Hi Magnus,
that should be pretty much identical to my recently acquired Racal MA259
that consists of a SA500 5 MHz oscillator and PU525 power supply /
battery pack.
The batteries have already been replaced by a 'battery simulator'. I
haven't looked inside yet, but it consists very likely just of a number
of series connected Z-diodes.
The diodes should be dimensioned to handle the high charge current of
200mA. The charging current is already limited by a series resistor, so
nothing else should be required.
A larger electrolytic cap in parallel to the Z-diode stack appares to
make sense.
I replaced all of the notoriously unreliable carbon composite resistors
in the oscillator and inner oven circuit.
Tonight I wound a new toroidal transformer for the inner oven
temperature control bridge.
The old one had developed a short between the primary and secondary
windings that I could make disappear for a while though not permanently.
Unfortunately, tonight it became conductive again and my 2nd attempt to
burn it away ended with a completely burned away winding.
However, at the first repair attempt, I had measured the inductance
values of the original transformer.
Thanks to Sulzer's brilliant idea to include an independent inner oven
temperature indicator, I was able to verify that nothing has changed.
Now I'm waiting for the frequency to stabilize again, which I'm
expecting to happen within the next 2...4 weeks.
Adrian
Magnus Danielson schrieb:
Fellow time-nuts,
Yesterday I picked up a Sulzer 5A + 5P without batteries. It is
supposed to have 21 D-cell NiCd batteries, but today those are not
easy to come by, so I wonder if I can either run the PSU safely
without battery or if I can swap in lead-batteries.
I know that some of you have these, so I would value your input.
I did try to run it a short time without batteries, but the 5 MHz
output did not work very well, so I turned it off.
Cheers,
Magnus
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