[Amps] Changing 3-500z to 8877
Tue, 20 Aug 2002 16:19:50 -0700
> 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
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,