[ARC5] Filaments - How Low Can You Go?

[Brian Clarke]

Bear in mind that the nominally 24 Vdc in an aircraft is actually 22 to 32 
Vdc. So, though I would look to RCA for info on the rated heater Voltage 
range of their tubes that were used in Command sets, in the end, the 
application platform will force the final decision. Even the nominally 12 
Vdc sets had dynamotors with '14 V' on their nomenclature plates. Perhaps 
the average life of an aircraft came into the risk management equation ...

73 de Brian, VK2GCE.

On Saturday, October 20, 2012 4:11 AM, Paddt sent, along with a great long 
tail:


> Yeah..this is always very interesting..I tried an R10A recently (28v
> unmodified) with 15v ac and 150v DC..it worked fine and probably not good
> for the tubes per the present correspondence..I then made up my own 
> version
> of Les's single 24v supply to give 60v B+ and it worked fine..thanks for 
> the
> circuit Les..the general feeling seems to be that the ARC5 receivers are
> very tolerant of variable A and B voltages which is nice to know..73 de
> Pat/EI7CN