[Moon-net] 70cm 4cx250b amp question.
Kim Liljekrans [OZ5IQ]
kim at oz5iq.dk
Fri Nov 7 11:35:44 CET 2008
HI VE6ZT , Jordan
Re.: Ur Amp - These 4CX250 tubes do have a tendency to use and generate
neg. g2 Current !! So its NOT wise to use a MOV, - why you only "protect"
the outer circuit !
The main protection you should use, is a 1 - 2 W resistor ie 47 Kohm,
connected to gnd from the G2 pin on the outer socket.
In this manner there is a path to GND, for current the tube is "generating"
when making this neg. G2 current.
Think of the old Voltage Reg tubes - when they are running in an Amp, the
may " blink" both due to the alternating current comsumption -
THUS were able to consume the extra current / neg current, these
4CX150/250 tubes can generate during the alternating level of current flow
in them. Thats ITS almost vital to have a resistor to GND as I wrote to
GL with the Amp
VY 73 de OZ5IQ, Kim
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