[ARC5] Filaments - How Low Can You Go?

[Scott Johnson]

22-32 VDC is a "withstand" voltage range, generally speaking , equipment is
designed to function nominally between 24 and 28 VDC.  Also keep in mind
that the radio master was usually not on when the engine wasn't running
(with the generator online), so unless there was a generator failure in
flight, the bust voltage would be nominally 27-28 VDC.  

Scott W7SVJ

-----Original Message-----
From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
Behalf Of Brian Clarke
Sent: Friday, October 19, 2012 10:41 PM
To: Paddy Ryan; arc5 at mailman.qth.net
Subject: Re: [ARC5] Filaments - How Low Can You Go?

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 

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