Antique Electronics and Vintage Solid State

I collect and restore antique vacuum tube electronics (i.e. "boatanchors") and vintage solid-state gear.

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This page only has the most recent posts, but you can view a full index of my posts to Antique Electronics and Vintage Solid State.

Waveforms, Inc

Over on the Antique Radio Forum, a denizen of the forum going by the monicker “Bonzo” posted some new information about Waveforms, Inc

UREI Waveforms acquisition

Bonzo posted the October 1967 issue of the United and Affiliates (aka United Recording Electronics Industries) Newsletter

Triplett 850 VTVM Restoration

I’ve started restoring my Triplett 850 VTVM

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The Triplett 850 Type 2 manual is available in my Liberated Manuals section. Didier (KO4BB) also has an excellent scan of a somewhat newer manual in his repository, along with an

Heathkit HM-10-A Tunnel Dipper

Over on the Antique Radio Forum, there’s a gathering of grid-dip oscillators.

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One of my contributions was this Heathkit HD-10-A Tunnel Dipper.

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It uses a tunnel diode as the active device in the oscillator.

Heathkit GD-1250 high frequency coil

Over on the Antique Radio Forum, Steve “azenithnut” mentioned he was missing the high frequency coil for his Heathkit GD-1250 Grid Dip Oscillator.

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His GD-1250 is missing this coil. I thought I’d post some photos of the coil from my GD-1250. …

Heathkit IM-13 VTVM Restoration

After warming up on my IM-28 restoration, I went on to do my IM-13.

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I don’t have a “before” picture, but the cosmetics were pretty much the same as this “after” photo. 

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One difference is that I swapped meters with the IM-28, as the red scale on the IM-13 had faded. 

Eico 320 Signal Generator Restoration

I’ve taken a liking to the blue art deco paint scheme on Eico’s old test equipment.

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This Eico Model 320 signal generator is a good example. 

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Internally, it is a very basic two-tube signal generator, with a 6X5 rectifier and a 6SN7 dual triode. …

Heathkit IM-28 VTVM Restoration

I recently restored a Heathkit IM-28 VTVM.

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I had always wanted Heathkit’s IM-13 bench model VTVM. The IM-28 is the “new look” version of the IM-13, and I couldn’t pass it by when I saw it at the MIT Flea.

Homebrew Switchable VTVM Probe

Here’s my homebrew switchable VTVM probe.

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This one was made up for a Heathkit IM-28.

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I used a tiny SPDT slide switch I purchased some time ago from Electronics Goldmine, a 1 MΩ resistor, and a scrap of Vector board to put together the switching circuit.

Switchable VTVM Probes

Many popular VTVMs used a switchable probe: a probe that contains a one megohm resistor for DC measurements, and a switch to bypass the resistor for AC and Ohms measurements.

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For example, here is the classic Heathkit probe from my IM-11 VTVM.

RCA WG-299D Probe Repair

One of my RCA WV-98’s from the MIT lab clean-out came with a WG-299D probe that was suffering from a very brittle plastic shell. 

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As soon as I started to use it, the main shell of the probe fragmented into shards of plastic. …

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