Hickok 3410 Microvolt Multimeter

[radhaz]

This is an early '70s 5 digit DMM. Observations about it's design and construction are welcome. 

P8270398 by ryuuoh, on Flickr

P8270397 by ryuuoh, on Flickr

P8270396 by ryuuoh, on Flickr

P8270395 by ryuuoh, on Flickr

P8270394 by ryuuoh, on Flickr

P8270393 by ryuuoh, on Flickr

P8270392 by ryuuoh, on Flickr

P8270391 by ryuuoh, on Flickr

P8270389 by ryuuoh, on Flickr

P8270388 by ryuuoh, on Flickr

P8270387 by ryuuoh, on Flickr

P8270386 by ryuuoh, on Flickr

P8270384 by ryuuoh, on Flickr

P8270383 by ryuuoh, on Flickr

P8270382 by ryuuoh, on Flickr

P8270380 by ryuuoh, on Flickr

P8270378 by ryuuoh, on Flickr

[Rbastler]

This is really awesome   
And it has Nixies  Does it work  and what is the reference ?

[radhaz]

It works. It appears to be out on AC volts and AC/DC current. On DC voltage, it matches my in-cal Iwatsu 7602. I think that aluminum block with what looks like metal can diodes might be the reference.

[radhaz]

For camera nuts, these pics were taken with an Olympus EM-1 with 60mm Macro and 12-40 Pro zoom, all hand held.

[Muxr]

For camera nuts, these pics were taken with an Olympus EM-1 with 60mm Macro and 12-40 Pro zoom, all hand held.

That's a great system. I am still using my e-m5, love the 60mm macro. Beats the pants of my full frame 105mm Nikkor Macro lens.

[Vgkid]

Thanks for the teardown. That AL block is very interesting, the datecodes are all over the place. From 74-78

[Cubdriver]

Cool old meter and nice photos, especially impressive as you're hand holding.  What are you using as a light source?

-Pat

[Gyro]

It works. It appears to be out on AC volts and AC/DC current. On DC voltage, it matches my in-cal Iwatsu 7602. I think that aluminum block with what looks like metal can diodes might be the reference.

That aluminium block looks a bit more like an optical chopper to me. Two LEDs and 2 phototransistors as part of a chopper stabilised amplifier.

[SeanB]

Look at all those vanished companies that made the parts in there, almost all of those companies either no longer exist, or are part of another through mergers and such.

[radhaz]

Lamps are a combo halogen desk lamp with a Chinese LED ring light attached and an Ikea goose neck table lamp.

Cool old meter and nice photos, especially impressive as you're hand holding.  What are you using as a light source?

-Pat

[Cubdriver]

Nicely done.  I normally use ambient lighting, a tripod, cable release and long exposures with the lens stopped down to about f/11 for decent DOF.

-Pat

[radhaz]

Hopefully the manual I ordered for the 3400 series meters will reveal the secrets.

It works. It appears to be out on AC volts and AC/DC current. On DC voltage, it matches my in-cal Iwatsu 7602. I think that aluminum block with what looks like metal can diodes might be the reference.

That aluminium block looks a bit more like an optical chopper to me. Two LEDs and 2 phototransistors as part of a chopper stabilised amplifier.

[radhaz]

Got the manual yesterday. The aluminum block is indeed a chopper amplifier using CL9D6CS photo cells and OSL6-3 solid state lamps. The voltage reference is a 1N827A temperature compensated zener diode and LM201A opamp.

[Gyro]

Ah, that's good - they used solid state rather than the flickery neons that HP used in their early opto choppers. I went over those photos with a fine tooth comb looking for a 1N82x, I still can't see it!

[radhaz]

The 1N827 is near the three grey trim pots. Picture P8270386  has the best view if it.

[Gyro]

Aha, yes, got it. The white body threw me. 

[radhaz]

Correction on the display technology, this is a VFD display multimeter. Sorry nixie fans.

[Whiteygabe]

Hi everyone,i need the squematic or the service manual
Thanks to all
Gabe