Help!!!! This is a Yaesu FT-101E that only puts out about 20 watts on 10, 12, 20 meters, (yes, the 15 meter band has been
replaced with the 12 meter band) and on the rest of the bands few .5 watts at most, also oscillates on 10 15 and 20 meters when trying to tune sometimes (while oscillating puts out about 40 to 50w, and usually it is the tubes full output power or close to it. so there must be something in the output tuning that I'm overlooking), Therefor I can never get to the neutralizing procedure (even though I have tried different positions on the neutralizing capacitor).
I have replaced the high voltage caps for the 600 plate voltage supply, all the electrolytic caps in the entire radio, the two 6js6c and 12by7a driver (NOS), replaced C2 100pf neutralizing cap for a 10 pf (this mod should done when American made tubes are used; to compensate for the difference in inner electrode capacitance from the original Japan manufactured brands), have aligned and peaked out all the trimmer caps for all the bands from the crystal to the input of the 12by7a and to its output to the final tubes.
On the oscilloscope I get a higher reading at the output of the 12by7a across all bands than I get from the final stage, for except 20 and 10 meters (20 to 30 W). I have cleaned all relays and swapped them out with good working ones, cleaned all the wafers on the band switch, mode switch and other switches. Took out the tank coil,cleaned it along with all the parts in the final section and assembled it with the same results. All the silver mica caps within the final stage check out close to their face value on my meter but not exact; as they have tolerances that might vary with temperature under operating conditions.
I have swapped out all the boards with no results. If anyone has had a similar problem and found the solution PLEASE LET ME KNOW. All the high voltage levels check out OK, and the 6V and 12 volts as well. Perhaps it can be a cap in the driver and final stages that appears to be good, but under working conditions might not; making it very difficult to troubleshoot during TX, due to the high voltage levels in the final stages. I have replaced the coupling cap c13 (80 pf) between the 12BY7A and the 6js6 finals and c104 (80pf) at the very output right before RL-2; which appeared to have been a leaky cap.
Please contact me at [email protected] if you or someone you know might be able to help. I've spent many days trying to figure this out and I really don't know what to do anymore for except start randomly start swapping out parts from another unit.
Thank you for reading.