[ARC5] Powering an ARC-5 Receiver After Long Storage

[Bill Cromwell]

On 05/21/2014 10:27 AM, J. Forster wrote:
> The only risk I see is possibly overvoltaging a capacitor connected to the
> tap on a resistive divider, where that tap also supplies tubes. An example
> is a decoupling network for prior stages in an amp.
>
> My reason for doing this is to test (and reform) bypass caps with no
> current through the tubes.
>
> Of course, if a tube is badly gassy, it could break down.
>
> It seems to me, the B+ test is an easy overall health check. I bought an
> HP 6209B Power Supply a while ago for this purpose.
>
> -John
>
>
Hi,

I remember something about some types of transmitting tubes with exotic 
chemistry that shouldn't be energized that way - for long periods of 
time. Receiving tubes don't seem to have any trouble with that. For the 
testing long idled gear you might consider some current limiting so as 
to limit or completely avoid smoke and destruction in case some ancient 
part fails.

With my command receivers I have started with as little as two 9 volts 
batteries in series and worked up from there. With the heaters on they 
will try to work with that low voltage but they won't wprk very well. 
They start to perk up around 45 volts - five of those batteries in 
series and seem to operate full bore at 90 volts. The batteries 
themselves might be sacrificed in a hurry in case of a catastrophic 
failure but there wouldn't be any smoke or flames. Those die right away 
with a short applied. Temporarily inserting a small fuse in the circuit 
will probably give the most protection for the expense and effort. I 
like solid state current limiters. Add a meter and you will know what is 
happening right away. That's probably not worth the effort for "once in 
a while".

73,

Bill  KU8H