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 Post subject: New Multi-Meter
PostPosted: Nov Wed 15, 2017 11:56 pm 
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Joined: Nov Sat 24, 2012 5:05 am
Posts: 90
My meters are on the fritz and a good 30 years old. Any recommendations for a replacement meter to work on tube radios? I hear a lot about Fluke but do not know if they are compatible with tube radio work or are for modern electronics. I have a VTVM but the connection probes to make checks are kind of bulky and sometimes will not get into a tight space. Any suggestions would be welcome.

Charles


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 12:15 am 
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Location: Maryland 20709, USA
Hi Charles,

A VTVM will enable you to make measurements you cannot make with any other meter.
VTVMs include an isolating resistor in the probe. That resistor isolates the capacitance and inductance of the probe cable from the circuit being measured. So you can measure voltages in a tuned circuit that would be de-tuned and not operate correctly when measured by other instruments.

The resistor is normally used only in the DC voltage mode, but that's where you need it.

I have used an EICO 249 with great success for many decades.
It's a 232 VTVM with a much larger panel meter.

I also recommend a Simpson 260 VOM. I use that primarily for current measurements, which most VTVMs won't do.

A modern digital meter will do AC/DC voltage and current as well as resistance.
But these will not work for measuring tuned circuits like a VTVM will.

Fluke makes the best meters in the world. Many different models are available depending on your accuracy and feature requirements and the depth of your pockets.

In fact, Fluke makes the calibration instruments that are used to check and set the meters.
Image

If you want the ultimate in accuracy, get an HP 3456A 6-1/2 digit DMM*. It has infinite input resistance on all but the 1000-volt range (that one is 10 Megohms). It's fully auto-ranging. But if you lock it on the 1000-volt range you have 1 millivolt resolution.

- Leigh

There is also an HP 3458A DMM, with higher resolution. The problem is that it uses a battery backed-up memory to hold calibration information. Those batteries are all dead by now. If the battery is not replaced before it dies, the meter loses all its calibration info. Don't buy a 3458A.

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http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 3:03 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 7339
Location: Minneapolis, MN USA
Any type of multi-meter can be used on tube radios, including Flukes. There is no reason to think Flukes and other digital multi-meters are limited to modern electronics. I like my Flukes but there are plenty of non Fluke digital meters available too. Most any digital meter will have more than enough precision and accuracy for tube radios so brand is less of a concern from an accuracy standpoint. Perhaps the first major choice when considering a digital multimeter is getting a hand held or bench style. You can also get a VOM instead of a digital meter. You have lots of probe and clip sizes to choose from when using a VOM or digital meter instead of a VTVM. One thing firm personal rule is I will NOT use a cheapie $10 and under Harbor Freight meter for radio or household line current work. I relegate them to the car and flash light batteries only.


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 5:19 am 
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Joined: Oct Sun 15, 2006 12:57 pm
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Quote:
Any type of multi-meter can be used on tube radios, including Flukes.
Not quite true, as Leigh explained. They all have their place, but any one of them isn't "the" solution for every situation.

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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 1:39 pm 
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Joined: May Tue 12, 2015 4:15 pm
Posts: 23
Location: Schomberg, Ontario, Canada
The main thing about name brand metres is not that they work better, but that they probably work more safely. One of the ways off brand/cheap metres can lower their cost is to use below spec components, poor component mounting practices, bad or inconsistent soldering, and bad PCB layout practices (where low and high voltage isolation is not properly maintained). He can be a bit over the top, but Dave Jones’, destructive testing and investigation of multimetres can be interesting/amusing depending on your taste.

Yes I know, we tend to work with high voltages at low currents (rather than high currents) but there are still some interesting discussions over on Dave’s blog and forum.

There are a couple of pinned topics at the top of this forum about multimeters and safety (and ranting).

https://www.eevblog.com/forum/testgear/


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 2:17 pm 
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if you want a nice bench DMM, why go expensive? Here's a GW Instek, $30 with free shipping. I have one, it works fine.
https://www.ebay.com/itm/GW-INSTEK-DIGI ... .l4275.c10

I see a lot of the used Flukes suffer LCD screen issues. But there is 30-40 dollar deals on used flukes too.

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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 2:34 pm 
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glue_ru wrote:
if you want a nice bench DMM, why go expensive? Here's a GW Instek, $30 with free shipping. .

+1
A basic DMM will do 98% of what you need. Don't go for the absolute cheapest, however.

My aging Triplett was under $50, and has all the basic functions, including a transistor test, diode test, and battery test. It's only real issue is the test lead jacks are falling apart.

And definitely have a VTVM available. My Eico 249 was under $20, including a recap.

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"It's always something". --Gilda Radner (1946 - 1989)


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 3:40 pm 
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if you want a fluke, here is a True RMS 8010a, about $41 w/shipping.
https://www.ebay.com/itm/Fluke-8010A-Wo ... 2722117822?

there are some deals to be had. I'll have some Heathkits VTVM IM-13/28's for sale shortly. Just finishing 4 of them.

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 Post subject: Re: New Multi-Meter
PostPosted: Nov Thu 16, 2017 8:44 pm 
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Joined: Nov Sun 07, 2010 7:16 pm
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Location: Rochester, MI
Because of the way they're constructed, almost all current DMMs, regardless of price, are reasonably accurate. Some more than others, of course, but even the throw away HF meters will mostly be right on. What the extra cost buys you is engineering and quality components that make something last. I like Fluke and the one I bought 30 years ago is still working fine (although it needed a replacement display). I also have had Triplett and Beckman which were fine. Check out the reviews, there are lots of relatively inexpensive DMMs that are good buys. I don't know if they'll last 30 years, but 5 is not an unreasonable expectation. I don't think any consumer item is built to last longer than 5 years any more anyway.

I also have some of the HF meters which are worth what I paid for them. I keep them around the garage for low voltage work; I wouldn't use them on high voltage. Might be OK if you replaced the probes, but for that amount of money you might as well buy a good meter to start with.

One thing you'll see on many DMMs is a plethora of features - frequency counters, capacitor ranges, transistor testers, etc. I've never cared for those, but they appeal to some people. I find those functions to be somewhat limited in capability and prefer separate instruments for those things. Still, if you're limited in space it's probably better to have a poor instrument than no instrument.


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 12:32 am 
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You can make a probe with a 10 meg resistor to isolate the DMM when making voltage measurements on high impedance circuits like avc, just multiply the reading X2. I do this with my Fluke 87. Don't use the VTVM much these days. The old time radio guys would have gone bonkers if they saw the auto ranging DMM's we have today!


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 2:04 am 
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Location: Tucson, Arizona U.S.A.
Quote:
I see a lot of the used Flukes suffer LCD screen issues.

My Fluke had dim/missing segments in the LCD display twice. I took it apart, cleaned the contacts on the display, PC board, and zebra connector and it went back to normal. I wonder how many people that have LCD problems try to fix it before replacing it?

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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 2:45 am 
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For general electronic work, I have a DMM similar to this:
http://www.newark.com/tenma/72-10410/digital-multimeter-dmm-auto-manual/dp/26W7010

For antique electronic work, I have a Weston 785 VOM, a Triplett 850 VTVM, and for RF a GR 1800B VTVM, depending on what I'm trying to measure.


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 2:57 am 
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Regarding accuracy...

I'm an accuracy freak. In fact, I have a complete voltage calibration system in the lab.

But schematic voltages usually have a tolerance of +/- 20%, so the meter need not be accurate.

- Leigh

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http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 3:14 am 
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Leigh wrote:
Regarding accuracy...

I'm an accuracy freak. In fact, I have a complete voltage calibration system in the lab.

But schematic voltages usually have a tolerance of +/- 20%, so the meter need not be accurate.

- Leigh

I built and repaired LOTS of stuff using nothing more than a VTVM and a low-end Heath signal generator.

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"It's always something". --Gilda Radner (1946 - 1989)


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 3:19 am 
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pixellany wrote:
I built and repaired LOTS of stuff using nothing more than a VTVM and a low-end Heath signal generator.

Me too. EICO 249 VTVM and an EICO sig gen.

That was back before I could afford the nonsense I have now.

- Leigh

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http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 4:23 am 
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Modern voltage references are plenty reliable for what I'm doing.

For reference I use my DMM and a Tek 2247A scope/counter. Since I'm not working any more I have to get by with those.

Funny story though, I was monitoring line voltage just a couple weeks ago and it started looking really low. Took me a couple hours, but I finally realized the battery was low in the DMM. :P


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 6:07 am 
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Quote:
The old time radio guys would have gone bonkers if they saw the auto ranging DMM's we have today!
I AM an old time radio guy, and the only thing that drives me bonkers is those last couple digits that never stop dancing around.

Quote:
...schematic voltages usually have a tolerance of +/- 20%, so the meter need not be accurate...
Amen to that, so a 3% analog meter is plenty good enough. Right?

The VTVM needle swings up scale and settles in about a second at 230 Volts. Oh, anything between 180 and 270 Volts is OK? Guess we're OK on this one Charlie. Next? Meanwhile, the digital is still sampling,"but getting ever closer".

Don't get me wrong, digital meters definitely have their place, but, like much of the test gear many of us have today, they're certainly over kill for what we do.

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 Post subject: Re: New Multi-Meter
PostPosted: Nov Fri 17, 2017 7:36 am 
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I have one of these which is well worth the price and does everything I have needed to on antique radio repair. And a fair price.
It also comes with an extra very nice handheld meter w/clamp probe for reading current on any AC wire around the house. Also comes with an AC non-contact sense probe.

https://www.ebay.com/itm/Extech-TK430-T ... SwWnFV8IIm

Image

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Last edited by Pbpix on Nov Sun 19, 2017 12:05 am, edited 1 time in total.

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 Post subject: Re: New Multi-Meter
PostPosted: Nov Sat 18, 2017 10:25 pm 
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Joined: May Sun 06, 2007 2:52 am
Posts: 2524
Location: Central New Hampshire
PaulAm wrote:
..... What the extra cost buys you is engineering and quality components that make something last......
.......


And most importantly-safety.A lot of those Chinese meters claim to be category III and IV rated and aren't.


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 Post subject: Re: New Multi-Meter
PostPosted: Nov Sun 19, 2017 12:08 am 
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Joined: Jan Mon 24, 2011 6:03 pm
Posts: 293
Location: Selkirk,MB,Canada
I have a digital meter that always worked fine.Then one day it quit so i checked the battery.The 9 volt battery was down to 3.5 volts,and the meter worked perfectly up till that point.I was really impressed.


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