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[AMPS] Final (??) Comments on B&W850A

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Subject: [AMPS] Final (??) Comments on B&W850A
From: (
Date: Fri, 12 Feb 1999 13:44:08 -0500

On Fri, 12 Feb 99 09:46:30 -0600 Jon Ogden <> writes:
>Well, after reading the messages that others have sent to me regarding 
>the B&W850A, I think I have come upon a solution - at least on paper.
>Some have suggested modifying the taps on the coil.  That is fine, but 
>messy.  Also, if I increase the inductance on 10M, it will demand a 
>smaller Ctune.  The problem is that Ctune could become unacheivable 
>a 10pF (min) variable plus the capacitance of the tube.
>The best solution I have seen is what several people suggested and 
>is to add a small coil between the blocking caps and the tune C. 

As mentioned here many times and in magazines is to take the ideal L you
want for 10M and run the C off the center tap. This will have the effect 
of requiring a 4X stepup in the C requirement. It and the L you mentioned
also affects all the other bands in decreasing amounts.

This idea is ancient and was used in commercial amps. There is very
little new in tube RF circuits,  just new people.

73  Carl   KM1H

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