[Amps] 4CX250 IMD

[Verner Topsøe-Jensen OZ5TG]

The tuning procedure described in "The VHF/UHF DX BOOK" Chapter 6 is excellent. 
That will bring you to a point where the G2 current is very low. (and you have max output)
Using that approach will also give you very good reports.

OZ5TG

----- Original Message ----- 
From: "Richard" <2@mail.vcnet.com>
To: "Harold E. Johnson" <w4zcb@mchsi.com>; " AMPS" <amps@contesting.com>
Sent: Monday, July 01, 2002 9:25 PM
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.
> >
> >W4ZCB
> >
> >
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> 
> -  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, 
> www.vcnet.com/measures.  
> end
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