|Globe 350 Re: [AMRadio] 4-65's|
jcandela at prodigy.net
Thu Apr 5 21:36:30 EDT 2007
I tried those 4-65's because I had them at the time. I got the B+ up by making the same power supply filter capacitor input instead of choke input. The power tranny protested by getting hot quickly, so this approach was not for 'old buzzard transmissions'. I switched out the 809's for a pair of 808's and added a 7.5 VCT @ 8a filament transformer. I recall beefing up the 6AQ5 audio driver to something like a 6V6.
The AX9909's are indirectly heated, and take 12 volts whereas the 4-65 are directly heated, and take 6 volts.An external 6v filament tranny with a CT would have been better, or I suppose you could use DC and make a balanced center with 100 ohm resistors.
That rig went on to Dr. John in Arkansas (WB5NTO). I heard he ended up in Florence Alabama with a new call. As for that rig, I wonder whatever became of it.
Another worthy option is a single 7094, or maybe two. Hoisy Hoisington, W4CJL, Founder of SPAM, used a single 7094 in his Globe Champ.
----- Original Message ----
From: RJ Mattson <rjmattson at hvi.net>
To: Discussion of AM Radio in the Amateur Service <amradio at mailman.qth.net>
Sent: Thursday, April 5, 2007 7:46:10 PM
Subject: Globe 350 Re: [AMRadio] 4-65's
I am always looking for substitutes for my Champs AX9909's.
The top of the list are two 5894's with the plates wired in parallel. I
believe there was a article in ER with is conversion?
How did you get the HV up to 1500v?
Would an additional fil xmfr resolve cathode modulation or could a DC fil
ckt and cap decoupling be the solution?
I have a stock of both 4-65s and 5894/7854s
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