Category Archives: Uncategorized

Today it’s overcast and much cooler in NYC.

If you connect the filament pins (2 & 7) together a 1B3GT, or similar vacuum diode makes an excellent HV capacitor capable or at least 15KV. Filament power is not applied. You can then use it as the upper cap … Continue reading →

An interesting box rarely seen today. Internally, it’s just an attenuator and a tunable bridged T network. Operation is simple: Select 400 Hz or 1 KC. Apply signal to the input terminals at corresponding frequency. View residual on a ‘scope. … Continue reading →

From the sublime (866) to the insane: Tung Sol 7791A hydrogen diode. Current rating: is 8 peak/2 ave. amperes and 25000 peak inverse voltage. Filament eats

The 3B28 has the same pin out and filament voltage (2.5 volt @ 5 amps) as the 866 but is filled with Xenon gas rather than mercury. Peak inverse anode voltage is 10000 volts at peak plate currents of 1 … Continue reading →

Here’s an ancient RCA 866 (non-A, S envelope) being given a quick test on Triplett 3444A tube tester. At the top of the envelope you can see the characteristic blue glow of mercury vapor. Not a good idea to stare … Continue reading →

Thermometer says it’s just about 100 degrees

This is quick and easy. All you need is: One bigger tin can One smaller tin – small enough to fit inside the big one without touching the side two short pieces of wire a sandpaper a soldering iron Wash … Continue reading →

An old vacuum rectifier. Filament: 5 volts @ 4 amperes, Peak inverse plate voltage: 20,000 volts. This version has uranium glass seals around the pins. (Greenish glass ) Uranium glass is also known as “Vaseline glass”. It is made by … Continue reading →

Another beauty. Model 432 No. 13661. Weston made several versions of this meter with different full scale and voltage/amperage ratings. On the left are terminals for 75 volts and 150 volts. On the right are terminals for up to 30 … Continue reading →