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G3RIK Pre-prepared Gi-7B and Gi-7BT valves
These valves require a period of pre-use processing.

I use the method suggested by UR4LL and Svetlana.

  • Raise heater voltage slowly, over a period of 4 hours.
  • Run with heaters only for 12 hours
  • Apply plate voltage via a 50k Resistor
  • Raise plate voltage slowly (at Ia of about 5mA)
    • 25% for 4 hours  (500V)
    • 50% for 4 hours  (1kV)
    • 75% for 4 hours  (1.5kV)
    • 100% for 4 hours (2.1kV)
    • 100% for 4 hours (no series R - 2.1kV)
The Gi7B and the hardier Gi7BT triode valves will run at up to 2.5kV, 12.6v heaters and 350W plate dissipation. Gain about x20 - x25. 

They can be used from HF to 10cm and provide a  low cost route to useful linears on most the amateur bands.

A pair will easily provide 1kW and just one should give 400 watts out on 23cm. A single valve linear will give about 500W out for 20W drive on 6m.
I occasionally have a few pre-prepared valves which are available for only £40 each (plus carriage at cost)

Just email G3RIK for availability and price delivered