As the title says I want to know your views on this: I have a receiver which requires 220 volts DC HT for the valve anodes and 12.6 volts DC for the heaters from a seperate PSU at the moment I have it run via a variac fed from an isolation TX the unfortunate thing is its audio output is a bit on the low side so I want to run it through an audio amplifier the thing is the amp has the mains neutral straight to chassis and one side of AF input also to the chassis so if I link the 2 beasts together my receiver RF Earth will also be taking the amps chassis to earth I could run it all from the isolation TX do you think that's the best option?
OK. so before you turned on the HT, all the heaters and the heater supply were fine ? If so , how long did you let it warm up ?
If more than a minute or two it sounds as if perhaps the HT is getting back into the LT supply and it does not like it. So to make sense of this we need more info.
How are HT and LT derived if you have two switched supplies ?
Traditionally the heater supply would just be a transformer down to 12 or 6V , maybe with one side or centre tap earthed. But it in a transformerless set, it may be a constant current string of really odd voltages - some Valve series E (as in the ECC83, double triode or EL509 pentode ) are constant voltage devices, and heaters are in parallel
Valve series P (As in the PCC83 or the PL509 pentode) are all 0.3A, but the larger devices take more volts - these are used in the transformerless designs with all the heaters in series across the mains, maybe with some resistance to make it up to 240V.
If the HT rectifier is a valve, then it needs a seperate heater supply, as the kathode of that rectifier is at the HT voltage. Silicon has largely done away with that.
So some more description, and we may be able to help.
also is either side of The HT or LT output earthed - a classic would be to earth both sides of the LT supply one at the PSU and the other at the rig. Result a hot LT supply and little else.
Is it possible one valve has developed a heater to kathode short? This can give very nasty HT- LT interaction.
OK. so before you turned on the HT, all the heaters and the heater supply were fine ? If so , how long did you let it warm up ?
If more than a minute or two it sounds as if perhaps the HT is getting back into the LT supply and it does not like it. So to make sense of this we need more info.
How are HT and LT derived if you have two switched supplies ?
Traditionally the heater supply would just be a transformer down to 12 or 6V , maybe with one side or centre tap earthed. But it in a transformerless set, it may be a constant current string of really odd voltages - some Valve series E (as in the ECC83, double triode or EL509 pentode ) are constant voltage devices, and heaters are in parallel
Valve series P (As in the PCC83 or the PL509 pentode) are all 0.3A, but the larger devices take more volts - these are used in the transformerless designs with all the heaters in series across the mains, maybe with some resistance to make it up to 240V.
If the HT rectifier is a valve, then it needs a seperate heater supply, as the kathode of that rectifier is at the HT voltage. Silicon has largely done away with that.
So some more description, and we may be able to help.
also is either side of The HT or LT output earthed - a classic would be to earth both sides of the LT supply one at the PSU and the other at the rig. Result a hot LT supply and little else.
Is it possible one valve has developed a heater to kathode short? This can give very nasty HT- LT interaction.
