002: 50MHz 5F35RA

Ep 2.0KV, Ip 430mA(Idle 125mA), 860W input, Esg 275V, Ig1=12mA(AB2),Ig2=25mA, 530W output,η=62%, Gain24dB

The legal power limit of 50MHz was 50W in Japan in those days. Semiconductors for linear amplification were still expensive, so I made a traditional G-K amplifier with 4F15R (pull out from the broadcasting station in Matsumoto, Pd=150W with forced air cooling), and it was used for DX-QSO and a contest for several years. To be conscious of a high-power license in 1990, I exchanged a vacuum tube to 5F35RA (Pd 350W) from 4F15R, and also changed the bias power supply to a shunt regulator. The result is as follows.

Ep 2.0KV, Ip 430mA (Idle 125mA), 860W input, Esg 275V, Ig1=12mA (AB2), Ig2=25mA, 530W output and η =62%, Gain24dB

I obtained 500W of output finally, but it was already in the saturation (non-linear) region. Its ability of the linear amplification was upto 400 W. I experimented DC2500V on the anode, but there is risk of blow, so I think it's better to use this tube with Ep of less than 2 kV. As the split-stator type of variable capacitor was chosen for the plate vtuning, the plate efficiency seemed to be always above 60%. Making was in 1980.



<<PREV _____ NEXT>>