[ARC5] Annual *Real Bench Challenge*

[Robert Nickels]

I'll try again as my first attempt with photo evidently angered the Mailman.

First,  here's the bench:   https://tinyurl.com/yafzuk4s

And now as Paul Harvey used to say, is the rest of the story - which I'd 
planned to post about on this list anyhow.

The HW-16 had to be pushed aside while waiting for parts, creating an 
opening just big enough for the homebrew receiver I got recently via 
eBay for $18.50,  plus 2X that to ship it here. I like saving and 
restoring old homebrew gear just out of respect for the amount of time 
and effort our forefathers put into making things from scratch, and this 
receiver intrigued me, as the IF transformers were from the Command Set.

More photos here:   https://tinyurl.com/yb8wo9ho

It's a 15 tube dual-conversion superhet covering 160-10 plus six meters 
(the 2-tube six meter converter was removed, but plugs into the sockets 
at the rear).   Naturally there was no documentation which only adds to 
the fun ;-)    I hadn't seen the underside of the chassis before it 
arrived but I was pleased that my assumption was correct, that anyone 
who went to the effort that was obvious from the top side layout would 
do a neat job of it.    The wiring is neat and makes uses of the 
8-terminal wiring terminal blocks and 3-in-1 bypass capacitors from the 
command set receivers, all of which are still good.   I suspect other 
components are of mil surplus origin as well.

The first IF at 1415 kHz uses the transformers from the 3-6 MHz 
receiver  and the second conversion is to 85 kHz where those wonderfully 
narrow BC-453 IF transformers make the receiver very usable to copy 
SSB.   The only problem was the IF was misaligned enough from the BFO 
range that it wasn't demodulating properly until I tweaked it up, with 
the help of the little Dentron MLX-Mini 80 meter QRP transceiver that is 
being held down by a D-104, which served as my SSB signal generator.

The results are very impressive, the stability is good enough to stay 
tuned to a SSB signal and sensitivity is under a microvolt on 20 meters 
without doing any more than IF alignment.   Routine preflight stuff like 
cleaning and de-oxiting controls and tube pins and replacing the filter 
caps resulted in a totally deaf receiver until I found a couple of 
components leads touching that shouldn't have been that was shorting the 
audio.     Then two dead tubes later I had radio!   Not bad for a set 
that hadn't been powered up in who knows how long?

The dial is hand-calibrated but seems to be reasonably close and 
provides a good tuning rate.   The panel is a little rough so I'll have 
to think about what if anything to do about that.    The S-meter is from 
a Breting 12 and seems to be defective, but that's easily corrected.   
The dial reminds me of the Marconi marine sets, it's just a dial cord 
reduction but is smooth and works well. Obviously damp basements or 
garages are not the best places to store old radios!

My $54 receiver is a keeper!   While using surplus parts was common in 
the 50s or 60s when this was built, I applaud the builder for taking the 
extra time to create a full-featured ham receiver using surplus parts 
rather than just hacking up a couple of command sets.   
Performance-wise, this receiver is in the same league as commercial 
offerings from Hammarlund, Hallicrafters, or National, which is pretty 
good for a homebrew job.

73, Bob W9RAN