Quote:
Originally Posted by Captainclock
From what I gathered from the manual I saw online for the Heathkit TC-3 Tube tester it appears that the Heathkit might be a mutual Conductance tube tester because they mention a function that the tester is capable of called "Transconductance Testing" which I figure must be Heathkit's version of Mutual Conductance testing (since "Mutual Conductance" was a Registered trademark of Hickock and couldn't be used by Heathkit.)
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Capt,
Both of those testers are emission testers. Watch your model numbers. The Heath TT-3 claimed to be a transconductance tester. I have never seen a schematic, so I cannot say for sure.
The TC-3 was the plain old Triplet circuit emission tester, despite the hype used in the advertisements in the latter years of Heath.
If you are only into pre-WWII radios, either would work and the Philco would be my choice. For any other use, the TC-3 would be better choice.
If you buy the TC-3, be sure to save the online manual that you found, as someone who claims to be the copyright owner, is actively trying to get all the online manuals removed.
Remember either tube tester will have to be rebuilt. Any capacitors in the circuit will have to be replaced and critical resistors checked for drift.
If you have a choice between an open top or one with a closable case, get the one in the case. The open top ones, collect dirt in the sockets and the switches and controls get ruined by accidental bumping in shipping and in storage.
For the record, my tube tester is the precursor to Knight 600, and was built in the 1950s. I have owned it since the mid-1960's, and it now has an updated tube chart. The circuit is electrically identical to the TC-3. (My Hickok 600 is still in line to be restored.)
James