[Amps] commander hf-2500 schematic

[Carl]

Ive been doing it a little bit one amp at a time but havent completed the 
job yet. Customers want their amps back and I have a steady backlog.

There are at least 3 control boards.

Carl
KM1H


----- Original Message ----- 
From: "K1TTT" <K1TTT at ARRL.NET>
To: <amps at contesting.com>
Sent: Wednesday, April 03, 2013 7:43 PM
Subject: [Amps] commander hf-2500 schematic


> Has anyone actually traced out the real schematic from an older commander
> hf-2500, around s/n 435???  The one in the book is not complete (parts 
> list
> missing stuff) nor correct. there appears to be lots of extra stuff on the
> control board, probably for stuff not used in this amp like qsk or grid
> current protection. I can't find the rx cutoff grid leak resistor nor the 
> tx
> bias zener and the relay contacts that should switch switch them don't 
> seem
> to be connected.   And the connections of the plate current shunt and 
> meter
> look backwards.
>
>
>
> When the amp died the transformer shorted primary to secondary causing a
> quite bright arc through the 1.5a B- fuse.  I have had the transformer
> rewound but now when I power it up it doesn't make full power and in rx 
> the
> idle plate current is about 400ma, so I am assuming the bias to the 
> cathodes
> is messed up.  So far I have found that a 200ohm 10w resistor that is in
> series with a 1n54?? diode on the power supply board going from B- to 
> ground
> is open, but the diode seems ok. I am assuming that this is the 
> replacement
> for the grid leak that should cut off the tubes in rx. but then there are
> some other things on the control board that may also be generating a bias
> voltage that I haven't identified yet.  Anyone puzzled one of these out???
>
>
>
>
>
>
>
> David Robbins K1TTT
> e-mail:  <mailto:k1ttt at arrl.net> mailto:k1ttt at arrl.net
> web:  <http://wiki.k1ttt.net/> http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or  <telnet://k1ttt.net/> telnet://k1ttt.net
>
>
>
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