[UK-CONTEST] O/T 4CX250

[David G3YYD]

A 4CX350 grid is much closer to the cathode than a 250 so it needs less 
bias circa -30v for the same anode current exact value is highly 
dependent on the screen voltage and not so dependent on the anode voltage.

On 14/06/2011 15:10, Ken Eastty wrote:
> According to the ARRL handbook the Bias should be -50V which should give
> a standing current of around 100m/A for AB1, that's about what I see on
> my 4CX250's (HF, 4&  2m)
> What HT, screen voltage&   method of  screen regulation (if any) does
> the (old) Nag use?
>
> 73...
>
> Ken
>
> G3LVP
>
>
>>
>> ?
>>
>> Please dont laugh but I have a very ancient NAG 144 Linear (NOT!) Amp.
>> Seems to work OK at the 200 watt plus level. So I assume valve is OK.
>>
>> Only odd thing is the BIAS contriol Reading in? the Jinglish handbook says set to 40 ma for 4CX150 or 350 (Mine has 4CX350)
>> Full adjustment of POT only allows me to set for 50ma
>> Does it matter,
>>
>> Have I a fault or is the info wrong.
>> Might be easier if? book was in English !
>>
>>
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