[Hallicrafters] SX-28: Fast HT rise - long term stress on thereceiver's tubes?

[Richard Knoppow]

----- Original Message ----- 
From: "jeff" <vortex6066 at yahoo.com.au>
To: <hallicrafters at mailman.qth.net>
Sent: Saturday, September 11, 2010 8:58 PM
Subject: [Hallicrafters] SX-28: Fast HT rise - long term
stress on thereceiver's tubes?


> Hi,
> Ive been wondering if the quick rise-time of the HT (4
> secs?) due to the directly heated 5Z3 can cause cathode
> stripping of the other receiving tubes which are slower to
> warm up, and therefore reduce the working life of those
> tubes?
>
> I havent had my SX-28 long enough to know if tube life is
> possibly shorter than it should be due to this.
>
> Id appreciate comments on this.
> regards,
> JEFF
> ZL3JK
>
     All I can say is if that's the case a hell of a lot of
other equipment suffers from the same problem. Nearly all
rectifiers found in receivers and low power transmitters are
of the filamentary cathode type and I don't think cathode
stripping is much of a problem. Actually, I am not sure if
indirectly heated cathodes suffer from this as much as
thoriated tungsten types found in transmitting tubes do.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com