It actually wasn't all that clever. I should know ... I was the one who did them. ;) http://www.ab7e.com/weak_signal/mdd.html 73, Dave AB7E A few years back there was someone who did a c
Is it a folded monopole? A 50 inch vertical section fed at the base looks to me (using EZNEC+) like it would have a native source impedance around 3.5 ohms, which a folded monopole with equal diamet
Hi, Steve. Depending upon the antenna, I don't think that SWR necessarily correlates all that well with gain. A better test might be to monitor some distant stations with the XA and rotate the 40 to
HFTA should never be used to try to optimize stacking distance. It simply does not actually calculate the stacking gain as a function of stacking distance like EZNEC would. 73, Dave AB7E On 6/21/2
That's just plain wrong. That's using HFTA to determine optimum height above ground ... not optimum stacking distance (i.e., separation). They are NOT the same thing. HFTA does NOT properly calcul
Funny ... Ron privately answered me to thank me for the correction. I never said that HFTA wasn't extremely valuable. I used it when designing my station to determine the optimum heights for my ante
Exactly this ... in every respect. 73, Dave AB7E The manual https://manualzz.com/doc/10293860/hfta--instructions states the following: The internal Yagi model in HFTA is a very simple mathematical
Not sure how many times it needs to be said, so just go back and read KK9A's post. But in a nutshell, HFTA is an extremely valuable tool for terrain assessment and deciding how high to put your anten
That long rant doesn't change anything, I'm afraid. Nobody is trying to trash anyone, but it doesn't serve you or anyone else for you to keep insisting something that isn't technically accurate. Thi
Same here. 73, Dave AB7E Billy, You are into arguing and taking things personal. I am not. I have nothing further to say to you. 73, Jim K9YC On 6/22/2022 8:21 AM, Billy Cox wrote: Jim, I have two e
Great suggestion. Jim. I ran HFTA for four conditions at 14 MHz over flat ground. 1. two dipoles at 50 feet and 70 feet 2. one dipole at 50 feet 3. one dipole at 70 feet 4. one dipole at 60 feet
Cushcraft has been making antennas for a very long time. I wonder if the design of that model simply dates back to when hams were only allowed 1 KW. Maybe nobody bothered to update the rating. The
And you're pretty certain that MFJ changed the design of that particular model? Sometimes I wonder what your problem is. Dave AB7E 73, Jim K9YC _______________________________________________ _____
EZNEC+ definitely takes into consideration the insulation. It's the far right hand column on the Wires entry table. 73, Dave AB7E Sent from the all new AOL app for iOS ____________________________
There is indeed a "return path" for a single wire. The wire capacitively couples back upon itself, and the dielectric affects that capacitance. That may sound strange, but think of a capacitive hat
You're thinking in terms of the wrong "return path". The current is only indirectly affected by the dielectric. The current creates a magnetic field around the wire, but the difference in voltage a
That sounds like the feed system on my OB16-3. I once looked up the formula for that and it came out roughly 100 ohms. When I used that in the EZNEC model I got almost identical results to the plot
Rules of thumb like that are almost useless. It would GREATLY depend upon the type of semiconductor. MOS memory would be pretty vulnerable, while bipolar power rectifiers would be very much less so
Have you checked telescope controllers? I'm sure there are lots of them out there, but I know that K9RS designs, builds, and sells them ... or at least used to. 73, Dave AB7E https://www.westmarin
Personally, I think the idea of using multiple U-bolts is the best way to go. As Rick says, the K7NV design doesn't really offer much additional surface area if the mast isn't perfect. I welded a p