[AMRadio] RF Amp


Brett gazdzinski brett.gazdzinski at verizonbusiness.com
Wed Dec 6 21:14:40 EST 2006


Yes, I agree, go oversize if you can.
I was lucky to get loads of great parts 20 years
ago when no one wanted the stuff, it was all
transistors they wanted.
I got a load of UTC commercial grade chokes rated
for 7000 volts 700ma ccs for $10.00 each!
BC610 transformers were free if you would remove them, 
etc.
 
Good deals can still be got sometimes, I got a nice Peter Dahl
power transformer that gives 3000 volts out at 500ma for
$75.00 at a fest.
I got some nice oil filled caps a few years ago at Gaithersburg
for $5.00 each.

The really big parts seem rare though...

Brett
N2DTS



> -----Original Message-----
> From: amradio-bounces at mailman.qth.net 
> [mailto:amradio-bounces at mailman.qth.net] On Behalf Of ARS W5OMR
> Sent: Wednesday, December 06, 2006 8:58 PM
> To: Discussion of AM Radio in the Amateur Service
> Subject: Re: [AMRadio] RF Amp
> 
> > If you've got the iron, I'd build up a 2kVDC supply, to run at 250mA
> > on the final, for 500w DC Input to the final.  at those 
> voltages, you
> > don't need nearly as big of value components as you would 
> if you were
> > running 4kV on a pair of 450's in the final.
> 
> Of course, build for reserve ;-)  Variac the thing, make the current
> handling capability double, and make it 2500v.  Got an old BC-610
> plate transformer laying around?
> 
> Double up on the modulator supply for the 450T's.  You're going to
> need 3 or 4kVDC.
> Pay attention to your DC power supply, think about things like
> critical inductance, capacitors rated for 1.5x the B+ level and so
> forth  I''ve just gone through all that here, trying to design a (yet
> another) power supply for my rig.
> 
> A Power supply for a Class AB(1) or AB(2) or Class B requires a -lot-
> more thought be put into it, than say one for a Class C circuit, that
> will -always- have a decent amount of current being drawn through it.
> 
> Got any Swinging Chokes?  ;-)
> 
> --
> Operating your AM rig without a scope
> is like driving our car at night without headlights.(~K4KYV)
> 
> 73 = Best Regards
> -Geoff/W5OMR
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