Its like going back in time Mike. A fascinating and good educational video. I love seeing vintage technology come to life. Thanks for posting the video. 73 M0DAD
On many occasions, I have heard similar signals from Cuba and parts of South America in my 52 years as a CW Ham Op after getting my Novice licenses, age 15 and in the 10th grade.. I suspect in some cases it was just bad electrolytic caps but maybe some were AC modulated. Thanks for the demo.. 73 de WA4AOS, Glenn dit dit
Great to work you! Those 27s are the key to getting on the air fast and with a lower cost plentiful tube. A lot of folks are using them in push-pull oscillators too!
Very interesting transmitter series! You confirmed in this video an old family story that my great-grandfather, W2WWG, was able to give permission by ham radio to a young man in New Zealand to marry his daughter in 1926. It's been hard for us to get our heads around the fact that a home-made one tube transmitter and an equally primitive receiver could actually send and receive intelligible radio signals all the way around the world from NYC to Auckland almost 100 years ago. I'd thought it was via AM or maybe experimental SSB (as some hams were doing at the time), but I see now that it was more likely by CW. Thanks, and 73. KD2ORG
Lovely transmitter and lovely sounds. Apparently i just missed the latest qso party. I barely have any access to 1920s tubes, but i just built something fun with a little DCC90 double triode. Sounds the same, but it's just a bit smaller and newer. I hope some day to make a qso with one of those old rigs, even though i don't have any 100 year old tubes. Though i might have one trick up my sleeve that's even dirtier and older than the self rectifying sets...
Michael, another enjoyable video. By extreme coincidence, as I watch this video I have Radio Handbook 10th edition in front of me on the kitchen table. My extremely patient XYL has been sending me code practice using the word list on page 11. 73 de Steve M0KOV
IIRC from reading some very old articles from QST, there were some self rectifying transmitters that used two tubes where one tube was the rectifier for the other one on alternate AC cycles. For the contest, does the tube have to be made before 1929, or just be of a type made back then? How about a 'later version' of the same tube, IE: a type 801A which is really an improved type 10Y, itself a newer version of the UX210 which WAS a 1929ish tube. Since you are feeding the antenna with coax via the transmitter coupling loop (at ~50 ohms), you could add a 'transmatch' or a low pass filter between the transmitter and antenna for even better harmonic suppression if needed to keep it 'legal'. Your transmitter circuit isn't exactly 100% true to the original because the tank is shunt fed. The old timers would have a 'HOT' tank that was in the plate circuit without any blocking capacitor! The capacitor roter would have had to have an insulated coupler to the knob (some of the WWII era national vernier dials had this built in). Of course, the original circuit often did have the RF choke in series with the DC feed, and a bypass capacitor, so the same number of parts were used. Just that the mindset of the day was that the shunt feed was inferior somehow.
@@user-em7lp1sb4k I have a type 810 in the junkbox that is sorta kinda like the type 838 and 211 except that it has the grid and plate are brought out to external caps rather than at the base.. There is also the type 841 that is very similar to the type 801 and 210 triodes. Really, ANY directly heated triode transmitting tube (809, 811, 812, etc) should be acceptable for this circuit as most of these tubes are directly descended from types introduced before 1929.
The Tube itself does not need to be vintage. The tube type needs to have been developed before 1930. Example UX210 or 310- any Type 10 variant would be a candidate. I think you are pushing it with the improved VT-25, 10Y, 801A or a 2A3, so I would say no go on those. The modern 211's are fine. Maybe one of the AWA guys could comment.
@@MIKROWAVE1 Well, I suppose one could build a transmitter using what ever pin compatible tube he could find, and then replace it with a vintage type when it becomes available....
@@user-em7lp1sb4k Somewhere in the junk box I remember I had an 838 in a socket. Haven't seen it in years. While technically that number is post 1929, it sure LOOKS like a 211 or 203.
Hi Mike. Great series. When you're taking the harmonic measurements, how far is the receive antenna from the transmit antenna? I'm not sure how large your lot is, but your receive antenna is probably within the near field of the transmit antenna and I would question the validity of the measurements. A receive antenna several wavelengths away would be more accurate, though undoubtedly not very practical or doable for most of us. Anyways, I really enjoyed this and all your videos are very inspiring. Keep up the good work. 73 de K3NG
Wow that sounds scary and all too possible. But those things (beyond being a bit dangerous to life) are notoriously poor for regulation. Turns out my supply did not have enough bleeder on the output to have decent regulation.
Great video once again! Thanks for posting and I have plans to build one of these. If I follow through… :^) would be great to work you next year. 73 es happy holidays de AF4QK.
Mike, would adding a water-cooled carbon microphone in series with the antenna help satisfy man's enduring need to modulate?? Just kidding. Thank you for your videos, Tim
So what did you use for the cap between the link coil and ground? I'd think a 1500pf variable would be pretty conspicuous, or did you omit that in your build?
In the event one of these transmitters doesn't meet requirements and one is concerned I don't think a LPF ('29 style or not) would be outside the sprit of the contest, not like the 50 ohm coax is period correct either. The goal is to build cool stuff and use it on the air, not fully replicate a 1929 ham shack.
@@MIKROWAVE1 разрешите последний вопрос . Я по переводу не совсем понял. В том регенеративном приемнике анодное напряжение какое? Сверх низкое, 9вольт?
