SCHEMATIC ONLY 1625 PENTODE SHORTWAVE REGEN RADIO (APPROX. 3.55 TO 14.15 MHZ)

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THIS LISTING IS FOR A HAND SKETCHED SCHEMATIC ONLY OF THE RADIO THAT YOU SEE IN THE PHOTOS. THE CIRCUIT SHOWS ALL PARTS VALUES, BUT THERE'S NO TEMPLATE OR INSTRUCTIONS, OTHER THAN SOME NOTES WITH COIL DATA. LAYING OUT THE CHASSIS AND CONSTRUCTING ONE OF THESE CAN BE LOTS OF FUN, BUT ALL THAT IS UP TO YOU. ALL I'M PROVIDING IN THIS LISTING IS THE SCHEMATIC AND PARTS VALUES.<br>THIS IS THE OLD TRADITIONAL STYLE OPEN FRAME 1625 SHORTWAVE REGEN RADIO RECEIVER. SOME OF THE PHOTOS MAY SHOW A 19BG6G TUBE ON THE CHASSIS. EXCEPT FOR THE FILAMENT VOLTAGE THE 1625 IS VIRTUALLY IDENTICAL TO THE 807, 6BG6, 19BG6, ETC. PHOTO #7 SHOWS A 1625/19BG6 COMPARISON.<br>THERE ARE NO PLUG-IN COILS TO CHANGE. THE COVERAGE IS CONTINUOUS FROM ABOUT 3.55 TO  14.15 MHZ, WITHIN 1 TO 2% TOLERANCE. THIS IS ANALOG TECHNOLOGY. WITH THE L/C COIL/CAPACITOR RATIO I CAN TYPICALLY GET A FREQUENCY SPAN OF ABOUT 10.5 MHZ OR MORE (I.E. 14.15 - 3.55 = 10.6 MHZ). BUT THIS IS APPROXIMATE, BASED ON TOLERANCES OF THE PARTS IN THE CIRCUIT, SO PLEASE EXPECT THERE COULD BE A FREQUENCY VARIANCE OF 100 TO 200 HZ, BASED ON ALLOWED TOLERANCES.<br>IF YOU CARE TO WIND PLUG-IN COILS, NO REASON WHY YOU CAN'T MAKE THIS RADIO WORK, FULL COVERAGE, FROM LONG WAVE, THROUGH THE AM BROADCAST BAND, AND UP TO AROUND 15 MHZ OR SO.<br>AS A BONUS THE CIRCUIT HAS A ONE STAGE TRANSISTOR HEADPHONE AMPLIFIER, WHICH INCREASES THE VOLUME CONSIDERABLY. THE TRANSISTOR AMP IS PART OF THE CIRCUITRY, AND RUNS OFF THE COMMON DC FILAMENT/B+ LINE.<br>THIS RADIO WILL WORK WITH A HIGH IMPEDANCE PIEZO HEADSET, USING DUAL PIEZO ELEMENT INSERTS, LIKE THE ONE IN THE PHOTOS. IT WILL ALSO WORK WITH THE HIGH IMPEDANCE 2 TO 4K OHMS INDUCTIVE TYPE HEADSETS THAT HAVE BEEN AROUND FOR OVER 100 YEARS.<br>A WELL FILTERED 12 TO 14 VOLT DC POWER SUPPLY (OR BATTERIES) IS REQUIRED TO RUN THIS RADIO. I FIND THE 12 VOLT CORDLESS DRILL BATTERIES MAKE AN EXCELLENT POWER SUPPLY FOR THIS TYPE OF RADIO. SOME OF THE WAL-WART TYPE POWER SUPPLIES WILL WORK OKAY, SO LONG AS THEY DO NOT INDUCE SWITCHING NOISE THAT CAN BE PICKED UP BY THE SUPER SENSITIVE REGENERATIVE DETECTOR. OTHER TYPES OF WELL FILTERED DC SOURCES WILL ALSO WORK, BUT I TRY TO USE BATTERIES WHEN POSSIBLE (ABOUT 0.6 AMPS REQUIRED).<br>THIS CIRCUIT HAS MAIN, FINE TUNING AND REGEN CONTROLS ON THE FRONT PANEL. SINCE THIS IS AN OPEN CHASSIS WITH NO SHIELDING YOU WILL GET SOME HAND CAPACITY EFFECT, MORE SO IN THE HIGHER FREQUENCIES.<br>YOU'LL NEED A WIRE ANTENNA OF AT LEAST 50FT TO 100 FT. IN LENGTH, ALONG WITH A GOOD EARTH GROUND.<br>SCHEMATICS MAILED TO THE US ONLY. THANKS FOR STOPPING BY......KW7T