In his e-mails, Michael mentions that the physics of the point contact devices are a bit of a mystery for him. I recall that the book "Crystal Fire" by Riordan and Hoddeson had some pretty good info on how these early transistors worked.
Here are some excerpts from Michael's e-mails on this project:
Yes, I had great fun with our little 2N110's this past week. Of of now, I've had well over a dozen radio contacts with five different stations. I used 10mW of output power to make these contacts. The distances shown are all "as the crow flies."
W1PID, Sanbornton, NH, 67miles; lowest power used on his end 100mW
VE3DJX, Smith Falls, Onatario, 319 miles; 10watts on his end
W1DFU, Wallingford, VT, 42 miles; his lowest power was 100mW
W1VZR, Limerick, ME, 100 miles; 40w
Pete, the last fellow listed, heard the 2N110 while it was running as a "beacon" with a continuously looped Morse code message. Having received my call-sign he located my email address and shot off a reception report. I saw his message pop up on my computer and quickly looked up his telephone number. He was still at his radio when he picked up the phone. I found him pretty excited as my signal strength had sharply risen in the last few minutes. He asked if there was a problem with my keying circuit as he could still hear a faint tone on my frequency when my transmitter should have been silent. "Ha!" sez I, "You're hearing a 100 microwatt back-wave radiation!" The distance separating us divided by the 100uW power is equivalent to 1 million miles per watt; a very impressive figure!
One more station answered my CQ this past week from near Hartford, CT. However, I can't recall his call sign and I'm currently at work but my logbook is at home. My output power was up to 17mW during that contact; on account of a temporary change that I made to the circuit. However, pushing the transistor to that power level reduced the quality of the keying, and so I returned to 10mW following that contact (earlier, I'd reported that my output power was 12mW, but a more careful measurement indicated that I was only putting out 10mW).
You might have noticed that I've posted the schematic to my web site. However, I expect the circuit will change over the next week, or so, as I still want to tinker with the keying circuit. By all reports my signal is good but it has just a touch of keying "chirp." Chirp is what hams call a variation in the received signal tone when the telegraph key is first depressed. Again, I expect to have that sorted out before long.
Yes, it was a real pleasure talking with Victor, G3JNB. FYI, I'll send you copies of all the documents that he provides. He said that he's including some original data sheets for point contact transistors that he's held on to these past 55 years. I'll keep copies and send the originals to you.
I asked Victor if he'd like me to build a duplicate radio for him using the second 2N110 that you sent me. I think he was thrilled to hear my offer. Don't you think it would wonderful if he, of all people, managed to make a contact using a reproduction of the point-contact transmitter that he and Tony, G3IEE, used in those pioneering days?
The order of business next week is to finalize the circuit design and begin building two identical circuits into permanent radios. Of course, I'll take time off, now and then, to try and make more contacts. I'm already astonished that it was possible to span a distance of 319 miles (not once, but thrice!) using your ancient transistor relic.
Acting on your suggestion, I looked up the other fellows mentioned in K2AH's article. It turns out that Tommy Thomas, W2UK, was quite a radio pioneer on VHF.
Unfortunately, I've learned that he passed away not so long ago. The call signs of the other two fellows are not currently in the FCC database (I suspect because they are gone as well). A quick search on the Internet turned up nothing on them.
Victor, G3JNB, remarked that he believes that he is the only one left of his original group of transistor enthusiasts. Doubtless, one reason is that he was only 21 years-old at the time of the experiments with G3IEE.
Victor reports that Tony, G3IEE, worked as an engineer for Mullard. I guess that explains where his transistors came from. Victor used a standard vacuum tube transmitter for his first contact with Tony, but sometime later he built his own one-transistor transmitter following Tony's design. Victor says that he used it to make one or two contacts across town before he put it on the shelf. Again, I'll be very interested to see the photocopy of his station log from that period.
One more thing, Jack. I'm fortunate to count George, G3RJV as a pal-o-mine. George is a recently retired Anglican vicar, but he also founded the GQRP; what began as a society of UK amateurs interested in low power operation. Since then, it has become something of an international institution. I had a message of congratulations this week from George; saying that he's keeping a watchful eye on our project. In return, I inquired if George might be able to put me in contact with folk that might help shed light on what was going on at that time (transistor-wise) in the rest of "Hamdom". That is, I'd like to assemble a folder on the topic of "first transistor QRP QSOs" for Japan, Western and Eastern Europe, Australia, etc.. I'll keep you apprised of any news.
That's all from here, Jack. Once again, I'd like to express my thanks to you for including me in your project. It's already been great fun and a real pleasure to meet some wonderful people.