[Elecraft] Intermittent 20m

Mon Aug 19 15:41:00 2002

Jonathan:
  The minute one hears 20 meter problems one's mind jumps to the well-known 
issue with the variable caps (I believe they are C21 and C23) in the 20/30 
BPF.  Often these two caps require being turned a full 360 several times to 
clear out stuff left from the manufacturing.  I do not know if it is 
possible for this problem in fact to be intermittent, but, if, after 
looking hard at all the other components in this BPF, you find nothing, I 
would consider rotating them a couple of times and resetting them.

best wishes,

dave belsley, w1euy

--On Monday, August 19, 2002 12:10 PM -0700 Ron D'Eau Claire 
<[email protected]> wrote:

> My K1 has an intermittent problem on 20 meters. Sometimes it workes
> great, and I work QSOs with it. Other times it goes out completely. It
> won't recieve anything, even band noise, the antenna tuner wont tune the
> antenna, and when I press the key, the wattmeter doesn't show any bars.
> Anybody have any hints, and how I can fix it without using a bunch fancy
> equipment?
>
> I had this problem before, and I replaced the 20 meters crystal and it
> worked again. However, I have a hard time believing that two crystals
> would go bad.
>
> I be grateful for any help that anyone might have, since 20 meters is my
> favorite band.
>
> Jonathan Broscious-KB3HVR
> _______________________________________________
>
>
> I'd be willing to be that the 20 meter crystal that you removed is good
> too. Did you check it in an oscillator after removing it?  Sometimes the
> act of replacing a component that is good will jiggle the intermittent,
> making it look like replacing the component fixed the
>
> Unfortunately, there is NO amount of "fancy equipment" that I've ever
> heard of that can trace down an intermittent like that. If it's working,
> it isn't broken, so nothing is going to show up in testing.
>
> There are only two approaches to the issue:
>
> 1 - Troubleshoot it to find the fault when it is NOT working.
>
> 2 - Look for ways to make it quit working "on demand" and fix whatever
> that is.
>
> To troubleshoot it when it is NOT working, from your symptoms I'd
> suggest first checking all of the circuits involved with 20 meters,
> assuming that everything associated with the other band(s) is working.
> One thing to look for is whether the latching relays are actually moving
> to the proper positions. Since they do latch, that is something you can
> confirm using resistance checks with the power off of the rig.
>
> To look for ways to make it quit working, I'd suggest taking an
> insulated probe (plastic barrel of an old ball point will do - remove
> the metal ball point or use the "back" end) and push against components
> and connectors associated with the 20 meter circuits. What you describe
> is most likely a missed/broken/bad solder joint somewhere, or possibly a
> cracked resistor or capacitor. Also a very close visual inspection of
> every solder joint often turns up a bad one. I recommend using a very
> strong magnifier, even if your eyes are good. The strong magnifier
> forces you to look at each joint and not "skip" over one.
>
> Ron AC7AC
> K2 #1289
> .
>
>
>
>
>
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----------------------------------
David A. Belsley
Professor of Economics