Using 2 rectifiers off 1 power supply

[duderduderini]

Hey
My geek mate says it shouldnt be done but can I hang 2 gz34 rectifiers off one heater supply? It can supply 5V at 4 amps. I realise the resistance of the heaters will be half of usual and hence the supply Voltage will be greater.. will need dropping resistors etc.
Or do I hang one off the 5v supply I have ,and one off a spare 6.3 V supply I have with the aforementioned dropping resistors
Much Appreciated
Nick

[SY]

Remember that the cathode is connected to the heater! If you're using two in parallel to increase the current rating, all should be well as long as the pin 8s are connected together. If you want to use them for two different supplies, you're out of luck.

[duderduderini]

Hi Sy
Thanks and yes they are paralleled to increase current capacity.
Nick

[kevinkr]

This should work just fine of off the 4A/5V winding since the filamentary load is resistive in nature. (Currents in winding will be sinusoidal and will not cause unusual heating problems.) I used to parallel 5AR4 in order to get higher current capability, particularly towards the top end of their voltage ratings.

In addition I recommend installing diodes such as UF4007 in series with each plate - you will be amazed at how many gremlins this quashes while keeping all of the advantages of tube rectification. (Things like arc over during warm up, hot flashing, etc.)

[duderduderini]

Hey
Well I thought I was right on this one. I shall place the diodes in series as per KevinKR's suggestions.. I have seen this flashover a few times on my first preamp and wondered why.
Thanks to all
Nick