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Highland Ham · July 14th 08, 01:04 PM posted to rec.radio.amateur.homebrew

wrote:
The main problem I have with it is the output transistors get hot,
they are well heatsinked. The voltage on the collector of the pass
transistors are 22volts. I think this is a little high. Is there a
good way to bring this down. The transformer doesnt have any taps. I
can put a big VARIAC on the front of of it to get it down but this is
not my first choice. I think I remember that Sorenson used to make a
power supply that used an SCR or TRIAC circuit on the primary side of
the transformer as the control element of their regulator.

Any ideas on how to make this a useful device would be appreciated
=========================================
There is an excellent article on SCR controlled power supplies in ARRL
mag QEX -July/Aug 1999 ,pages 50 - 55.
"A regulated 2400 V Power Supply by VE6AXW"
It has a 'soft start' facility and voltage control is very good (voltage
drops only a few volts between zero and 1 Ampere load conditions (and
that at 2400V)).
The SCR or triac type of control can obviously be applied to any power
supply unit . It can hence also be used for a controlled (soft start)
filament voltage for expensive high power valves (tubes)

In order not to get a 'dirty' 115/230 V AC system on the premises
,because of the SCRs /triac ,it might be necessary to include an
'upstream' AC filter.

Frank GM0CSZ / KN6WH