and off a couple of times to clean the female pins. Be sure the cable is correctly aligned and fully seated. Likewise for edge connectors and the one to the KPA100a power amp. Pull the filters in the receiver and clean those pins as well. Same process.

NEVER spray anything into the radio. You'll really be sorry for doing so.

It doesn't sound like a serious issue to me. It is time and patience consuming however.

73

Bob, K4TAX



On 9/13/2021 2:49 PM, Chet, N8RA wrote:
My K3 transmitter has been struggling for months to behave. I've heard the
service dept turnaround in CA is very long so I might not see it the rest of
the year if I sent it in and wanted to avoid that if possible. I've followed
advice suggested here with no lasting success.

Especially on 6M the power sometimes takes a long time deciding to reach the
setpoint. Sometimes it will be OK, but a few hours later after just sitting
there, it again won't, and drops to a low output level.

I've run the transmitter gain calibration routine again and again and it
fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W
calibration shows errtxg as it runs but the utility says the calibration had
succeeded.

I've checked that the bandpass filters are OK by using an antenna analyzer
with an attenuator to check receiver sensitivity- all bands seem pretty
close.

I've rechecked if the LPA FET's are ok (I changed two last year), and set
their bias current levels again and all seems well with them.

I've upped the supply voltage- that seems to work for a day or two but then
same old problems come back

I've replaced the fwd and rev power meter Schottky diodes, no fix.

Sometimes when the transmitter fails to reach the set power level, I can
tweak the pwr knob and it will reach the changed level, but sometimes not
and it falls back to a lower value. On 6M, while in "tune" if the power does
not reach the setpoint (e.g. 30W) and I turn the pwr knob down below 12
where the 100w amp is bypassed and then turn it back up to reengage the 100w
amp, the power will sometimes reach and stay at the setpoint (30W). But that
condition does not stay Ok too long.

The transverter output also exhibits similar power problems

I've reloaded the firmware. The utility initially reported "checksum
reconciliation value" and I have no idea what that means.

And finally, this weekend, when I set the receive mode to data-a, the audio
output had shifted to a higher freq spectrum width (e.g. 500-3300) on the
WSJT spectrum display with clearly more hiss in the speaker. Cycling the
xtal filters, normalling the shifts and widths had no effect. Changed the
mode to USB and the audio spectrum was normal, change back to data-a and it
was shifted. So I operated WSJT-X in USB. Hours later, data-a was back to
normal. First time I've observed that. Today it is AOK. GOK what happened
Saturday.

Any other suggestions before I bit the bullet and prepare to send it to
Elecraft? Thanks for any ideas.

Chet, N8RA






Re: K3 transmitter power woes

Bob McGraw - K4TAX
 

Sounds suspiciously like dirty connectors inside the radio. Which one?   All of them.  Your guess is as good as mine.

I use a good contact cleaner which I apply to a Q-Tip swab. You'll need several.    Unplug a cable and scrub the male pins. Then work that connector on and off a couple of times to clean the female pins.  Be sure the cable is correctly aligned and fully seated.     Likewise for edge connectors and the one to the KPA100a power amp.  Pull the filters in the receiver and clean those pins as well.   Same process.

NEVER spray anything into the radio.   You'll really be sorry for doing so.

It doesn't sound like a serious issue to me.   It is time and patience consuming however.

73

Bob, K4TAX

On 9/13/2021 2:49 PM, Chet, N8RA wrote:
My K3 transmitter has been struggling for months to behave. I've heard the
service dept turnaround in CA is very long so I might not see it the rest of
the year if I sent it in and wanted to avoid that if possible. I've followed
advice suggested here with no lasting success.

Especially on 6M the power sometimes takes a long time deciding to reach the
setpoint. Sometimes it will be OK, but a few hours later after just sitting
there, it again won't, and drops to a low output level.

I've run the transmitter gain calibration routine again and again and it
fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W
calibration shows errtxg as it runs but the utility says the calibration had
succeeded.

I've checked that the bandpass filters are OK by using an antenna analyzer
with an attenuator to check receiver sensitivity- all bands seem pretty
close.

I've rechecked if the LPA FET's are ok (I changed two last year), and set
their bias current levels again and all seems well with them.

I've upped the supply voltage- that seems to work for a day or two but then
same old problems come back

I've replaced the fwd and rev power meter Schottky diodes, no fix.

Sometimes when the transmitter fails to reach the set power level, I can
tweak the pwr knob and it will reach the changed level, but sometimes not
and it falls back to a lower value. On 6M, while in "tune" if the power does
not reach the setpoint (e.g. 30W) and I turn the pwr knob down below 12
where the 100w amp is bypassed and then turn it back up to reengage the 100w
amp, the power will sometimes reach and stay at the setpoint (30W). But that
condition does not stay Ok too long.

The transverter output also exhibits similar power problems

I've reloaded the firmware. The utility initially reported "checksum
reconciliation value" and I have no idea what that means.

And finally, this weekend, when I set the receive mode to data-a, the audio
output had shifted to a higher freq spectrum width (e.g. 500-3300) on the
WSJT spectrum display with clearly more hiss in the speaker. Cycling the
xtal filters, normalling the shifts and widths had no effect. Changed the
mode to USB and the audio spectrum was normal, change back to data-a and it
was shifted. So I operated WSJT-X in USB. Hours later, data-a was back to
normal. First time I've observed that. Today it is AOK. GOK what happened
Saturday.

Any other suggestions before I bit the bullet and prepare to send it to
Elecraft? Thanks for any ideas.

Chet, N8RA






Re: Small hiccup on K3

Jim Brown
 

On 9/13/2021 2:41 PM, Bob McGraw - K4TAX wrote:
No, not missing anything.........except some common mode choke(s). Either on the coax between the KPA500 and KAT500
No good reason for this.

and/or on the USB cable
between the radio and computer.
Maybe on interconnecting cables, but more important, implement proper grounding and bonding. Study N0AX's ARRL book on the topic, and/or
http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC


Re: Small hiccup on K3

Bob McGraw - K4TAX
 

No, not missing anything.........except some common mode choke(s).   Either on the coax between the KPA500 and KAT500 and/or on the USB cable between the radio and computer.

73

Bob, K4TAX



On 9/13/2021 2:26 PM, Steve Fox wrote:
I’ve been using a K3 with the KPA and KAT500 for about six months now.  Works great except for one minor thing.

On 40m FT8, when the transmission cycle is over, I get a second or two receive audio from the internal speaker.  I have monitor set to zero, and I am using the front headphone plug for audio out for the PC.  It only happens on 40m;  all the other bands end an FT8 normally without sound.

I am assuming I am missing some band specific setting in CONFIG.  Any thoughts?


Re: K3 transmitter power woes

Wes Stewart
 

On Mon, Sep 13, 2021 at 12:50 PM, Chet, N8RA wrote:
My K3 transmitter has been struggling for months to behave. I've heard the
service dept turnaround in CA is very long so I might not see it the rest of
the year if I sent it in and wanted to avoid that if possible. I've followed
advice suggested here with no lasting success.

Especially on 6M the power sometimes takes a long time deciding to reach the
setpoint. Sometimes it will be OK, but a few hours later after just sitting
there, it again won't, and drops to a low output level.

I've run the transmitter gain calibration routine again and again and it
fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W
calibration shows errtxg as it runs but the utility says the calibration had
succeeded.

I've checked that the bandpass filters are OK by using an antenna analyzer
with an attenuator to check receiver sensitivity- all bands seem pretty
close.

I've rechecked if the LPA FET's are ok (I changed two last year), and set
their bias current levels again and all seems well with them.

I've upped the supply voltage- that seems to work for a day or two but then
same old problems come back

I've replaced the fwd and rev power meter Schottky diodes, no fix.

Sometimes when the transmitter fails to reach the set power level, I can
tweak the pwr knob and it will reach the changed level, but sometimes not
and it falls back to a lower value. On 6M, while in "tune" if the power does
not reach the setpoint (e.g. 30W) and I turn the pwr knob down below 12
where the 100w amp is bypassed and then turn it back up to reengage the 100w
amp, the power will sometimes reach and stay at the setpoint (30W). But that
condition does not stay Ok too long.

The transverter output also exhibits similar power problems

I've reloaded the firmware. The utility initially reported "checksum
reconciliation value" and I have no idea what that means.

And finally, this weekend, when I set the receive mode to data-a, the audio
output had shifted to a higher freq spectrum width (e.g. 500-3300) on the
WSJT spectrum display with clearly more hiss in the speaker. Cycling the
xtal filters, normalling the shifts and widths had no effect. Changed the
mode to USB and the audio spectrum was normal, change back to data-a and it
was shifted. So I operated WSJT-X in USB. Hours later, data-a was back to
normal. First time I've observed that. Today it is AOK. GOK what happened
Saturday.

Any other suggestions before I bit the bullet and prepare to send it to
Elecraft? Thanks for any ideas.

Chet, N8RA

 I know you think the BPF tuning is okay.  I would tweak C128, C147 and C148 and see what happens.  Just move them and put them back where they were.  I've found flaky caps in my K3S, that "get well" when you do this, but they will eventually fail again.


K3 transmitter power woes

Chet, N8RA
 

My K3 transmitter has been struggling for months to behave. I've heard the
service dept turnaround in CA is very long so I might not see it the rest of
the year if I sent it in and wanted to avoid that if possible. I've followed
advice suggested here with no lasting success.

Especially on 6M the power sometimes takes a long time deciding to reach the
setpoint. Sometimes it will be OK, but a few hours later after just sitting
there, it again won't, and drops to a low output level.

I've run the transmitter gain calibration routine again and again and it
fails. Sometimes I get an ERRTXG on 160, 80, 40M. Sometimes the 5W
calibration shows errtxg as it runs but the utility says the calibration had
succeeded.

I've checked that the bandpass filters are OK by using an antenna analyzer
with an attenuator to check receiver sensitivity- all bands seem pretty
close.

I've rechecked if the LPA FET's are ok (I changed two last year), and set
their bias current levels again and all seems well with them.

I've upped the supply voltage- that seems to work for a day or two but then
same old problems come back

I've replaced the fwd and rev power meter Schottky diodes, no fix.

Sometimes when the transmitter fails to reach the set power level, I can
tweak the pwr knob and it will reach the changed level, but sometimes not
and it falls back to a lower value. On 6M, while in "tune" if the power does
not reach the setpoint (e.g. 30W) and I turn the pwr knob down below 12
where the 100w amp is bypassed and then turn it back up to reengage the 100w
amp, the power will sometimes reach and stay at the setpoint (30W). But that
condition does not stay Ok too long.

The transverter output also exhibits similar power problems

I've reloaded the firmware. The utility initially reported "checksum
reconciliation value" and I have no idea what that means.

And finally, this weekend, when I set the receive mode to data-a, the audio
output had shifted to a higher freq spectrum width (e.g. 500-3300) on the
WSJT spectrum display with clearly more hiss in the speaker. Cycling the
xtal filters, normalling the shifts and widths had no effect. Changed the
mode to USB and the audio spectrum was normal, change back to data-a and it
was shifted. So I operated WSJT-X in USB. Hours later, data-a was back to
normal. First time I've observed that. Today it is AOK. GOK what happened
Saturday.

Any other suggestions before I bit the bullet and prepare to send it to
Elecraft? Thanks for any ideas.

Chet, N8RA


Re: Small hiccup on K3

Mike Flowers
 

As this is band specific, I suspect RFI is the culprit.  

Does this happen at 1W RF output or into a dummy load?  If not, it’s likely RFI. 

Jim K9YC has a great article on grounding and bonding here:

http://audiosystemsgroup.com/GroundingAndAudio.pdf

-- 73 de Mike Flowers, K6MKF, NCDXC - "It's about DX!"

On Sep 13, 2021, at 9:26 AM, Steve Fox <ka4fox@...> wrote:

I’ve been using a K3 with the KPA and KAT500 for about six months now.  Works great except for one minor thing.

On 40m FT8, when the transmission cycle is over, I get a second or two receive audio from the internal speaker.  I have monitor set to zero, and I am using the front headphone plug for audio out for the PC.  It only happens on 40m;  all the other bands end an FT8 normally without sound.

I am assuming I am missing some band specific setting in CONFIG.  Any thoughts?


Small hiccup on K3

Steve Fox
 

I’ve been using a K3 with the KPA and KAT500 for about six months now.  Works great except for one minor thing.

On 40m FT8, when the transmission cycle is over, I get a second or two receive audio from the internal speaker.  I have monitor set to zero, and I am using the front headphone plug for audio out for the PC.  It only happens on 40m;  all the other bands end an FT8 normally without sound.

I am assuming I am missing some band specific setting in CONFIG.  Any thoughts?


#forsale #forsale

Steve Smith
 

Need a new KSYN3A (new version sync) to replace a defective one past repair option.

Steve W9HBH

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