Re: Elecraft Digest, Vol 32, Issue 27

[N5BZ, Bob 'BZ' Zinn]

I had a similar problem, yesterday.

I just built K2/100 #5884 and everything was ok until I started
alignment of the KPA100. After a few minutes of getting normal output at
5 watts, I suddenly started getting 'High Current', intermittently on 7
MHz, then on every band.

Dropped back to signal tracing using the antenna as a source. No
received signal.

Removed the KPA100. K2 worked fine.

Ohm meter showed TP2 dead short to ground. Pulled board. Path way up to
Low Pass filter showed dead short to ground.

Removed input relay (didn't want to cut traces). (RADIOSHACK solder
sucker WORKS GREAT!) Short was cleared from TP2. Removed P6 jumper cable.

Short localized to jumper cable, PLUG seemed to be shorted. Looked a
plug carefully.

I found that the coax center conductor insulator was pulled tight during
the alignment and had pulled the braid into contact with the 'HOT' rf
pin on the plug. The insulation on the center conductor slides back and
forth easily!

A small tie wrap, around the center conductor, at the plug end makes
sure this will never happen again.

Perhaps you are having the same problem.

73 de N5bz

> Message: 5
> Date: Sat, 23 Dec 2006 05:28:53 -0500
> From: "Smythe" <[hidden email]>
> Subject: RE: [Elecraft] KPA - High current
> To: <[hidden email]>, <[hidden email]>
> Message-ID: <000301c7267d$2504af60$6e01a8c0@FAMILY>
> Content-Type: text/plain; charset="us-ascii"
>
> It is happening on all bands (the high curr reading.  I will make the
> suggested resistance measurements today.  I assume you mean to check
> resistance from TP2 to the "center lead" of the antenna jack.  Or which
> portion of the jack? By continuity I assume you mean little if any
> resistance.  Correct?
>
> Dohn

--
-bz-
pardon my infinite ignorance. The set-of-things-I-do-not-know is infinite.

Robert R. "bz" Zinn          -------------------------------------------
programmer                   |opinions expressed are only mine now.    |
Department of Chemistry      |Tomorrow, or later today I may change.   |
Louisiana State University   |-----------------------------------------|
Baton Rouge, LA.  70803-1804 |interests: amateur radio [N5BZ],    F&AM |
[phone]  audio        |box turtles. http://chemistry.lsu.edu/bz |
[phone] (FAXual)      |-----------------------------------------|
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