I'm further convinced of the need for shunt chokes on ungrounded driven elements on shunt fed towers. See the recent QST article by N9NB. Hopefully, this will be of use to someone else. It may even s
The shunt chokes may not be as critical with the slopers, as the voltage near the top of the tower is probably lower than with a shunt fed tower. I can provide details of the chokes ala N9NB and W5JA
I'm not sure ground the coax shield at the feedpoint is really necessary, provided the driven element is connected to the boom either via a matching network (omega match, as on a TH7) or through a sh
Long ago, I brought some approximately AWG 14 hard drawn copper back from Finland. The 40 meter full wave I made from it stayed up for nearly 30 years. So did the 80 meter dipole, of the same wire. I
Here's the mystery: After a long transmission on 160 at 1.5 kW, the SWR suddenly, but smoothly, rises to 1.4:1, but rises no further. A pause of a few seconds allows the SWR to drop back to 1:1, but
Another very interesting data point: The 40m full wave is supported near the top of the tower on a short side arm. That's the feedpoint, 1/4 wave from one end. It's like a lopsided inverted V or slop
I'd recommend Phillystran for the top guys, but EHS the first few feet from the tower, and up about 15 feet from the ground. The former protects against something getting dropped from the tower, the
I don't know how similar it is, but it might be worthwhile downloading the JK403 manual to see if there are any ideas there you can use. 73, Scott K9MA Im rebuilding my Force12 40m yagi. What would y
I'd think SS would be heavy and lossy. 73, Scott K9MA I have a JK 403 40M yagi. It does not use the linear loading wires like the older Force 12 did. It uses a small shunt coil at the antenna feed po
I put one up last summer. It seems to work fine, though the f/b appears to be only 12-15 dB. Thats not necessarily a bad thing. The SWR looks very good measured at the shack, closely matching the pub
Im not sure the trade off of f/b for forward gain was deliberate, as the published model results show higher f/b. I am pretty sure my measurements are good. I did them with two other stations, one ab
No, I do not have the 40 meter version. (Alas, no room.) 73, Scott K9MA -- Scott Ellington -- via iPad _______________________________________________ _______________________________________________
You really don't want to do that without bracing the mast with something like the braces Tim suggested. Years ago, I made something similar out of steel angle stock and U-bolts. BTW, although the DXE
Bob, Are you putting the rotator in the tower with a thrust bearing or sleeve? 73, Scott K9MA Dave Hachadorian, K6LL Yuma, AZ Hi All - Could someone point me to a source for antenna mast? It needs to
That's interesting. DXE did not have the 11 foot version available last spring when I rebuilt my antenna system. I ordered the 10 ft. Rohn mast from Texas Towers, which was adequate for my needs. It
-de John NI0K Many, many years ago when I was in college, I strung a piece of AWG 28 magnet wire out the window of my dorm room. The dark brown enamel was almost invisible. When I had to replace it,
Stranded copperweld used for antennas and feedlines can corrode due to the strands rubbing together and wearing through the copper, exposing the steel. 73, Scott K9MA I discovered Rudy's paper after
There certainly is for other kinds of crimped connectors. Crimp tools for high-rel projects must be calibrated using a pull test. 73, Scott K9MA -- Scott K9MA k9ma@sdellington.us ____________________
I wish I had know about the RF Parts tool a couple years ago. I bought the DXE one, which works fine on RG-8 and RG-58, but I had to crime ONE RG-174 BNC. The DXE RG-58 die has a smaller crimper, but
I got away with not bypassing the balun on my TH7 for years. However, with all the other elements grounded, there may not have been much current flowing through the balun in shunt feed mode. I would