DUAL 12A6GT QRP CW TRANSMITTER/REGEN RECEIVER 80/40/30 METER CW

Description: This item has exposed high voltage underneath the chassis. I used good wiring practices, but if you are not experienced in working around lethal voltage, then PLEASE DO NOT purchase this item. I make these radios from scratch, so please allow 10 12 days for shipment, once purchased. The radio you receive will look very similar to the photos. The large tuning dials may vary, depending on what I have in stock. Also, the big brass tuning capacitors are hard to find, so you will likely receive a radio that has the standard gray plates. The circuit has a battery powered dc to ac inverter, and the no load dc voltage underneath the hood is over 300 volts! So even though the power source comes from harmless low voltage batteries it can still be lethal if not handled responsibly. This is a vacuum tube ham radio QRP cw transmitter and regen radio. The circuit uses a 12A6GT tubes for both the receiver and transmitter. It will also work with 12V6, 12W6 or 12L6 tubes. Or if you prefer I can build this radio with a 12SK7 regen detector and a 12V6 transmitter. Your choice, just let me know at time of purchase, same price. The 6SK7 (12SK7) tubes were used in the old WWII Paraset Spy radio and they work well for a regenerative receiver. The 12A6 transmitter tube requires only 0.15 amps drain from the power source and since a 12L6, 12V6 or 12W6 tube needs considerably more amps for the filament and produced only about a 5% to 10% gain in power out, I decided to just go with the 12A6 tubes for this listing. The inverter, which powers only the transmitter tube, turns off instantly when switched to receive mode. So it is not working at all when in the regenerative receive mode. The chassis requires an external 12 volt power source. I like to use a small motorcycle or golf cart battery, but so much the better if you have an old car battery that you are not using. This powers the filaments and inverter when in transmit mode. On the chassis a 9 volt rechargeable battery is require for the receiver, which is connected in series with the incoming 12 volt source, providing about 20 volts or so to run the regen detector. This is quite adequate. The receiver requires high impedance 2 to 4k ohm inductive or piezo headphones (not included). You may use a well filtered 12 volt bench supply to run this radio. It should be capable of about 2.5 amps in transmit mode. For this circuit there's only a few ma drain on the 9 volt battery, so it will go for many hours if not days before needing to be recharged. Depending on the crystal and band, the transmitter output on 80 and 40 meters is about 3 watts. It drops to about 1.8 to 2 watts on 30 meters. I'll provide one each, QRP HC49 crystal types, for 80 and 40 meter cw. For 30 meters the higher power HC49 frequencies are not available, so I parallel 2x HC49s types. The smaller 49s crystals cannot handle as much power as the larger 49U types, so on 30 meters I can hear a little chirp, but with careful tuning the signal is still quite good enough to put on the air. Plug-in coils are provided for the bands mentioned. The receiver coverage is pretty much continuous from about 3 to 12.5 mhz, by changing the coils. No reason why you couldn't make a receive only coil for the am broadcast band if desired. With the right coil this set will also work quite well on 160 meters. The dc inverter circuit employs a pair of TIP41C power transistors, working with a 6-0-6 volt 5 watt transformer that has a secondary winding of 220 volts. The output is then rectified by a 1N4007 diode, then filtered, for well over 300 volts dc, no load. I will include a hand-sketched wiring diagram of this item, plus a sketch of all control panel functions. The controls are receiver main tuning, fine tuning, receive antenna coupling and regenerative action/power on/off switch. The transmitter has a single control for power out, with link coupling to the antenna. There's a single send/receive switch which controls all necessary functions, including high voltage power on for transmit and switching the antenna. So you only need a single antenna for send/receive. In send mode the audio output will automatically be muted. No batteries, headphones or other power sources are included in this auction. AGAIN, EVEN THOUGH POWERED BY BATTERIES, IT CAN BE QUITE LETHAL IF NOT HANDLED WITH RESPECT! This is a given for most any ham radio transmitter. I'll include a hand sketched diagram of this radio when purchased. Schematics are available for most of my radios, which you can find on my other listings. Included also will be a pictorial diagram showing the location and function of all controls. SHIPPING TO THE UNITED STATES ONLY

Price: 198 USD

Location: Grand Junction, Colorado

End Time: 2024-01-26T19:48:04.000Z

Shipping Cost: 19.5 USD