Date   

Re: Question on the power meter board ...

Garey Barrell
 

Jim -

Are you planning a shield 'wall' UNDER the board as well?? Probably not necessary with the SM version.

Is the intent for a wall or a box on top??

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>

n5ib@... wrote:

Yes, That was the intent. To allow you do do at least some shielding around the front end components. I have one in the works at the home QTH and will post photos when I'm done, but that will be at least a week.

I had built a prototype (homemade PCB) without shielding and it workes fine, but I thought... maybe more is better :^))

I have some 1/32" PCB stock I was going to try, if that was unmanageable then brass shim stock could be bent into sort of a quonset hut affair top and bottom.

Jim, N5IB




Re: Question on the power meter board ...

N5IB
 

Yes, That was the intent. To allow you do do at least some shielding around the front end components. I have one in the works at the home QTH and will post photos when I'm done, but that will be at least a week.

I had built a prototype (homemade PCB) without shielding and it workes fine, but I thought... maybe more is better :^))

I have some 1/32" PCB stock I was going to try, if that was unmanageable then brass shim stock could be bent into sort of a quonset hut affair top and bottom.

Jim, N5IB

 




Re: Question on the power meter board ...

Paul Schumacher
 

Okay, that area is for an rf shield I take it.  thanks,

I have lots of copper clad to make small enclosures.

Paul  K0ZYV



On Tuesday, October 29, 2013 10:57 AM, Garey Barrell wrote:
 
Thin brass 'shim stock' is available at most hobby and craft stores. It can be cut with scissors and bent to shape.
The holes all along those strips are 'plated through' and tie the top and bottom strip together. Small pieces of wire
may be soldered through several to solder to the 'shield' material.

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs


wnpauls@... wrote:
>
> The power meter board has a silver u shaped trace on the top and bottom of the board
> by the rf input. Is this there to facilitate an rf sheild for that part of the board. If so,
> does anyone have a picture of how they did it?
>
> thanks,
>
> Paul, K0ZYV
>
>




Re: Question on the power meter board ...

Garey Barrell
 

Thin brass 'shim stock' is available at most hobby and craft stores. It can be cut with scissors and bent to shape. The holes all along those strips are 'plated through' and tie the top and bottom strip together. Small pieces of wire may be soldered through several to solder to the 'shield' material.

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>

wnpauls@... wrote:


The power meter board has a silver u shaped trace on the top and bottom of the board
by the rf input. Is this there to facilitate an rf sheild for that part of the board. If so,
does anyone have a picture of how they did it?

thanks,

Paul, K0ZYV


Re: Question on the power meter board ...

Gene Dorcas <gene@...>
 

I haven’t done it yet but what I’m going to try is to cut small pieces of copper clad and form a small enclosure.  I have some thin matl from Electronic Goldmine that is thin enough to cut with scissors.

 

Gene, W5DOR

gene@...

www.w5dor.com

 

 

From: PHSNA@... [mailto:PHSNA@...] On Behalf Of wnpauls@...
Sent: Tuesday, October 29, 2013 9:52 AM
To: PHSNA@...
Subject: [PHSNA] Question on the power meter board ...

 

 

The power meter board has a silver u shaped trace on the top and bottom of the board
by the rf input.  Is this there to facilitate an rf sheild for that part of the board.  If so,
does anyone have a picture of how they did it?

thanks,

Paul, K0ZYV


Question on the power meter board ...

Paul Schumacher
 

The power meter board has a silver u shaped trace on the top and bottom of the board
by the rf input.  Is this there to facilitate an rf sheild for that part of the board.  If so,
does anyone have a picture of how they did it?

thanks,

Paul, K0ZYV


Re: New BOM file for SSNA

N5IB
 

Just posted a new BOM for the SSNA that distinguishes the 5109 and the ERA versions.
 
Jim, N5IB
 
 
 
On Wed, 23 Oct 2013 11:45:23 -0500 n5ib@... writes

  Short of comparing line by line, what are the changes in the new SSNA BOM file?

Jay

AJ4AY

Mobile, AL


Re: SSNA/Power Meter PCB order status

N5IB
 

The boards left Cincinnati OH at 0544 EDT today (24th)
Maybe they'll arrive tomorrow. Not sure if DHL does residential deliveries on Saturdays.

In any event, I will be on a road trip for a few days next week, so it will be the end of next week before they go out.

Keep an eye on the SOTA announcements page for my hoped for activation of Monte Sano Mountain, most likely Oct 31.

73,
Jim, N5IB


Re: New BOM file for SSNA

Jay Henson
 

Thanks Jim.

 

I am working at producing a Mouser order based on the combined BOM’s for the SSNA and PM, minus my junk box parts.  Hope to have it finished today.

 

Jay

AJ4AY

Mobile, AL

 

From: PHSNA@... [mailto:PHSNA@...] On Behalf Of n5ib@...
Sent: Wednesday, October 23, 2013 11:57 AM
To: PHSNA@...
Subject: Re: [PHSNA] New BOM file for SSNA

 

 



No changes, just made it an Excel97 (xls) file instead of the xlsx that some folks couldn't open.

 

Jim, N5IB

 

 

 

On Wed, 23 Oct 2013 11:45:23 -0500 n5ib@... writes

 Short of comparing line by line, what are the changes in the new SSNA BOM file?

Jay

AJ4AY

Mobile, AL


Re: New BOM file for SSNA

N5IB
 


No changes, just made it an Excel97 (xls) file instead of the xlsx that some folks couldn't open.
 
Jim, N5IB
 
 
 
On Wed, 23 Oct 2013 11:45:23 -0500 n5ib@... writes

 Short of comparing line by line, what are the changes in the new SSNA BOM file?

Jay

AJ4AY

Mobile, AL


New BOM file for SSNA

Jay Henson
 

Jim,

 

Short of comparing line by line, what are the changes in the new SSNA BOM file?

 

Jay

AJ4AY

Mobile, AL


Re: Output level and crystal drive

Jerry Haigwood
 

Hi Nick,

    I chose -10 dbm as the output to prevent damaging crystals.  I think -10 dbm is good maximum based on some emails I had with Kerry Powers (can’t remember his call).  However, the extra attenuation was put in so that people could decide how much power they wanted.  You can get up to +20 db more out of the SSNA.  Of course if you decide to increase the power out of the SSNA, you will have to change the amount of voltage you get out of the power meter.  A value of +5 VDC is the absolute maximum you can feed back into the SSNA.

Jerry W5JH

"building something without experimenting is just solder practice"

 

From: PHSNA@... [mailto:PHSNA@...] On Behalf Of kennnick@...
Sent: Monday, October 21, 2013 7:40 PM
To: PHSNA@...
Subject: [PHSNA] Output level and crystal drive

 

 

I've been looking at the circuit and thinking of stuff I might want to try.  One is that I think I want to get some more juice out of the DDS + amplifier.  The circuit has a lot of attenuation to hit the desired -10 dBm level.  I'd like to go with maybe +10 dBm or so and attenuate externally when I need to.

Which got me to thinking about how much drive is too much when testing a crystal. Funny, I did a presentation on crystal measurements at 4SQRP but didn't even get into this sub-topic.  For one thing, there are a lot of variables.  I looked at some references including an excellent PDF paper by Corning / John R. Vig which showed typical dissipation values of 10 uW and 100 uW and typical drive currents of 100 uA to 1 mA.  (I see drive expressed in units of current and of power, at different times.)

The ECS data sheet for a typical HC49/U 8MHz crystal I used in a filter gave a maximum drive number of 1 mW, but no "typical".  So I'd think you'd actually want a lot less -- say 10% to 20% of that as a maximum.

Factors include your crystal's series resistance Rs and the loss in your measurement fixture, if any.  A pair of resistive minimum loss pads 50 to 12.5 ohms back to back with the crystal in between is sometimes used. It has 16 dB loss in each section.  I used LTSpice to check some dissipations and currents in this configuration with various Rs values.  I used a source with 50 ohms internal resistance and voltage set to give 1 mW (0 dBm) to an external 50 ohm load.

Here are the numbers I got with Rs of 10, 20 and 50 ohms:

10 ohms, Ix = 1mA, Px = 10.2 uW

20 ohms, Ix = 786 uA, Px = 12.4 uW

50 ohms, Ix = 471 uA, Px = 11.1 uW

So with that configuration, you should be able to drive with +10 dBm and not over-do it. (Your dissipations would be a bit over 100 uW.)

I also use a fixture that also puts the crystal in a 12.5 ohm environment but uses back to back 4:1 transformers.  Here you don't have resistive losses, plus the configuration gives twice as much current through the crystal as comes out of the generator.  With a 0 dBm source, your crystal might get close to the 1 mW limit and dropping down 10 dB or more might be a good idea.

73-

Nick, WA5BDU

 

 

 


Output level and crystal drive

Nick Kennedy
 

I've been looking at the circuit and thinking of stuff I might want to try.  One is that I think I want to get some more juice out of the DDS + amplifier.  The circuit has a lot of attenuation to hit the desired -10 dBm level.  I'd like to go with maybe +10 dBm or so and attenuate externally when I need to.

Which got me to thinking about how much drive is too much when testing a crystal. Funny, I did a presentation on crystal measurements at 4SQRP but didn't even get into this sub-topic.  For one thing, there are a lot of variables.  I looked at some references including an excellent PDF paper by Corning / John R. Vig which showed typical dissipation values of 10 uW and 100 uW and typical drive currents of 100 uA to 1 mA.  (I see drive expressed in units of current and of power, at different times.)
The ECS data sheet for a typical HC49/U 8MHz crystal I used in a filter gave a maximum drive number of 1 mW, but no "typical".  So I'd think you'd actually want a lot less -- say 10% to 20% of that as a maximum.
Factors include your crystal's series resistance Rs and the loss in your measurement fixture, if any.  A pair of resistive minimum loss pads 50 to 12.5 ohms back to back with the crystal in between is sometimes used. It has 16 dB loss in each section.  I used LTSpice to check some dissipations and currents in this configuration with various Rs values.  I used a source with 50 ohms internal resistance and voltage set to give 1 mW (0 dBm) to an external 50 ohm load.
Here are the numbers I got with Rs of 10, 20 and 50 ohms:
10 ohms, Ix = 1mA, Px = 10.2 uW
20 ohms, Ix = 786 uA, Px = 12.4 uW
50 ohms, Ix = 471 uA, Px = 11.1 uW
So with that configuration, you should be able to drive with +10 dBm and not over-do it. (Your dissipations would be a bit over 100 uW.)
I also use a fixture that also puts the crystal in a 12.5 ohm environment but uses back to back 4:1 transformers.  Here you don't have resistive losses, plus the configuration gives twice as much current through the crystal as comes out of the generator.  With a 0 dBm source, your crystal might get close to the 1 mW limit and dropping down 10 dB or more might be a good idea.
73-
Nick, WA5BDU




Re: Unfiltered AD9850 Output

Nick Kennedy
 

Yeah, I was kind of figuring we were going to bypass the filter on the DDS board rather than cascade the two.  Looks like it's designed for 200 ohms input & output also.


73-


Nick, WA5BDU


Re: SSNA/Power Meter PCB order status

N5IB
 

I have received notice the the boards are being shipped (DHL)
Not yet in the hands of DHL, though they have received the shipping info, so I don't have a delivery date, but might be by the end of the week.

If you haven't yet paid for you order (6 are pending), not a bad time to do so.
PayPal  to   jerry (at) w5jh (dot) net

73,
Jim, N5IB


Unfiltered AD9850 Output

N5IB
 

As others have commented, there is no need for both the LPF on the 9850 module and the one on the SSNA. Jerry has found that the one on the 9850 module seems of particularly low quality, given the use of SMT inductors. The LPF Jerry designed for the SSNA should be much better.

I've uploaded a file "Unfiltered AD9850 Output" that has some information about modifying the 9850 module. There are two options, depending on how good you are at SMT rework. Extra pads are provided on the SSNA board to assist with this.

I have NOT yet done either of these. But plan to do the "elegant" one when the SSNA boards arrive, since I have access to a rework station, and a spare 9850 module I can afford to botch up in the attempt  :^))

73
Jim, N5IB


Re: Mouser/Digikey Parts List for Power Meter?

Jerry Haigwood
 

Hi Folks,

    I used a meter from Allelectronics for my power meter.  It is a small square meter, 0-1 mA movement, 0-15 VDC scale.  This meter matched the specs of the meter that Wes Hayward used when he and W7PUA designed the power meter. The little square meter sells for $3.50.  Here is a link for it.

<http://www.allelectronics.com/make-a-store/item/PM-376/PANEL-METER-FULL-SCALE-1MA/1.html>

Jerry W5JH

"building something without experimenting is just solder practice"

 

From: PHSNA@... [mailto:PHSNA@...] On Behalf Of gene@...
Sent: Friday, October 18, 2013 12:50 PM
To: PHSNA@...
Subject: [PHSNA] RE: Mouser/Digikey Parts List for Power Meter?

 

 

Here's an inexpensive meter.  http://www.goldmine-elec-products.com/prodinfo.asp?number=G19419

I have one and found that the cover snaps off easily and the scale comes right off allowing for an easy way to apply a custom scale.

Gene, W5DOR

 



---In phsna@..., <n5ib@...> wrote:

I've updated the Bill of Materials for the power meter to include Mouser catalog numbers. Not always the least expensive, but at least readily obtainable in US.

Remember that other op amps can be substituted for the AD820, as long as they operate from a single supply and have outputs that swing to near ground. FET input preferred. Remember also that Analog Devices still does offer samples of the AD8307.

No enclosure listed yet, Mostly depends on whether you include an analog meter, and then how big the meter movement is. The analog meter is not needed for the SSNA, but very convenient for general use. The actual circuit board is roughly 3 cm x 10 cm.

Jim, N5IB


Re: Mouser/Digikey Parts List for Power Meter?

gene@...
 

Here's an inexpensive meter.  http://www.goldmine-elec-products.com/prodinfo.asp?number=G19419

I have one and found that the cover snaps off easily and the scale comes right off allowing for an easy way to apply a custom scale.

Gene, W5DOR

 



---In phsna@..., <n5ib@...> wrote:

I've updated the Bill of Materials for the power meter to include Mouser catalog numbers. Not always the least expensive, but at least readily obtainable in US.

Remember that other op amps can be substituted for the AD820, as long as they operate from a single supply and have outputs that swing to near ground. FET input preferred. Remember also that Analog Devices still does offer samples of the AD8307.

No enclosure listed yet, Mostly depends on whether you include an analog meter, and then how big the meter movement is. The analog meter is not needed for the SSNA, but very convenient for general use. The actual circuit board is roughly 3 cm x 10 cm.

Jim, N5IB



Re: Mouser/Digikey Parts List for Power Meter?

N5IB
 

I've updated the Bill of Materials for the power meter to include Mouser catalog numbers. Not always the least expensive, but at least readily obtainable in US.

Remember that other op amps can be substituted for the AD820, as long as they operate from a single supply and have outputs that swing to near ground. FET input preferred. Remember also that Analog Devices still does offer samples of the AD8307.

No enclosure listed yet, Mostly depends on whether you include an analog meter, and then how big the meter movement is. The analog meter is not needed for the SSNA, but very convenient for general use. The actual circuit board is roughly 3 cm x 10 cm.

Jim, N5IB



Mouser/Digikey Parts List for Power Meter?

patt896
 

Anyone compiled one yet?

 

Richard