I collect and restore antique vacuum tube electronics (i.e. "boatanchors") and vintage solid-state gear.
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.
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.
One of my contributions was this Heathkit HD-10-A Tunnel Dipper.
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.
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.
I don’t have a “before” picture, but the cosmetics were pretty much the same as this “after” photo.
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.
This Eico Model 320 signal generator is a good example.
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.
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.
This one was made up for a Heathkit IM-28.
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.
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.
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.
For an economical service-grade instrument, it’s also well designed and crafted.
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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