Folks,
It seems the limitation on the Drake L-4B wrt trying for 1500 watts out, is
due to the low plate voltage design chosen from times past, making the
3-500Zs less capable of maximum power out. Raising the plate voltage makes
the 3-500zs capable of legal limits, but changes the plate impedance some.
Does the impedance change enough to require tap changes in the L-4B PI net
Coil?
Can the L-4B sustain safely high duty cycle 1300 watts out, without the
stock power supply cooking? if cooking is likely, can that be forstalled
with continuous muffin fans cooling thru the perforated PS chassis cage?
tnx, Pat aa6eg@hotmail.com
>Dan,
>
>I would suggest you talk to Stan, K5GO. I
>think he is using Drake L-4B's with homebrew
>power supplies. Myself I have a couple of
>Drake L-7's here which can be found pretty
>cheap on Ebay, but they won't quite do 1500W
>with the stock power supply (1200-1300W). You
>might consider a hybrid approach along the
>lines of what Pete, N4ZR suggested. Drake
>L-4B's and an L-7 (for 160 meters) in concert
>with a big homebrew supply ala W3LPL. The
>Drake's are already setup for external
>supplies, so you wouldn't need to modify the
>RF decks at all (the L-7 and the L-4B use the
>same external supply). You could keep the
>light duty external supplies as backup's or
>sell them on Ebay to fund the homebrew supply.
>
>BTW, it may be possible to raise the anode
>voltage on the Drake's up from 2500V to
>increase the output capability, but this may
>entail chaning from zero-bias to some kind of
>zener regulator. There may also be issues
>related to the ratings of the tank components.
>Check with Stan, K5GO as I think he raised
>the anode voltage on the L-4B significantly
>and has had good results.
>
>If you can afford the Alpha 76PA's that
>is also a good choice.
>
>73 de Mike, W4EF...........................
>
>
>----- Original Message -----
>From: "Phil Clements" <philk5pc@tyler.net>
>To: "Dan Levin" <djl@andlev.com>; <amps@contesting.com>
>Sent: Friday, February 14, 2003 4:52 AM
>Subject: Re: [Amps] Cheap 1500 Watt Amps?
>
>
> > > What would your suggestion be for a low cost, reasonably reliable amp
>that
> > > will do 1500 watts out in contest use?
> >
> > We have all been waiting for this gem for years!
> > There is no such thing as a free lunch, Dan.
> > There is no such thing as cheap, reliable, and 1500 watts out, key down.
> > Truly an oxymoron, IMO.
> >
> > (((73)))
> > Phil, K5PC
> >
> >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
>
>
>
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