[Hallicrafters] SX-71 Progress

[Carole White-Connor]

Thanks to all of your help, I'm making good progress. You guys are the best.
People took the time to pull up stored files from their computer to send to
me. Others responded unbelievably quickly with on-point advice and
suggestions. Unbelievable.

I have a question on the S-meter. It works but not well. It takes a very
strong signal to move it. One thing I see is a 92-ohm resistor coming off
the rear of the S meter. I don't see that in any of the schematics. Any
ideas?

As for the progress, here's the full report:

1. The 2nd mixer was malfunctioning because it had the wrong tube (a 6BY6 in
place of a 6BE6). The correct tube gave me reception, albeit weak, on Bands
3 and 4. My 6BE6 tested marginal on my tester so I'll be ordering a new one.

2. The filter caps seemed good. However, I've heard of too many hum-free
caps exploding without warning. Therefore, I changed them out. There's
plenty of room in the power-supply area for the new caps.

3. I replaced all the wax paper caps. The two .25 units were really leaking.
The .05s were somewhat leaky, too. The new caps perked up performance quite
a bit.

4. I checked the resistors. Surprisingly, only 3-4 were out of spec. That
surprised me. From what I had read in the archives, I suspected there would
be more.

5. An IF alignment (455 khz) really improved performance. I suspect a prior
owner had aligned the IFs with selectivity on the normal setting instead of
the sharp setting. They were pretty far off. I also aligned the 2,075 khz
IFs. They seemed to be pretty close.

6. I did the routine things, too, such as a drop of oil in each of the
tuning-cap ball bearings and a squirt of contact cleaner in each pot.

7. Thankfully, the front plate and the cabinet are in very nice shape. Car
wax seems to do a great job on the black surfaces.

Joe Connor