VTVM's & Test Equipment

[Joe Rossi]

Lord willing, I'm going to be doing some steady repair/restoration work and I'm looking at equipment. E-bay has VTVM's, but I'm not sure spending close to $60 for a good (?) VTVM is sound money management. I'm seeing B&K and Extech Multimeters for $90, and wondering why I should get the old technology. Is there a solid reason to invest in old equipment? Will the new stuff hold up (ruggedness) and perform (high voltages)? Will I really have need for a 'scope (unless someone drops one on my doorstep)? I've seen the discussion on Signal generators, and I have access to a Heath IG-102; they work well. I'd appreciate any discussion and guideance. Thanks!

[Ron Ramirez]

Just about any modern DMM is a good investment. You get the convenience of a digital readout plus high input impedances for accurate voltage measurements. Some modern DMMs also read capacitance, but not all are accurate! You definitely want one that will measure voltage, current and resiatance; the ability to measure capacitance will be a bonus and could come in handy, but will cost you more.

In my opinion, an oscilloscope is a necessity. While you can get by without one, I think they are better as an output indicator than an analog multimeter. A digital multimeter is not useful as an output indicator, in my view. So, rather than buying a DMM AND an "old school" analog multimeter, I think your money would be better spent on a DMM and a 'scope.

And when it comes to 'scopes, you don't need a fancy, expensive unit. You'll be measuring mostly audio level signals and maybe a little RF but not much. So you do not need a 'scope with a huge bandwidth capability. I do not remember how high my 'scope goes, but it is in the low MHz range.

You also need an accurate signal generator, and a bonus here is a good frequency counter to check the accuracy of your signal generator. Just because a signal generator says 455 kc on its dial does not mean it is putting out 455 kc! The only way to know that is to check its output with a frequency counter.

This will involve a bit of $$$, but if you plan to repair a number of radios, I feel these things are essential.

One man's opinion...that's all.

[Joe Rossi]

Thanks Ron, your opinion is valued. I noticed that a couple of the DMM's I was looking at measured frequency and felt that this would be a plus when it came to insuring the signal generator was where it should be. I'll keep in mind (and a lookout for) the 'scope. Have a great one!

[MinnesotaHam]

Both DMM and VTVM are very useful for antique radio servicing. Both can be damaged by technician goofs, but some Fluke DMMs can survive just about any abuse they face. A DMM has more precision and percentage accuracy than a VTVM, but it usually makes no difference for antique radio repair. Nothing wrong with using a VTVM for output level measurements as techs did it for decades. A scope is great, nothing can compare to it, nothing equal to it, but not at the top of the purchase order list. High input impedance of VTVM and DMM not always an advantage for antique radio repair. They will read voltages high compared to readings on old schematics. DMMs sometimes don't respond well when fed a non pure AC or DC signal--mix some RF in the signal and they sometimes go goofy. Capacitance function works great on new caps, but may read wrong on old leaky caps due to design of that meter function. A vintage cap meter usually better for reading vintage caps. DMM better for design work than a VTVM. A VTVM will often give a better, more accurate and stable low ohms (coil resistance for example) reading than a VTVM. If I was starting over, I would purchase a DMM first over a VTVM--but no DMM will ever push a VTVM off my bench.

[Chuck Schwark]

I love both my Fluke 8060A DMM and my RCA WV-98C VTVM.
Of course, the Simpson 260-7 is right in between . . . .

[Carl Travis]

Joe,
Don't forget an isolation transformer if you plan on working on AA5 radios.

[exray]

Maybe its an odd mix but I'm sort of fond of newish test gear (albeit inexpensive models because I'm a cheapskate) even for old radios. I suppose it has much to do with what you are most comfortable with. My RCA VTVM hasn't seen the light of day in probably 10 years. My $30 no-name chinese DMM runs rings around it in every respect that I can think of. I'm much happier peaking things with a digital readout. I kinda hate to admit that but...

If I never see another tube type o'scope it will be too soon!

In the longer run it really doesn't matter that much. You have to learn how your 'tools' behave whether they are 30s vintage or 2000-era. I always use the logic that the test equipment must be more sophisticated than whatever it is you're working on otherwise you might as well do it 'by ear'. Most any gear has *some* shortcomings that can be recognized whether it was made 'back then' or today - all through the price gamut. The question is "is it significant for what you are doing" .

Fiddling with older test gear can easily become a distinct hobby in itself. Some of the guys like that sort of shopping, tweaking and twiddling just like radio guys do to obtain top performance out of the project at hand. If you are just starting out it makes sense to look for units appropriate for the task. In the case of old radios that need not require any significant investment or head-scratching. You can squeeze a lot of service out of inexpensive gear once you learn how to utilize it. And frankly, for a newcomer, thats the same amount of effort that is required for anything more sophisticated.

[Joe Rossi]

Thanks to all. I used to be in electronics years ago (graduated in 1974 from R.E.T.S. in Detroit), but went from electronics purchasing to Healthcare Materials Management, fatherhood and being way too busy. I'd 'forgotten' some things but gradually the unused info pops back, and with the Phorum I've been able to not fry myself. I gave all my stuff away (VTVM, Signal generator, Simpson tube tester, a couple-hundred tubes, arrgh!) to someone 10-15 years ago who is now using it daily, so they're in a good home. Recently, having refurbished my Allied SX-190 and restoring the Philco 37-650, I realised how much I missed doing this but that I needed more than a cheap Radio Shack voltmeter. What a joy! I'm having a load of fun. My frustration with VTVM's is that they tend to be, in my mind, either overpriced (e-bay) and/or someone is using shipping as a profit center. The DMM seemed like a great alternative choice for now, and I'll look at the next MARC swapmeet for a VTVM (I like analog meters). I'll remember the isolation transformer. Thanks again!

[Ron Ramirez]

Joe,

Too bad you're in Michigan. I'm taking some extra (unneeded) test equipment to Nashville, TN to their swap meet this Saturday.

But you should be able to find just about anything you might need at MARC swap meets.

[Joe Rossi]

Ron,

Somebody has to stay here (Michigan) to turn the lights off! Thanks for the thought on your extra equip. I'm adding pieces in due time, no rush. Have a great evening,

[Joe Rossi]

Have another question about test equipment. Found some equipment (signal generator & bench DMM) on-line marketed by LDB (ldbepurchase.com). Has anyone used/purchased this stuff? Their DMM's look reminiscent of Temna euipment. The prices were very low, $103 for the signal generator and $115 for the bench DMM. They also sell on e-bay. Thanks,

[Chuck Schwark]

Service grade RF sig gens like Heathkits, EICO 324 and the like can be found in the $15-40 range and serve just as well.

[Michael Dennis]

You know, if anyone has any recommendations for specific models of these test instruments as far as reliability, accuracy, versatility, new or used, recent models or old stand-bys, cost effectiveness, etc. I think it could be very helpful to we newbies who don't know what to pick out from a bewildering variety of equipment.

Mike

[Joe Rossi]

Mikhail raises a great idea. It would be nice if the 'veterans' could compile a list of good, relatively inexpensive equipment for the new folks to use as a starting point, and a second list of "if you can afford it" equipment. I can say from past experience that the Heathkit IM-18, IM-28 and RCA WV-98 series VTVMs are good, solid units. I can also recommend the Heathkit RF-1, IG-102 and IG-42 signal generators. The problem is, where to get them in good shape at a reasonable price. Instead, I'm opting for a Tenma 72-7750 DMM which "will run rings around" a VTVM (exray, thanks for the quote!), and am holding out for a Heathkit IG-102 or RF-1. When I eventually get a scope, I'd like to get a Tenma 72-6800 for around $300. I'm not looking to purchase a used scope that may need repair "above my pay-grade", either at the outset or afterward. For a tube tester, as long as it tests the older tubes with the two larger pins, Octals, loctals and 7- and 9-pin miniatures, Simpson, Hickock and EICO made good ones. I'm sure there are others. Heck, I once bought the tube tester from the local Radio Shack when they stopped selling 'em! Paid $5. Thanks for letting me ramble...

[Michael Dennis]

Hello Joe!

Sounds like you got a great deal on the tubetester! And it sounds like you got quite a list of recommended equipment already. Thanks for that!

Mike