• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Mystery tubes on FB?

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OK, I've seen a lot of tubes but not miniatures with plate caps -- a friend posted this pic on FB -- can anyone identify:
 

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Yes, looks like a PL81 (or maybe EL81). PL81 and PY81 were very common in European black&white TV sets. PY82 is a supply rectifier, with no top cap.

Probably rare in the US is the Brimar 6BS7, a miniature low noise pentode with a top cap for the grid. Probably a variant of the 6BR7.

Philips, it seems were a little confused on the subject of top-cap for the PY82; the line drawing shows the anode connection at the top of the valve, whilst the base diagram shows anode at pin 9!

I had a Marconi valve voltmeter that was fitted with 6BS7 (or 6BS8?) with grid top caps. I converted my Quad IIs to run 6BR7s as suggested by Chris Beeching. Very satisfactory.

7N7
 
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