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THIS IS OBVIOUSLY NOT AN EXACT REPLICA OF THE 1929 HULL HARTLEY. I'VE ADDED A FEW UPGRADES TO THE ORIGINAL, AND RESERVE THE RIGHT TO ADD IMPROVEMENTS, WHEN DEVELOPED. AT 9 MA PLATE CURRENT THIS 01A TUBE POWER HOUSE WILL SET THE SKIES ABLAZE WITH ABOUT 1,000 MILLIWATTS INPUT. WITH THE 400 PF OSCILLATOR CONTROL CAPACITOR THE TUNING RANGE IS ABOUT 468 KHZ TO 8.0 MHZ, USING DIFFERENT PLUG-IN COILS PROVIDED. THE OLD BRASS PLATE VARIABLES ARE GETTING REALLY DIFFICULT TO COME BY, SO YOU WILL LIKELY RECEIVE A TRANSMITTER WITH THE TYPICAL GRAY PLATE CAPACITOR, IN LIEU OF THE BRASS TYPE THAT YOU SEE IN THE PHOTOS. I'LL TRUST YOU, WITH A VALID HAM RADIO LICENSE, TO TRANSMIT ONLY IN THE HAM BANDS. TO SIMPLY THINGS, USING JUST ONE LITHIUM BATTERY FOR FILAMENT POWER, I'M RUNNING THE 5 VOLT FILAMENT AT 3.8 TO 4.0 VOLTS DC. THIS IS ADEQUATE AND THE TRANSMITTER WORKS GREAT, EVEN THOUGH THE VOLTAGE IS LESS THAN NOMINAL. I'VE ADDED A FINE TUNE CAP TO THE OSCILLATOR CONTROL, AND A SERIES TUNED OUTPUT LINK TO THE ANTENNA. ADJUSTMENT OF THESE SINGLE TUBE OSCILLATOR/TRANSMITTERS IS ALWAYS CRITICAL, SO THE ANTENNA TUNING CAP REALLY HELPS. JUST LIKE A REGEN RECEIVER, IF YOUR ANTENNA LOADING IS TOO HEAVY, THEN IT WILL SHUT THE OSCILLATOR DOWN. SO THE ANTENNA COUPLING CAPACITOR THAT I'VE ADDED TO THE CIRCUIT REALLY HELPS IN THIS REGARD. WITH MY LITTLE DC TO AC INVERTER POWER SUPPLY I'M ABLE TO GET ABOUT 125 VOLTS B+, KEY DOWN, USING A SINGLE 4 VOLT LITHIUM BATTERY TO FIRE THE INVERTER. 125 VOLTS DC IS STILL HIGH ENOUGH TO CAUSE INJURY OR DEATH, IF NOT HANDLED WITH CAUTION AND RESPECT. SO PLEASE BE CAREFUL! THIS CIRCUIT USES SHUNT FEED FOR THE PLATE CIRCUIT, SO THERE ARE NO EXPOSED VOLTAGES OUTSIDE THE CHASSIS FRAME. TYPICAL OF THE TRANSMITTERS OF THAT ERA, YOU GET A SING-SONG WARBLE TONE FOR THE CW SIGNAL, WITH JUST A HINT OF NOSTALGIC CHIRP. WITH THE COILS IN THE PHOTO THIS TRANSMITTER WILL TUNE THE 630, 160 AND 80 METER BANDS. I'LL ALSO INCLUDE A COIL FOR 40 METERS, BUT JUST LIKE AN OSCILLATING REGEN RECEIVER, THE STABILITY AND QUALITY OF THE TONE TENDS TO DEGENERATE AS YOU GO UP IN FREQUENCY. SO IT WILL DEFINITELY WORK ON 40 METERS WITH CAREFUL ADJUSTMENT, BUT THE TONE QUALITY IS INFERIOR TO THAT OBTAINABLE ON THE LOWER FREQUENCIES. IN THE PRIMITIVE YEARS OF HAM RADIO, THESE HARTLEY TRANSMITTERS WERE CALLED "GROWLERS." I WOULDN'T SAY THE TONE IS THAT BAD ON 40, BUT IS DEFINITELY BETTER ON LOWER FREQUENCIES. THE 01A FILAMENT PULLS ONLY ABOUT 250 MA CURRENT, SO YOU'LL WANT TO RECHARGE THE LITHIUM BATTERY AFTER 2 TO 3 HOURS OF USE. YOU'LL BE LUCKY TO GET MORE THAN AN HOUR OF CONTINUOUS OPERATION ON THE INVERTER BATTERY, AS THE KEY DOWN CURRENT RUNS ABOUT 1.5 TO 2.0 AMPS. TO MITIGATE THE SHORT TERM LIFE OF THE INVERTER BATTERY I'VE PROVIDED A FRONT PANEL INVERTER STANDBY SWITCH, WHICH IS TOTALLY INDEPENDENT OF THE FILAMENT CIRCUIT. SO YOU CAN LET THE FILAMENT RUN, BUT ONLY SWITCH THE B+ VOLTAGE ON WHEN READY TO TRANSMIT. THIS EXTENDS THE RUN TIME OF THE B+ INVERTER BATTERY. SINCE THE INVERTER USES TRANSISTORS, ITS POWER OUTPUT IS INSTANTANEOUS AND READY TO GO WHEN YOU THROW THE SWITCH. THE INVERTER IS COMPLETELY OFF IN STANDBY MODE, WITH FILAMENT ON. THE CIRCUIT USES 2X 26650 LITHIUM-ION RECHARGEABLE BATTERIES (NOT INCLUDED), WHICH ARE READILY AVAILABLE ON eBAY. I WILL INCLUDE A COMPLETE HAND SKETCHED SCHEMATIC OF MY VERSION OF THIS 1929 TRANSMITTER ALONG WITH THE PURCHASE, WITH POWER SUPPLY DOCUMENTATION. I GUARANTEE THAT WITH PROPER ADJUSTMENT TO YOUR ANTENNA, THIS TRANSMITTER WILL WORK IN THE FASHION OF SIMILAR RIGS OF THAT ERA. SHIPPING TO THE UNITED STATES ONLY