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K2 bandwidth modification issue

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Steve Garwood

K2 bandwidth modification issue

Hello!

I am working on a K2, <3000 s/n in which I installed the K2 SSBCAPKT along with the 14 crystal kit.

Receive is working, audio level is low on the OP1 filter, normal on FL1, etc.
I have transmit, with good audio, however, no measurable power output or ALC reading.

I've been searching for something similar to this, no luck so far.....

It seems that the filter output is low, but functioning..... Alignment addresses adjusting BFO frequency, but nothing about output level.

I checked soldering again, but I have not made it any further than this....

Any ideas?

Thanks

73,

Steve, N0CZV
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Don Wilhelm-4

Re: K2 bandwidth modification issue

Steve,

How does the OP1 filter passband look when viewed on Spectrogram? It
should show a nice flat passband. If it has a dip or valley in it, look
for a bad connection on one of the capacitors or crystals.

What is the possibility that you damaged one of the thru-plated holes
when removing the old crystals and capacitors. Use the schematic to
determine 'which is connected to what' and check all those connections
with your ohmmeter.

You may also have a problem with T1 or T2 soldering or a poor solder
connection in the switching diodes or R-Paks. Re-flow the solder in
those areas with a hot (750 degF) soldering iron.

73,
Don W3FPR

On 2/10/2014 2:30 AM, Steve Garwood wrote:

> Hello!
>
> I am working on a K2, <3000 s/n in which I installed the K2 SSBCAPKT along with the 14 crystal kit.
>
> Receive is working, audio level is low on the OP1 filter, normal on FL1, etc.
> I have transmit, with good audio, however, no measurable power output or ALC reading.
>
> I've been searching for something similar to this, no luck so far.....
>
> It seems that the filter output is low, but functioning..... Alignment addresses adjusting BFO frequency, but nothing about output level.
>
> I checked soldering again, but I have not made it any further than this....
>
> Any ideas?
>
>

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Steve Garwood

Re: K2 bandwidth modification issue

Don,

I am not the original builder of the K2, so I will be downloading
Spectrogram. I will go through the individual connection points for the
swapped crystals and capacitors with the ohmmeter to make sure that there
are no connection issues. Thanks for identifying a troubleshooting path!

I will advise on results.

Thanks again!

73,

Steve, N0CZV

-----Original Message-----

Steve,

How does the OP1 filter passband look when viewed on Spectrogram? It should
show a nice flat passband. If it has a dip or valley in it, look for a bad
connection on one of the capacitors or crystals.

What is the possibility that you damaged one of the thru-plated holes when
removing the old crystals and capacitors. Use the schematic to determine
'which is connected to what' and check all those connections with your
ohmmeter.

You may also have a problem with T1 or T2 soldering or a poor solder
connection in the switching diodes or R-Paks. Re-flow the solder in those
areas with a hot (750 degF) soldering iron.

73,
Don W3FPR

On 2/10/2014 2:30 AM, Steve Garwood wrote:
> Hello!
>
> I am working on a K2, <3000 s/n in which I installed the K2 SSBCAPKT
along with the 14 crystal kit.
>
> Receive is working, audio level is low on the OP1 filter, normal on FL1,
etc.
> I have transmit, with good audio, however, no measurable power output or
ALC reading.
>
> I've been searching for something similar to this, no luck so far.....
>
> It seems that the filter output is low, but functioning..... Alignment
addresses adjusting BFO frequency, but nothing about output level.
>
> I checked soldering again, but I have not made it any further than
this....
>
> Any ideas?
>
>

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Phil Wheeler-2

Re: K2 bandwidth modification issue

I'm reading with interest, Steve. I build my K2
early on (#380) and have done many of the mods,
but not that one as yet -- xtals earlier but not
all the caps, etc.; I'm not excited by working on
that closely-spaced board. (I'm just returning to
it after a ten-year hiatus, and have done other
updates in the past week). So I'll be following
your results here as part of my decision-making
process :-)

73, Phil

On 2/10/14, 7:09 AM, Steve Garwood wrote:

> Don,
>
> I am not the original builder of the K2, so I will be downloading
> Spectrogram. I will go through the individual connection points for the
> swapped crystals and capacitors with the ohmmeter to make sure that there
> are no connection issues. Thanks for identifying a troubleshooting path!
>
> I will advise on results.
>
> Thanks again!
>
> 73,
>
> Steve, N0CZV
>
>
> -----Original Message-----
>
>
> Steve,
>
> How does the OP1 filter passband look when viewed on Spectrogram? It should
> show a nice flat passband. If it has a dip or valley in it, look for a bad
> connection on one of the capacitors or crystals.
>
> What is the possibility that you damaged one of the thru-plated holes when
> removing the old crystals and capacitors. Use the schematic to determine
> 'which is connected to what' and check all those connections with your
> ohmmeter.
>
> You may also have a problem with T1 or T2 soldering or a poor solder
> connection in the switching diodes or R-Paks. Re-flow the solder in those
> areas with a hot (750 degF) soldering iron.
>
> 73,
> Don W3FPR
>
> On 2/10/2014 2:30 AM, Steve Garwood wrote:
>> Hello!
>>
>> I am working on a K2, <3000 s/n in which I installed the K2 SSBCAPKT
> along with the 14 crystal kit.
>> Receive is working, audio level is low on the OP1 filter, normal on FL1,
> etc.
>> I have transmit, with good audio, however, no measurable power output or
> ALC reading.
>> I've been searching for something similar to this, no luck so far.....
>>
>> It seems that the filter output is low, but functioning..... Alignment
> addresses adjusting BFO frequency, but nothing about output level.
>> I checked soldering again, but I have not made it any further than
> this....
>> Any ideas?
>>
>>
>

Steve Garwood

Re: K2 bandwidth modification issue --- Success!-----

In reply to this post by Don Wilhelm-4

Don,

I pulled the KSB2 board again and ran through the connections between the
crystals with the ohmmeter. I found a short to ground between X5 and X6
that should not have been there. I ended up pulling the two crystals. I
found a small piece of copper lifted on the board, shorting the crystal can
to ground on X5. Operator error on this one.
Reassembled, and now I have the desired wider bandwidth on OP1.

Thanks for the jump start on a troubleshooting path. I was already looking
past the possibility of error and seeking an alignment sequence. Attention
to detail being the order of the day, things are in good shape once again!

73,
Steve, N0CZV

Steve,

How does the OP1 filter passband look when viewed on Spectrogram? It should
show a nice flat passband. If it has a dip or valley in it, look for a bad
connection on one of the capacitors or crystals.

What is the possibility that you damaged one of the thru-plated holes when
removing the old crystals and capacitors. Use the schematic to determine
'which is connected to what' and check all those connections with your
ohmmeter.

You may also have a problem with T1 or T2 soldering or a poor solder
connection in the switching diodes or R-Paks. Re-flow the solder in those
areas with a hot (750 degF) soldering iron.

73,
Don W3FPR

On 2/10/2014 2:30 AM, Steve Garwood wrote:
> Hello!
>
> I am working on a K2, <3000 s/n in which I installed the K2 SSBCAPKT
along with the 14 crystal kit.
>
> Receive is working, audio level is low on the OP1 filter, normal on FL1,
etc.
> I have transmit, with good audio, however, no measurable power output or
ALC reading.
>
> I've been searching for something similar to this, no luck so far.....
>
> It seems that the filter output is low, but functioning..... Alignment
addresses adjusting BFO frequency, but nothing about output level.
>
> I checked soldering again, but I have not made it any further than
this....
>
> Any ideas?
>
>

---
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http://www.avast.com

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Don Wilhelm-4

Re: K2 bandwidth modification issue --- Success!-----

Steve,

Great for finding that problem. Something like that is not easy to
find, but it sounds like you have 'found success' Good work.

73,
Don W3FPR

On 2/17/2014 9:52 PM, Steve Garwood wrote:

> Don,
>
> I pulled the KSB2 board again and ran through the connections between the
> crystals with the ohmmeter. I found a short to ground between X5 and X6
> that should not have been there. I ended up pulling the two crystals. I
> found a small piece of copper lifted on the board, shorting the crystal can
> to ground on X5. Operator error on this one.
> Reassembled, and now I have the desired wider bandwidth on OP1.
>
>