Metropoulos Forum

For all those who buy vintage tubes that sellers claim to be strong and "like new" or "NOS" and then realize you purchased a dud I say get yourself a tube tester!

Here is my 1963 Hickok 539c. A beautiful piece of test equipment hand wired and built extremely well. I have owned it for some time now and am in the process of re-calibrating it. This time around though I replaced the 83 Mercury vapor rectifier tube with a solid state replacement. Easy to construct using a few diodes and a 4 pin tube socket, I added a large aluminum heat sink to the tube bracket where I then attached the necessary 2.5ohm wire wound resistor. This will reduce the heat otherwise generated by the 83, as well as eliminate the stress that the 83 put on the transformer. I have a 3.3ohm resistor staged on the heat sink as well just in case I want to eventually replace the 5Y3GT tube.
This mod can easily be reversed as no permanent holes were drilled.

I also finally replaced a few of the capacitors that were way out of tolerance - this has been a fun project and having a fully calibrated vintage 539c is the best way to weed out the good eggs from the bad

Very nice! I have a 539C also, but yours is much nicer than mine. I did install diodes in place of the 83 also. But I didn't add the resistor. I'll have to do that next time I pull it out. Thanks for the info.

I agree, a tester is essential.

George

Hey George take a look at the attached - this is from Bill Eccher.

I was lucky enough to get hold of one of his 539c All-In-One Calibration units that was designed by Bill and built by TubesLab - works like a charm!

Mike

Great info, thanks!

george

I have a 533A that I believe is essential. I have bought some random lots of NOS tubes off ebay and found out that yes indeed they are in good shape. I just wish I had a VTV tester to check for noise. Who makes a tester like the VTV for noise besides installing them inside an amp?