Ancient Heathkit Oscilloscope

Another project: I restored an ancient Heathkit O-8 scope. The design is based upon a 5CP1 CRT as used in various WWII Military radars and IFF sets; the tube was introduced by Tung Sol in 1944. The Scope kit was built in 1952, still has all original parts and manual ! Heath apparently bought a ton of surplus military electronic parts after WWII, including a bunch of 5CP1 tubes. I understand their first or second kit was a 5″ scope, the O-8 came sometime later. Still needs some additional cleaning – and then there’s those waxed-paper capacitors that look suspicious.

A guy gave this to me about 30 years ago and it had been sitting underneath a leaking can of black paint which trashed the cabinet and front panel – so it sat in the garage waiting 30 years for a clean-up and smoke test. Pretty crude by today’s standards (hell, I am too !) but it still works! There is something about a glowing green phosphor and a red jeweled # 47 pilot lamp….and the smell of hot dust….It’s looking at a 10 KC “RF” signal from my URM-25…

The Heathkit O-8 Oscilloscope. The sweep linearity needs some work and the Sync selector slide switch is frozen in place but it does still work. The original builder of this scope bought the Heathkit C-08 Conversion Kit as an after market upgrade. (This included some improvements made in the Heath O-9 Scope kit.) The Conversion Kit consisted of the addition of an OA2 and OB2 voltage regulator tubes to regulate the B+ to the vertical and horizontal amps as well as the sawtooth sweep generator. It also included some component changes to improve the bandwidth of the scope. The builder mounted the voltage regulators but did not connect them for some reason! He also did not install the changed components. Wonder why. So I connected the VR tubes; they do the job. The component changes are yet to be done. Fun little project to restore a classic piece of test equipment from the early 1950’s. Plus, it looks cool just sitting there sweeping away….