That might work. The other idea about RF detection, used to trigger a latching relay has some merit if the relay is used at the right location. If you use the relay to disconnect the end segment of a
Sic-em Tom! They deserve it! You are correct. I see this kind of stuff ocassionally appearing in QST and CQ. I'm sure it's in other magazines as well, but I only get those two. I also see it in the A
I didn't see that reference. It is a good one. Exactly the information I was trying to convey, with more detail. When you have something as complicated as what N6RK was building, it may justify tryin
This is the second time I have seen this question posted. It received no reply either time. I also now own my first crankup, and was looking forward to the answer to this question. US Tower doesn't s
As a bit of summary: Tom started this discussion off by saying: "That's why our transmitters can be shielded perfectly with copper shield or aluminum shields as long as the shield is several skin dep
Interesting question. I have never reasearched this one, even though I have thought about doing it, so I tried a few quick simulations. At first the suggestion of making the reflector 5% longer seem
Jim I also get 3.26MHz resonant frequency for the ground reflector. I don't know how I got the number I quoted, must have done something really funky. Jerry __________________________________________
Denn Check Tom's message in this same thread to see what he does for lightning protection. He, and others, have found, it is possible to survive lightning hits if you do things right. Lots of other i
It's pretty easy to get this if you have a long antenna attached (80 or 160 M). At first it may seem to do no damage, but each little arc will leave small metal particles across the area where the ar
<snip> Yep, a 3/4 wave antenna is not a low angle radiator. Anything longer than 5/8 wave and the maximum lobe starts to go up. That's the reason you see so many 5/8 wave mobile 2M antennas. You may
You should be OK. You can crank it from the side, but you won't be able to crank it from the front. If you have 3 feet between the house and the edge of the concrete pad, you should be able to crank
I hope you mean: center fed zepp = dipole. It's impossible to exactly answer your question as stated, but here are some things to consider. If you are feeding that 80M dipole with coax, you are going
Tom To answer your question a little more directly, I made a few simulations. I considered the configuration you mentioned, loading coils at the end of the 80M dipole, and 10 ft sections hanging down
Good reference Tom, and I notice it is your write-up. Nicely done. I didn't want to recommend the approach of adding coils into the antenna, because the 80M dipole is just too short, and this approac
I don't see anyone else answering this, so maybe I'll take a crack at it. Just to make sure, we are talking about the same thing, this half square is really half of a bob-tail-curtain, right? (1/4 wa
K4SAV: I know I have seen antennas built and fed like this, but now that I am thinking about it, it doesn't seem right. If you feed the half square at the top corner, the phase of the currents in the
OOPS! Can I retract the last message. It is all incorrect. Half square works OK fed at the top. Brain took day off today. Jerry, K4SAV -- A closed mouth gathers no feet. -- __________________________
The MFJ259 doesn't give you the resistive part of the impedance when the SWR is not equal to 1:1. From the tests I have done with it , I think it is giving you the total impedance. In the mnual, they
If there is no reactance, then yes this would be true. But it's not likely to be either one of those (16.6 or 150 ohms). Go back to the definitions of SWR. You most likely have some reactance in the
Good point Tom. I overlooked the feedline. You are absolutely correct, the feedline combined with the 80M antenna could be resonant as a T on 160. As a test, the feedline length could be changed to s