All Things Wireless & Letterpress

All Things Wireless & Letterpress

Thursday, November 26, 2015

Revisiting another Home Brew Classic: the One Transistor Rig for 40 meters.

For this classic, we step back a few years further to April of 1978.  The magazine featuring this article was Ham Radio Horizons, singularly the best magazine ever printed for beginners, novices, and the Not-So-Novice.  "HRH" was the daughter publication of Ham Radio Report, and had a very respectable authorship.  Jim Fisk, Skip Tenney, Nagle, Orr, and more of this ilk of writers all had a contributory hand in authorship. This particular article was co written by Ed Marriner,  W6BLZ and John Merideth, K5GXR.  It's a shortie, only a couple pages.

The best way to view these images is to click on it, and then save the image from the linked location.  You should be able to enlarge the image considerably.

The project itself appears to have begun as a curiosity.  Looking over the schematic, I might conclude the "curiosity" must have had something to do with how few parts one can assemble and still have a respectable transmitter!  It seems to be a Xtal Pierce, keyed at the collector, and inductively coupled to the outside world through an Amidon ferrite toroidial inductor, a T-97 type.  Of course, a traditional hand-wound output tank would do, really.

This rig has the feel of the famous (or alternately, "infamous") QSL-40, which was another very spartan, bare-bones single element transmitter dating to 1938.  Whereas the QSL-40 made use of the then two year old 6L6G beam power tetrode, this one takes advantage of a transistor designed for television service, the 2n3553.  Oddly enough, I still have a couple of these transistors. 

I am very curious how these little rigs sounded!  The author(s) recommended an old car battery and trickle charge arrangement to power this little 2.5 watt marvel.  My suspicion this rig has considerable current flow.  Figure about three watts output at 12.6 vdc - probably a loaded average of 250 - 300 mA at key-down.  Definitely a battery burner.  

You probably will not tear up 7050.  But it might be fun for Novice Rig Round-Up this February!  After all, that is the collective group to which this article was aimed: the Novice Home-brewer of 1978.  Which included . . . me!  What fun building our own gear was.  And while I did not build this particular transmitter (I was still working on my 6AG7-6L6G MOPA!) - it was articles like these that kept our interest and excitement with Amateur Radio whetted.  We learnt early that the most satisfying contact is a Home Brew contact!

This concludes this little jaunt down memory lane.  I am hoping soon to post the matching transmitter to the recently posted "Fun-Ceiver".  

73 es CUL, de gary // wd4nka.

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