[Elecraft] K1 no output on 20m

[John Pfeifer - KLØWN]

Hello again,

After posting my initial message, I decided to do some "Cheap 'N Dirty" signal tracing as described by Tom Hammond(NØSS).

I have a KFL1-4 filter board set up for 40m, 30m, 20m & 17m.

I used a 15ft length of wire with a 550pF blocking capacitor.

At test point #1 (RF Board, T1-1, input winding of the transformer feeding the mixer), I got clearly discernable signals on 40m, 30m & 17m.  No change detected at all on 20m.

I tried a few more test points for all bands and--once again--signals were present on all bands except 20m.

On the chance 20m was totally dead, I even hooked up my Wilderness SST to a dummy load (1 watt) and used it as a poor-man's signal generator.  Wrapped the "signal probe" wire around the dummy load and tuned around a bit with the K1 while holding the test probe on T1-1, lead 1. Couldn't find a signal anywhere.

If no signal is present at T1-1, lead 1, the problem must be downstream of the filter board.  But how come 20m is the only band that doesn't work.  Seems like if there's a problem at input of the receive mixer, all four bands would be dead...

Any ideas?

BTW, my K1 is serial #1456 and it has the newer, blue trimmers.

Thanks!

John Pfeifer - KLØWN
Kodiak, Alaska

At 11:58 AM 8/3/2003 -0600, Rod N0RC wrote:
>John,
>
>Do you have a 2 or 4 band K1? Is 20m the only band affected?
>
>First. double check all of your toroids. Are they tinned and soldered in
>properly. As Gary from tech service has said, PTTL are often the cause.
>(PTTL = poorly tinned toroid leads)
>
>Next thing to are check trimmer caps, if you have a 4 bander. If you
>have a 4 band K1 does it have the older white trimmers or the new blue
>ones? If older white ones, give the trimmers associated with 20m (and/or
>other affected bands) a few complete turns, 5-10. Some foreign matter
>(oxide, dust...) may have worked its way into the trimmer(s).
>
>Also, recently, I worked on a 4 band K1 with older white trimmers,
>output was down on some band. I noticed some of the trimmer caps were
>loose, very easy to turn. I suspected vibration from transporting the
>unit might have caused them to move a tiny bit.
>
>73, Rod N0RC
>
>
>----- Original Message ----- 
>From: "John Pfeifer - KLØWN" <qrp@johnpfeifer.com>
>To: <elecraft@mailman.qth.net>
>Sent: Sunday, August 03, 2003 11:33 AM
>Subject: [Elecraft] K1 no output on 20m
>
>
>Hello all,
>
>My K1 was behaving normally until yesterday.  As I was trying to tune
>the rig up on a 1/4-wave 20m vertical, the KAT1 relays clicked endlessly
>and I saw the following: