80/40/30M HOMEBREW CW TRANSMITTER/REGEN RADIO (WORKING)

Description

THIS IS ANOTHER QRP RECEIVER/TRANSMITTER FROM MY COLLECTION. IT HAS A SINGLE TUBE 25DQ6 FOR THE CW TRANSMITTER AND A 25SN7 (AKA 1633) TWINPLEX REGEN RECEIVER.
YOU WILL NEED A SEPARATE POWER SUPPLY TO RUN THIS RADIO. THE REQUIREMENTS ARE 25 VOLTS DC FOR THE FILAMENTS AND 50 TO 75 VOLTS FOR THE OPERATING B+ SUPPLY. YOUR POWER SUPPLY SHOULD BE CAPABLE OF 0.6 AMPS FOR THE FILAMENTS AND AROUND 100 TO 125 MILLIAMPS FOR THE 25DQ6 B+ OPERATING VOLTAGE. ALL VOLTAGES MUST BE FROM WELL FILTERED DC SOURCES.
THE RECEIVER COVERAGE, WITH THE 2 PLUG-IN COILS PROVIDED, IS FROM THE TOP END OF THE BROADCAST BAND, UP TO ABOUT 12.45 MHZ.
IT WILL WORK BEST WITH ONE OF THE OLD STYLE HIGH IMPEDANCE (2 TO 4K OHMS) INDUCTIVE/MAGNETIC HEADSETS, BUT YOU CAN ALSO USE A HIGH IMPEDANCE PIEZO ELEMENT HEADPHONES. THERE'S A 1/4" PHONE JACK ON THE REAR OF THE CHASSIS FOR THE AUDIO OUTPUT.
I'M PROVIDING 2 COILS AND 3 CRYSTALS. ONE CRYSTAL EACH FOR 80, 40 AND 30 METERS. I'VE NEVER USED THIS LITTLE QRP STATION ON 30, BUT I DID TRY A 10.116 QRP CRYSTAL AND GOT IT TO LOAD UP ON 30 METERS, USING THE 40M COIL AND A RANDOM WIRE ANTENNA. THE TRANSMITTER PA AND LOADING CAPS WERE AT THE HIGH END, BUT I DID GET IT TO TUNE TO TUNE TO RESONANCE ON 30M, USING WITH MY ANTENNA AND THE 40M PLUG-IN COIL.
BETTER PERFORMANCE MIGHT BE OBTAINED WITH A COIL SPECIFICALLY WOUND FOR THE 30 METER BAND. SO I'LL THROW IN THE 10.116 CRYSTAL IN CASE YOU WANT TO GIVE IT A TRY.
QRP CAN BE A CHALLENGE, BUT I'VE MADE 1,000 MILE CONTACTS ON 80M CW USING HALF THE POWER THIS RIG PRODUCES. MY ANTENNA IS A SIMPLE INVERTED L, WORKING AGAINST GROUND, ELEVATED ONLY ABOUT 20 TO 25 FEET.
AT 50 VOLTS DC ON THE 25DQ6 PLATE CIRCUIT I CAN GET JUST UNDER ONE WATT OUTPUT. AT 65 TO 70 VOLTS THE OUTPUT DOUBLES TO OVER 1.5 WATTS. YOU SHOULDN'T GO MUCH HIGHER THAN 70 TO 75 VOLTS, AS THE 25DQ6 B+ ALSO PROVIDES OPERATING VOLTAGE FOR THE 25SN7 REGEN TUBE. YOU'LL RUN OUT OF REGEN CONTROL RANGE IS YOU PUSH THE CIRCUIT WITH TOO MUCH DC OPERATING VOLTAGE.
PA AND ANTENNA TRANSMITTER LOADING CONTROLS ARE ON THE FRONT PANEL, ALONG WITH RECEIVER MAIN AND FINE TUNING, PLUS REGEN AND ANTENNA COUPLING CONTROLS FOR THE RECEIVER. YOU ONLY NEED ONE ANTENNA AND A GOOD EARTH GROUND. THERE'S A SEND/RECEIVE SWITCH ON THE FRONT PANEL FOR THE ANTENNA TRANSFER.
I'LL PROVIDE A ROUGH HAND SKETCHED SCHEMATIC DIAGRAM. IT WON'T BE VERY PROFESSIONAL, BUT COMPLETELY READABLE AND ADEQUATE FOR TROUBLING SHOOTING OR EXPERIMENTING.
THIS IS A USED ITEM, SOLD AS IS, BUT GUARANTEED TO WORK IF YOU HOOK IT UP PROPERLY.
SHIPPING TO THE UNITED STATES ONLY.