Hi Jim 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 bob...w2ami
----- Original Message ----- From: "Jim Candela" <[EMAIL PROTECTED]> Subject: Re: [AMRadio] 4-65's Geoff, I used a pair of 4-65's in a Globe Champion 350 conversion from AX9909's. This was kind of tricky to do, but since I had the tubes, and the sockets were the same, i gave it a try. Some recollections from that conversion: The 4-65 is a Higher voltage, and lower current tube. In class C service, the efficiency is really great at 3kv plate voltage, and is diminished at lower voltages. Used 4-65's like a lot of thoriated tungsten tubes have a filament that is very brittle, and therefore shipping them is risky since the filament might be rattling around when you take them out of the box. The 304 TL is also a good example of this. In the Globe 350, with a beefed up plate supply (~ 1500v instead of 1000), I could easily run 500 watts DC input at about 80% efficiency, The in/out ratio was pretty constant from 160-10m. The tubes had little color. The only fly in this conversion was that I wired the two tube filaments in series to use the existing 12 volts AC for the 9909's. This resulted in some 60 hz cathode modulation making the rig sound like a BC-610 running on the internal VFO. Regards, Jim JKO ______________________________________________________________ AMRadio mailing list List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:[email protected] To unsubscribe, send an email to [EMAIL PROTECTED] with the word unsubscribe in the message body.
