The SOTA tuner is a kit from QRPkits.com. It is designed for end fed half wave wires. It consists of an SWR indicator with an LED and a parallel tuned circuit for the matching. It turns out I had built a SWR indicator previously from QRPkits.com so I just used that board instead of the supplied parts. There was a hiccup on the first checkout and I sent an please help email to QRPKits.com. I a reply from Ken LoCasale WA4MNT with corrected instructions. The corrections were:
1. - Tap the toriod at 4 turns, not 6 turns.
2. - Run a ground jumper from the BNC ground lug to the counterpoise ground lug.
Note the corrected instructions are now on the QRPkits.com web site. After the corrections were made the SOTA works like a champ.
In my backyard test I ran a 33 ft wire for 20 meters to a limb 10 feet high. I worked KD2JC Joe in Howell NJ with no problem. Then I put a Black Widow 13 foot pole up to support the mid point of the wire. My next QSO was CO2KK in Cuba. OK 20 meters is good so how about 40 meters. I doubled the wire to 66 foot and moved the pole to the mid point. I snagged W4UOR Bill in NC right off the bat. My tests used 4 to 5 watts with the Ten Tec R4020. During my testing I found the tuner works fine without a 1/4 wave counterpoise. I was using a six foot BNC cable and I figure it supplies the necessary counterpoise.
The small size of the tuner is a definte plus. Now I can get a lighter packup for QRP with this arrangement. Along these lines, notice in the pictures that I taped the Black Widow pole to an electric fence post which has a stake at the end. I also used a fence post to hold the tuner. This lets me move the rig around without disturbing the antenna wires. So maybe on the next outing I'll venture from the parking lot out to the beach.
1. - Tap the toriod at 4 turns, not 6 turns.
2. - Run a ground jumper from the BNC ground lug to the counterpoise ground lug.
Note the corrected instructions are now on the QRPkits.com web site. After the corrections were made the SOTA works like a champ.
In my backyard test I ran a 33 ft wire for 20 meters to a limb 10 feet high. I worked KD2JC Joe in Howell NJ with no problem. Then I put a Black Widow 13 foot pole up to support the mid point of the wire. My next QSO was CO2KK in Cuba. OK 20 meters is good so how about 40 meters. I doubled the wire to 66 foot and moved the pole to the mid point. I snagged W4UOR Bill in NC right off the bat. My tests used 4 to 5 watts with the Ten Tec R4020. During my testing I found the tuner works fine without a 1/4 wave counterpoise. I was using a six foot BNC cable and I figure it supplies the necessary counterpoise.
The small size of the tuner is a definte plus. Now I can get a lighter packup for QRP with this arrangement. Along these lines, notice in the pictures that I taped the Black Widow pole to an electric fence post which has a stake at the end. I also used a fence post to hold the tuner. This lets me move the rig around without disturbing the antenna wires. So maybe on the next outing I'll venture from the parking lot out to the beach.