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.

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. …

Precision E-200-C Signal Generator Restoration

The styling of the Precision Apparatus Company E-200-C signal generator has always appealed to me.

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For an economical service-grade instrument, it’s also well designed and crafted.

Hand Calibrated Reference Frequencies

Precision supplied a hand-calibrated reference frequency chart with each instrument as part of their “Servicing by Signal Substitution” instruction booklet. …

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