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For more info. on this tube visit: www.tubecollector.org/ For a data sheet see: http://www.nj7p.org/Tube4.php?tube=15E The Start of Building a GlowBug QRP with a 15E Tube Evening One
This is made up from two "Converter" boxes from Bud // Transformers 24V for Keying & Filament
I modified a trimmer cap for lower capacitance and higher voltage by "Carefully" removing plates
This will be my tank coil, but first it was grimy (Left) so.....As the Lady of the house, I ran it through the dish washer (Cascade Complete) Guys you better ask first!
Evening Two
Mounted switches, pilot lamps, the small crystal socket in the center, was modified to fit the 15E. The phone jack is for the key, actual crystal socket is just above it. The fuse in on the far Right.
The phone jack is for 24V out to the T/R switching system. The brown Cap is a broadcast mica type, 90 pF 3 KV @ 2A. The tank inductor is a Vario coupling type. (load matching)
EVENING THREE
Started the wiring while waiting for the power transformer and choke to arrive from OldRadioParts.com The vacuum Keying Relay from Max-Gain Systems arrived today. In the left picture it is center top. In the Right picture it is just in front of the big brown mica cap. This completes the AC wiring, 24V keying power supply and 15E heater (filament) power supply.
EVENING FOUR
Today the High Voltage Power Supply, Tomorrow the RF Section! EVENING 5,6 &7 ! Well things were going too smoothly any way.
As it turns out this little tube is only just starting to operate at my B+ voltage level of 450V so it was a "Little Stinker" to get work. Every thing had to be optimal to get 1 Watt out. I even made a HV trim cap from some copper water pipe strap, to put the tuning cap in mid range. The nylon screw made the critical adjustment. From this I got an idea of what size "Real"cap I needed. As you can see the connectors on the 15E are home made. The parts were hot air soldered with preformed solder rings between the sections.
The solution to getting this little experiment to work is increase the High Voltage to around 1 KV. This means back up and redo the power supply, that's the fun of experimenting and learning. So Today I ordered the items from Oldradioparts.com to finish this project successfully. An easy 5 WATTS ....... I Hope PS: By limiting the output power to 5 watts the crystal current should be low enough to prevent heating and thus frequency drift. ( a whoop sound )
This is the feed back coil that is connected to the crystal / grid circuit. More after I get my parts. THE NEXT WEEKEND (THE PARTS ARE HERE!!!)
WELL I DID SAY THAT THE POWER SUPPLY HAD TO BE CHANGED IT IS NOW RIGHT AT 1 KV, THE TWO OIL FILLED HV CAPS ARE ON THE LEFT THEY ARE RATED 1uF @ 1.5 KV. THE POWER TRANSFORMER IS A "NEW OLD STOCK" MIL SPEC TYPE. ONE PROBLEM WAS THE RECTIFIER TUBES THE STANDARD 5V4 TYPES COULD NOT HANDLE THE HIGH VOLTAGE AND I DIDN'T WANT TO USE THE LARGE TRANSMITTER TYPE SO......TRY USING TWO 6W4's THE GOOD OLD TV DAMPER TUBE BECAUSE I WAS NOT RUNNING HIGH CURRENT, I TRIED PUTTING THE FILAMENTS IN SERIES. THE TRANSFORMER ONLY HAD ONE 6.3V @ 1.2A / 1.5KV INSULATED WINDING AND IT WORKED GREAT (YOU DO HAVE TO ALLOW FOR A LONGER WARM UP TIME)
THE BIG FEEDBACK COIL WAS NOT NEEDED . A SMALL PISTON NEUTRALIZATION CAP REPLACE THE HOME MADE ONE. BUT TO GET PROPER OPERATION THE 15E's FILAMENT VOLTAGE HAD TO BE INCREASED TO 4V. THE PLATE DISSIPATION IS 20W SO I ADDED A SMALL FAN TO KEEP IT COOL AND EXTEND LIFE
WITH THE FAN I AM RUNNING THIS LITTLE GUY AS HARD AS I DARE. THE PLATE STARTS TO GLOW SLIGHTLY.
BUT SUCCESS AT LAST! 2.5 TO 3 WATTS OUT ON 7.100 MHz. SOUNDS VERY CLEAN FOR A SINGLE TUBE OSCILLATOR / TRANSMITTER IT MAY NOT BE VERY EFFICIENT BUT A LOT OF FUN. I WILL BE RUNNING IT AS THE QRP COMPANION TO MY 200W 813 I HOPE YOU ENJOYED WATCHING THIS QRP 15E EXPERIMENT. IT MAY BE AN "ODD DUCK" BUT A FUN LEARNING PROJECT.
73! BE LISTENING FOR "15E QRP N3SGR" ON 40 METERS 7.100
http://faculty.frostburg.edu/phys/latta/ee/6cl6xmtr/6cl6xmtr.html
My 40 Meter Long Wire Antenna
The 500 Ohm NON inductive termination resistor came from DigiKey www.digikey.com 510 Ohm is the closest standard value Part # TA025PW510J-ND for $5.85 The antenna runs from West (feed point) to the East (The termination point) It is called a "Terminated Long Wire". (HF Antenna Section of The Radio Communications Handbook RSGB)
A ONE TUBE 40-METER QRP TRANSCEIVER Anything less would be two cans and a string... www.glowbugkits.com/
FOR A GREAT SOURCE OF VINTAGE PARTS Visit & MAX-GAIN SYSTEMS @ www.mgs4u.com
For reasonably priced vacuum relays check here.
Narrow the band width go CW!
See The FMJ-418 Morse Code / CW Tutor with LCD Display http://www.mfjenterprises.com/products.php?prodid=MFJ-418 
http://www.mfjenterprises.com/index.php For Ham Radio to fit your budget see: Small
Wonder Labs Large
inventory for servicing and manufacturing Amateur, Commercial and Broadcast Communications Equipment. http://www.rfparts.com/ http://diamondantenna.net
RF CONNECTORS, TRANSFORMERS, HAMMOND BOXES & A LOT MORE Click here to go to Glowbugs
The Rad-Shark is an ultra-miniature Geiger Counter Join & Support the ARRL, they
ARE our voice to the FCC ! Click Here
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