Some time ago while running an errand in the mobile I ran across Gene Schaffner, W2GMX on the local repeater. After chatting for a while Gene mentioned 
he had 40 some odd rigs!!
Well did that ever get my attention. Seems Gene was into building qrp rigs. All 47 (at that time) of them. He has used each and every one of them and in one case has 267 contacts with
a "Peanut Whistle" running a few hundred milliwatts!!!. Well I just had to meet Gene and we arranged for a visit. I'll not forget the day of the visit for some time. I was like a kid in a
candy shop. Gene pulled out rig after rig and showed them to me. One design in particular caught my attention. It was a smallish single tube, 6aq5 crystal controlled
40M transmitter of his own design. You can imagine my delight when Gene told me to take the transmitter home and give it a try. I also took a copy of the schematic just in
case I decided to give building one a try. Since that day my interest in ham Radio changed forever. I have acquired the necessary savvy, with Gene's to build my own simple radios and
have enjoyed with much pride making contacts spanning continents running only 4 watts. You see I built a similar 6aq5 and after a few attempts managed to get it on the air with a nice
clean note. In fact my key, keyer, antenna control box and OCF dipole antenna are all home brew. They are just a natural extension of building your own radio. A nice spin off is
throughout this entire process my CW has greatly improved. Make no mistake about it QRP is a challenge. It takes a lot of patience and at times can be frustrating. However the rewards
of making a contact with your own home brewed equipment and low power are very rewarding. There is plenty of interest and activity in QRP so you won?t have to look far to find other
Hams that share your interest. You won?t have to look very far for contacts either. So come on in and get your feet wet, I promise you'll have a good time.
What follows are some photos and the schematic of my 6aq5. The cost of building this rig will vary depending on your resources. A well stocked Junk box is a good start,
Ham fests are another place to find components. Look in the flea market section of the "fest". Other Hams may be able to help so ask around and as a last resort there are the
commercial parts houses. As for my first rig, no junk box! I scrounged what I could and wound up buying the rest. I figure I have about forty five dollars rapped up in this rig. Believe me,
I have gotten a thousand times that back from the fun of operating it. Gene has since passed and is missed by all he touched. This QRP section of my site is dedicated to Gene.
First of all I'm not an engineer. Hell I'm not even smart. I some times wonder
how I have progressed as far as I have with what little the Lord gave me. Having said that please
proceede at your own risk. You may feel that there are better ways to acomplish what's presented
here but this is the path I followed. I will graciously listen to any comments or suggestions concerning
my projects. As I'm always willing to learn. Now if you skipped over the Safety Intro page please go back and read it. Safety Info
The following schematics of the 6aq5 and miscellianous circuits were mostly created by the desire to build a tube type QRP rig
that departed from using non-standard hard to find, expensive parts and this is the end result. It has been a interesting journey.
The rig that is described here is my first attempt at constructing a Glowbug. .
I live in Up-state New York and have worked as far south as the Caribbean, into EU to the east and as far west as California in
the time that I have been using this rig. No real DX at this time (conditions are improving). Comments on the quality of the signal have been very favorable. I currently use a windom wire antenna and a small
antenna tuner. circuit here Unfortunately this antenna is at modest height of 22 feet and slopes down at about 35 degrees at the short end.
CONSTRUCTION NOTES:
CHASSIS MEASURES 7" X 5" X 2" - BUD #AC402
POWER TRANSFORMER IS A HAMMOND 269EX (380VCT AT 66mADC.)
ALL THE CAPS ARE DISC CERMIC EXCEPT THE SILVER MICA BLOCKING CAPACITOR IN THE PLATE CIRCUIT.THE USE OF A SM CAP
ASSURES BETTER FREQUENCY STABILITY. ALL RESISTORS ARE 1/2 WATT EXCEPT AS NOTED ON THE SCHEMATIC.
NOT SHOWN IN THE PHOTOS IS THE HOT GLUE APPLIED OVER THE CONNECTIONS AT THE BASE OF THE COIL. THIS WAS APPLIED TO PREVENT
THE POSSIBILITY OF SHOCK.
I MEASURED THE RECTIFIED CW OUTPUT ACROSS A 50 OHM NON INDUCTIVE LOAD AND OBSERVED 19.6 VOLTS. THE VOLTAGE SQUARED DIVIDED
BY THE RESTANCE EQUALS POWER. IN THIS CASE 7 WATTS. ( I HAVE A 100MA
METER ON ORDER SO I CAN MEASURE THE CATHODE CURRENT AND DETERMINE THE PLATE POWER INPUT )
I WOULD CONSIDER THE FOLLOWING PHYSICAL LAYOUT CHANGES: MOVE THE CRYSTAL HOLDER AND SWITCH TOWARD THE CENTER OF THE CHASSIS, MOVE THE
LOCATION OF THE TUBE FORWARD AND RELOCATE THE COIL TO THE RIGHT REAR OF THE CHASSIS.
CLICK HERE TO DOWNLOAD A PRINTABLE PDF OF THE FINIAL CHASSIS LAYOUT
COIL WINDING DETAILS:
TO GET STARTED YOU CAN USE ANY TYPE OF PLASTIC OR NON CONDUCTIVE TUBING, PILL BOTTLE OR PVC PIPE BETWEEN 1 AND 1 1/8 INCH ACROSS.
I USED A NYLON TUBE 1 1/8 " IN DIAMETER BUT I'M SURE A 1" PIECE OF PCV PIPE WOULD ALSO WORK AS WELL. MY COIL FORM IS
1 3/4" HIGH. THIS PROVIDES AMPLE SPACE FOR THE WINDINGS. IF YOU USE A FORM SMALLER THAN 1" IN DIAMETER ADD A TURN OR TWO
TO COMPENSATE FOR THE SMALLER DIAMETER.
YOU CAN MOUNT THE COIL VERTICALL BY EITHER EPOXYING IT TO A SMALL
PRINTED CIRCUIT BOARD (RS # 276-159B OR 276-148) OR ANY OTHER SUITABLE MATERIAL YOU MAY HAVE. I PREFER THE 276-159B BECAUSE YOU CAN CONVIENTLY
TERMINATE THE WINDINGS AT THE BASE OF THE COIL BY SOLDERING THEM TO THE BOARD. YOU COULD ALSO LEAVE THE
THE ENDS OF THE COIL LONG ENOUGH TO REACH THE APPROPREATE POINTS IN THE CIRCUIT THROUGH A HOLE IN THE CHASSIS. THE COIL COULD ALSO
BE MOUNTED DIRECTLY TO THE CHASSIS, ELIMINATING THE PCB BY USING SMALL "L" BRACKES. IN THIS CASE ADJUST THE LENGTH OF THE COIL FORM TO ALLOW ROOM FOR THE BRACKET/S.
I USED INSULATED 22 GA. STRANDED HOOK UP WIRE FOR THE COIL WINDINGS. (L1) WIND THE FIRST 18 TURNS WHILE NOTEING THE DIRECTION
OF THE WRAP. WHEN FINISHED WRAP THIS WINDING WITH A SINGLE LAYER OF BLACK ELECTRICIANS TAPE. THIS WILL MAKE
IT EASIER TO LAY DOWN THE SECOND WINDING. (L2) NEXT WRAP 4 TURNS, EVENLY SPACED OVER THE SPAN OF THE FIRST WINDING. BE SURE TO WRAP
THE SECOND COIL IN THE SAME DIRECTION AS THE FIRST. USE A WRAP OF ELECTRICAL TAPE OR HEAT SHRINK TUBING
TO HOLD THE SECOND WINDING IN PLACE. LOTS OF FLEXIBILITY HERE SO USE YOUR IMAGANATION.
THE COIL COULD ALSO BE MOUNTED ON IT'S SIDE BY MAKING IT 2" LONG AND DRILLING A HOLE AT EACH END AND USING 4/40 OR 6/32
HARDWARE TO MOUNT IT ON ITS SIDE USING ADDITIONAL NUTS OR WASHERS TO PROVIDE THE NECESSARY SPACE BETWEEN THE SIDE OF THE
COIL AND THE CHASSIS.
AS TIME PERMITS I PLAN ON MAKING ANOTHER COIL AND PHOTOGRAPHING IT AS I GO ALONG TO HELP SHOW HOW THE COIL IS CONSTRUCTED.
I USED AN AIR VARIABLE CAPACITOR IN THE FINIAL TANK CIRCUIT BUT YOU COULD PROBABLY USE A COMPRESSION TRIMMER
AS WELL. JUST MOUNT IT SO YOU CAN EASLY ADJUST IT WITH A SCREWDRIVER. THE OUTPUT CIRCUIT IS PRETTY BROAD (LOW Q?)
AND DOSENT'T REQUIRE A LOT OF TOUCH UP WHEN MAKING SMALLISH FREQUENCY CHANGES.
WHILE NOT SHOWN IN THE SCHEMATIC THE B+ SUPPLY IS TOGGELED ON AND OFF BY A DPDT SWITCH. ONE SIDE OF THE
SWITCH CONNECTES THE CENTER TAP OF THE POWER TRANSFORMER SECONDARY TO GROUND. THAT TOGGLES THE B+ ON AND OFF. THE OTHER SIDE OF THE SWITCH
TOGGLES THE ANTENNA BETWEEN THE OUTPUT (L2) LOOP OF THE COIL AND A RCA JACK ON THE REAR APRON OF THE CHASSIS.
THIS RCA JACK IS CONNECTED TO MY RECEIVER. A SIMPLE, INEXPENSIVE TRANSMITT/RECEIVE SWITCH. CIRCUIT HERE
FOR A MORE "VINTAGE" LOOK YOU COULD SUBSTITUTE A 6N7, 6AR6 OR 6V6 FOR THE FINAL BEING SURE TO NOTE THE TUBE PINOUT CHANGES. THE 6AQ5, 6BQ5,
THE 6N1N (RUSSIAN EQUIVILENT OF THE 6BQ5) OR EL84 WILL PRETTY MUCH DO ANYTHING THE EARLY TUBE TYPES WILL DO, THEY ARE MORE READILY AVALABLE AND
REASONABLY PRICED.
CAUTION!
THIS TYPE OF RIG WILL HAVE A SUBSTAINTAL AMOUNT OF VOLTAGE ACROSS THE KEY CONTACTS WHEN THE KEY IS
OPEN. I MEASURED 52VDC ACROSS THE KEY ON THIS RIG. IF YOU USE A STRAIGHT KEY OR A BUG DON'T GET YOURSELF ACROSS THE KEY CONTATCS.
IF YOU USE A SOLD STATE KEYER THIS IS MORE VOLTAGE THAN A SOLID STATE KEYER CAN SAFELY PULL TO GROUND. I RESOLVED THIS BY RECTIFYING
THE FILAMENT VOLTAGE AND RUNNING IT THROUGH A DROPPING RESISTOR TO ACTIVATE THE 5 VDC RELAY. I KEY THE RELAY
AND THE RELAY KEYS THE CATHODE CIRCUIT OF THE 6AQ5. CIRCUIT HERE IF THE RECTIFIED FILAMENT VOLTAGE IS TOO HIGH EXPERMENT WITH A DROPPING RESISTOR IN SERIES
WITH THE RELAY COIL TO KEEP THE RELAY FROM CHATTERING FROM TOO HIGH OF A COIL VOLTAGE. I PURCHASED THE 5 VDC RELAY FROM RADIO SHACK. AN ALTERNATIVE WOULD BE TO BUY
A KEY ALL KEYER KIT OR A
HAM GADGETS UNIVERSAL KEYER TO KEY THE CATHODE. IF YOU ADD
EITHER ONE OF THESE ADD-ONS TO YOUR KEYER IT WILL BE ABLE TO KEY ANY CATHODE, SOLID STATE OR GRID BLOCKED RIG.
IF YOU BUILD THIS RIG, PLEASE CONTACT ME WITH YOUR BUILDING EXPIERENCE AND END RESULTS. I WOULD ENJOY HEARING FROM YOU.
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ADDITIONAL QRP CIRCUITS
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