ESSENTIALLY A PARASET 2.0 RADIO 12AQ5/12BA6 TRANSMITTER/RECEIVER (RUNS ON 12VDC)

Description: This is a bit of old world nostalgia. In the 1940's the Allied Underground had this 6v6/6sk7 Spy Transceiver that used a 6v6 for a one tube transmitter and two 6sk7's for a regenerative receiver. With a little modern day updating I've used the 12AQ5 (aka 12V6) for the transmitter, one 12BA6 (12SK7) for the regenerative detector, followed by a single transistor audio amp. With this set-up the headphone volume is quite adequate. Essentially it operates just like the old WWII Paraset, but has a built-in 12 volt power inverter, and whereas the original Spy Radio only operated on 80 and 40 meters, this radio, with proper coils and crystals, will work any band, from 630 to 20 meters. A big plus is that it also has a fine tuning control so you can clarify cw and ssb signals much easier. The price is for any two bands, 160 thru 20 meters. You specify the bands? Additional bands are $27.00 each for the coil and one HC49 crystal, with the exception that for the 630 meter band, the price of a coil and additional circuitry is $38.00. With an optional coil the receiver can even be made to work on long wave, well below below the 630 meter ham band. Built on a Bud Aluminum chassis. You may request hammered black or gray, as pictured, or I can just leave the chassis unpainted in natural aluminum, your choice. As shown in the photos, two dial face options are available. Just sent me a note when ordering to let me know which option you prefer. In lieu of an ac power supply I have incorporated a small dc to ac inverter circuit, which produces just over 200 volts key down for the transmitter B+. You can see the inverter transformer in the photos. With no load the rectified and filtered voltage output from the inverter is about 325 volts dc. So needless to say, this can be quite lethal, even though the inverter requires only 12 volts dc as a source. Please do not purchase this item if you are not familiar with the dangers of working around high voltage circuits! Most any vacuum tube transmitter has voltage high enough to cause serious injury or death, if not handled responsibility! This is not a toy. It is quite safe for a skilled operator, but can be lethal if not approached with proper respect. The receiver spectrum coverage can be made continuous, from below the am broadcast band to 17 mhz. As stated earlier, the price is going to depend on how many coils you want to allow for frequency coverage. I can even make one of these radios using the 12V6 tube, in lieu of the 6AQ5 for the transmitter, and a 12SK7 for the receiver (same price). Problem is, on the 630 meter band, unless you have a very good antenna system for transmitting, you'll be lucky to get across the county line with QRP power! With a fully charged 12 volt battery I get just over about 3.75 watts cw RF output with the transmitter on 630, 160 and 80 meters, and about 2.5 watts on 40. That's how these old audio tubes work for power out. It keeps dropping as you go up in frequency. About 1.5 to 2.0 watts is all it will do on 30 meters, and one watt (or less) on 20 meter cw. The QRP HC-49/U crystals provided, are being pushed close to the limit, so I do hear a slight tendency toward chirp (more like sing-song warble). However, with careful tuning of the pa load variable capacitor I can get rid of about 90 to 95% of the chirp, so the tone is quite presentable for on air use. With regular FT-243 crystals I hear no chirp at all when the tank circuit is properly adjusted for transmitting. The RF tank circuit of this single tube transmitter is similar to that used in the Paraset Spy radio. With the appropriate plug-in coil it will load into most any reasonable random length wire antenna. You will need a 3 amp 12 volt dc battery or well filtered bench power supply to power this radio (not included in this listing). The wal-wart type power packs will work great for the transmitter, but they often tend to generate hash that is picked up by the sensitive regen detector. I try to avoid the wal-wart switching supplies when possible, but now and then do find some that work just fine. A good 12 to 14 volt battery works best if you have one. Motor cycle or golf cart type lead acid batteries are best and fairly inexpensive. I can usually find them, complete with a charger, for about $20.00, shipped price. Your 12 volt source provides filament voltage for the inverter circuit and the 12AQ5/12BA6 filaments, but the B+ for the regen detector and audio amp is supplied by two 9 volt rechargeable Li-ion batteries (not included). They will run for many hours (if not days) before needing to be recharged. In series with the 12 volt power source, the two 9 volt batteries gives about 30 volts dc for the receiver circuit, which produces good volume for your high impedance headphones. You'll need either one of the old traditional 2 to 4k ohm inductive headsets, or will also work quite well with the high impedance piezo type headphones. This listing does not include headphones. The color and/or appearance of the six binding posts on the back of the chassis may vary slightly, depending on what I have in stock. If you need different connectors on the chassis for the various functions, please send me a note and I'll try to accommodate you. I guarantee this radio will work if properly connected to a power source and your ham radio antenna. A good earth ground is always essential for best performance. A hand sketched schematic diagram of the circuit will be provided with your purchase, along with a block diagram showing the location of all controls, power, headset, cw key and antenna connectors. Again, no power source of any kind is included. If you decide to purchase this radio please inquire about coil and crystal prices for the extra bands, as desired. Again, for receive I can make coils for long wave, going well below the am broadcast band. SHIPPING TO THE US ONLY.

Price: 279 USD

Location: Grand Junction, Colorado

End Time: 2024-08-13T23:49:47.000Z

Shipping Cost: 19.48 USD