Tram2 6AS7 and 5U4 alternate tubes

[Desmo]

Hi Thorsten (or others in the know...),

I found this nice old RCA black plate 5R4GY rectifier tube and wonder if this can be used as rectifier in the TRAM II?

Based on info I have been able to find on the Internet the main difference to the 5U4 seems to be a slightly different voltage drop across the diodes in the tubes, but I suppose this can be corrected with a simple adjustment of the CCS?

[Desmo]

Originally Posted by Desmo

Hi Thorsten (or others in the know...),

I found this nice old RCA black plate 5R4GY rectifier tube and wonder if this can be used as rectifier in the TRAM II?

Based on info I have been able to find on the Internet the main difference to the 5U4 seems to be a slightly different voltage drop across the diodes in the tubes, but I suppose this can be corrected with a simple adjustment of the CCS?

Noone bites, so let me answer my own question I've found some data indicating that the 5R4GY should be OK to use in the Tram II. If any difference it could be a larger voltage drop over the diodes in the rectifier. I have installed the tube and it works fine, and there is no change in B+ and the 120V DC from the CCS compared to my other rectifiers.

At least this RCA 5R4GY seems to send out less hum than other rectifiers, so for now I will continue to use it. The level of hum is a bit lower than with the Svetlana I normally use.

The rectifiers I have tried so far are:

Valve Art 274 (with some triodes, there is quite a lot of hum with this one).

NOS Svetlana 5U3C (Highly recommended for less hum than the VA 274).

I should mention, that I don't have hum with all the tubes, just some of the NOS tubes. The dilemma is, that IMHO the NOS RCA 2A3 are the best sounding tubes I have tried, but they also seem to pick up more hum, so I'm searching for the most quiet rectifiers to use with the RCA triodes...