Old TRF becomes vintage ham station

[Don K Dulmage]

I am big into vintage pre1929 ham radio and have several clones of those old designs. I also have a few collectables and like most some radios that are in rough enough shape they will never be collection worthy. One such radio was my King Neutrodyne. Under the hood was pretty good except for a fried input coil but the cabinet and face plate will never be show quality. I often wondered did early hams take these old radios and make them into a transmitter and a regen receiver. Everything is there. I decided to try and so now I have a 2 tube MOPA transmitter (pair of 01As. one is a VFO and the other a Rf PA.) The third stage or original detector stage was modified slightly to allow it to function as a regen using the heater control for the dector tube to control gain and thus regen. It took 7 parts, some rewiring but it works and the best part about it is looking at it nothing looks different. No holes drilled no parts moved. Tonight I am calling CQ with it. If I get lucky I will let you know. If you are a ham 3590 KC more or less at the top of each hour tonight till 9PM (last try) Any QSLs are also welcome.
don VE3LYX

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[Peter Heembrock]

Interesting re-purposing of antique equipment. I am going to file this away for the future…can you share any drawings on the circuits you came up with for the regen portion?

I have some AK radios that still need to be reviewed to see if they are worth restoring or?

PH

[Don K Dulmage]

I added a 100pf cap in the grid leak tank circuit, left the original grid leak resistor as is.(measured 870k) Installed a Rf choke in the plate lead.Took the coil off and removed te inside coupling coil from the previous stage , rewound the coil to 17 turns (for 80M) original was around 120 turns and reinstalled it. Fired the set up with the Detector heater on full voltage and hunted for the signal on a portable rx. found it easily. Turned the heater voltage down till the signal in the portable was gone, just. Put on the phones and tuned around and all was well. In fact first signal heard was CHU. That was it. used the original 45 volts first but now have about 55 to 60 on it. That is the detector B+. the audio stage still use the original design voltage. I didn’t draw a schematic. But that is the skinny on it. It works pretty good all considered and in 1925 would have been wonderful. I coupled the antenna with a gimmick cap made of insulted wire wound around the grid bus lead but not connected. It is would around about 2 1/2 inches of it and in a long easy style of perhaps 4 turns. Just tried a UTAH 1000 ohm speaker and it looks like it will work just fine. I will know better tonight. I have an AK here too. unfortunately it is too good to mess with however I do have a rough Fried Eisen. Using 01A in a regen presents some challenges and I have done that before. The direct heated cathode can get in the way of more exotic regen designs. Keeping the design as basic and simple as possible was the trick I found so I used it when I did this one.
don
don

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