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Dual Channel VTVM - Any recommendations?

Scorpion8

Scorpion8

Addicted Member
It appears that I have reached the point in my techie-newbieness that I need a dual channel VTVM. Does anybody have any recommendations for a current offering (as picking up old test equipment around my area has proven to be fruitless and it's not a thing I'd eBay)? Do they make dual channel DMMs? Can two DMMs be used to replicate a dual channel VTVM?

Help? :sigh:
 
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I don't recall ever seeing a dual channel VTVM. If you want to check voltage differentials in real time, PM me and I can walk you through a simple circuit to build that will help.

If you are doing what I think you are, you may be ready for a dual channel o-scope, not a dual channel meter.
 
I have one. It's a National (Panasonic) VP-9623A. Dual channel AC voltmeter, 300µV to 100V, and good to 1MHz. It's a bit old now but you can find used ones on the net occasionally.

Bryan
 
Let's talk about what you want to measure first then discuss alternatives to get there. This would probably be your best way to spend your $$ to get the most value for the test gear you'll use.

BTW, buying vintage test gear can be fun but you really do need at least one piece that is stable and can be trusted to provide the correct readings. Been there....done that wrong too many times.

BTW, I've never seen a dual channel AC VTVM - cute idea. I'm pretty sure our poster was asking about a dual channel scope. Right?

Cheers,

David
 
No, actually, if you look thru many many of HK's cassette deck SM's, they specify a dual channel AC VTVM. I would've attached the hk100m deck SM as an example (but alas too big), but you can find it here: http://manuals.harman.com/HK/Service Manual/hk100m sm.pdf. Starts on the 2nd page with connection diagrams. They use them on consecutive procedures to perform tape deck head alignments and such. So they gotta exist.
 
I looked at the alignment procedure and concluded you could use an o-scope alone to perform the alignment procedure.

Or, good luck on your search....
 
Scorpion8 said:
No, actually, if you look thru many many of HK's cassette deck SM's, they specify a dual channel AC VTVM. I would've attached the hk100m deck SM as an example (but alas too big), but you can find it here: http://manuals.harman.com/HK/Service Manual/hk100m sm.pdf. Starts on the 2nd page with connection diagrams. They use them on consecutive procedures to perform tape deck head alignments and such. So they gotta exist.
Click to expand...

Ok, that bit of info helps. Yes, many of the Service Manuals usually called for a test jig not unlike what was found on the manufacturing floor for those models. So, calling for VTVMs would certainly date that SM since they pretty much went away when FET-based voltmeters became commonplace in the 70s.

Frankly, I did all my tape deck alignments with a scope as many of the AC voltmeters of the 70s - at least the lower cost ones - weren't all that accurate and had limited bandwidth which affected the readings. You did have to do some math to convert the signal levels but once they were worked out, then it was a lot easier. Most DVMs today have far better specs than those old ones, too. It would be much cheaper to buy 2 of them rather than any scope or old VTVMs, IMHO.

Cheers,

David
 
So I could use two DMMs in the place of the dual channel VTVM instead? Placing one on each test spot and grounded to the same point?
 
Scorpion8 said:
So I could use two DMMs in the place of the dual channel VTVM instead? Placing one on each test spot and grounded to the same point?
Click to expand...

Yes, that's the idea. If you're planning to do tape deck alignments, where have you found alignment tapes? Seems like they'd be really difficult to source - I haven't done one in 20+ years, I'm sure, so I'm likely the one out of the loop on this.

Cheers,

David
 
I found a cheap tape (meaning price, I haven't used it yet) here. I haven't called Teac to inquire about their test tapes, but it was discussed in a recent thread. I mostly plan to do my own decks to the best electronically that I can and to "the ear" as there's no market here in my little cut-off place in the world for this type of service.
 
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