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 from scratch when ordered, so please allow about 20 business days for shipment, once purchased. Most any reasonable chassis color may be requested. Please inquire if you'd like something different than that pictured. The appearance of the larger main tuning dial may vary, depending on what I have in stock (see photos). Essentially, this is just a modern day version of the old WWII Paraset Spy Radio, with a few improvements. The circuit has a battery powered 12 volt dc to ac inverter, and the rectified, no load dc voltage underneath the hood is over 200 volts. So even though the power source comes from harmless low voltage batteries it can still be just as lethal as 117 volt ac power from a wall outlet, if not handled responsibly. This is a vacuum tube ham radio QRP cw transmitter and regen radio. Patterned somewhat after the Paraset Spy radio, it uses two 6SK7 pentode tubes for the receiver and a 12V6 in lieu of the 6V6 for the transmitter. It has a Pi-network output tank circuit for harmonic reduction. With my bench top 12 volt dc power supply, or a 12 volt battery, I get about 5 watts out on 80 meter cw. The receiver circuit requires 4 nine volt batteries to power the detector and audio amp circuits. The 9 volt snaps are located on top of the chassis. In the original circuit, as pictured, there were 8 of the 9 volt batteries, but I have updated and improved the circuit so that only 4 are now required. If you intend to power this radio with a 12 to 14 volt dc bench power supply, it should be capable of delivering about 2.5 to 3 amps of dc current when the high voltage inverter is running. No batteries or other powers sources are included in this listing. The inherent problem with regen radios is that it is difficult to run them with rectified dc from an ac transformer located on the same chassis. I gave up with that sort of design, as any sensitive regen typically picks up a horrid ac background hum. So this regen runs strictly off battery power (or imported dc from a separate power supply). This eliminates the hum problem, since, in transmit mode, this is the only time that the dc inverter is running, at which time the send/rec switch mutes the headphones. The inverter, which powers only the transmitter tube, turns off instantly when switched to receive mode. This little rig loads up nicely on 80, 40 and 30 meters, with the plug-in inductors and 3 QRP crystals provided (one for each band). In my experience I have very little issues with chirp when using the 49/U QRP crystals. On those occasions when I get a hint of chirp I can usually tune it out by careful adjustment of the plate input capacitor to the Pi-network tank circuit. Also included in the purchase are plug-in coils for the receiver, allowing reception from about 1750 khz, up to 15.0 mhz, continuous, by use of the different coils. As an improvement over the old Paraset design, I have included a fine tuning control for clarifying cw and ssb signals. You will need high impedance headphones for the receiver (not included), either the old standard 2 to 4K ohm inductive types or piezo headsets will work. Included is a hand-sketched wiring diagram of this item, plus a sketch of all control panel functions. SHIPPING TO THE UNITED STATES ONLY