On 24 Dec 2001 Phil wrote:
>I'm gathering thoughts (not to mention steam) towards putting
>a tube onto HF and I'd welcome any comments from the Group.
>I've got the following tubes currently available to me:
>
>1. GS35b.
>2. GU84b.
>3. DOD006.
>I have an existing 3.2Kv HV PSU which I use on my 432MHz GS23b amplifier -
>could this be used - current limits permitting - on the anode of the GU84b?
>The specifications suggest that 2.2Kv is the nominal voltage and 4Kv or so
>pulse. Would it be OK to use 3.2KV? If so, then maybe I should build a
>dedicated PSU for, say, 3.2KV at 2.5 amps....?
>Over the last year to two, I've gained much wisdom and guidance from
>'Reflect-ees' and I would very much welcome anyone's thoughts and assistance
>in the choice of tube to use.
>A very Merry Christmas and a Happy & Peaceful 2002 to all.
>
>
>Phil
>G0HSS
Hi Phil
If you want my opinion the GS-35b is your best choice. Triode circuitry is
a little simpler. The 35b has a unique feature, the anode cooler separates
from the tube. It requires a little more airflow to keep them cool but
reduces replacement costs when they go soft. The tube can be had for 90 to
150 USD, replacements cost 50 bucks. With prices like these you can buy a
tube and a half a dozen spares. If a couple are duds so what toss em,
you've only spent 2/3 of the cost of an 8877 and you're set for a
lifetime...maybe a couple of lifetimes on 2nd thought. They are not as easy
to drive as an 8877 but still produce ample suds. 100 watts in will yield
an 1 amp of plate current.
As to the GU-84 it is not advisable to run the type of plate voltage you
are talking about. The GU-78 sounds better suited to your requirements and
has an additional 500 watts extra plate dissipation over the 84. Looking
for extra suds rig up a 4:1 transformer on the input and up the swamping
resistor value to 200 ohms. Guarranteed to smash those big pile ups and
speed you on your way.
I don't have any experience with nor know anything about the D0D006
Cheers Merry Christmas and 73s
Bob K1TA
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