-----Original Message-----
From: Richard [mailto:2@mail.vcnet.com]
Sent: 02 July 2002 02:06
To: g0ruz@btinternet.com; AMPS
Subject: RE: [Amps] 4CX250 IMD
>
>
>-----Original Message-----
>From: amps-admin@contesting.com [mailto:amps-admin@contesting.com]On
>Behalf Of Richard
>Sent: 01 July 2002 23:34
>To: AMPS
>Subject: Re: [Amps] 4CX250 IMD
>
>
>
>
>>
>>
>>> Compared to poor regulation, yes. Compared to a well-engineered zener
>>> shunt screen regulator, probably not a significant improvement. To
>>> arrive at good linearity with a 4cx250B/R/BC/7203, load for less screen
>>> current, use maximal anode supply V. and add c. 5-ohms of RF-NFB R in
the
>>> cathode (Rk). See Fig 10 on my Web site.
>>>
>>> >G3SEK is vacationing in the states at the moment, but he gets
>significant
>>> >improvement in IMD suppression with the tube by holding the screens
>>within
>>> >millivolts using active regulation.
>>
>>You might take a look at his website, he compares the active regulator to
>>the active regulator with an 150 ohm series resistor to raise the
impedance
>>of the regulation, (Probably no worse than the Z of VR tubes or zeners)
and
>>a zener string with 100 uF to stabilize the transients (By far the worst
of
>>the three tests).
>
>** Would you trust a stock buy recommend from a brokerage that gave
>salesmen a commission on stock sold?
>
>
>Huh what does that mean?
>
** I built a 2 x 4cx250 2m AB1 amplifier with a conservatively run zener
shunt screen regulator. It was as clean as Eimac claimed. // It means
that foxes should probably not be entrusted with hen-house security
evaluations.
> ...
I trust the data provided by John Nelson GW4FRX who has no pecuniary
interest in publishing the data as far as I am aware, why do you feel it
necessary to disregard his measured data when you have only tried the zener
regulator? John measured both methods and the improvements were worthwhile
in his opinion and in the opinion of many other mid 80's VHF ops in Europe.
Have you actually read the article?
If I have the inference of your riddles correct you are suggesting that we
should not trust the advice of either GW4FRX or G3SEK because they have
been involved with the development of the tetrode boards provided by Ian. I
find that utterly preposterous because as well you know from your own
various retrofits nobody gets rich selling amp bits to radio amateurs.
People occasionally do us all a service, there are many examples of this out
there. Indeed I do it myself, regularly passing on parts to others and
merely meeting costs.
I really wish that you would try speaking in plain English, It's my native
tongue and even I can't understand you, what have foxes got to do with
amplifiers :-)
Conrad G0RUZ
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