The Radio Pages

The Hammarlund Super-Pro SP-400-X

Prolouge

When I was an aspiring young Novice operator, I saw my first pictures of Hammarlund gear. At the tender age of fifteen, I was susceptible to appearances, in girls, cars, and radios, and the HQ family and its variants LOOKED like real radios.

I even made an attempts to buy an HQ series. A great disappointment came the day I saw an ad in the now-defunct Houston Post announcing an HQ series for sale in Houston's Westbury neighborhood. A woman answered the phone, and she really wanted to sell that radio, NOW; however, by the time my mother could drive me down there, her husband was home and politely but frowningly told me there had been a mistake, the radio was not for sale!

One day I called Associated Radio up in Overland Park, Kansas, and tried to buy an HQ-129 over the phone. The salesman, thinking I needed a good SSB receiver, tried desperately to talk me into buying a rig with a product detector. Failing there, as I simply couldn't afford one, he persuaded me a Hallicrafters SX-110 would make a MUCH better rig for general listening, and sold me an SX-110, which was my main broadcast receiver for ten years. Happily, it did an excellent job before it died in 1986; one of the last news broadcasts I heard on it was a Radio Moscow denial that the situation in Chernobyl was all THAT bad.

It followed me home. Can I keep it?

Thirty years after I first fell in love with the look of Hammarlunds, Bob Nagy, AB5N, was preparing to move to Arkansas. In the process of deciding what to keep, what to sell, and what to toss, he came across a Hammarlund SP-400-X. No one wanted it. It wasn't particularly ugly, and it worked, but it looked like it was going to have to go to the landfill.

So, Bob proposed giving the Hammarlund to me, knowing I have a LOT of storage space in the Lesser Cave of Parts. His wife Karen, a lovely and wise woman and also a ham (N5PQU), insisted that they get permission from my wife first. Happily, she consented, and the Hammarlund was mine.

The '400 is essentially a pre-war design; there is little difference between it and the Super-Pro 200, which came out in the dark days of 1939. In addition, many thousands were made during the war in several varieties, the most common nomenclature being BC-779. These radios, a popular Lend-Lease item, were used in all theaters. They were optimized as AM communications receivers, and so were extensively employed in air/ground communications. This emphasis on weak-signal AM made them very popular after the war as shortwave broadcast receivers, although performance is also excellent on CW (but not on SSB, as we shall see), and I imagine many a happy ham worked his first real DX with a surplus BC-779, either on AM or CW.

Obviously, I'm rather impressed with this radio, and the more I use it, the more impressed I am. It probably has the best overall performance of any radio I've ever become familiar with, excepting the "Collins" R-390 family, and certainly the best of any single-conversion rig I've ever used.

The '400 only occasionally hears anything my Drake R8-A can't, but its audio (push-pull 6F6s) is so superior that the weak ones are MUCH more listenable. The bandset/bandspread tuning is straightforward and intuitive, at least for those of us who grew up in the analog era, and even more importantly, the loggings are easy to duplicate. The tuning rate is a wee bit fast on 15m, however, and fine tuning of SSB signals is best done by tweaking the BFO. The crystal filter is very effective at removing heterodynes, as was the one on my SX-110, and overall the rig is a joy to use.

It works especially well on medium wave. Many older rigs have poor AM broadcast performance on MW; the urban myth is that the manufacturers purposely underdesigned the medium-wave section to save money and/or avoid overloading after dark. But the Hammarlund, although it does overload when connected to my 320m dipoles, has excellent sensitivity. I can't wait to get another good, working antenna phasing unit (alas, an unexpected lightning strike killed my Quantum Phaser) and do some MW DXing.

The '400 has a few small drawbacks, and two big ones. The noise limiter doesn't do much against power-line noise, although it is extraordinarily effective against QRN (known as "static" to you BCLs) in very weak-signal situations. In addition, weak but readable image signals tend to force their way through 455 KC away from extremely strong stations on the shorter wave bands. They are not audible in the middle of a given broadcast band, where even the weakest legitimate signals cover them up. But if strong enough signals are near the edge of the band, they can occasionally show up out-of-band where there is nothing to mask them. I gather this is typical of single-conversion sets of this era, and it is a minuscule annoyance at worst. There is noticeably less sensitivity above about 20m than below, a common problem with pre-war designs; this problem is alleviated somewhat by using a resonant antenna and a teevee balun as suggested by Glen Zook, K9STH, on his web site.

But these minor inconveniences are nothing compared to the paucity of the BFO injection. This rig overloads on any moderately strong SSB signal, forcing one to turn the Sensitivity (RF gain) control waaayyy down to avoid overloading. This means riding the gain while reading the mail, which is tricky to do with the VOX roundtable format and resultant two-second transmissions that constitute so many of today's QSOs. In addition, it DRIFTS! I have left the rig on for as long as ten hours and still encountered audible drift. The '400 seems to have no temperature-compensating capacitors in it (as opposed to Hallicrafters, which made extensive use of them in most of their medium/high price rigs) and requires constant touching-up when monitoring SSB nets.

In fact, I think it must have been the weak SSB performance of these rigs that made that Associated Radio salesman feel he was "Elmering" me by selling me the '110. I've heard less technically-astute old-timers talk about how SSB was "too loud" for existing receivers when it first became popular in the mid-fifties; if they were using a Super-Pro or BC-779, I understand how they came to this conclusion. If they had more on the ball technically, they converted the 6N7 noise-limiter stage to a product detector for use on SSB. Ken Gordon (W7EKB) says the noise floor of these converted Hammarlunds was astoundingly quiet; and since the product detector could be switched in and out they retained their outstanding AM/CW performance.

He who does not remember history...

It isn't surprising that the '400 was arguably the best mass-produced receiver in the world in 1946; Hammarlund had, after all, given us what many call the first true superhet communications receiver in 1933 (which was a hell of a year to introduce a new product of any kind), with the Comet Pro.

Although it appears very archaic to us today, the Comet Pro (which is not to be confused with the Hammarlund Comet, an all-wave console-model broadcast receiver) was surprisingly modern, featuring a BFO for CW reception (inability to hear CW signals had kept superhets from competing effectively with regens for communications purposes), bandset/bandspread tuning, and an internal power supply.

Hammarlund did not have the field to themselves for long; in 1935, RME entered the fray with the '69 and then that fall Hallicrafters introduced the SX-9.

Hammarlund countered, first by adding an excellent IF crystal filter, then by coming out with the Super-Pro in 1935; the Super-Pro is also known today as the SP-100, which gives it a number-series nomenclature. The '100 became the '200 about the time Chamberlain, much to Hitler's surprise, was standing firm on Danzig. After the fall of France in 1940, President Roosevelt began the big military buildup that ended only after Hitler committed suicide in April of 1945, and the War Department wisely ordered many thousands of these excellent radios. The '200 (which had developed an external power supply somewhere along the line) became the BC-779 for the duration, as noted above.

After the war, the '400 was announced; it retained the separate power supply, which is missing from many of the surviving '400s today. There are few other salient differences between the '200 (or for that matter, the '779 or '100) and the '400. The '200 had chrome on the top and bottom of the cabinet, and the '400 does not, chrome being hard to come by in the years right after Gen. MacArthur's big party on the Missouri. The biggest cosmetic difference is probably the elegant tear-drop knobs of the '400, much harder to find replacements for than the so-called "bumpy" knobs of the '200/'779.

The case of the '400 also has carrying handles. If you are physically able, you first disconnect the power supply, then use the handles only to pick the '400 up, and swing it onto one shoulder or the head, using one of the handles to stabilize it. Only the strongest can carry the 67 lb. weight of the '400 for any considerable distance by holding it out in front of them like an electronic "shame stone." Perhaps the biggest operational difference between the '200 and the '400 is the "band-in-use" masking on the '400, which covers up the dial scales for the bands not in use.

Like Lincoln with the Zephyr and Packard with the Clipper, Hammarlund had found it expedient to introduce a less-expensive model to survive the shrunken wallets of the Depression; so, with the HQ-120 of 1938 the famous HQ series was born. The HQ series was extremely popular, and became a much more common sight than the old SP series ever had. The '120 was a single-conversion job with a BFO; later models introduced during the giddy years of post-war prosperity had dual conversion RF sections feeding product detectors, like the '175 pictured above. With these advancements, the HQ series after twenty years finally surpassed the performance of the old Super-Pro 200/400 models. These later HQs are prized by collectors today for their ability to outperform all but the most expensive solid-state radios (except for, in the eyes of newer hams, ease of use).

As for the SP series, Hammarlund made a bid to retain its status as the world's finest with the '600 in the early fifties.

With dual-conversion, an allegedly silky-smooth tuning mechanism (I've never had the chance to use one), improved anti-drift performance, calibrated BFO, and myriad other features, the SP-600 was the kind of radio everyone dreamed about owning in the Eisenhower era, even if few could afford the near-thousand dollar price tag. After all, for a couple of hundred dollars more you could buy a nice, new Chevy if you skipped the power steering and Torque-Flite automatic transmission. Today we are more fortunate, in that thousands of SP-600s have been decommissioned from Military, scientific research, and other services, and good examples can commonly be had for less than half their new price (NOT adjusted for inflation!). Of course, if you HAVE to buy that cosmetically perfect example on e-bay, you might end up paying several times that...

For a while this radio and the "Collins" R-390 were accepted worldwide as proof of America's technical superiority. In fact, many ops prefer the '600 to the '390 series, because of the latter's clunky, elaborate, difficult to maintain, and slow mechanical "digital" tuning. With its discrete steps and overly distinct detents, the Collin's tuning mechanism is ideally suited for channelized use in the military and broadcast services, but a distinct disadvantage for non-channalized services.

Epilouge

In spite of the technical triumph represented by the SP-600, the mid-sixties found Hammarlund (and just about every other communications receiver manufacturer) in trouble. Perhaps as many as a third of the thousands of radios they had made during the war were still in use; in addition, each of the major American manufacturers had made more thousands of radios each succeeding year. By the early sixties the market was saturated. In addition, the Japanese had figured out how to build cheap transistor radios; true, these had little impact on the communications market as of 1965, but everyone could see the future clearly in this regard, and the Americans all had antiquated manufacturing plants and Union contracts which committed them to spend a lot of money before they could switch from tubes. The final blow was the end of the Vietnam War, the last war fought partially with WW II surplus weapons, technology, and equipment. After Vietnamization started the Defense Department began canceling contracts left and right, American manufacturing began to give way to the service sector of the economy ("You want fries with that economic dislocation?"), and the spectacular collapse of the American electronics industry was on. Hammarlund survived only as a parts manufacturer, a role they maintain today as a division of Cardwell Condenser. If you've been looking for that elusive variable cap for a glowbug project, they can probably fix you up, although they are not cheap.

Speaking of caps, eventually I'll have to re-cap this rig to get rid of those Methusala foil/paper caps, which by rights ought to have died twenty years ago; when I'm through, I'm confidant the '400 will be the best all-around receiver I've ever owned.

(And maybe, just maybe, I can start softening up the wife for a nice SP-600.)