---   The Exciter ---




The November, 1940, issue of QST, contained an article by Asst. Technical Editor Don MIx, W1TS. Mix described a “Simple Two Tube Exciter” built into a 19" x 3" rack-panel assembly, so designed to save panel space in rack-mount applications. The transmitter used a 6L6G in a crystal oscillator, using the tri-tet oscillator configuration to provide multiband output from a single crystal. Crystals were expensive. The final was an 807 "beam power" tetrode (real radiomen know that 807s make R.F., not foam), and the exciter used an external power supply. The versatility and low cost of the exciter made it quite popular among hams.

James Millen, W1HRX, once chief engineer of National Corp., and designer of the fabulous National HRO receivers, had left National in 1939, to found James Millen Manufacturing. Millen, like National, manufactured some of the most elegant equipment and components to be found in the radio industry, with a special emphasis on the engineering philosophy that fine electronic equipment must be based on excellent mechanical design. A hugely successful example of this thinking is the precision multi-gang tuning capacitor and dial mechanism of the HRO receivers. If there're any builders left out there, be aware that the James Millen Company lives on, at jamesmillenco.com

Well, I’m rambling . . . perhaps Millen’s most well-known product was a commercialized version of Mix’s exciter, a 50-watt CW transmitter. The “Millen Exciter” began to see wide usage, not only as an exciter for higher-power rigs, but as a stand-alone low-power CW transmitter. Some hams even plate-modulated the 807 to obtain an economical ‘phone station. The Millen transmitter-exciter remains today the subject of considerable nostalgia and popularity among Millen afficianados and others, and lots can be read about it on the internet. It also appears that the name “Millen exciter” is so generically applied to the ham-built versions that Don Mix might feel slighted!

So, there were and are, two kinds of Millen exciters in the world, those factory-built by Millen, and those ham-built and based on Don Mix’s article. As might be expected, the ham-built versions varied unit-to-unit in construction and in circuit, according to the size of the builder’s junkbox, his wallet, and his skills.

The story of BigRig’s exciter is somewhat convoluted. It was originally ham-built, along with the rest of the rig. And, also along with the rest of the rig, it spent 40 years lying on a damp concrete floor. For proof, just take a look at the pictures!

Somewhere in the middle of those 40 years, and with no thought whatsoever of BigRig or its exciter, I was at a swap on the outskirts of Chicago. There on a table, its brand-new looks belying its age, was a pristine factory-built Millen exciter, looking like it had never entertained even a fingerprint, let alone made any R.F. The owner wanted exactly 5 dollars. I had absolutely no use for it but I knew that I just had to have it, so I parted with my fiver without even haggling over the price.

Eventually, I tired of seeing it gathering dust in my garage, and I accepted an offer (or made the offer, I don’t remember) to trade it for another piece of vintage gear, an Abbott 2 1/2 meter modulated-oscillator tranceiver. Anybody here remember the 2 1/2 meter band? Anybody remember modulated oscillators? Tranceiver transformers? Well, at least the Abbott made a nice mantle-piece adornment.

Now move the calendar forward. When I “liberated” BigRig from its Chicago custodian, I saw that the exciter was in particularly bad shape. I remembered my former factory Millen, then residing in a local ham’s basement, and I called its owner to ask whether he’d like to trade it for a very nice Abbott 2 1/2 meter tranceiver that I had on my hamshack shelf. He graciously accepted this new offer, so he got his Abbott back, I got my Millen back, and now I have two exciters - a very tired dad-built Millen exciter, and a splendid Millen-built Millen exciter.

I know I got the better of the trade, because I can put the Millen on the air, but if the Abbott tranceiver ever goes on the air, at least two major FCC regs will be instantly shattered and the operator will surely go to jail!

So, now I have a serious dilemma. Should I rebuild the tired VE1MZ-built Millen exciter, or should I clean up and use the like-new factory-built unit? The decision is couple of months away, but votes are solicited. Neither VE1MZ nor James Millen, will be voting.

                    * * * *

Well, I resolved the dilemma. I re-built it. Interesting, because for several reasons, it took more time, sweat, cussing, and money, than any of the other decks so far. Strange, because it's certainly the smallest. It was fun cranking it up today, and seeing the first RF after all these years. I got alarmed after the first few minutes of operation, as the thing started making smoke. Real smoke. It was coming from a particular resistor, an Ohmite Brown Devil 12-watt vitreous ceramic resistor. It was a brand-new resistor that had arrived from the vendor only two days ago. I made some voltage measurements, and they all seemed ok. Then, I shut it down and made some resistance measurements. They too, seemed ok. The stupid resistor was dissipating between 4 and 6 watts, was rated at 12 watts, was the correct resistance, and was making smoke! I studied the schematic a few dozen times, took more voltage readings, made more calculations, scratched my head at great length, utttered several harsh words that I'd forgotten I knew, and re-took all the measurements, but I could not come to any technical conclusion as to why the silly thing was smoking. - - - Then I did a careful visual inspection using a bright flashlight. Some fool - I won't mention his name - seems to have allowed a big blob of solder paste to alight on the rear side of the resistor, where it couldn't readily be seen, and under quite normal dissipation, it was smoking happily away. I think I'll give up ham radio and run away and join the circus.


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