Products > Test Equipment

Do you have any test equipment in your lab that uses vacuum tubes?

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schmitt trigger:
General Radio products  were truly the Rolls-Royces of test equipment for many decades.

Not only they had very high performance, but they were beautifully crafted products.

And the mechanical bits and pieces on the inside were simply awesome.

MarkL:

--- Quote from: med6753 on September 10, 2019, 07:27:43 pm ---
--- Quote from: MarkL on September 10, 2019, 06:34:30 pm ---
--- Quote from: med6753 on September 10, 2019, 05:26:02 pm ---
--- Quote from: MarkL on September 10, 2019, 03:11:39 pm ---I have two pieces of test equipment that has vacuum tubes:  A Heathkit IT-28 capacitor checker, and a Spellman 15kV @ 4mA HV supply.  The Spellman has an interesting set of gas voltage regulator tubes in addition to the usual drivers and rectifier tubes.  I've posted photos of it before:

  https://www.eevblog.com/forum/chat/how-many-psu_s-do-you-have/msg393637/#msg393637

I'm still looking for a model ID or schematics if anyone recognizes it.

I also have a tube-powered (5514/811A) Tesla coil which is physically in my lab, but it's not really a piece of test equipment.  It probably has no business being in there given the other sensitive electronics.

--- End quote ---

Judging from the photos you posted if those metal 6L6's are original I place that supply earlier than 1960. Perhaps early to mid 1950's. It does appear that the tube on the far right....probably a 5U4....has at some point been replaced. If original it would have had a glass envelope just like your 0A3 VR tubes.

--- End quote ---
Sharp eye!  Yes, I had to replace the shattered 5U4 tube when I first got the unit, so I don't know what the original envelope looked like.  It was an attractive target, sticking out on the corner like that.  Alas, the replacement 5U4 eventually died a natural death since that photo was taken and has since been re-replaced with a diode bridge equivalent.

All the other tubes are original except the two HV rectifiers inside the plastic case, at least as when purchased by me.  The HV rectifiers were not performing well.  The unit still works perfectly.

I'd believe 1950's.  Odd that there's not a trace of a model number.  Only "Spellman" on the meter faces.  Maybe it was a custom unit for someone.  I saw a similar one on ebay many years ago, but mounted in a small metal rack case with a flip-up lid to get to the tubes.

--- End quote ---

Are the HV rectifiers 1B3's by chance? From what I can see it appears so.

--- End quote ---

Close - They're 1G3.

I guess they needed more plate current than the 1B3.  Difficult to tell them apart by looking at the internal structure.  1G3 is a sub for 1B3.

med6753:

--- Quote from: MarkL on September 14, 2019, 02:49:59 pm ---
Close - They're 1G3.

I guess they needed more plate current than the 1B3.  Difficult to tell them apart by looking at the internal structure.  1G3 is a sub for 1B3.

--- End quote ---

According to the RCA Receiving Tube Manual 1G3/1B3 are identical....no difference in characteristics.

xrunner:
Um ... just a CRT scope - Agilent 54622D mixed signal scope.  8)

Addicted2AnalogTek:
I'm only a minor player in the tube gear world.  I've got a few old Tek cal fixtures:

(2) Type 106 square wave generators
067-0502-01 amplitude calibrator
Type 191 constant amplitude sine wave gen
067-0532-01 constant amplitude sine wave gen
067-0532-00 constant amplitude sine wave gen (in pieces)

This of course excludes all of the CRTs

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