12987	2016-06-30 12:41:22	jmlynesjr	What have I found?
Message	Date	From	Subject
While trolling through my XYLs favorite antique store, I spied a wooden box with knobs sticking out. After digging it out of the pile, I saw tubes and air variable capacitors. I figured the caps alone were worth the very low asking price. Back at home, I can find no make/model markings at all. There is a "modern" asset tag (Magna-Tech 1258) glued to the back of the cabinet. The particulars as I can determine them: ---------------------------------------------------------- 2- Jefferson Chicago Transformers Marked 6 to 1 and 3 to 1 Primary marked "P" and "B" Secondary marked "G" and "F" 3- Regal wire-wound rheostats 3- Tubes - Markings illegible, one missing 4 contact base(no pins) with twist-lock sockets One tube has a "Songbird" sticker affixed (no idea if sticker is original) 3- Air variable capacitors 2- Phenolic "Sandwiches" (Caps?) (1 1/8" x 1 1/8" x 1/8") 2- 3" diameter flat air coils (Ant?) 1- Wooden case with hinged top (8" H x 18 3/4" W x 7 1/2" D) Wooden chassis Wooden front panel Point to point wiring with all wires terminating on thumb-screw terminals or spring clips. Anyone have any idea what this might be? Is there any historical value vs. salvaging the air variables? I will post a panel and a chassis pic to the photo section. Thanks for your input! 73s James KE4MIQ
12988	2016-06-30 14:25:20	David Bamford	Re: What have I found?
James: I can’t answer your question but I am wondering what the value of the air variable capacitors are. I am just starting out in home brew but I am looking for a 5 - 80 range AVC as I am trying to build the first receiver in EMRFD described in chapter one. All the best and 73, Dave W2DAB I m_
12990	2016-06-30 20:42:01	N0UU	Re: What have I found?
Maybe no economic value, but if can be repaired or preserved someday might show a different generation what was. Although probably more or those around than you would expect. N0UU > While trolling through my XYLs favorite antique store, I spied a wooden > box with knobs sticking out. After digging it out of the pile, I saw tubes > and air variable capacitors. I figured the caps alone were worth the very > low asking price. > > Back at home, I can find no make/model markings at all. There is a > "modern" asset tag (Magna-Tech 1258) glued to the back of the cabinet. > > The particulars as I can determine them: > ---------------------------------------------------------- > > 2- Jefferson Chicago Transformers > Marked 6 to 1 and 3 to 1 > Primary marked "P" and "B" > Secondary marked "G" and "F" > > 3- Regal wire-wound rheostats > > 3- Tubes - Markings illegible, one missing > 4 contact base(no pins) with twist-lock sockets > One tube has a "Songbird" sticker affixed (no idea if sticker is > original) > > 3- Air variable capacitors > > 2- Phenolic "Sandwiches" (Caps?) (1 1/8" x 1 1/8" x 1/8") > > 2- 3" diameter flat air coils (Ant?) > > 1- Wooden case with hinged top (8" H x 18 3/4" W x 7 1/2" D) > Wooden chassis > Wooden front panel > > Point to point wiring with all wires terminating on thumb-screw terminals > or spring clips. > > Anyone have any idea what this might be? Is there any historical value vs. > salvaging the air variables? > > I will post a panel and a chassis pic to the photo section. > > Thanks for your input! > > 73s > James > KE4MIQ > > > > > > > >
12993	2016-07-01 04:41:43	dan_halbert	Re: What have I found?
It looks to me like a rather roughly homebrewed TRF receiver, with a coil for the antenna. If you do a Google image search for "TRF receiver", you'll find a bunch of schematics and photos. Not sure what the rheostats are for. But I'm just guessing. You could draw a rough schematic and see if it matches. Dan, KB1RT
12995	2016-07-02 18:33:15	jmlynesjr	Re: What have I found?
Thanks, Dan. I'll try the search. James
12996	2016-07-02 18:40:28	jmlynesjr	Re: What have I found?
Hi Dave: No markings on the air variables. I bought the box mainly to reuse the caps. The last one I bought off of ebay was used for $15 plus shipping. James
12997	2016-07-03 21:31:50	jmlynesjr	Re: What have I found?
Dan: It seems your TRF guess was correct. I found an article, "The Receiving Tube Story", in the Antique Wireless Association(AWA) March 2011 newsletter, that described the history of the RCA Radiotron stubby pin tubes(UV 199) manufactured prior to 1925. GE was the original manufacturer under license to RCA. TRF radios were available from manufacturers as well as in kit form. I would assume mine is from a kit due to a total lack of manufacturer markings. The rheostats were used to adjust the tube filament voltages as the automobile type 6V batteries discharged. The early tubes required 1A at 5v. Later tubes used 3.3v at much lower current and dry cell batteries. As this is a 3 tube design, I believe is has 2 stages of RF amplification followed by a detector stage. This design has no audio amplifier and is setup to drive ear phones only. The air variables are not ganged together which would have required the user to tune each stage separately to change frequencies. I put in an inquiry to the AWA concerning any historical value that may exist. Thanks for your help. James