Could somebody advise me as to the resting plate current and operating ctrl grid bias voltage they are using on a GU-74B (plate voltage is 2500V, screen grid 300V)? Also, does the tube draw grid curr
Jim, ACOM1000 and ACOM2000A are without doubt the most popular amplifiers based on GU74B. Many thousands of them are working under the following conditions at1000W output: Plate 2350-2400V Screen 340
Val, For the sake of completeness, I believe the typical "three state" bias voltages for the ACOM 2000A (GU74B) are as follows: -124V on standby; -75V during plate idling with PTT key line enabled; a
Paul, You are absolutely right. I omitted the standby state as I think that Jim doesn't care about it. 73, Val LZ1VB Val, For the sake of completeness, I believe the typical "three state" bias voltag
I sure hope its not Class B Paul; more likely AB2 if there is some small amount of Ig on peaks. There is also over 500W of idle dissipation per tube in order to make some attempt at decent IMD and th
71% overall efficiency is remarkable for a class AB1 amplifier. ACOM1000 and ACOM2000A are without doubt the most popular amplifiers based on GU74B. Many thousands of them are working under the follo
Thats being rather polite about it (-; Carl KM1H 71% overall efficiency is remarkable for a class AB1 amplifier. ACOM1000 and ACOM2000A are without doubt the most popular amplifiers based on GU74B. M
Yes, the ACOM-1000 and ACOM-2000A are two good examples of what good amp designers can do with good tubes. These GU74B tube based amplifier products have been immensely successful for ACOM and others
Yeah sure. A 600W rated tube fraudently labled 800W to grab US dollars. At least ACOM has erased the GU74B for a 4CX800A even tho running them just as hard. They will soon go the way of the dodo bird
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Agreed Carl; but the labelling is unimportant. Quibbling over whether the tube's plate dissipation is 600W or 800W is rather pointless. It's a function of air supply CFM anyway as the cathode emissio
WOW! What a line of.... I bet the 4CX1600 was the best thing going too? Now that they are TOTALLY not available anymore. I tried to build an amp out of a pair of them... One tube shorted. Before it d
What a line of.... I bet the 4CX1600 was the best thing going too? Now that they are TOTALLY not available anymore. From what I've read the 4CX1600B really was an excellent tube. I think Carl has exp
Hi All, Russian GU43b works up to 100MHz and it is equal 4cx1600 tetrodes. It runs 1600W easy, 2 kW is possible also. Its price is $65, the price of its original socket is $90. Another not very known
YEAH Jim, just shows you the Hammy Hambone engineering capability of a few. It reminds me a bit of WW2 when the 450TL wouldnt make enough power as a radar pulse modulator. So Eimac increased the fila
The 1600B was a decent tube and a few manufacturers, including Ten Tec, jumped on it. Unfortunately there wasnt enough Russian surplus to go around so manufacturers and owners were left holding the b
Carl, The 800W labeling of GU74B wasn't fraudent, but a pretty fair. If this tube was designed by EIMAC, or other western company it would have been undoubtedly labeled 4CX800. Compare its size, grid
Corrected by Svetlana? Please send a copy of the revised data sheet of the GU74b. 73 Peter, DJ7WW The 800W labeling of GU74B wasn't fraudent, but a pretty fair. If this tube was designed by EIMAC, or
Val, I suspect the real reason is that the Russian engineers designed the tube to a specific military specification and it was rated to perform reliably at that point. Part of the problem is the anod
Thats being rather polite about it (-; Carl KM1H 71% overall efficiency is remarkable for a class AB1 amplifier. I was going to say something similar, but I think Carl has it about covered! <:-)) 73