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 Post subject: Test equipment
PostPosted: Feb Thu 01, 2018 6:35 am 
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Back in the late 60's and early 70's I used to do some radio repair. The only test equipment I have now is a tube tester, what kind of tester or multimeter do you all recommend for testing capacitors and resisters? I just need to get some ideas, thank you!

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 Post subject: Re: Test equipment
PostPosted: Feb Thu 01, 2018 2:13 pm 
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Start with a digital multimeter (DMM). There is a wide range of choices, but the basic requirements are simple: measure AC and DC voltage, current, and resistance. There are many other features, but I would avoid paying extra for a feature if you don't know why you need it.
<<brace yourself for a flood of opinions as to the "best" model.>>

Other things that you should consider:
Variac with voltage and current meters**
Isolation transformer
Signal generator
Oscilloscope***

None of this directly addresses testing of capacitors. Many of us test caps only rarely....certain types are simply replaced on sight (eg electrolytics, paper/wax), and most can be tested for leakage using a DMM. For the occasions that you really need to test the value of a cap, the best choice is an impedance bridge--which also provides for measuiring inductance and resistance (more accurately than a DMM). For the best leakage testing, you need a variable HV power supply.

** for controlled startup of a radio. You'll also hear about "dim-bulb" testing, but I recommend the Variac approach. (Many threads on just this debate). The variac is useful for many things beyond startup.

*** a scope might be used infrequently, but it is very often the most powerful tool in the shop. I would personally never be without one.

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 Post subject: Re: Test equipment
PostPosted: Feb Thu 01, 2018 3:31 pm 
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Thank you!!

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 Post subject: Re: Test equipment
PostPosted: Feb Thu 01, 2018 3:33 pm 
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Be prepared for the onslaught! There will be as many opinions as there
are people on ARF. And no one will be wrong. My suggestions for good,
solid equipment that can be found fairly easily and are a good value;

VOM; Simpson 260
VTVM: RCA/VIZ WV-98C
cap checker; any of the Heathkit or EICO units with an eye tube
RF signal generator; HP 606 and HP 608 if you need to go > 20 MC
audio sig gen; HP 200CD (or any version)
'scope; Tektronix 465
a good variac and isolation transformer are important items too

a controversial item that I really like are the chinese multi-testers,
model M328 available on ebay for less than $20
Steve

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 Post subject: Re: Test equipment
PostPosted: Feb Thu 01, 2018 3:50 pm 
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+1 to the above, and some comments

#1 - I consider an isolation transformer to be absolutely mandatory. It's used to power the radio you're working on, and only that one item. All other equipment plugs into the wall as usual. This arrangement breaks the connection between the AC power line and earth ground, eliminating a shock hazard. An isolation transformer can save your life.

A Variac (variable AC transformer) is a useful item, allowing you to set the line voltage to the exact value used at the factory for taking measurements shown on a schematic. These come in many sizes, from 1 or 2 amp rating to huge 3-phase units designed to control auditorium lights. This item is a useful adjunct to an iso, but NOT a substitute for same.

#2 - A VTVM (Vacuum Tube VoltMeter) is uniquely useful. These meters have an isolating resistor right at the probe tip, so you can make DC voltage measurements in resonant circuits without disturbing their operation. No other type of meter, vintage or modern, can do this.

#3 - You do not need an oscilloscope to repair old radios. You may want one or prefer one over other instruments for some measurements, but you don't need one. They take up a lot of bench space and cost a lot of money (if they're any good).

#4 - As Mark said, certain categories of capacitors just get replaced without testing. That's because their failure rate is so high that testing them is just wasting your time. If you want to test them, an instrument like a Sprague TO-series TelOhmike bridge or an Eico 950B work well. A DMM is useless in testing for leakage because it cannot apply full rated voltage to the cap.

#5 - A VOM like a Simpson 260 (my favorite) or a Triplett 630 is very useful. These measure the same voltages that the VTVM measures, but also measure current, which VTVM's don't.

#6 - An HP 606B signal generator is an excellent piece of gear, but rather large. If you have the bux, you might find a more modern digital generator easier to work with since you can usually bump them up and down to the band edges quite easily.

DO NOT get a modern function generator or anything that puts out square waves, triangles, etc. These are not suitable for doing receiver alignments.

#7 - Any equipment not listed is generally selected by personal preference. You can end up with lots of goodies if you want. I have four 8-foot-wide benches stacked 3 feet high with gear.

- Leigh

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 Post subject: Re: Test equipment
PostPosted: Feb Thu 01, 2018 4:00 pm 
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zarco wrote:
Be prepared for the onslaught! There will be as many opinions as there
are people on ARF.
more....;)

HP606 and 608: Nice choices, but do you enjoy dealing with big heavy things? Lot's of good options that are MUCH smaller

HP200CD: Yes!!! I just finished refurbishing mine. Almost exactly 1/2 century ago, I was using and repairing these in the cal lab of General Dynamics in Pomona, CA

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 Post subject: Re: Test equipment
PostPosted: Feb Thu 01, 2018 8:22 pm 
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The fact that nearly everyone on this forum replaces certain capacitor types without testing them reflects the fact that we are generally restoring vintage equipment rather than doing repair of more modern equipment. Two somewhat different mind sets. Usually you can't make a living restoring vintage electronics, its more a labor of love or hobby.
If you would by working on FM radios or TVs a scope would be very useful. Then you would be getting into sweep generators and such.
Another point about VOMs is that many voltage measurements are documented in service data using them and the slight current load is accounted for.
Analog meters make adjustments and alignment easier.

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 12:03 am 
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Lots of good opinions here but you asked about testing capacitors and resistors without regard to what they are in. Test equipment is determined to a certain extent by what you intend to test with it.

If you are working on vintage tube gear, vintage test instruments can be a great way to go. They will give results comparable to the measurements and readings in old service manuals, and will test old parts the way they were tested back in the day. If I was going to pick one instrument to own, it would be a decent VTVM. There are lots to choose from, but the B&K 177 or the RCA WV-98C are two of my favorites. As for something that tests resistors and capacitors directly, RC bridge like an Eico 950B, Heathkit C-3, IT-11, or IT-28 is good to have. You'll find it most valuable for testing parts like mica and ceramic capacitors which are not normally replaced unless bad, and for checking new parts before you put them in. You'll get tired of testing old electrolytics and paper capacitors as the majority of them will fail in one or more ways today.

With most VTVMs and some bench DMMs (digital multimeters), the negative or common lead connects to the chassis and case of the instrument. This makes them unsuitable for line voltage measurements. So you should look for a VOM or battery operated (hand held) DMM to handle situations the VTVM cannot.

There is a type of capacitor tester that has no bridge dial on it, just an eye tube and a couple of knobs or switches. These are intended to discover open or shorted capacitors without disconnecting them from the circuit. Such testers are not of much use today since they do not check for leakage with high voltage, and that is the main thing of interest when testing both old and new capacitors.

With solid state gear, voltage and resistance levels become more critical and you should consider a new digital multimeter (DMM). There are many choices and price ranges available, from free if you have a Harbor Freight coupon to many hundreds of dollars if you want a Fluke or a FLIR with every safety certification necessary to use it on power lines anywhere in the world. Your best bet is with mid-range meters which are aimed at the technician market; Extech and Amprobe are just two examples of many brands that are available. Most full featured DMMs can measure capacitance, audio frequencies, and test transistors. If you plan on working a lot with newer solid state gear, an ESR meter may come in handy. This is basically a low range ohmmeter that uses low voltage AC to check for open electrolytics without unsoldering them from the board.

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 2:05 am 
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If you are going to get a digital meter be sure it has an input resistance of 10 megohms (or more but those are rare). Many of the cheap ones are only 1 megohm and won't give as accurate readings in some circuits (although they are fine other places). One quick way to spot a cheap one is that the lowest AC voltage range is only 200 volts but the real way to tell is to look at the spec sheet. BTW, you will need to make AC measurements much less than 200 volts as well.

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 12:11 pm 
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The bottom line here is that you will need to have all three types of instruments. Chris' recommendation of the RCA 98 or B&K clone is an excellent choice for a VTVM, and either a Triplett 630 or Simpson 260 are the best of the VOMs.

As for DVMs there are more makes and models out there than you could evaluate in a life time. I suggest you can either spend a lot of money on a Fluke DVM, or a little money for a Harbor Freight model 37772 DVM. When it comes to "on the bench hobby use" an expensive DVM is for the most part, just throwing money down a rat hole. I have both digital meters mentioned, and from a practical point of view, there's no significant difference, and the HF meter actually has far more measurement capability than my Fluke 27FM.

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 2:06 pm 
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You can get a larger bench DMM for $32 and up. GW Instek, maybe not NASA quality, but are you in a life and death adjustment?
I have one, it works just fine, and if it breaks or blows up, it's disposable and get another. But for a $100, you can get a brand name,
true RMS and all the extra stuff you may never use.
https://www.ebay.com/itm/GW-Instek-GDM- ... SwXsFac0wU

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 2:53 pm 
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Quote:
HP606 and 608: Nice choices, but do you enjoy dealing with big heavy things? Lot's of good options that are MUCH smaller


What would anybody want with a HP-608 for in antique radio repair? It's a cubic yard of electronics that is as heavy as it looks, and goes from 50 MHz into the stratospheric UHF range, AM, CW, or pulse. If fixing FM radios is a concern, there are much more practical signal generators one could get--some of which even produce FM!

The lower frequency HP-606 is of course better suited for antique radios, but even that is massive overkill (emphasis on "mass.") How often do you really need to force three volts of RF into something? If you cannot fix and align a household radio with an Eico 324 or a Heathkit SG-8 or an RCA WR-50B, or the many other similar small signal generators out there, you probably won't get any further with a HP boatanchor either.

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 3:38 pm 
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Chris108 wrote:
Quote:
HP606 and 608: Nice choices, but do you enjoy dealing with big heavy things? Lot's of good options that are MUCH smaller


What would anybody want with a HP-608 for in antique radio repair? It's a cubic yard of electronics that is as heavy as it looks, and goes from 50 MHz into the stratospheric UHF range, AM, CW, or pulse. If fixing FM radios is a concern, there are much more practical signal generators one could get--some of which even produce FM!

The lower frequency HP-606 is of course better suited for antique radios, but even that is massive overkill (emphasis on "mass.") How often do you really need to force three volts of RF into something? If you cannot fix and align a household radio with an Eico 324 or a Heathkit SG-8 or an RCA WR-50B, or the many other similar small signal generators out there, you probably won't get any further with a HP boatanchor either.


Yes, the HP 608 and even HP 606 are huge and take up lots of space.
The reason they are on my list for someone building up their first test
bench is they are top notch instruments, available, repairable and
cheap. The HP 608 is something more useful to hams (like me).
Its claim to fame is its excellent shielding and calibrated output
attenuator that can output levels below 0.1 uV. You won't find
a modern instrument capable of this.

Why waste money on crappy Heath, EICO, RCA or other low end sig
gens when you can get top notch gear cheap? And the HP will
help warm the shop on cold days. ;-)
Steve

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 4:01 pm 
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Quote:
And the HP will help warm the shop on cold days. ;-)

I keep my Tek 585 around for that ;-)

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 Post subject: Re: Test equipment
PostPosted: Feb Fri 02, 2018 4:37 pm 
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Barry H Bennett wrote:
Quote:
And the HP will help warm the shop on cold days. ;-)
I keep my Tek 585 around for that ;-)
A 585 will certainly accomplish that... in the Arctic.

- Leigh

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 Post subject: Re: Test equipment
PostPosted: Feb Sat 03, 2018 1:09 am 
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 Post subject: Re: Test equipment
PostPosted: Feb Sat 03, 2018 3:17 am 
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Retired Radio Man wrote:
Don't forget the forklift.

RRM


You know what they say, "strong back weak mind".....

Seems like I'm in the minority here where large and heavy equipment
is concerned. But the way I deal with it is to put the large stuff
in an equipment rack next to my bench. The only test equipment
permanatly on the bench are a Simpson 260 and WV-98C.
Also hand tools and soldering iron. Everything else, including the
HP 606 and 608 are in the rack. This helps keep the bench clean
(well, sort of) and allows more room to work.
Steve

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 Post subject: Re: Test equipment
PostPosted: Feb Sat 03, 2018 3:48 am 
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I think there is some merit to the space heater aspect of the gear mentioned, but on a serious note, the old 606 though fairly big will, after a few minutes, stay on frequency, put out only one frequency, provide fairly well calibrated(+/- a db or two) output levels, has a built-in frequency calibrator, gives fairly accurate modulation levels, and doesn't leak R.F., important when you're trying to determine how sensitive your receiver is. The generator is ideal for servicing most any HF receiver with a frequency range of 50KC up to 65MC, so it can also do any of the low frequency I.F. strips.

Image

Image

I used a 606, 608 and 612, for probably 10 years, and although they aren't sleek push button all mode generators, they are well engineered quality built equipment.

BTW the 608 covered 10 to 480 MC.

Image

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 Post subject: Re: Test equipment
PostPosted: Feb Sat 03, 2018 3:58 am 
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Mikeinkcmo wrote:
BTW the 608 covered 10 to 480 MC.
Hi Mike,

Different versions of the 608 had different high-end frequency limits.

I too have a 606B. Excellent generator, solid and stable as a rock.

- Leigh

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 Post subject: Re: Test equipment
PostPosted: Feb Sat 03, 2018 4:29 am 
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Quote:
Different versions of the 608 had different high-end frequency limits.
True, the A/B went to 500MC, the C/E/F went to 480MC and the D to 420MC.

Hard to believe, but the 608 was introduced in 1950 and the last "F" rolled off the line in 81.

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