[Amps] GI-46B Revisited..
vk3zl at bigpond.com
Wed Jan 16 03:50:51 EST 2013
Gidday all..I have built around 25 VHF amplifiers over the past three
years using the Russian triodes, GS-35 and 31B tubes as well as GI-6 and
7B tubes..All of these amplifiers are in daily service on 6 and 2 meters
and trouble free..
I have looked through all the information on the GI-46B tube and a few
things don't add up..A company in Europe uses these tubes in their
amplifier product's..I also see many retro fits in You Tube clips for
TL-922 and Heathkit amplifiers replacing the 3-500Z and supposed power
outputs of 1600 watts..
Just taking the TL922 conversion to GI-46B tubes as an example the tubes
are openly mounted with GI-7B coolers in place of the GI-46B
coolers..These film clips show the TL-922 cooling fan retained blowing
against the tubes..I question how are they getting rid of all the heat
produced with such a pissy set up..I would have thought the tubes should
be set up mounted in a box construction and pressurised with a good
blower, chimneys etc..The mind boggles..
According to the Russian GI-46B specifications the tube is only rated at
350 watts anode dissipation..Most of these conversions will be running
at close to 3kv and to produce 1500 watts output even at 55% efficiency
a pair of tubes will have to be dissipating a lot more heat than the
tube anode ratings..
Obviously the sketchy information for the GI-46B supplied on the Russian
spec sheet must be very conservative..
I am wondering if there are any members on this reflector have used the
GI-46B triode as in an amplifier or a retrofit conversion and what the
real results are and also the cooling used..I am about to build a pair
of amplifiers 6 and 2 meters using the GI-46B tube for a client..I am
confident that with proper attention to cooling etc that the amplifiers
will turn out ok..
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