Heathkit IM-13 VTVM : Test and Calibrate
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- Опубліковано 1 жов 2024
- Heathkit IM-13 VTVM : Test and Calibrate
In this video I finally get round to having a look at the Heathkit IM-13 VTVM that I bought from Ebay before Christmas last year. Built sometime between 1964 and 1968 this vacuum tube voltmeter is a very clean example of the model. It hasn't suffered badly from leaky battery syndrome and has a fairly damage free meter.
The first thing to be done is a basic safety check to see that internally there are no loose wires, broken components or stray bits of metal that could lead to a fatal electric shock. After that is done I decide to replace the 50 plus year old capacitors rather than test them because it seemed pointless to have to remove them to test only to have to replace them at a later date. Some of the resistors have changed value but not to any significant amount so I decided against doing a full rebuild as I had done in the V-7A meter that was shown in a previous series.
I then go into a full calibration, showing that the meter itself isn't too bad after a bit of a cleaning of the potentiometers. Without doing the rebuild, the accuracy is not as good as some more modern test equipment but it is ideal as an indicative meter and actually is better for some tasks than modern digital equipment. I plan to use this on the bench for amateur radio, vintage radio restoration, general radio repair and any other task that requires an analogue meter.
Hi George, just found one of these here in Peru. Curious you did not verify the capacitor polarity prior to placement.
Sorry, that was just experience and knowing by sight which polarity was which. I did not explain that which was an error on my part.
That is a nice VTVM, it is very stable unlike my RCA Voltomist which even after calibrating it will not stay, switching between "-" and "+" DC voltage range the needle has to be adjusted every time.
I know I could improve it with modern components at 1% tolerance instead of the 10% ones it has but it wasn't so bad as to warrant it. Maybe in the future...
Never had a heathkit so it's ll greek to me, lol. I do have a VTVM but mine was made either by or for DeVry as that's it's brand name anyhow. I've never seen that type of Everready, I suppose the equivalent here would have been the chrome looking battery with the cat jumping through the number 9 on it. Been quite a few years since I've seen one of those myself.
I actually have a 9 with the cat on it here somewhere! Turns out that this one is from around the time the meter was built, and it was a special high power zinc chloride battery rather than zinc carbon. I found a group online who collect batteries and cells and they identified it for me!
Nice job on the Taylor 22 George, man that one was really grungy! Looks like a neat little fault finder/ST. Your repairs are first rate sir!
Many thanks Gregg. I don't like doing a half job if I can do it properly, especially for my own test equipment. Occasionally I will throw something together to get it working or as a demonstration but I don't like doing it all the time.
What amazes me about the battery...it did NOT leak....try that with a battery today.............
I know! I have new batteries that kill terminals in six months, let alone 50 years.
Looks like a pretty clean VTVM!
I was surprised how clean it was inside too. I was expecting it to be filthy and full of corrosion.
A Heathkit VTVM is a Heathkit VTVM. Different cases, different colors, same circuit. 😁 That one capacitor you changed looked awful small for a 1600 volt unit.😋 👍👍
Yep. The original in that spot was rated at 600v and I put in the 630v one. The two ceramics were rated for 1.5Kv but all the others were lower rated than what I put in there. I have still to work out if this was supplied built or was a home build. It is very neat for a home build but then, that isn't uncommon for stuff made back then.
Hello George, I love the vintage test gear and enjoyed the video. If you have time in some of your repairs to explain how the important circuits work and maybe have a look at the schematic, we newbies will learn a lot I'm sure. I've been successful so far in restoring quite a bit of vintage test gear by replacing components but I'm still struggling somewhat with understanding the role the "bits" I'm replacing play in how the machine operates. There, I used "bits" for components. What is happening to me? Must be the effects of those lava lamps. Doc.
I can certainly add stuff like that in. I do try and keep things simple so I can understand them myself. Much as I learnt all of this, it was the theory side that I really didn't get on with but it is a necessary part of the process. Oh, lava lamps... I now have Alexa controlling them because I am too lazy to reach behind the desk to turn them on and off. Might have to do the soldering iron next.
Amazing that the battery was that old and not corroded my vtvm I worked on the IM7a the battery was extremely corroded so lucky you. Very nice looking VTVM on the inside and outside George looks like you really lucked out buying that one.
I was actually very impressed with how clean it was inside. The battery itself turned out to be one of the first of a range of zinc/chloride batteries instead of the standard carbon cell. I actually found a group who collect batteries online!
I was surprised to see an HPII in there, did you get any voltage at all? I still have an SPII that hasn't leaked but has no voltage. It came from the UK with me in '75
@@Wenlocktvdx At one point it seemed to read 1.6v but I think that was just an error because I never had another voltage after that.
Merci 👍