HI all,
I am trying to feed my 5ar4 filament with DC voltage...., since my transformer doesn't have any 5vac winding. It turns there is no DC output at its cathode! I only measured 260AC at its cathode. It's like the rectifier got no function at all. The DC pass the tube directly! What gives? I flow the filament supply. It should be OK.
Lhchen
I am trying to feed my 5ar4 filament with DC voltage...., since my transformer doesn't have any 5vac winding. It turns there is no DC output at its cathode! I only measured 260AC at its cathode. It's like the rectifier got no function at all. The DC pass the tube directly! What gives? I flow the filament supply. It should be OK.
Lhchen
Thanks!
I do float the filament supply...
This is interesting. Anybody else? I have only two 5ar4.
Thanks.
Lhchen
I have tried the second one, but the problem is still there...I'm going to assume there is internal damage to the rectifier tube, between cathode and one of the plates...
I do float the filament supply...
This is interesting. Anybody else? I have only two 5ar4.
Thanks.
Lhchen
Remember that often DMMs actually DO measure an AC when there is DC... But also remember that at the output of a rectifier you won't see DC or AC... they are just pulses... Try to filterit with the proper capaicitors and measure then... maybe an oscilloscope will tell what's goin on there...
5AR4
My only question is WHY????
You do not need DC on the rect filament. Just hook the rect. to the 5V winding. The output comes off of the cathode-heater pin.
Your schematic does not show a center tap on the HV secondary. This must be connected to ground to get a positive voltage at the cathode of the rectifier.
There will be pulsating DC at the cathode. This requires filtering to be used.
Hope this helps
Ed
My only question is WHY????
You do not need DC on the rect filament. Just hook the rect. to the 5V winding. The output comes off of the cathode-heater pin.
Your schematic does not show a center tap on the HV secondary. This must be connected to ground to get a positive voltage at the cathode of the rectifier.
There will be pulsating DC at the cathode. This requires filtering to be used.
Hope this helps
Ed
No, as shown in the picture it doesn't have any center tap. I am thinking about giving up tube rectifiers. That is.its not clear from you schematic. I'm assuming that the ht transformer is centre tapped
Lhchen
I think 530vac is not a problem for 5ar4.What is the peak reverse voltage of that bridge recifier? You are probably exceeding it terribly...my guess.......
Thanks for replying.
Lhchen
contaxchen said:[No, as shown in the picture it doesn't have any center tap. I am thinking about giving up tube rectifiers.
Without a centre tap that circuit won't work... you'd need to use both rectifiers to make a full wave bridge.
dave
martinab2 said:Ok, this might be a silly question... but its not clear from you schematic. I'm assuming that the ht transformer is centre tapped with the centre connection being the negative side of your circuit. Can you confirm that this is the case?
Nice pick up, Martin I never thought it was something so basic...
Lhchen, don't give up on valve rectifiers - the transformer is the problem, and not the rectifier. I suppose you could try using two solid state diodes to make a hybrid Graetz bridge rectifier using your transformer without a centre tap. I think you should get 700VDC or so out of it that way.
audiousername said:I suppose you could try using two solid state diodes to make a hybrid Graetz bridge rectifier using your transformer without a centre tap.
something like this...
Attachments
Lhchen, don't give up on valve rectifiers - the transformer is the problem, and not the rectifier. I suppose you could try using two solid state diodes to make a hybrid Graetz bridge rectifier using your transformer without a centre tap. I think you should get 700VDC or so out of it that way.
I am using that Graetz already. Thanks for the help!
I have never tried this tube rectifier before. It's too much trouble really. I am considering 5ar4 this time, because I got a large Lundahl transformer and a large chassis. There is plenty of power and space to WASTE.
Thanks for all the help
Lhchen
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