[Amps] Drake L-7 amplifier power supply requirements

[gudguyham at aol.com]

The Drake RF deck already has 5v filament transformer built in so no need for running 5 v up to the deck.  Switch the RF deck to self bias  so you have no need fir 120vdc from the supply.  ALC not needed anyhow which derived from the 120vdc you’d need to provide that now you won’t have to.  So with that bias mod done up in the RF deck that leaves only a few simple connections.  DC B+ and B- and switching the supply on.  Forget about all the Hi Lo plate voltage and just run the supply voltage your HB supply makes.  Like that it’s a very easy hook up.  Do you already have the connecting cord?  Do you have the original supply that is dead or no supply at all?  Just wondering.  I recondition supplies with blown transformers.  Lou


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On Monday, January 17, 2022, 11:31 PM, Mickey Baker <n4mb at arrl.net> wrote:

Larry,

You’ll find a manual and a schematic here:
https://bama.edebris.com/manuals/drake/l7/

Hope that helps.

73,

Mickey Baker N4MB
Palm Beach Gardens, FL

On Sat, Jan 15, 2022 at 1:24 PM A Lawrence Fibich <lfibich at sbcglobal.net>
wrote:

> I could use assistance from anyone who knows this Drake Amplifier and it's
> power supply. 1st I have advertized widely for an original one to buy -
> nothing.2ndly I did get a 'home built' power supply but at a road block as
> how to connect parts of it.  The HV section OK, and a secondary transformer
> provides a 120VAC to run through the on/off switch of the Amp to work the
> finals heaters circuit.  But I come to 'stop' in trying to know/figure out
> what more it needs into the circuits to the right of the finals on the
> schematic - like the interlock, ALC, meter, etc.  This homebuilt power
> supply does put out 5 VAC on the secondary but I don't know how to connect
> that to the Amp.Any assistance really appreciated.
> 73Larry FW6EFFair Oaks, CA (Sub of Sacramento, CA)
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