It uses the phasing method of sideband generation. No crystal filters in this one. You need TWO balanced modulators. You have a 90 degree phase shift network for the RF (from the carrier oscillator) and a second 90 degree phase shift network for the AF from the mic amplifier. When you combine the signals from the two balanced modulators -- viola! -- one of the sidebands disappears. The balanced modulators take care of the carrier, and an SSB signal is launched. That is how my old HT-37 works, and similar ideas seem to be at work in modern SDR rigs.
G3TXQ has the complete set of Break-In articles (it includes a VFO):
http://www.karinya.net/g3txq/temp/tucker_tin/
Here is a Canadian article on the rig. A "Tucker Tin" is apparently what the Kiwis call a lunch boxes (shades of Benton Harbor...).
Thanks Pete!
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The advantage of simple SSB transmitters over simple receivers, is that you have a controlled bandwidth. The voice is limited in frequency, and you can reinforce that with a low bandwidth microphone or audio bandpass filter. The filter (or phasing) just has to knock out the opposite sideband.
ReplyDeleteFor a receiver, it sees a wider range of signals, so the lack of skirt in a simple crystal filter, or in an imperfect phasing setup, may result in in-band or opposite sideband feedthrough.
The tucker tin was covered in CQ in the early sixties, maybe as an exciter for a transverter to VHF, I can't remember.
But the article suggested "tucker tin" was a cookie tin, which makes more sense than a lunchbox. That photo even shows more of a bread pan.
Lester Earnshaw did a lot, put together an early book on transistor SSB and was involved in some company like Astros, and designed the Hammarlund HQ-215 transistorized receiver. Someone needs to write a short biography of him.
Michael
My father is Lester Earnshaw. He's still alive and well at 92. If you'd like some biographical info you can go right to the source! You can email me at adele.earnshaw@gmail.com
ReplyDeleteAtlas, not Astros, owned by Herb Johnson.
ReplyDeleteTucker is a Kiwi slang for Food. It doubtless derived from (or arose alongside) the expression "Tuck in". I note the depicted Tucker Tin Two is actually built on an upturned Loaf tin, a common household item (here in NZ at least).
ReplyDeleteAn Australian expression, too.. for an amusingly informative reference listen to Phil Garland's "Nine Mile From Gundagai". :)
ReplyDeleteI wonder if i can tweak this to 14mhz with 1ж29б sputnik pencil tubes. I made a solar a and b battery so i have to choose daytime bands as im not using batterys
ReplyDeleteFred ZL2AMJ later developed a solid state version, the Tucker Tin Mark II, with a single valve PA stage, which was kitted up and sold in a kit to many New Zealand hams.
ReplyDelete