Can you give me any info on this antique item. (non CB)

justified paranoid ..... and the carbon resisters gasp

 

I would check BAMA to see if they had anything on it.

http://bama.edebris.com/manuals/

 

agree ! a good source

 

I don't think it will help Him though. I searched. My next guess would be possibly it was made under contract meaning the same identical VTVM could exist under another company name. Something common in the WWII era test gear. In any case current flow was minute in all stages of the circuitry, so I highly doubt he will have any badly crystallized carbon resistors. If it were me and it is all there I would replace any high voltage polarized electrolytic in the power supply and add a line cord (newer grounded type, put the green on a ring terminal and bolt to a chassis screw/nut somewhere), put on my football helmet, and plug that sucker in. Oh yeah, grab a can of hexane (CRC QD Electronic Cleaner) from Wall mart and spray the controls while turning them, directing the spray inside them. Do this before you plug it in, letting it all evaporate first of course. Remember the spray is extremely flammable, do it outside.

 

A voltmeter does not have a control to vary the output... It looks like a variable AC source...

120 in/ .005 - 500 out... the transformer would bump it up.

I would place it about in the 50's.

Mark

 

It clearly says VOLTMETER ....... it may be a low power regulated PS / and meter for some test ...... Carbon resistors soak up moisture and become very unstable after 50 years ..... using TUBES in a AC power supply .... might be to somehow regulate the output voltage any rate it is probley cormmercal since military would have a label/part number / contract date

 

I know it says Voltmeter. Look at the dial. It ranges from .005 to 500. You have a dial to vary the output. A voltmeter to measure a voltage would not have a output jack.

The Tubes would regulate the output waveform since it is RMS output.

It all depends on how it was stored.

I would worry about the caps leaking.

Who knows how they labeled for the military back then. It could be on the plate on the back cover. I used items back in the 70's that did not have labeling on the front and they were in the military... The old TV-7D, tube tester we used was the exact same thing in Radio Shack. When mine went into Cal, I simply went to Radio Shack to test my tubes.

mark

 

Well, it appears to have input terminals at the bottom and the afore mentioned output jack, so something's probably going in before something else comes out. The output jack looks like a regular 1/4" job so I don't think it's for anything real critical, maybe a different meter, an amplifier, or could even be audio out. The thing that worries me most is that big green and hairy cap right in front. Variable AC supplies can be had pretty cheap, I think I paid $30 new for the small one I use at a harbor freight type of place. I use it a lot working with uncertain circuits.

 

Originally Posted by cc194217 "A voltmeter does not have a control to vary the output."

Well stupid me I was going by the label on front "Voltmeter Model 1520", and the bottom input terminals. Clearly there are two 'controls' right up front, which should be cleaned with the proper solvent (switches are also 'controls'). There will also likely be trimmers inside for calibration and when restoring all things should be cleaned. Otherwise years of dust will destroy carbon tracks as well as scratch up plated switch contacts not to mention making operation unreliable. I was restoring WWII era test gear back in the 70's so it's not exactly my first foray. Clearly the device is two instruments in one, not for a source of power but rather accurate measurement and calibration of low level audio signals, look at the decibel scale. Probably it was used in servicing by signal tracing audio gear for some military purpose. Would have also been handy in a TV shop in the 60's especially if they took in HI-FI consoles to work on. I would guess an audio source for tracing audio stages as well as measuring audio amplitude when aligning receivers. The ugly looking capacitor is not going to be a problem, it is not an electrolytic. Looks more like a foil/mylar layer rolled capacitor and these would survive a hundred years. Only the two orange Mallory capacitors would be replaced to begin with if I were restoring it and also there are no visible sweat beads on the carbon resistors. As I stated previously the currents in this circuit were low and everything looks in extremely good condition. The RMS volts and decibel scales could apply to both the source going to the output jack as well as measuring RMS or decibel input amplitudes, commonly done aligning old communications gear. As I said, it would have also been very useful in a TV shop back in the 70's. I ran one at the time and this would have been a nice addition to my bench. I still have a half dozen old tuning eye metered test instruments which I have made brand new, they are more fun than my modern equipment. Who needs digital storage scopes when you can play with cool looking tuning eye displays.

Come to think of it if you are going to toss it PM me for my mailing address, I would not mind making this thing new again. A neat looking piece of history which would still have functional use.