11-10-2016, 04:20 PM
(11-10-2016, 04:00 PM)Sparks Wrote: I know nothing about it! Just assumed that 2 Volt valves preferred DC current, but it appears that as far as this tester goes, I was wrong! After replacing the diode, the LT was still AC, but I found that I now had HT. I put a B4 PM256 in it (condition unknown). I set the heater to 6 Volts, and selected 100 Volts HT. The meter needle banged right across, not with enough force to damage it though. It only went down within the scale when I turned the anode volts selector switch down to REC. But I have no idea what REC means. Maybe it is working and I have a dud valve, or maybe I am using it wrong. Don't know at the moment, but I feel sure it is almost working again. But I really need to sort out the tatty wirning on the valve-holder unit.
Bob
It's an AC tester, it applies AC to the valve electrodes and AC to the heaters, the rectifier is part of the meter set zero circuit, it provides a DC (unfiltered) "backing off" current to counter act the valves standing anode current.
If you download the manual in the link I posted earlier then scroll down to page number 1010 of that manual it will show the schematic of the business panel, if you then scroll up to the page that follows page 17 of the manual you will see that the subsequent pages give a technical description, which for yours starts at page 3 of that section..."Tester, Valve, Avo, No 1"
Lawrence.
