I did a static analysis of my 70 foot Rohn 25 tower by assuming the tower behaved like it was perfectly rigid, but "hinged" at the base and lower guy point. I believe that's close to a worst case sit
See the N9NB article in QST a little while ago on chokes to shunt isolated elements to the mast for shunt feed. It works fine on two of my antennas. I can provide details on the choke design. 73, Sco
Do you have another amplifier with which to run a test? 73, Scott K9MA Now I have to look and see why this antenna load is causing this instability. Ed On 10/20/2019 12:49 PM, ed_richardson@shaw.ca w
It's possible the adapter isn't defective, but just changed the impedance seen at the amplifier input enough to cause the instability. The transmitter output impedance (NOT 50 Ohms!), reflected throu
If in understand correctly, the bottom 10' of the tower is stationary, and all above that rotates. FWIW, here's what I would do: Install a temporary gamma feed to find out where it needs to short to
The reason the parasitic elements are isolated from the boom is that the boom would detune them. AFAIK, no one has figured out a way to model elements shorted to a boom, and experimentally tuning an
Does anyone know of a modern NEC-designed yagi that does NOT use isolated elements? Perhaps there is some software that can accurately model the effect of the boom, but I suspect it's way out of the
Gee, I remember the days when you had to take a stack of cards to the computing center, and come back the next day to find out you made a typo in card 134. Joking aside, I think it would be great if
Unfortunately, I've recently had a lot of experience with Cushcraft traps. To get them apart, remove the end caps, place the inboard end on a vice with the jaws just catching the case (not the insula
What I've done when lifting 100+ pound antennas is to run the lifting rope down to a pulley low on the tower, then back up to the top. I then wrap two slings of smaller rope around the lifting rope
I would want a fail-safe to cut the power, in case that Northern Tool switch shorts out. When I first heard that W0AIH was riding a winch up towers, I almost had nightmares about what would happen if
The new MFJ/Hy-Gain traps are of pretty low quality, so you're probably better off fixing the old one, if it hasn't been fried. Insect debris or water are the most likely suspects. Just take it apart
Wait! Unless I missed something, we don't even know whether this is a matter of RF susceptibility at the neighbor's end, or something spurious from the transmitter. Is the interference to a device wh
Yes, please give us more information, including your call. It does, however, sound like its just RF overload, which would not be your fault. It can usually be fixed with ferrite cores on the long wir
Great, Wayne! Thats exactly how to turn a potentially hostile neighbor into a grateful one. 73, Scott K9MA -- Scott Ellington -- via iPad _______________________________________________ _____________
Ask your neighbors to note the time when these problems occur, then compare with your log. There may be no correlation at all. If the times don't correlate, it definitely has nothing to do with you.
On the other hand, my own garage door used to open when I transmitted on 160. No code required. Ferrite cores on the wires fixed that. 73, Scott K9MA Sent from my iPad .......Some years ago, a neighb
Imagine the FCC taking an interest in such a case today! 73, Scott K9MA On 11/19/2019 06:14, Patrick Greenlee wrote: I was first licensed in 1962 and when in the USAF in 1966 I had the base commander
The second problem is there is a lot of friction in the pulleys. I've seen tests for hardware store ones where the output tension is only half of the input tension. I can confirm that. When I put up
Where some of us live, it's not a lot of fun to climb towers this time of year! 73, Scott K9MA -- Scott K9MA k9ma@sdellington.us _______________________________________________ ______________________