Correct! -- Scott Ellington. K9MA -- via iPhone _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://
I hope others have better luck with that than I did. I hired a well-known local outfit, Wave Communication, to replace my Rohn 25 this spring. They sent two inexperienced guys to take it down, with n
I recently ordered some replacement traps for my old A3S. One was defective, so I took it apart. I was appalled at the poor quality. While the original traps had several pop rivets, in addition to th
The Cushcraft traps also have a thick aluminum washer on the case grounding screw. The MFJ ones do not. BTW, it's very hard to test Cushcraft traps with a dip meter, as you can't couple to the coil m
I disagree, Jim. If trap losses were really significant, 1.5 kW would burn them up very quickly. Sure, a trapped beam is less effective than full sized monobanders, but can be made to work quite well
I actually measured the pattern of my TH7 and its replacement, a JK Mid-Tri, under exactly the same conditions. The TH7 pattern actually looked a bit better, with better f/b. I can't compare forward
Yes, all three bands. My point is that, forward gain aside, the TH7 had a very "nice" looking pattern. That was obvious just from using it, too. 73, Scott K9MA On all bands? And yes, better F/B doesn
Here are links to photos of the A3 TC 15m trap, the original Cushcraft version circa 1992 and the recent MFJ one: sdellington.us/hr/TC_CC1.jpg sdellington.us/hr/TC_MFJ1.jpg Note the two pop rivets in
Since MFJ also owns Hy-Gain, it wouldn't surprise me if they were using a common trap design. If so, I'd suspect the Hy-Gain traps would have the same issues. Has anyone seen the insides of one? I ca
Does anyone have a reference for calculating worst-case guy wire tension for a 3-wire system? The only thing I'm unsure of is the effect of wind direction. One source states that worst case is for wi
Hi Hans, By coincidence, I just finished doing the math, recalled from my statics course some 50 years ago. 1.15 at 30 degrees is indeed the worst-case factor. It's really a simple calculation, but I
Hi Bob, Here's the equation for guy wire tension as a function of wind force and direction: T = F*(cos(a)+sin(a)/2*sin(120)) or approximately, T = F*(cos(a)+0.58*sin(a)) where: T = horizontal com
Correction: T = horizontal component of _*guy tension*_ at guy point F = wind force at guy point a = angle between wind and guy wire Here's the equation for guy wire tension as a function of wind for
My old A3 traps, from the original Cushcraft, not MFJ, have coils coated with some sort of thick material. It also serves as a staking compound for the sheet metal screws on each end of the coil, non
I recently ordered some replacement traps from Cushcraft/MFJ. Quality was appalling, resonances were all over the place, and one didn't work at all. After fixing the coil terminations and adding extr
My 1992 A3S (original Cushcraft, not MFJ), was always strange on 15 meters. After taking it down, testing all the traps, and putting it back up, it seems even worse on that band, consistently 10-12 d
Some of us don't have room for that. -- Scott K9MA k9ma@sdellington.us _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk
The dimensions of the MFJ version of the A3 are the same as the original. (The manual is identical, basically just a copy.) The trap design is slightly different, with fewer turns on a slightly large
i recently put up 70 feet of Rohn 25 using Phillystran. The first 4-5 feet from the tower are EHS, to minimize the chance of something dropped from the tower cutting the Phillystran. From the anchor
If you dont understand vectors and trigonometry, this is going to be very hard. Perhaps someone has written as step by step procedure, but that would be a lot of work. I wouldnt trust a procedure, sp