Gudguyham@aol.com wrote:
>
> In a message dated 3/6/2006 1:43:18 PM Eastern Standard Time,
> john.brewer@us.schneider-electric.com writes:
>
> I'll agree re the GS-35B...certainly a bargin at the moment.
>
> Gentlemen, I have found that a single GS-35B used with the same power
> supply as with a pair of 3-500's will make about 100 watts more power
> output with 100 watts drive. Should you drive the GS-35B with more
> power they should outperform the pair of 3-500's with better
> linearity. The GS-35B tube will take 1.2 amps anode current vs only
> 800 mills for the 3-500's in linear operation. At first the GS-35B
> was touted as the poor mans 8877 so I picked up a few of the
> GS-35B's myself. Unfortunately they do not perform as well in the
> output dept. with the same amount of drive as the 8877, probably
> down by a factor of 35-40% for same drive levels.
That's right where it should be. With only 13dB of gain vs the 8877's
15dB of gain, that's right on target. It takes a little more drive but
most folks have more drive today than they know what to do with and with
that much drive, it'll drive an 8877 crazy (and illegal if you're
concerned about that). Show me a "LEGAL OUTPUT" amp that needs 200
Watts of drive from a modern transceiver. Go up 13dB from 100 Watts
(thats ONE GS-35B) and you have 2000 Watts output and you still have
plenty of headroom. Although the GS-35B is most happy running between
3500 Volts and 4000 Volts, you can run it with considerably less voltage
and get plenty of usable power output. If I only had 2000 Volts, for a
hundred bucks, I'd still use a single GS-35B.
However, no
> problem making LEGAL limit with 100 watts with the GS-35B, but with
> the 8877 and the same 100 watts drive, we are talking about 600 to
> 700 watts difference which easily exceeds legal limit. The GS-35B
> is certainly more rugged than the 8877 if that is one of your
> concerns.
Indeed! The anode cooler alone of the GS-35B weighs 3 lbs 7 oz which is
more than TWO complete 8877's! The GS-35B is of planar construction
and the huge domed grid supported all the way around its perimeter is
practically indestructible unless you try to run too high a voltage and
have a big bang event. Never run over 4000 Volts on the GS-35B.
This is why the contesters like the 3CX1200 vs. the 8877.
> Also, like the 8877 the GS-35B is a very stable tube. All and all
> it is a GREAT tube for the money! 73 Louie W1QJ
Truer words were never spoken, Louie. The GS-35B was built to run full
power to 1,000 MHz with extremely little feedback capacitance. Ground
the grid properly and it will serve you well. Anytime you can get a
tube that is so rugged and produces so much clean power with so little
drive for so little money you better buy TWO.
It is true that you can make a dirty GS-35B amp but you can also do it
with 8877's, 3-500's, a YC-156, a 4-1000, 813's, 833's, 811's, 807's or
any other choice of tube(s). Build conservatively and it'll last forever
and the filament wont eat you out of house and home either; it's only 38
watts!
73, Tony W4ZT
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