Hello, i'm going to build a KT88 PP amplifier, and i'd love to use a direct heating rectifier tube... the problem is that i'm having trouble finding a tube capable of these specs: in AC 550v 200mA, because i need 600v after filtering... any ideas??
Hi!
The 5R4 you mentioned IS directly heated...
But why insist on DH rectifiers? If you open yourself for indirectly heated rectifiers an abundance of choices opens up: TV Dampers. They can easily handle the voltage and current requirement. However If you have not settled on the power transformer yet, go for choke input supply and a full wave Graetz bridge.
Best regards
Thomas
The 5R4 you mentioned IS directly heated...
But why insist on DH rectifiers? If you open yourself for indirectly heated rectifiers an abundance of choices opens up: TV Dampers. They can easily handle the voltage and current requirement. However If you have not settled on the power transformer yet, go for choke input supply and a full wave Graetz bridge.
Best regards
Thomas
5R4-GYB fits perfectly thanks 🙂
hello Thomas, do you mean using diodes instead of tubes for rectifing??
hello Thomas, do you mean using diodes instead of tubes for rectifing??
In the olde days, it was common to use two dual diodes of lower voltage rating in a doubler configuration. The dual diodes in each valve were paralleled to cope with the higher current levels, and the advantage was that the diode voltage spec didn't have to be high, and the filter caps were placed in series and clamped to half HT. The disadvantage was you needed 2x 5V heaters.
However it is sometimes difficult to design the capacitor for valve rectifier circuits, especially doubler, as the ripple current ratings are quite low for low uF electrolytics with high voltage ratings. The only simple workaround is to use larger uF caps of lower voltage rating in series. Many possibly don't check the capacitor ratings.
Ciao, Tim
However it is sometimes difficult to design the capacitor for valve rectifier circuits, especially doubler, as the ripple current ratings are quite low for low uF electrolytics with high voltage ratings. The only simple workaround is to use larger uF caps of lower voltage rating in series. Many possibly don't check the capacitor ratings.
Ciao, Tim
Hi!
I mean vacuum tube diodes like the 6AX4, 6AU4, 6Cj3, etc these are single diodes.
Thomas
I mean vacuum tube diodes like the 6AX4, 6AU4, 6Cj3, etc these are single diodes.
Thomas
Hi!
A single 5R4 will be marginal in your application. If you want to use it, use at least two and parallel them.
Thomas
A single 5R4 will be marginal in your application. If you want to use it, use at least two and parallel them.
Thomas
I prefer 3B28's. They drop in place of an 866A without the mercury. No blue glow though. It is possible to wire two filaments in series off of a 5 volt winding if you have a 5 amp 5 volt winding.
try the soviet 5c3s its €4 each and will rectify 250ma max
it also glows very nicely . whit the four inverted V"s heaters
it also glows very nicely . whit the four inverted V"s heaters
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