[ARC5] Radios and the Canal

[Todd, KA1KAQ]

On Fri, May 17, 2013 at 7:46 AM, Mike Everette <radiocompass at yahoo.com>wrote:

> Hammarlund built a very fine radio indeed, except for one thing...
> trademark drift.  It seemed the same in the HQ-120-X, HQ-129-X, BC-779,
> BC-794, HQ-150, HQ-170 and HQ-180... I've used them all.  Oddly enough, the
> HQ-180 doesn't appear to be as pronounced as the 170 for some reason.
>

A trademark that appears to be exclusive to amateur operators, apparently.
Can't speak to all of the lesser models Mike, have only used the 120 and
150, both of which seemed quite stable after a reasonable warm up period. I
do know that the Super Pro line was very clear in their manuals that the
receivers were meant to be left on to stabilize. All that mass wasn't meant
to be switched on and off on a whim like the old kitchen AA5. Use them as
intended and keep them in fighting trim, they're tough to beat by any
standard. Military and commercial ops seem to have done quite well with
them.

Hammarlund did recognize this as a potential problem and issued a fix to
help them stabilize faster. I believe the postwar SP-400 aimed primarily at
the amateur market included it, or at least every one I've seen had it. It
involves installing one small cap, and the results are well worth it. But
back in the day, with racks of receivers left on 24/7, it probably never
entered anyone's head.

In my experience with the HRO, NC-173 and NC-183-D, the National radios
> don't have this issue to near the same degree.
>

I've used a couple pre-war HROs and have a 5TA now. All have some amount of
warmup drift, 30-45 minutes or so. Swap out the coil and it's off to the
races unless you kept it warm atop the set. If not in a cold room, my
SP-100 will stabilize in that period. Since the 173 and 183D are a
generation or so newer, one would hope they'd be much more stable than the
Hammarlunds which were for the most part, still 1930s designs through the
HQ-150.


> But as far as tube radios exclusive of Collins, the RCA AR-88 is the best
> tube receiver I've ever used.
>

Certainly the best sounding single-ended audio output rig I've ever come
across. With a good speaker attached it sounds much like the push-pull
receivers of the day. And the flywheel tuning is a joy to use. Falls down
in other areas, but again - it's a late 30s design. When you keep in
perspective when these sets were born and used, it's even more amazing how
well the designs hold up.

~ Todd,  KA1KAQ/4