If you have been following this blog for long, you know that I'm fond of nixie tubes. In the linked post, I cleaned up and repaired a General Radio frequency counter with a beautiful nixie display. Other people like nixie displays too, so anything that uses nixie tubes typically isn't cheap.
Truth told though, I don't need a frequency counter. I have a dozen oscilloscopes that I can use to calculate a radio frequency. Some of the better oscilloscopes have an on-screen display that displays the frequency.
I recently came across a reasonably-priced old voltmeter that has a nixie display. It's not very pretty, and it was sold as a hobby assembly kit. But it works. And it has nixies!!! Just four of them however.
This is a Heathkit IM-102 Digital Multimeter. These hobby kits were manufactured 1971-1973. I haven't done anything with it yet, other than plug it in and test a couple of voltages on it.
I plugged it into a regulated DC power supply and it read spot-on the same voltage.
Then I plugged the leads into a wall outlet to see if it would display AC voltage. Yes it does. How accurate it is, that's something I didn't check. It's approximately correct though.
I'll open it up later on and get some pictures, and clean it up. It will never be pretty, just because of the style of the case. But it has nixie tubes, so it's cool that way!
Below, a brief video by someone else who picked up one of these.
UPDATE:
I finally got around to testing the accuracy of the AC voltage of the Heathkit against one of the more modern meters. As the old saying goes: "A man with one watch always knows what time it is, but a man with two watches is never sure."
What I mean by that is that neither of these meters are calibrated. I'm just assuming that the newer voltmeter is probably more accurate than the older hobby-kit voltmeter. That could be a poor assumption.
That said, here are some pictures I took at various AC voltages. The Heathkit is reading just a tad low. Now I need to figure out how to adjust the readout.
10 AC volts. Looking good! Compare the Heathkit at top right to the Instek, bottom left.
50 Volts AC. Showing about 1 volt low.
100 Volts. Starting to show some drift now. Not much, just about 3%
And at 120 Volts AC, about 4 volts off. Not bad, but it can be better. I'll look into it soon.
2 comments:
I remember those kits but never did try any of them, but think my older brother did. How are you with old tube amplifiers? I have an old one dad gave me that has a bunch of static on it, and to the point where I can't use it. It's possible my dad put it all together but not sure about that. Also think it is rated at 55 watts per channel, with separate controls for left and right channel(one reason why I like it). I'm no good at fixing things and for reasons I think you are partly aware of. So,if we can get together sometime can you look at it? No rush as it has been this way for at least 10-15 years(perhaps more). Anyway, remembering the old Heathkits brought that old amp to mind.
Heya Marc,
I still remember those killer speakers your dad made. Bad-ass! I wouldn't be surprised if he did some other cool custom work!
Pretty sure I can get an older tube amp working again. Those are pretty cool items, and quite valuable. I saw an old Fisher tube amp go for $900 at an online auction, working condition unknown!
Usually it's just capacitors that start passing DC current when they shouldn't, and/or the knobs getting a bit scratchy due to dust build-up. All pretty easy to correct.
Let me know when you want to have a go at it!
Mark
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