|Globe 350 Re: [AMRadio] 4-65's|
rjmattson at hvi.net
Thu Apr 5 20:46:10 EDT 2007
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
----- Original Message -----
From: "Jim Candela" <jcandela at prodigy.net>
Subject: Re: [AMRadio] 4-65's
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
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
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