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[Amps] Changing 3-500z to 8877

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Subject: [Amps] Changing 3-500z to 8877
From: (2)
Date: Tue, 20 Aug 2002 16:19:50 -0700
>Hi all
>    I can get an 8877 & socket for a very inexpensive price from a friend.
>My question is can I convert my SB220 over to the 8877 ??? Aside from the
>mechanical aspect of the blower, mounting platform for the tube, Timer delay
>& so on .. I assume the tuned input will have to be modified .. But will the
>pi output be OK ??? I want to do this because I have the tube & I have NO
>love for 3-500z with all there parasitic problems & standby heat !! I know
>the output would be the same or maybe a hair better ,but the drive power
>will be lower ..and that is nice.. Richard or Tom can you give me any
>pointers ....
It's a big job.  No one at the Rx-end will see the 1/6 S-unit increase.  
Keep the filament choke.  It can be used as the heater-choke for the 
8877. (Don't ground one side of the heater.   Connect the cathode to the 
heater to prevent heater/cathode arcs.)
-    The tuned input should be reworked for a Q of 2 - 3.   Drive power 
will be about half.  However, an 8877 has almost as much feedback-C as a 
3-500Z and it has way more VHF amplification, so I wouldn't assume that 
its going to be less squirrelly.

have fun, John. 

-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,  

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