Hello Carl
>>>BUT what is the IMD if one runs say 1700V, proper drive and
>>stabilized
>>>screens?
>>
>>Worse than at 2000V for the same "attempted" power output; or
>>alternatively less output for the same general IMD levels - see below.
>
>That was not what I asked Ian and I am sure that you know that.
I'm not trying to evade your question, Carl. Give me time to talk this
though with GW4FRX and I *will* come back to you and the group this
time. (It may take a few days, depending on what John is doing.)
However, there's one point we can clear up right now. Concerning used
tubes with some screen emission, I said:
>>If the screen supply keeps a very
>>tightly-regulated grip on the voltage for all values of screen current
>>across the drive cycle, the linearity problems shouldn't be too bad.
>
>Hmmm, last year you said quite the opposite and cautioned against any
>pull with screen emission "unless it was going to remain in FM service".
Sorry, Carl, somebody else might have said that, but I most definitely
did not. My position has always been what I said above and below.
>>On the other hand, a poorly-regulated screen supply that lets the
>>screen
>>current yank the voltage all over the place is bound to give IMD
>>problems.
>
>We finally agree on a point.
Indeed we do! I think we probably agree on some others too, but are
approaching them from different angles.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
www.ifwtech.demon.co.uk/g3sek
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