I built my first Russian tube in 1998 (GS-35b) after a ham friend swapped
me a tube at the Puyallup electronics flea market (In the Seattle area) I
was quite impressed at the time with how well it worked on HF..True,it`s a
medium mu tube&requires a lot of bias, but with 100 watt exciters legal
limit is easily done.Now if you do the research you will find the tube is
designed for 500 hrs operation... The Eimac tubes are rated in the thousands
of hrs...But the price is right for the Russian jugs, at least until the
supply dries up(if you get good tubes!.)..I don`t understand why you fear
the 8877 Larry..If you design&build with protective circuitry/grid
trip/plate glitch protection,etc how can you fail? I consider the quality
over the quantity and prices are going down for 8877`s as the surplus supply
goes up too....How many Russian tubes are going to match (Each others)
specs&performance? Not too many from my experiance,you will be hard pressed
to find two GS-35b`s that match each other fairly close,not a real big deal
unless your amp uses a pair of tubes...The guys that run much more than
3.5kv on the Russian tubes? Big chance of tube arcs no amount of "Nichrome"
can cure. Just my opinion from personal experiance, for what it`s worth
73,Jim..
----- Original Message -----
From: Larry
To: Gudguyham@aol.com
Cc: k7rdx@charter.net ; amps@contesting.com
Sent: Saturday, January 27, 2007 4:56 PM
Subject: Re: [Amps] Bad tubes from ebay, update
Well.....
Are there any "american" tubes besides Eimac?
I would, if I could, use Eimac tubes, but never, ever an 8877. I flat
guarantee that within 30 days of putting an 8877 into service in this ham
shack, the grid would be puddled around the cathode. Nope, nearly 50 years
of doing this has taught me that it is very important to use a tube or tubes
that I can't break. A dainty little thing like an 8877 just don't stand a
chance. It's true that a GS-35B exhibits lower gain than an 8877 but with
200 watts of drive power available on HF, I just don't care. The important
thing is how much power do you get out before you hit the 1 dB compression
point.
My 6 meter GS-35B easily runs 1600 out with 75 watts of drive and that at
only 3100 volts on the anode under load. Since I built the thing to run EME,
it met all my design goals. It runs cool, key down WSJT, 48 seconds on, 72
seconds off, for hours and hours.
I'm not very fond of the russian triodes, but they are cost effective
(sometimes).
The important thing is to have fun doing all this. I find that diverting
grocery money to Eimac is not a good way to have fun.
73, Larry
Larry - W7IUV
DN07dg
http://w7iuv.com
Gudguyham@aol.com wrote:
In a message dated 1/27/2007 6:25:43 P.M. Eastern Standard Time,
k7rdx@charter.net writes:
Russian tubes are really great for what they cost...American tubes
cost more
but you get much more...73,Jim K7RDX...
Jim, You're so right. With all things being equal here is what I
discovered. An 8877 with 100 watts drive 2300 watts. In the same amp with
a tube change to GS-35B with 100 watts 1600 watts max. That's a difference
of 700 watts, that's a big difference in my book with all being equal. Now
perhaps with more drive the GS-35B would do more, but not with the usual 100
watts most of us have for drive.
Lou
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