Hi folks - I'm brand new to the list. My interest in reduced-size HF antennas has often led me to consider the technique proposed by N0KHQ (amongst others) of using coaxial cable as an antenna elemen
Dan, Thanks for the supportive comments. Yes, I spotted that. Interestingly, on another site he has the braid and inner conductor open circuit at one end of the reflector, although in the next drawin
Many years ago I used a 50ft vertical on 160m quite successfully. Top loading was key to its success. I top-loaded it using 6 equally spaced wires which came away at 45 degrees from the vertical and
Hi Al, The "capacity umbrella" was formed from 6 radial wires, each 30ft long coming away from the top of the mast at 45 degrees to the vertical. From the 30ft point onwards they became insulated guy
John, I made a mistake in thinking it was an IERE paper. In fact it was an article by Jack Belrose (VE2CV) in the September 1982 edition of Ham Radio entitled: "Folded umbrella top-loaded vertical an
Clint, About 20.5uH according to the usual formula for solenoid coils. Steve G3TXQ _______________________________________________ _______________________________________________ TowerTalk mailing li
Or if you really can't be bothered with the maths, try one of the many online calculators, e.g.: http://www.66pacific.com/calculators/coil_calc.aspx http://www.crystalradio.net/cal/indcal2.shtml Stev
Ronnie, A couple of considerations which might tip the balance one way or the other: 1) Do you want VHF coverage? The ZM30 doesn't go above 30MHz. 2) Do you want to do measurements at the top of your
Bill, You might also want to look at another small wire beam called the Hexbeam. It has a smaller turning radius than the Moxon, and can be built as a 5 band (20m thru 10m) version, or even a 6 band
John, I have a 2-element home-built Broadband Hexbeam at 20ft and a 132ft centre-fed doublet with its apex at 20ft. The Hexbeam consistently outperforms the doublet on 14MHz and up. There's an audio
Dave, Just to be pedantic ...... .... the 132ft doublet IS a dipole (it has 2 elements), and it IS resonant on 20m - it just happens to be 4 half-waves instead of one :) And the 132ft doublet in its
Dave, 1) The doublet was fed with a short length of open-wire and correctly matched through a Palstar balanced ATU. 2) The AGC on the receiver was OFF, and the RF GAIN backed off to preserve linearit
Roger, I'm no mechanical engineer - just a lowly communications engineer - but I'm trying to understand the point you are making: Isn't this exactly what happens when you tighten the head on a conven
Roger, OK I think I understand what you are saying. In my layman's terms, when you torque up a conventional bolt some of the torque converts to a linear "stretch" force on the bolt (via the ramp) and
I'm with Jerry. "In physical science the first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality
K8JHR, The Kelvin quote was slightly "tongue in cheek", but I think his appeal for "numeracy" has some value. I wasn't arguing that modelling is better than empirical measurement, but that modelling
At the risk of "flogging this horse to death", but just to re-inforce Jim's point: In developing my new Broadband Hexbeam I consistently saw a small, but significant, frequency offset between what EZ
The Paul Baldock I used to know would just have built it and it would have worked straight off :) How are you doing, Paul? Steve G3TXQ _______________________________________________ ________________
Because open-wire feeder is often used in applications where it is unmatched - for example a doublet. Although the characteristic impedance of the feeder might be 450 Ohms, in these applications the
Also, if you are talking about vertical stacking you can actually make things worse at low take-off angles, depending on how high you can get the lower antenna(s). Take a look at this analysis on my