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previous: Steve Keay In the Amp FAQS, R.G. has noted put... -- 9/8/1997 10:03 AM

Re: rectifier diodes

9/8/1997 11:47 AM
R.G.	Re: rectifier diodes Hi, Steve. Lemme see... A rectifier tube looks like two diodes, the anodes connected, one each, to the two wires from the power transformer, and the cathodes (bar end) connected together and also connected to the filter caps. The mod is to just put a silicon diode in series with each transformer wire, one per, into the rectifier tube, cathode to the anode of the rectifire tube. That way, the rectifier tube can short out and the diodes still prevent AC from getting to the filter caps and causing them to short out from reverse polarity, which would then kill the power transformer. The "3 - 1N4007's" are intended (I think...) to catch the spikes that are generated if the speaker lines ever open up or are connected to too high an impedance. The spike can cause arcing at the tube socket, burning a path across the socket and causing the socket to lead to tube runaway for that and successor tubes. It's probably simpler to put a 100 ohm 5W resistor across the output wires. The mods aren't used because the amps work withoug them, and they do cost money. Us DIY'ers, though, we can spend extra money on amps that already work....

9/8/1997 11:47 AM

R.G.

Re: rectifier diodes

Hi, Steve. Lemme see...

A rectifier tube looks like two diodes, the anodes connected, one each, to the two wires from the power transformer, and the cathodes (bar end) connected together and also connected to the filter caps. The mod is to just put a silicon diode in series with each transformer wire, one per, into the rectifier tube, cathode to the anode of the rectifire tube.

That way, the rectifier tube can short out and the diodes still prevent AC from getting to the filter caps and causing them to short out from reverse polarity, which would then kill the power transformer.

The "3 - 1N4007's" are intended (I think...) to catch the spikes that are generated if the speaker lines ever open up or are connected to too high an impedance. The spike can cause arcing at the tube socket, burning a path across the socket and causing the socket to lead to tube runaway for that and successor tubes. It's probably simpler to put a 100 ohm 5W resistor across the output wires.

The mods aren't used because the amps work withoug them, and they do cost money. Us DIY'ers, though, we can spend extra money on amps that already work.... :-)

Replies:

Steve Keay Thanks for the info RG. And for all... -- 9/8/1997 12:20 PM
Charles >>The mods aren't used because the ... -- 9/8/1997 5:37 PM