Hi all,
I am in the process of restoring a huge HP 524B counter. 100 tubes
and about 100 lbs makes it qualify in spades as a boatanchor!
After looking for many years I recently found one to replace my
butchered unit which was beyond restoration.
My (slight) problem is that the behemoth I have is a later model than
the manual I have. The main difference relates to the readout system
for the fastest two decades, which are centre-zero meters calibrated
0-9. The older manual shows the staircase voltage for these meters
derived from a resistor network driven from the plates of the counter
flip flop tubes. The actual unit I have has a plug in unit labelled
"524B-65A staircase amplifier" with four 12AX7 tubes.
Does anyone have any info on this change? I suspect the amplifier was
added to reduce loading on the counters which were already pushed to
the limit of what you could do with vacuum tubes. The 10 MHz decade
counter is a very complex bit of circuitry.
Thanks, and happy holidays,
Morris
