[Elecraft] K1 dead band on 20M - Follow-up

[COLIN WHITMORE]

Well I do believe that I've traced the problem down to the trimmer cap (C=
C) on 20M. Tom's advice (copied below) was just the ticket. Placing the "=
Cheap 'n Dirty Signal Tracer" on P2 pin 1 then P2 pin 8 (on KFL1) produce=
d signals on all bands save 20M. This eliminated T3 and T4 as well as the=
 relays (verified with resistance checks) and the trimmer caps associated=
 with its respective band. Due to the lack of a signal on P2 pin 8 tells =
me that the culprit has to be either CC or CD.

A little history on trimmer CC; when I first completed the K1 I had probl=
ems with 20M and it turned out to be the trimmer cap CC. The trimmer caps=
 have a little metal screwhead on the top and are soldered to a phenolic =
wafer. When I attempted to peak the band I noticed that the screw would t=
urn but not the wafer. After dropping a bit of solder to secure the screw=
 to the wafer, peaking the cap was no problem. I know I could have just a=
sked Elecraft to send out a new cap but it was easier just to warm-up the=
 iron.

Well I guess that little electrical shock was enough to make it finally g=
ive up the ghost, so I guess in the end, I will be asking Elecraft to sen=
d out a new cap. Though I believe for ten bucks I can get a set of their =
less sensitive trimmer caps, maybe that's the route I'll go.

Thanks to all who responded. And a special thanks to Tom (N=D8SS), his C&=
D Signal Tracer really did the trick.

72 ES GD,
N=D8YGY
Colin
K1 - #942 (weathering the storm, pun intended)
K2 - #2833 (waiting patiently to be assembled)

PS - I believe that the "Cheap 'n Dirty Signal Tracer" pdf file that Tom =
sent me is available on Elecraft's website.
 =20
----- Original Message -----
From: Tom HammondN=D8SS
Sent: Friday, September 06, 2002 12:07 PM
To: COLIN WHITMORE
Subject: Re: [Elecraft] K1 dead band on 20M
 =20
<snipped>

Before you build that RF probe, which may be of limited utility, see if y=
ou =20
can use my Cheap 'n Dirty Signal Tracing file to find your problem.

Of course, tailor the BPF and LPF test points to the specific band on whi=
ch =20
you are having a problem... in this instance, 20M.

KK5F's suggestion to check the 20M Osc Xtal is a good idea as well... =20
probably worth checking BEFORE venturing into signal tracing.

Good luck, hope this helps.

Tom Hammond   N0SS


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