[AMPS] Questions on homebrew PS

[Doug Hall]

Hi all,
Recently I started a search for a reasonably priced amp that would
perform well in RTTY contests. During that time I've stumbled across
enough parts that I've decided to build an amp. So far I'm having a
good time & learning a lot. I may not end up with the ultimate RTTY
amp, but it's cheap education & keeps me off the streets. Presently
I'm working on the power supply.

I've acquired a transformer that I'd like to use, but I'd like an
opinion regarding it. It's an old girl, but it works, and the price
was right (free). It was made by Union Electric & Mfg. Co. (part no.
TF4RX02YY), has a 220v primary (0/207/220/235?) and a 2800-0-2800v
secondary. It weighs about 60 lbs, and I'm pretty sure it's got oil
inside it. Nothing is leaking, but when I picked it up to weigh it I
could hear some liquid sloshing around inside it. Anyway, here's the
sticky part - the current rating on the side of the transformer says
530 mA DC. The amp I want to build will require about 600 mA from the
B+ supply. My question is this: Does anyone know if the 530 mA rating
is a CCS rating? Is it a conservative figure?

I also got a 16 uF 7500vdc oil-filled capacitor. It's nearly as big as
the transformer. Is there any reason not to use it? What problems to
oil-filled caps suffer from? I brought the PS up on a variac and
everythig looked OK at approx. 4000vdc, but I haven't done any load
tests yet. Partly because I have no way to do any load tests yet.

I've also collected a number of parts for the RF deck (pair of
4-400A's, yeah, I know, there are better tubes, but I got 4 of them,
including 2 NOS Eimacs, for next to nothing.) I should be able to get
close to a KW out of them, I'd think. I'll save the RF deck questions
for another time.

Thanks & 73,
Doug, KF4KL


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