Saturday, February 23, 2013


     The acronym stands for "Super Regenerative Receiver" and I think it was their first foray into the old amateur radio 5 meter band, before the sophisticated 1-10 "Ultra High frequency" receiver was much more than a gleam in James Millen's eye.

     It's a tiny thing, 7¾" x 7¾" x 7" and 5 meters is where it tops out; with a minor reshuffling of coil connections, it covers the lower ham bands, from 10 meters down to 160 meters.

     As a "rushbox" super-regen without an RF amplifier to isolate the detector from the antenna, it's not a good citizen on any of them; in operation, it radiates a broad swath of noise, inherent in the superregeneration process.*

     And I own one.  There it was, at the Indiana Historical Radio Society's Spring swapmeet, standing out on a seller's table to anyone with an eye for old National equipment, at a remarkably low price.  I made an offer and somehow ended up with a nice homebrew absorption wavemeter in the bargain.

     Have a look inside the receiver:
     The coil and socket are standard 4-pin "tube base" configuration, unusual for a National product; they usually preferred their own designs.  But that will make it simpler to wind new coils.  The one in the socket probably isn't for this receiver -- not just the "Hammarlund" name on it, it lacks the cathode tap found on all SRR coils.  I may have coil-winding data.  I'm certainly going to give it a try!

     Rough schematic:
        It uses a version of National's "S-101" interstage coupler that I had not seen before.  The S-101 is a weak point in the design, as the internal audio choke (inductor) has a very high impedance, meaning many turns of small-gauge wire, which tends to perish in the potting compound.    Checking that will be the first order of business.
* I believe it was Howard Hughes' 1938 around-the-world flight that found radio communication nearly wiped out by interference from people trying to listen in with simple superregenerative receivers.  This is why the later 1-10 had an RF amp, to keep that detector from getting in the way!

Sunday, February 17, 2013


     Yes, there's a new one: Chinese kit-maker YouKits offers their TT1A two-tube transmitter kit for US$129, less power transformer, HV rectifier and filter (though they supply all the info to build the B+ supply).

     It's a nice-looking little kit, with a tube lineup that appears to be close to 6C4 - 6AQ5.  The instruction manual is very clear, which solves the main concern of internationally-marketed kits.  Have no fear, YouKits has found someone bilingual in Ham.

     They also offer more-modern kits and an impressive antenna analyzer that is also sold in the U.S. by Ten-Tec.

Saturday, February 2, 2013


     It really existed; in fact, it was part of the appliance package for the higher-end models of all-metal Lustron homes: the Thor Automagic Clothing and Dish Washer!

     Even though you changed out the entire wash basket to swap from washing clothing to washing dishes, a lot of people just couldn't feel comfortable about cleaning dungarees and dinner plates in the same machine.  It wasn't a success.

     Sadly, under new ownership the company tried a comeback early in this century with a slick ventless all-in-the-same-drum washer/dryer and that doesn't appear to have worked, either.  The company website is gone and their last official Tweet was in 2010.