Sunday, February 1, 2015

End Fed Tuner

I finished this a while ago but have not had a chance to see if it works until now. It is based off of the design on the SOTABeams Web Site. In fact I purchased one of the SOTA Beams tuners as a gift for someone and took the opportunity to take a look see and it is very well constructed. The only thing I would do different is to attach the coax and make the container smaller but the SOTA Beams case is very functional and designed that way for a reason, outlined on their website. So if you do not want to build one you can always buy one from SOTA Beams.

Here is the schematic:



For the case I used a plastic mint case. You can make one much smaller but I liked having the extra room. I ran the RG-174 into the case and tied it into a knot so it could not come out or put stress on the components. Unfortunately I did not take a picture of the inside of the finished product before I sealed it up.

The wire lengths are as follows:
40 Meter is 66.6 feet
30 Meter is 46.6
20 Meter is 33.2
17 Meter is 25.9

I had to adjust the coil turns to get it on 17 meters but it works fine. I am using about 6 feet for a counterpoise but was able to tune it fine without the counterpoise save 17 meters. The antenna wire is number 26 teflon coated slippery stuff linked together with connectors I picked up from Hobby King a long time ago. Any type of an electrical connector will work fine.

Tuner and Counterpoise
40 through 17 Meters (this is so I will remember when on a summit)
Complete antenna/tuner/coax weighing in at 5.6 oz
For my first use I used my ATS4b transceiver on Mount Herman (a SOTA summit).

ATS4b

tuner connected to the antenna and counterpoise

antenna going into a tree
You cannot see the antenna but the Old Snag center frame is where the other end is connected

My friend wG0AT operating, you can see the tuner to the right, hanging down
This was a fun little project and the tuner is functional and practical. Plus if you do not want to build one it is offered from SOTA Beams complete and in a neat container weighing almost nothing.  Unfortunatley my ATS4b has 15 meters vice 17 meters so it is not a good match for that radio.

Video:


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