Recommended spacing for multiple 5AR4's

[tomchr]

Folks,

I'm building a power supply for a stereo amp. The supply will have two 5AR4 tubes in it for rectification. These tubes run rather hot during normal operation so I'm a little concerned of placing the tubes close together.

What's the minimum recommended spacing (center to center) of 5AR4 tubes?

The tubes are SOVTEK brand new stock.

Thanks,

~Tom

[Rod Coleman]

THe old Marconi-OSRAM data sheets sometimes gave separation specs. For instance, designers choosing the KT66, operated with 30W pounding the anode, and about 8,5W of heater, were invited to cut their hole-centres 3.5 inch [90mm] asunder.

The Sovtek drops only about 20V, but the rms current through it for its maximum 250mA of dc, is nearly 500mA when Cin is 50 .. 60uF. So you have about 10 anode watts and 10 heater watts, in a smaller bulb. I'd say the 3.5 inch would be about right here too.

[tomchr]

I was secretly thinking 3~4 inches (75~100 mm). So 3.5 sounds good...

Thanks,

~Tom

[indianajo]

A Hammond H100 power supply has the two 5AR4's spaced 4" apart, center to center, with a FP can cap in between. They were very careful to ground their caps to the appropriate part of the rectifier feeding it. Ground leads are explicit, bare, and very short. No ground current runs through the chassis, although it is at the same voltage as the returns.

[Richard Ellis]

The only recommendation I've seen is one and a half envelope widths spacing for tubes........No notations for Rectifyer vs. Power tubes.

__________________________________________________ _____Rick...........