Peter - A sudden change strongly suggests failure of a component.
Your idle current at 70 mA suggests that something before the finals is off and that the finals are probably okay. Do you get the same output regardless of whether you use the receiver or the transmitter to control the frequency? 73, Steve Wedge, W1ES/4 Live free or die: Death is not the worst of evils. John Stark. All my computers have my signature with various pearls of wisdom appended thereto. From: Peter Ravn Sent: Sunday, February 05, 2012 7:03 AM To: [email protected] Subject: [Drakelist] T4XB tune and load problem Although I strictly follow the tuning procedure described in section B on p. 14 in the instruction manual, my T4XB has suddenly changed behavoiur. The output power on all bands has gone down from on average of 100 watts to 45 watts. The AC-4 bias reads .07 on the plate meter when the gain is fully CCW, and the mode switch is on TUNE. With the GAIN at app. 9 o'clock, the reading is 0.15 A, and with the PLATE control the plate current is dipped - more distinctly on some bands than others. Increasing the GAIN to maximum the reading is 0.2 A. Alternately adjusting the PLATE and LOAD controls for maximum RF output, the result is 45 Watts. As before SWR is low, so apparently the T4XB is able to tune the antenna. But the LOADING control on 80 meters has to be turned fully CCW to achieve the best result, whereas it before was between 3 and 4, which might indicate that the tuner doesn't work as it should. Add to that the finals get hotter than before. So there must be a mismatch. The question is where? 73 de Peter OZ8CTH -------------------------------------------------------------------------------- _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
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