[Heathkit] HW-101 Low output on 40 meters

[Miles Anderson]

This is a tale of two HW-101s -- one of which I have used for years in my
own station (Rig #1) and the other of which I inherited from my
father-in-law when he became an SK (Rig #2).

I had kept Rig #2 in storage for years, never operated it, and never knew
much about its history except that my father-in-law built it from the
original kit. I have no idea whether it ever worked according to Hoyle,
though the builder's manual shows that he followed all of the tune-up steps
and checked them off.

When I fired up Rig #2 for the first time into a dummy load, I got good
output on 80 Meters, but everything above that was just about zilch. I went
through driver coil the tuning procedure, and this brought the output on 20,
15 and 10 Meters up to par. Try as I may, I can't get the output on 40
Meters above 70 watts.

The rig is entirely stock except that my father-in-law was never able to get
a tin on the two steel shield partitions in the driver compartment. I had no
better luck than he, so I replaced them with sheet brass, soldered to the
comb rails on both ends, to the ground plane with a piece of tinned braid
and soldered to the center pins of the tube sockets. I have also torqued
down the screws mounting the driver board and the 6146 sockets to the
chassis within an inch of their lives.

I have tried everything I can think of. I swapped the 6CL6 driver and 6146s
from my good transmitter. I have double-checked the wiring, cleaned the
contacts on the bandswitch, and even measured the capacitors in the tuned
circuits. I have checked the other caps for leakage and double-checked the
resistance values.

I have been careful in tuning the driver grid and plate coils, and the slugs
pass through an actual output peak (so I know they are neither all the way
in or all the way out). I used a VTVM with an RF probe to measure the signal
level at the 6CL6 control grid, and it is actually higher than my working
transmitter. Increasing the drive to the 6CL6 doesn't help. I get maximum
output with the microphone gain control set about 2/3 open on all bands.

The only other thing possibly out of line is that the panel meter deflects
negative when the switch is in the ALC position and the transmitter is set
to TUNE. My other rig doesn't do this, but this rig does it on all bands.

I seem to have a problem in the 6CL6 driver stage, the PA or the
coupling/switching between them.

Any suggestions?

Miles Anderson, K2CBY
16 Round Pond Lane
Sag Harbor, NY 11963