Thermistors (was) Re: [Hallicrafters] Some HT-37 questions

[Philip Atchley]

Mark et al,

Knowing more than a little basic electronics, I think that putting a 
Thermistor in the primary side of the transformer would have exactly the 
same slow startup effect as it would in the high Voltage secondary.  In fact 
it'd probably be better as the more or less "constant" filament load (after 
initial inrush) would probably present a more stable load than the B+ alone. 
Putting it in the B+ line only may make it take wider "swings" as B+ current 
can change with signal strength (AGC on tubes), turning BFO on/off etc 
(though if the set has a VR tube it'd take up some of the "slack" when the 
BFO is turned off).

73 de Phil,  KO6BB
http://users.mercednet.com/beaconeer/
Merced, Central California, 37.3N  120.48W  CM97sh

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----- Original Message ----- 
From: "Mark Bell" <bell at blazenet.net>


>>  Not really. eliminating some filament current isn't going to
>> help enough to bother with, and the stock rectifier tubes
>> will allow a "soft" start up.
>
> I've wondered about the soft startup issue.  Most of the folks I know that
> have solid stated their radios (Hallicrafters and others) never seem to
> address the soft startup.  On the other hand, they do like to put a
> Thermister in series with the HV switch.  I'm kinda wondering why a
> thermister in series with the solid state rectifiers is overlooked.
>
> 73 Mark K3MSB