[AMRadio] 4-65's

Jim Candela jcandela at prodigy.net
Thu Apr 5 11:26:24 EDT 2007


   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.


----- Original Message ----
From: Geoff/W5OMR <ars.w5omr at gmail.com>
To: Discussion of AM Radio in the Amateur Service <amradio at mailman.qth.net>
Sent: Thursday, April 5, 2007 6:58:39 AM
Subject: Re: [AMRadio] 4-65's

gkb wrote:
> Geoff:
>     I mite have three of these 4-65's. Will check and let you know.
> Regards,
> Gary...WZ1M

thanks, Gary.

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