HP 521C Electronic Counter 1Hz to 120kHz test teardown 1963

[oz2cpu]

wow this monster contain 44 tubes :-)
all details here
https://youtu.be/0DHNVEqzso4

[CaptDon]

That's nothing!!! You should see their units with the mixer front ends going into the hundreds of megahertz. I think some of those had 10 columns.
Some dinosaurs are worth feeding, those old HP units are not.

[coromonadalix]

Man thats something i never saw, beautiful to say the least 

[jonpaul]

used them in 1967 at  LBL

a walk down memory lane

Jon

[Colt45]

I still regret not getting one of these from the same family, when it was available for free



My car was already full of other test equipment, is the only consolation... they are gigantic.

[alm]

Interesting device! So this was a frequency counter already? And not the older type of frequency meter where a cap is charged with pulses from a constant current source at the same frequency as the input. The HP memory page describes it as a counter but does not go into details.

Funny how this was considered portable and small...

[CaptDon]

That monster of a counter with the nixies is actually the 'smaller' version of the counter with around 10 columns of neon bulbs like the counter in your first picture. Some of those old counters used 'Beam Switching Tubes' with ten cylindrical magnets inside. I had a 4 digit El Segundo Electric audio frequency counter that used the 'ring around the rosey' glow transfer tubes. It had a syncronis line frequency motorized timebase!! Wish I still owned it, it was a real eye-catcher to see it in operation!!