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Reviews For: GU43b

Category: Electron Tubes

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Review Summary For : GU43b
Reviews: 1MSRP: 50
Description:
Russian tetrode
Product is not in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0015
G4TCB Rating: 2018-06-11
excellent performer Time Owned: more than 12 months.
Recently I modified a Kenwood TL922 amplifier. The owner had a row of faulty 3-500z valves on his shelf. He lamented the unavailability of decent quality 3-500z valves.
I suggested putting in a military quality valve instead of the Chinese copies available, looking at the devices available and the prices offered, I chose the GU43b. Reason is the heater voltage is comparable, and the price is around $50 each. The GU43b is a tetrode however, the anode voltage is perfect for the job, current the same so impedance isn?t a problem. The big Russian tetrode is offered as an equivalent to a 4CX1000a. It is certainly not, but is a very tough reliable valve.
To get the heater voltage, the heater transformer which is marked 10.7 volts was set to 220volts, the mains being around 240v. This gave 12.6v on the terminals, perfect. The control grid bias was derived from the bias terminals of the heater transformer and duly stabilised to the correct bias for the valve. The same bias output was tripled to provide the screen supply, suitably stabilised. I fabricated a base using feed through capacitors to support the screen ring and copper tube to make the connections to control grid and cathode.
The valve has been in regular use for over a year now, after being used for a month on the low anode voltage. After this period of burn in the valve has been used and abused mercilessly by the owner, occasionally producing 2Kw. The TL922 has been transformed from a piece of scrap to a better than new amplifier with a $50 valve, and some TLC. I cannot recommend the GU43b more highly, even more so for the modest price.