This is a bit of old world nostalgia. In the 1950's the 6AQ5 (aka 6V6) became quite popular for homebrew ham radio projects. The 6AQ5/6V6 tubes are frequently used for cw transmitters, but less known is the fact that these tubes also make excellent detectors for regenerative receivers. 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 an optional coil the receiver can even be made to work on long wave, below the am band.

For this circuit I have used one 6AQ5 for each function, send and receive. Many are familiar with the ARRL's Novice Special regenerative receiver from the nostalgic days of the 1950/60's. It used 2x 6AQ5's, but for this circuit I used only one 6AQ5 (regen detector), then added a one stage transistor audio amp to drive the headphones. This works out quite well.

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!

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 standard 6V6 tubes, in lieu of the 6AQ5's. Or, for that matter with the right coil and crystal it will even work on 630 meter cw (inquire for price). Problem is, with the 630 meter band, unless you have a very good antenna system, you'll be lucky to get across the county line with QRP power on the 630 meter band.  

With a fully charged 12 volt battery I get just over about 3.75 watts cw RF output with the transmitter on 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 down into the milliwatt range 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 of the 1940's WWII fame. 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 6AQ5 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 headphones.

This listing does not include headphones. You will need a high impedance headset, like the red Piezo types that I have on some of my other listings. The high impedance 2 to 4K ohm inductive type headphones will also work well with this receiver. 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.  

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.  For receive I can make coils for the long wave, going well below the am broadcast band.

SHIPPING TO THE US ONLY.