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K2-100 SSB distortion

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g4amt

K2-100 SSB distortion

My K2-100 has an intermittent distortion on SSB whereby the signal appears
clean `on frequency` but has very bad splatter up and down the band `almost
like something arcing` to quote my local op who is monitoring it. LSB and
USB the same; CW clean. Have yet to determine if it is constant with KPA 100
in and out.
Distortion clears for no obvious reason and does not return despite abusing
power etc to try and instigate it.
My intial problem is that I have no efficient `in shack` way of monitoring
this and I need to resolve this.
I have checked and checked again the KSB2 board and all looks ok; have
searched through the reflector archives and notice someone may have had
similar and carried out a hard reset with some success ... anyone any ideas
please ?
Thank you
Terry

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Don Wilhelm-3

RE: K2-100 SSB distortion

Terry,

WARNING - Do not do a hard reset without first writing down all your menu
and filter settings - they will be set back to factory defaults with a hard
reset.

I have trouble believing that a hard reset will correct any problem of that
nature - it seems analog in nature and the reset will only correct digital
stuff.

If the problem is actually in the K2, and nothing shows up on CW, the
problem is likely on the KSB2 board. You will probably find that the real
source is a bad solder connection. That is the most frequent source of
intermittent behavior.

It would be wise to check your antenna system as well. If there is an
intermittent connection there, it could cause intermittent RF feedback that
may only be noticable at the microphone input. Try grounding the mic jack,
it may not cure things, but is a good first step, and while you have the
front panel off, check the soldering on the area around the mic
configuration header.

Yes, try to determine if you can reproduce the problem at low power. If you
can, then the most likely problem area is the KSB2 board, but if it does not
show up at low power, the likely source would be RF Feedback IMHO.

On the KSB2, check carefully the ALC section - look at the schematic to see
the associated components.

Can you borrow a receiver and listen to your signal in the shack while
operating into a dummy load. That will keep the airways clean while you are
searching for the cause.

73,
Don W3FPR

> -----Original Message-----
>
> My K2-100 has an intermittent distortion on SSB whereby the
> signal appears
> clean `on frequency` but has very bad splatter up and down the
> band `almost
> like something arcing` to quote my local op who is monitoring it. LSB and
> USB the same; CW clean. Have yet to determine if it is constant
> with KPA 100
> in and out.
> Distortion clears for no obvious reason and does not return
> despite abusing
> power etc to try and instigate it.
> My intial problem is that I have no efficient `in shack` way of
> monitoring
> this and I need to resolve this.
> I have checked and checked again the KSB2 board and all looks ok; have
> searched through the reflector archives and notice someone may have had
> similar and carried out a hard reset with some success ... anyone
> any ideas
> please ?
> Thank you
> Terry
>

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John Huffman-2

Re: K2-100 SSB distortion

In reply to this post by g4amt

Terry -

I had this problem. The cause was in the KPA100 T-R switch. Don W3FPR came up
with the solution. He increased C31 to 0.2 uf.

Don may chime in with better words of wisdom, but it's a place to start.

73 de K1ESE
John

[hidden email] wrote:

> My K2-100 has an intermittent distortion on SSB whereby the signal
> appears clean `on frequency` but has very bad splatter up and down the
> band `almost like something arcing` to quote my local op who is
> monitoring it. LSB and USB the same; CW clean. Have yet to determine if
> it is constant with KPA 100 in and out.
> Distortion clears for no obvious reason and does not return despite
> abusing power etc to try and instigate it.
> My intial problem is that I have no efficient `in shack` way of
> monitoring this and I need to resolve this.
> I have checked and checked again the KSB2 board and all looks ok; have
> searched through the reflector archives and notice someone may have had
> similar and carried out a hard reset with some success ... anyone any
> ideas please ?
> Thank you
> Terry
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>

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Don Wilhelm-3

RE: K2-100 SSB distortion

John,

Your problem may have been different. That would only occur in a KPA100
that is either of very recent purchase (last two months) or has had the
latest upgrade applied.
The change of C31 to .22 uF will be included with all KPA100s and upgrade
kits. If anyone happens to have a new KPA100 or KPA100UPKT, they should
contact mailto:[hidden email] to obtain a new C31.

Terry, does your KPA100 fall into the category where this might be
applicable? If it is an older, non-upgraded KPA100, then it does not.

73,
Don W3FPR

> -----Original Message-----
>
> Terry -
>
> I had this problem. The cause was in the KPA100 T-R switch. Don
> W3FPR came up
> with the solution. He increased C31 to 0.2 uf.
>
> Don may chime in with better words of wisdom, but it's a place to start.
>
> 73 de K1ESE
> John
>
> [hidden email] wrote:
> > My K2-100 has an intermittent distortion on SSB whereby the signal
> > appears clean `on frequency` but has very bad splatter up and down the
> > band `almost like something arcing` to quote my local op who is
> > monitoring it. LSB and USB the same; CW clean. Have yet to determine if
> > it is constant with KPA 100 in and out.
> > Distortion clears for no obvious reason and does not return despite
> > abusing power etc to try and instigate it.
> > My intial problem is that I have no efficient `in shack` way of
> > monitoring this and I need to resolve this.
> > I have checked and checked again the KSB2 board and all looks ok; have
> > searched through the reflector archives and notice someone may have had
> > similar and carried out a hard reset with some success ... anyone any
> > ideas please ?
> > Thank you
> > Terry
>