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Author Topic: Analog Multimeter  (Read 821 times)

RADMANCF

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Analog Multimeter
« on: June 21, 2021, 10:16:47 AM »

Hey folks, I'm in the market for an analog multimeter, and would like something that's a step up in quality from the $20 Gardner Bender unit I've been using. I've done a bit of searching and haven't found much of anything beyond imports on amazon. Apparently Fluke doesn't make any at present. My reason for wanting an analog multimeter is that I recall reading a while back that an analog meter can be better suited for measurements on tuned circuits than a DMM; am I off base on this?
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RADMANCF

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Re: Analog Multimeter
« Reply #1 on: June 21, 2021, 10:18:04 AM »

And I see I've totally fat-fingered this. I meant to post in the homebrew forum. My apologies.
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K1KP

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Re: Analog Multimeter
« Reply #2 on: June 21, 2021, 01:11:42 PM »

An analog meter is much better for certain applications, like aligning analog electronics. It's much easier to watch a needle move up and down thatn to be constantly doing math in your head while gazing at constantly changing digits, to see if they are going up or down.

I don't have a good recommendation for a modern analog meter. On my bench I have a Heathkit VTVM. I have the IM-28, but there are many incantations of the same basic design. Yes, it has vacuum tubes. Yes, it needs to warm up for a while before it settles down. But after that, it is very stable and accurate - as accurate as a 6" analog meter can be. If I need an absolutely accurate measurement I'll use my HP 3468A. But for aligning a boatanchor, watching a slowly varying analog voltage, or measuring >1Megohms without autoranging hysterics, I'll warm up the ole' Heathkit.

-Tony, K1KP
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W3PX

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Re: Analog Multimeter
« Reply #3 on: June 21, 2021, 02:03:45 PM »

Hard to beat a good old rugged Simpson 260. If you can find a nice used working one it will serve you well.

73 Frank W3PX

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"So, we just went ahead and fixed the glitch" - Bob Slydell

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K0UA

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Re: Analog Multimeter
« Reply #4 on: June 21, 2021, 02:31:27 PM »

Some DMM have a bargraph below the digital readout that is an approximation of an analog scale. This is useful when using it as a tuning aid. My "no name" Korean DMM has such a scale.
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73  James K0UA

KB1NO

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Re: Analog Multimeter
« Reply #5 on: June 21, 2021, 03:49:42 PM »

There are a couple of Analog / Digital combo meters on Amazon.     One for ~$25 and one for ~$60.
I have one that I bought years ago, but it can be frustrating because the Analog and Digital meters don't always agree.   So I seldom use it. 
You mentioned the example of tuned circuits,  so I gather that you may be measuring at kHz or MHz.   
In that case,  a VTVM or RF voltmeter may be the best tool, as K1KP noted. 

GL,
John 

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WA2EIO

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Re: Analog Multimeter
« Reply #6 on: June 21, 2021, 04:54:31 PM »

   There are various Triplett  models.  Other older units would include the RCA Voltohmists, Hewlett-Packard's HP 210B or HP 210C, and as has been mentioned, the Heathkit IM-28 series (I don't remember the model numbers, but there were 'vertical' and 'horizontal' style ones)  or the one of the venerable Simpson 260 series.   Radio Shack (MIcronta) even had some decent VOMs.    A quick search on e-bay should turn up some good possibilities.  A moving needle can be most helpful for some types of work, even more so than a moving bar graph type display. 
« Last Edit: June 21, 2021, 04:58:05 PM by WA2EIO »
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W9WQA

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Re: Analog Multimeter
« Reply #7 on: June 21, 2021, 08:07:43 PM »

cute little digital scopes for under 50 bucks can show ac or dc volts.'
so you have it all. just watch the trace as you would a needle.

i got one for 25$
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KC6RWI

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Re: Analog Multimeter
« Reply #8 on: June 22, 2021, 10:14:13 AM »

I remember the vtvm, it was one of the few pieces of test equipment that the tv repair shop had next door to a shop I worked in.
Sometimes a scope was borrowed, but mostly the shop relied on that vtvm.
I am pretty sure at one time the the tech was using it to find a bad cap, but now I wonder; if the point of the vtvm is not load the circuit how can you do that? ripple?
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W3PX

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Re: Analog Multimeter
« Reply #9 on: June 22, 2021, 10:19:31 AM »

I remember the vtvm, it was one of the few pieces of test equipment that the tv repair shop had next door to a shop I worked in.
Sometimes a scope was borrowed, but mostly the shop relied on that vtvm.
I am pretty sure at one time the the tech was using it to find a bad cap, but now I wonder; if the point of the vtvm is not load the circuit how can you do that? ripple?

Yes. Make both AC and DC voltage measurements on the B+ line.  An abnormally high AC reading will usually indicate a bad cap.

73 Frank W3PX
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"So, we just went ahead and fixed the glitch" - Bob Slydell

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K7MEM

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Re: Analog Multimeter
« Reply #10 on: June 22, 2021, 11:00:23 AM »

I have several analog VOMs. In fact, I still have the one I bought in 1965 for $3. It only had a few scales and was 1000 Ohm/Volt. So I don't use it very often.

Over the years I have found out that some people can learn to use a VOM or VTVM to trouble shoot almost anything. In the early 70's I worked as a repair technician in the production department for Burroughs Corporation (think Nixie Tubes). They provided the techs with very nice clean spacious work areas. They also provided an oscilloscope (I had a Tech 454) and a Simpson 260 VOM. All of my work was on digital circuitry so I used the scope 99% of the time.

But there were some old timer techs in the "programmer" department. A "programmer" was part of a Xerox duplication machine that set in the number of copies. It had 5 decades of counter with rotary switches that set the initial count. The count was displayed on a Nixie tube. But the internal counters were not simple ICs, like the old SN7490. Each counter section was built with 10 SCS (Silicon Controlled Switch) circuit boards. These were small circuit boards with discrete components mounted on top, and then dipped in a sealant. Just a group of 10-12 wires hung out of one side. They used these 10 section counters because they drove Nixie tubes and could easily handle the high voltage (+170VDC).

Anyway, there were tons of these "programmers". They would come in almost daily, stacked high on a rolling rack. And these old timer techs would sit there and repair them one by one. They used nothing but the Simpson 260 for trouble shooting. And they were quick. I don't think I ever saw a "programmer" sit on their bench for more than 10 minutes, before it was diagnosed and on it's way.

The only time a "programmer" was not repairable was when the Xerox tech, who was responsible for fixing the duplicator, would rip the "programmer" out of the front panel, without removing the switch shaft nuts. It would rip the rotary switches right from the units. They made a real mess of the "programmer".
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Martin - K7MEM
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KC6RWI

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Re: Analog Multimeter
« Reply #11 on: June 22, 2021, 01:39:35 PM »

I looked up that Simpson 260.
That is a meter for the OP, they still make it, for over $300.(yikes) I guess there is a market for that sort of meter?
I wonder at that price if the meter is protected against damage to meter movement if over voltage is applied?
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VK6HP

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Re: Analog Multimeter
« Reply #12 on: June 22, 2021, 08:34:11 PM »

Assuming you're going to keep your present cheap analog meter for quick and dirty tests around the shack, house and car, I'd have a look for one of the solid state (FET) types such as a Heathkit, Kyoritsu etc. from the 70s and 80s.  I'm not sure if Heathkit's drifting components had been resolved by the time of the later meters and, for that reason, I'd probably look for a good quality commercial FET unit. 

I own quite a few digital and analog meters and have recently bought a Keysight 34461A 6.5 digit meter as my "best" meter for some project work.  However, the commonest meter I reach for is a fairly new, rather basic and cheap, ProsKit MT-2017 20k ohm/volt analog meter.  My restored VTVM with a truly huge meter is great for classic radio work but I have the feeling that a FET meter would be a good substitute and would get more use because of it's convenience and portability.  Maybe there's room for one more ;)

73, Peter.
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N7EKU

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Re: Analog Multimeter
« Reply #13 on: June 23, 2021, 06:32:17 AM »

Hi,

As the OP was asking about RF circuits, a little info:

Multimeters are not made for AC RF measurements as most are limited to less than 1 MHz (and more likely less than 100 kHz.)  But they are good for making DC measurements on transistor circuits (transistor base, emiter, and collector voltages, etc.)

They can be used for making AC RF measurements if you make a simple RF probe.

Cheaper digital meters can have trouble with RF interfering with their internal circuitry, so that is the big problem.

They will all have less influence on measurements than standard analog VOM's (like the Simpson) as they are 10 megohm/V vs 20 kohm/V.

The other issue is lead capacitance affecting tuned RF circuits.  This can be overcome by adding a 1 megohm resistor to the probe of a meter lead.  You will need to add 10% to the DC reading on the meter, but that's not hard to do.

Most VTVM's and most solid statge (FET) analog meters are designed to use this 1 megohm resistor in the probe and they also have high input impedance like DMM's so they are good for DC measurements on RF circuits.  Most Heathkit solid state analog meters are simply copies of their VTVM design substituting FET's for tubes.

73,   Mark
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Mark -- N7EKU/VE3

VK6HP

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Re: Analog Multimeter
« Reply #14 on: June 23, 2021, 07:04:22 PM »

it's worth emphasizing that one of the roles for VTVMs and later FET VOMs was to measure ac, rf, signals with minimum loading in an era when oscilloscopes were rarer than they are now.  In addition to simple external rectifying probes, many better instruments had quite decent internal rectifiers and appropriate probes and cables.  For example, my venerable AWA "VOLTOHMYST" (which I mentioned earlier as the super-sized meter) has ac ranges incorporating a 6AL5 dual-diode rectifier tube which gives good measurements to a specified 65 MHz and, in practice, useful relative readings to beyond 100 MHz.
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