The link says that ~2500V is the best point for AB1 in modulator service
with a slight decrease at 3kV.
http://tubes.mkdw.net/sheets/088/4/4-250A.pdf
Without full testing its hard to say if there would be any benefit on
SSB but I suspect the change wont be worth the effort.
Carl
KM1H
----- Original Message -----
From: "JamesHorne" <hornej@sasktel.net>
To: <amps@contesting.com>
Sent: Thursday, January 22, 2009 2:54 PM
Subject: [Amps] 4-250a
> Hello:
>
> Presently using a pair of 4-250a in hb linear. have two questions
> about these tubes.
>
> 1.. I understand that the 4-250a and 4-400 are identical
> electrically, and differ only in the dissipation rating of the anode.
> Indeed if I place the two graphs of the constant current
> characteristics one on top of the other, there is no difference.
>
> Given that this is so, then I instictively think that if the two are
> driven to their respective max dissipation limits, and under the
> same operating conditions, then the 4-250a would be operating well
> within it's saturation limits, and incurr no loss of linearity if
> overdriven a bit. Is this correct?
>
>
> 2. Presently operating the 4-250a pair with anode voltage of 2400V.
> Trying to decide if it is worthwhile increasing anode voltage to about
> 3400 V, and dropping current, for same power input. Instinct once
> again suggests to me that higner voltage/lower current leads to better
> linearity over lower voltage/higher current. Your thoughts on this
> welcome.
>
> Regards
>
> James VE5OB
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