[Amps] commander hf-2500 schematic

[Alek Petkovic]

It would be nice if you could pdf all the variants that you have and 
upload them to BAMA.

http://bama.edebris.com/manuals/

73, Alek.

On 7/04/2013 9:33 PM, K1TTT wrote:
> Ok, now I'm making some progress... thanks for some of the tips in here.
> Yesterday I traced out the circuits for the rf deck, hv power supply, and
> meter board, and was able to connect up the whole loop from B+ to B-, and it
> obviously didn't match the schematic that came with that amp... mainly the
> schematic showed a 8.2v 50w zener doing the biasing during tx and a grid
> leak resistor during rx that were switched by a relay... well, that relay
> existed but the terminals that should have switched the bias weren't hooked
> up.   So today I was going to trace out the control and bias board which is
> up against the side frame of the inner case and partially blocked from view.
> So last night I dismounted it and got it so I could expose the whole thing
> so I could take pictures of the top and bottom to make tracing it out
> easier.  This morning after another hint, and in looking at the board I
> found a label on it "QSK-1"... I don't have QSK in this amp and the old
> schematic had no reference to that.  BUT, the circuit started looking
> familiar, and since I have several generations of those amps (8 of them in
> total from s/n 427 to s/n 765) I flipped through a couple of the newer books
> where I remembered seeing schematics for QSK boards and other variations.
> It appears that Pat started using newer boards but shipped some of the older
> amps without updating the schematics.  So by s/n 427, bought in 1993, he had
> changed the control board in non-qsk amps to use the qsk bias and control
> board that is documented in later manuals.  I have found one of the 400
> series ones where he stuck in an updated schematic for the control board,
> but not all of them have that.... and that schematic isn't the same as the
> one I have, nor the same as is documented in a 700 series book.  So this is
> progress... I went from having one bad schematic yesterday, to at least 4
> different schematics this morning, one of which looks like the right one...
> and also comes with a board layout diagram that looks correct.
>
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>
>
> -----Original Message-----
> From: K1TTT [mailto:K1TTT at ARRL.NET]
> Sent: Saturday, April 06, 2013 14:05
> To: 'amps at contesting.com'
> Subject: RE: [Amps] commander hf-2500 schematic
>
> What would you expect the voltage to be from Cathode to Ground when keyed
> and when idle on this thing??
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>
>
> -----Original Message-----
> From: K1TTT [mailto:K1TTT at ARRL.NET]
> Sent: Wednesday, April 03, 2013 23:43
> To: amps at contesting.com
> 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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>    

-- 
 From sunny Binningup, Western Australia.

Family Businesses:
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