This is my homebrew magnetic loop using the MFJ-936B loop tuner. I used .5 inch copper tubing. It works really well and easy to tune using the remote control system as in the video.
just took a NOS 936B acquired this week /P w/a 705... 13ft 10ga wire on a pvc frame... made 1500km contacts on 20M... tuning is sharp, but doable... not as convenient as my alpha, alexloop or cha floop 3.0, but still a lot of fun... the 936B's meters are great for qrp rigs with no SWR readout...
@jasonfrankovich1378
2 жыл бұрын
This is great! This is what makes ham radio fun. Nice craftsmanship. 73 -Jason KB6Q
@cj5947
4 жыл бұрын
Since I posted this video, I have switched from acrylic to a UHMW material that allows me to use a higher wattage output. I also added 2 doorknob capacitors. Now I can run approximately 500 watts. It can be configured for 10, 12, 15, 17, 20, 30, 40, 60 and 80 meters easily.
@kd5inm
3 жыл бұрын
can you do another video on the modification using the doorknob capacitors please. KD5INM
@Mark300win
3 жыл бұрын
Did you add the doorknob capacitors in parallel to the existing variable capacitors?
@cj5947
3 жыл бұрын
@@Mark300win Yes it is in parallel with the 936B
@andrewhill4226
3 жыл бұрын
Excellent ! I have a smaller MFJ Loop tuner and I made a single loop for 20m & 15m and then one for 10m and 12m. Have not made a bigger one, but I like your idea of multiloops. I find that mine is very jittery to tune anywhere near a good SWR and was going to sell it. I might have another go with it and produce some more copper tube loops like yours and connectors. Thanks for posting 73's Andy M6APJ
@SidneyJonesSid
4 жыл бұрын
Very nice job CJ! Very innovative. Good luck - 73 KF6YXK
@zhaoji406
4 жыл бұрын
Excellent loop design!
@cj5947
4 жыл бұрын
Thanks Ji. I was really surprised how well it worked. It is easy to disassemble/reassemble for use when I go camping. Each loop is 12 ft. not counting the links. Using the MFJ-936B I can run 150 watts. I would like to try a 16 ft. loop to see how that works on 20 Meters.
@CripSkillz
4 жыл бұрын
That's some ingenuity right there,. Nice I'm working on one myself.. 73 W9THC
@n4qxu
3 жыл бұрын
Hello Jack Looks good Haven't heard you in a while. :)
@captaintripps7354
2 жыл бұрын
It is an excellent loop tuner that really works and works incredibly well for what it does. I added a door knob capacitor in parallel to the output ( I forget the value ) and I was able to tune 80M across the band using my 8ft x 8ft square loop in a second floor room.
@Mark300win
Жыл бұрын
Do you know what is the kv rating of the capacitor?
@PiotrBagniewski
3 жыл бұрын
Hello, do you think it work the same way if you ran a window line to the tunner instead of connecting it directly to antenna?
@cj5947
3 жыл бұрын
Not sure. Have not done much experimenting lately. Perhaps this summer i will give it a try.
@James_Bowie
4 жыл бұрын
Ingenious, but how far away from the loop are you sitting when operating at 500 watts?
@cj5947
4 жыл бұрын
I sit a LONG way from it. My tuning wires are about 35 feet. It is very rare i would use more than 100 watts. The higher power was an experiment.
@James_Bowie
4 жыл бұрын
@@cj5947 Thanks. Another question, if I may, because I'm thinking of making a similar remote control: I note that between the motors and the tuning shafts you have some sort of bearing arrangement on a 'mini stanchion'. Why is that? I would have thought that the ultra slow servos would have been able to be directly connected to the tuning shafts, or maybe via a short flexible coupling.
@cj5947
4 жыл бұрын
With the reducers i don't have to worry so much about overshoot. Tuning is a little slower but easier. I thought about flexible coupling but i wanted to minimize stress on the motor shafts.
@cj5947
3 жыл бұрын
@@James_Bowie Those are 6:1 reduction gears. They make tuning easier, less frustrating
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