[Hallicrafters] Thanks for the vacuum tube info.

[Carl]

You need a system NF of 6-8dB to get below the external noise on 10M. 
The 75A4 I rebuilt in 1965 with a 6GM6 RF and 7360 mixer measured 6.5dB 
and is darn near overload proof.

The Nuvista-plug was a commercial item that was copied by many. 
http://www.mines.uidaho.edu/~glowbugs/receivers.htm

Forget about the 6J6 in a cascode circuit as it has a common cathode. 
You could always use 2 with sections in parallel for signal handling 
experiments.

Carl
KM1H


----- Original Message ----- 
From: "Waldo Magnuson" <magnuson at mac.com>
To: <hallicrafters at mailman.qth.net>
Cc: "Waldo Magnuson" <magnuson at mac.com>
Sent: Tuesday, April 14, 2009 10:57 PM
Subject: [Hallicrafters] Thanks for the vacuum tube info.


> Thank you Ed, Carl, Roy, Glen and John for the suggestions on
> possible vacuum tubes for a cascode RF booster for my SX-28A.  Tubes
> suggested for consideration were:  6BK7, 6BQ7, 6BZ7, 6DJ8, 6ES8, 6J6
> and the Nuvistor 6CW4.  The MIT Rad Lab Series book Vacuum Tube
> Amplifers by Valley and Wallman has some noise figure formulae which
> I will next use to attempt to evaluate the above tubes.  Thanks for
> the suggestions.
> 73,  Skip  W7WGM
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