On Sat, 13 Dec 2003 14:14:03 +0000, Dave Plowman wrote:

I collect old test gear as a hobby, and like to have it working too. I
recently bought a 110v valve sig gen in very nice condition and it works
fine off a 110 supply.

Looking inside - as you do - I noticed that the transformer primary was
two windings in parallel. This, of course, is common these days - parallel
operation for 115 volts and series for 230.

So I removed the transformer, and series the windings. On UK mains, under
500mA load, the heater volts are 7 volts rather than 6.3 which makes sense
if the windings are 110 volt. Will this matter?

You should get away with it as this sort of equipment isn't usually left
on for days on end - at this time of its life, anyway! If it worries you,
connect the AC terminals of a small bridge rectifier in series with the
heater winding. That should drop enough volts to keep things happy.
(ignore the + & - terminals).

--
Mick
http://www.nascom.info for Nascom & Gemini information
Also at http://www.mixtel.co.uk where the collection started.
Currently deserting M$ for linux... :-)