[AMPS] RE: RF Amplifier Discussion Digest V4 #283

[Dick Green]

Jim,

If the resistor is a cement wirewound unit mounted on a board underneath the
QSK board (at the left rear of the chassis), and the board also has a large
black plastic box, then it's part of the step start circuit. The box is the
step start relay. If the resistor is blown you won't get any HV. My LK-500ZC
randomly blew that resistor a couple of times until I replaced it with a
higher-quality ceramic wirewound. I don't recall it being a 5W 1-ohm,
though. I thought it was a 10W or 20W 10-ohm. but I could be wrong. I can't
tell without pulling the cover, and I don't have time for that right at the
moment.

If it's a glitch resistor attached to the B- or B+, it's not a stock part. I
had to add one of those to my amp to protect the plate circuit components.
Actually, the step start might be a modification, too.

The best source of information about these amps is Billy Edwards at Omega
Electronics (http://www.omega-electronics.com/). He can tell you all about
the step start unit.

73, Dick WC1M


> Date: Sun, 2 Sep 2001 14:53:26 -0400
> From: "Jim Spears" <n1nk@home.com>
> Subject: [AMPS] need help with old amp supply lk-500z amp
>
> greetings fellow ampians,
>
> I was inactive for a few years and after moving to rhode island
> and putting
> a station back together I discovered that the lk-500 had
> problems.  started
> looking at things and suspect power supply area is the culprit.  initial
> power up had no high voltage but every other thing looked ok.
> tubes lit up,
> fan turned, etc.
>
> first thing I ran into was the manual for the amp did not have a schematic
> for the power supply portion.  if someone has one and could mail, scan and
> email, or fax to me I would greatly appreciate it.
>
> one problem that I see for sure is a blown wire wound resistor.
> label says
> 5W1'ohm symbol'J  so I assume that means it is a 5 watt 1 ohm wire wound
> device.
>
> right now I am trying to figure out how to get at the board to
> determine if
> the filter caps, diodes, and other parts are bad or good.  looking like
> major dissambly.
>
> jim spears
> N1NK


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