I'll second that motion, hihi
It would be super to have more schematics for these amps. !!
If you do publish the schematics, please advise us on this reflector.
It is a shame they weren't revised with each change but it is what it
is...............
Bob
K6UJ
On Apr 7, 2013, at 7:12 PM, Alek Petkovic wrote:
> 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@arrl.net
>> web: http://wiki.k1ttt.net
>> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>>
>>
>> -----Original Message-----
>> From: K1TTT [mailto:K1TTT@ARRL.NET]
>> Sent: Saturday, April 06, 2013 14:05
>> To: 'amps@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@arrl.net
>> web: http://wiki.k1ttt.net
>> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>>
>>
>> -----Original Message-----
>> From: K1TTT [mailto:K1TTT@ARRL.NET]
>> Sent: Wednesday, April 03, 2013 23:43
>> To: amps@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@arrl.net> mailto:k1ttt@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.
>
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