Sailor T218
back on this somewhat recalcitrant T128 transmitter.
I seem to have a problem with the cathode current of the middle (nr.2) tube. I was trying to neutralise (?) the PA tubes, per the manual. Believe that I am supposed to adjust kathode kurrent for 35mA.
Initially, Ik2 was pegging hard over 100mA on Tx, and I discovered that the adjustment VR P605 was failed opencircuit, as was the 22 ohm R807 between kathode & ground. I replaced these and got a more sensible Ik2 = 55mA but adjusting P605 did not change the current.
The problem is defninitely in the position, not the bottle.
occasionally, the valve in this position also starts to glow alarmingly red on Tx.
I am convinced that the PA stage is just not "working"; there is no aerial current, and I can just hear & see that the tubes are not loading up with Tx drive. I am working straight into a big oil filled dummyload. I can hear the signal on frequency, with convincing sounding audio mod on a nearby Rx.
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