Merc-o-Tronic 172 Peak Kilovolt meter – History? | Antique Outboard Motor Club,Inc

This topic has 16 replies, 8 voices, and was last updated 8 years, 3 months ago by powerabout.

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July 1, 2015 at 12:11 am #1908
legendre
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Came across this today, "Merc Tronic Model 172" peak-reading kilovolt meter. I have what appears to be the front panel, with meter, switches, jacks, circuit board and a pair of 9V battery connectors coming off the rear. There is no rear case, just the front panel electronics.

What’s the history of this equipment, and how / where was it used? I assume it’s for ignition work of some sort, but..
July 1, 2015 at 12:51 am #19261
legendre
Participant
I took a moment to test it out, and it seems to be in working order. Using a pair of 9V batteries for power, the 6V, 60V and 600V scales respond roughly as expected with a 10V (DC) input to the PV jacks. The "set" knob also zeroes the meter, as it should.

Presently, the working assumption is that PV = Primary Voltage and KV = Kilovolt (Secondary) Voltage.. which if correct would mean they were very loose with their ‘standard’ nomenclature.

One thing really doesn’t make sense, though. Take a look at the back side of the panel.. both sets of jacks are wired in parallel! They’re swapped for polarity / phase, but otherwise, they are hard-wired together. Why would they need to do that?

ETA: No replies of this writing. Not surprising, as the Google doesn’t know anything about the mdl. 172. There are references to other Merc-o-Tronic instruments, but they concern a tachometer or two, and a couple other basic instruments.

Otherwise, it’s like the 172 never even existed.. 😉
July 3, 2015 at 4:07 am #19380
legendre
Participant
Last pop..

So apparently no one knows anything about this piece. It’s not real surprising, as a google search turns up nothing.. must be I have the only one in the world, or something. I did learn that Merc-o-Tronic turned out a few different instruments, like tachometers, dwell meters, coil testers, standard items like that. But this one is an orphan, for now.

One other thing I noticed.. there aren’t many parts on the board, and nothing looks like it’s built for dealing with 60kV! There are a couple very high-value resistors (22M, 10M) and the lone active device – an LM308 op-amp – has a very high input impedance, on the order of 40M or better.

So it might be possible that it can handle those levels, though I’m still doubting it. It’s like something else (important) is missing from it.. I’ll have to come up with a serious HV supply to test it, though.
July 3, 2015 at 4:14 am #19381
phil-b
Participant
Merc-o-tronic is still around, but their web site isn’t working…

215 Branch St, Almont, MI 48003
(586) 894-9529
July 3, 2015 at 6:02 am #19384
legendre
Participant
Hey Phil.

quote Phil B:

Merc-o-tronic is still around, but their web site isn’t working…

215 Branch St, Almont, MI 48003
(586) 894-9529

I checked archive.org and it seems that there was a site, but it’s been way gone since 2013 or so. Here’s a snapshot from 2001 that has a few models listed. The 172 isn’t among them.

So this might be a silly question, but I was assuming that Merc-o-tronic was the house brand for instrumentation produced by/for Mercury marine.

Is it now, or was that ever the case?
July 3, 2015 at 6:27 am #19386
debe
Participant
Might be worth posting a picture & Question of it on Smokstak site, in Magnetos-ignition coils& spark plugs. Its free to join & post pics.
July 3, 2015 at 9:45 am #19390
billw
Participant
US Member - 2 Years
I have something hanging on my wall in the dungeon that is VERY similar looking in my mind…..but I thought it was a Stevens. I will have to check that out later today…..

Long live American manufacturing!
July 4, 2015 at 1:08 pm #19445
phil
Participant
US Member - 2 Years
There may be a high voltage probe missing from the input side. 172 KV is going to need a lot of insulation.

http://www.omc-boats.org
http://www.aerocraft-boats.org
July 4, 2015 at 2:06 pm #19446
frankr
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US Member - 1 Year (includes $3 online payment fee)
I think Phil nailed it. Needs a high voltage probe.
Could it have been intended for TV work? They used high voltage for the CRT.
July 5, 2015 at 6:34 am #19496
legendre
Participant
quote FrankR:

I think Phil nailed it. Needs a high voltage probe.
Could it have been intended for TV work? They used high voltage for the CRT.

That’s entirely possible, though I don’t know why they would have bothered to implement those lower voltage scales.. what’s the use?

Also, I was under the impression that Merc-o-Tronic limited themselves to making instruments for the mechanical service industry.. had no idea if they made instruments for electronic (TV in this case) servicemen.
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