[ARC5] Quick sensistivity comparison

[J. Forster]

Simply operating the tube with plate and filament is not sufficient. You
MUST have some plate current.

About 10-20% of rated is a good compromise between cathode poisoning and
enough electron flow to make ionizizing collisions w/ neutral gas atoms.

-John

================



>
> ----- Original Message -----
> From: "J. Forster" <jfor at quikus.com>
> To: <kgordon2006 at frontier.com>
> Cc: "ARC5" <arc5 at mailman.qth.net>
> Sent: Thursday, June 13, 2013 10:33 AM
> Subject: Re: [ARC5] Quick sensistivity comparison
>
>
>> In my experience, just about all WWII vintage receivng
>> tubes can benefit
>> from some gettering time.
>>
>> I just put them in a tube tester, adjust the grid for the
>> suggested plate
>> current, and lo9ck down the TEST button and go do
>> something else for a day
>> or so.
>>
>> -John
>
>     I have just been reading a large tome on tube design
> published long ago by RCA. The types of getters used in
> receiving tubes changed at varous times. The earliest
> getters relied on ionization for maintaining the vacuum,
> later getters less so.  However, where tubes have been cold
> for many years its possible the conditions for "keeping" the
> vacuum have not been met. Operating the tube with some
> voltage on it may activate the ionization part of the
> getter.  Of course there is also the question of how much
> gas came out of the parts or got in through the seals.
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
>