12W6 transmitter 80/40m QRP CW

Description

YOU ARE BIDDING FOR ONE HOME BREW SLAT BOARD DESIGN VINTAGE TYPE CW TRANSMITTER:
KW7T  12W6 SLATBOARD QRP 80/40M CW TRANSMITTER
Original Description:
THIS TRANSMITTER WORKS ON 80 AND 40 METER CW, BUT COILS FOR OTHER BANDS ARE FAIRLY EASY TO MAKE, AS DESIRED. YOU  WILL RECEIVE 2 COILS AND 2 QRP CRYSTALS, ONE EACH FOR THE 80 AND 40 METER BANDS.
I TRIED A NUMBER OF DIFFERENT TUBES IN THIS ONE TUBE GLOWBUG CIRCUIT AND THE 12L6/12W6 (OR OTHER FILAMENT VERSIONS) PRODUCED THE MOST POWER OUTPUT.
AT 75 VOLTS ON THE PLATE I CAN GET ABOUT 1 WATT OUTPUT--AROUND 1.5 WATTS OUT AT 100 VOLTS DC. FOR MORE POWER YOU CAN OPERATE WITH UP TO 200 VOLTS OR SO ON THE PLATE, NO PROBLEM.
NICE THING ABOUT THIS RADIO IS THAT YOU CAN USE MANY DIFFERENT PENTODE TUBES, SO LONG AS YOU CHANGE THE FILAMENT VOLTAGE TO MATCH THE TUBE CHOICE. THE 6V6, 6L6, 6U6, 6W6, 6Y6, 12L6 AND 12W6 TUBES (AND PROBABLY OTHERS) ALL HAVE THE SAME PIN OUTS AND WILL WORK IN THIS CIRCUIT, WITH VARYING RESULTS.
AGAIN, I TRIED MOST EVERYTHING THAT FITS THE CIRCUIT AND FINALLY SETTLED ON THE 12W6 WHICH I WILL INCLUDE WITH THIS LISTING. THE 12L6 PERFORMANCE IS ALMOST IDENTICAL TO THE 12W6. A 6V6 WORKS WELL, BUT HAS A LITTLE LESS POWER OUTPUT AS COMPARED TO THE 12W6.
I HAVE THE POWER SUPPLY FOR THIS TRANSMITTER ON ANOTHER LISTING. ON 80 METERS I COULD GET ABOUT 3.8 WATTS CW OUTPUT USING THE POWER SUPPLY THAT I HAVE LISTED, USING A 12W6 VACUUM TUBE FOR THE TRANSMITTER/OSCILLATOR.
IF YOU USE A POWER SUPPLY CAPABLE OF 250 TO 300 VOLTS, THEN YOU'LL PROBABLY WANT TO ADD A SCREEN DROPPING RESISTOR TO THE CIRCUIT TO LIMIT THE PLATE CURRENT. WITH THESE LITTLE QRP RIGS I'VE ALWAYS HAD THE MOST FUN JUST USING 50 TO 100 DC VOLTS ON THE PLATE, KEEPING THE POWER AT ABOUT 700MW TO 1.25 WATTS OUT.
I USED A SHUNT FED PARASET STYLE CIRCUIT FOR TUNING THE PLATE/ANTENNA TANK OUTPUT. I'M NOT SURE THAT IT WORKS ANY BETTER THAN A PI-NETWORK CIRCUIT, BUT IT WORKS GREAT WITH MY MULTI-BAND OR RANDOM LENGTH ANTENNAS, AND SEEMS TO HAVE GOOD HARMONIC REJECTION. I LIKE THE SHUNT FED TANK OUTPUT CIRCUIT BECAUSE IT TAKES THE DC VOLTAGE OFF THE EXPOSED PLATE TUNING CAPACITOR FOR IMPROVED SAFETY.
AS ALWAYS, ALONG WITH THE ANTENNA, YOU'LL NEED A GOOD EARTH GROUND FOR BEST PERFORMANCE.
NO POWER SUPPLY IS INCLUDED WITH THIS LISTING, BUT I WILL PROVIDE A LEGIBLE HAND SKETCHED SCHEMATIC DIAGRAM OF THE TRANSMITTER. AGAIN, THE TRANSMITTER COMES WITH 2 COILS AND 2 CRYSTALS FOR 80 AND 40 METERS.
PLEASE SEE MY SEPARATE LISTING FOR A POWER SUPPLY THAT WILL WORK WITH THIS RADIO.
OBVIOUSLY, YOU'LL NEED A VALID AMATEUR RADIO LICENSE TO PUT THIS LITTLE RIG ON THE AIR. I GUARANTEE THAT THIS RADIO WILL WORK IF HOOKED UP PROPERLY.
HERE'S A WELL BUILT LITTLE QRP TRANSMITTER FOR SOME NOSTALGIC FUN. IT HAS THE OLD WORLD SLAT BOARD STYLE CHASSIS, FINISHED IN POLYURETHANE.