I have some photographs of the botton input side of my amp. I'll send them to
From: Jan Ditzian <firstname.lastname@example.org>
Sent: Sun, Feb 27, 2011 1:44 pm
Subject: [Amps] Alpha 77 start up
Gentlemen and all others,
I have begun troubleshooting and I would like to share the results, and
think I have found the problem. All the following continuity
easurements are with the amp off and the power disconnected. Go
irectly to number 6 for what appears to be the problem.
1. There is no continuity between the input coax and the RF out coax,
no matter what the position of the two slide switches
(tuned/untuned input and separate and thru antenna), and I believe
that I tried all positions.
2. The thru/separate antenna switch shows switched continuity between
the center and the two poles.
3. The tuned/untuned switch does not appear to work, but it appears
to be shorted in the tuned position. One position has no soldered
connections, and this never shorts to the center, while the other
has a connection that appears to go to a bandswitch wafer on the
chassis bottom, and this is always shorted to the center. I
suspect that someone made a command decision long ago not to
operate the amp in the untuned position, and saved the cost of
painting a label on the switch by shorting it somehow.
4. The RF input (exciter) coax is shorted to a pole on the top of
what I think is K5 when the thru switch is in thru position, but
not in separate position. This sounds right.
5. On the bottom of K5, there are two poles that I assume are the
power. There is about 290 ohms between these. This sounds right,
but I cannot really know.
6. *On the top of K5, no two pins are connected.* AHA! It seems to
me that the pins on top are the contact pins, and that two of
these should be connected at all times.
Where is the nearest K5 salesroom? This is a Kilovac HC-1/ITTRJ1A. I
ound this relay at Surplus Sales of Nebraska for $99 and at Max Gain
ystems for $40 used or $70 new. I will order one of these on Tuesday
probably from Max-Gain), lacking any input from the Amps group on a
etter alternative or a possible other problem that I have not divined.
Thank you to Paul (W9AC) and Bob (K8MLM) for directing me this far, and
o all others who have offered suggestions. Also thank s to K6GI--I did
et a manual with the amp, and I had also downloaded one, but I thank
ou for taking the effort to include one in your e-mail. I will keep
he group posted on the results of any repair.
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