Roger, N1RJ kindly sent me an updated and cleaned-up schematic from
Ameritron (current as of 2011) that now shows a 22-ohm glitch resistor in
the B+ line. Unfortunately, that schematic is not yet part of the on-line
AL-1200 manual.
Paul, W9AC
-----Original Message-----
From: Paul Christensen
Sent: Sunday, April 12, 2015 9:10 AM
To: amps@contesting.com
Subject: Re: [Amps] AL-1200 Glitch Resistor
Carl,
Any idea when it went into production? I see it in the on-line parts list
as P/N 10-10154 for $19.11 but I don’t see it on the current PDF schematic.
In this particular AL-1200, the only HV fault current limit is though the
filament choke, plate choke, PCB traces, and wiring post HV filter cap
board.
A single 1N5408 does exist between B- and chassis ground.
Their schematics need a thorough clean-up. I noticed several parts,
off-sheet connect points, and module numbers that don't match-up. Some of
this may be due to evolutionary changes.
Paul, W9AC
-----Original Message-----
From: Carl
Sent: Sunday, April 12, 2015 8:45 AM
To: Paul Christensen ; amps@contesting.com
Subject: Re: [Amps] AL-1200 Glitch Resistor
See the photos of the current big Ameritron series. They use a big carbon
resistor that is in the parts list, sort of pricey however.
Carl
KM1H
----- Original Message -----
From: "Paul Christensen" <w9ac@arrl.net>
To: <amps@contesting.com>
Sent: Sunday, April 12, 2015 8:25 AM
Subject: [Amps] AL-1200 Glitch Resistor
I'm working on an AL-1200 for a friend. While finding the problem in the
PS, I noticed that a glitch resistor is absent in the design that would
otherwise limit HV fault current. I verified this on both the schematic
and by tracing actual amp wiring. I was expecting a resistor (e.g.,
50/50W) in the B- lead, or in the alternative, in the B+ lead with
appropriate isolation. While the 3CX1200 may be statistically immune to
flashover, it seems a good idea to include one to ensure that HV fault
current is limited under all conditions.
Has anyone here added one to their AL-1200?
Paul, W9AC
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