4.5kV Power Supply GW4RWR

This was built in 1990 to supply the 3CX1500A7, and was conceived to provide plenty of power, just in case I ever had grander designs. The transformer is rated 3500V 1.5A.

The mains input is switched via a relay from the amplifier cabinet, arranged such that excess anode current will cut out the anode supply. There's a front panel switch in parallel with this relay, to enable the PSU to be used 'without protection'. I've operated the PSU with the rear panel off since I build it, but with a two year old who is more inquisitive each day, I finally fastened the rear panel securely in December 2011. If my wife ever understood what went on in my 'shack'..

GW4HBZ is to be thanked for the large current meter, which was suitably printed with 1500mA FSD. By luck I eventually discovered an identically sized meter, 50uA fsd, perfect for measuring EHV. I like large meters, and plenty of them. Too many commercial amps use multi-function metering. But a meter is an insignificant portion of amp's cost amp, and it's convenient to be able to glance at the meters, rather than have to switch to the function required. Update: I've broken the voltmeter - has anyone a replacement I could buy?

I have had resistors fail open-circuit, in the HV meter divider chain, due to excessive volts across each one, even though the power consumed was well within limits. Symptoms were that the volt meter would display fluctuating readings, and then settle near zero. I'm currently metering across just the lowest electrolytic in the stack.

My only complaint is the weight. This thing is huge. I have to remove the transformer, itself a difficult task since it must weigh over500N, just to move this monster across the my attic shack. I had it on casters, but they collapsed! Please don't ask me to bring this along to VHF NFD!

The PSU always brought up using a 25A Variac, by which point the transformer has quite a perturbing buzz