I have precisely the same problem with one of my 425's and had also
concluded that a meter resistor is the problem. I am also living with it.
73, Joe
ac5e@comcast.net wrote:
Hi Marcel: My 425 also indicates 1.8 "Plate Kilovolts" on the front panel meter. I was suspicious when that started, about five years ago, since the drive wattage and Tune/Load settings remained the same for the same power output so I checked the actual HV out of the power supply.
CAREFULLY!!!
My power supply itself puts out 2,320 Volts when the plate meter sits on the dot between the numbers 1 and 8 in the 1.8 red scale. Running CW with 1500 W measured output the actual voltage drops to 2,230 V - while the meter on the Titan drops to just a bit to the left of the 1 in 1.8. I suspect a dropping resistor in the metering circuit, but I haven't been curious enough to tear my setup down to get to the circuitry. Too much work for too small a concern.
Now, I was suspicious for three reasons. Besides the fact that my logged settings for max output had not changed, local hams who can hear me very well and know my voice report NO AC HUM on my signal with or without the amplifier in line. And the final reason is that when the filter caps go bad there's usually a very substantial drop in voltage between no load and full load.
If you don't show a big drop in HV between idling and operating I would not worry too much about it. If it worries you find a calibrated high voltage meter or a probe that will work with a meter you have and measure the HV at the power cable at the back of the RF deck. And have everything hooked up and metering - AND YOUR HANDS WELL CLEAR - before you turn the power on! Failure to do this can result in a well done ham!!!!
If the HV meter agrees with the built in meter, you may have a power supply problem worth fixing. If it reads much higher than the built in meter you probably have a voltage divider problem in the Titan's metering circuit.
73 Pete Allen AC5E
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|