Jim, Good data. It looks like the RG-5000 consists of two back-to-back diodes (in IC1) with the other components not contributing. Do you have a part number for IC1? GDT/ES1A diodes The GDT (gas disc
AA6VB, QTH San Jose, California looks like *8 mS/m* FCC ground conductivity map https://www.fcc.gov/media/radio/m3-ground-conductivity-map A more detailed map https://www.americanradiohistory.com/FCC
Robert, an EZNEC model of your vertical as described in your QRZ bio shows your measured 29.7 ohm input resistance when ground conductivity is set to *0.008 S/m*. EZNEC calls this (0.0075S/12) ground
Albert Einstein: You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly t
EZNEC Rohn 25 top loading 115' Rohn 25 4 spoke top hat, 66" x 0.500" tubing SWR in a 30 ohm system (match 30 ohms to 50 ohms) 1.800 MHz, 2.2:1 1.900 MHz, 1.2:1 2.000 MHz, 2.2:1 KH6AQ (formerly WX7G)
The balun heating hypothesis could be tested by disconnecting the balun. Dave, KH6AQ _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Steve, *I believe there is a measurement error. * 1. The reactive part of the input impedance should not become more inductive as the frequency is decreased. 1904kHz --> Z=68.1 + j0.3 and 1844kHz -->
The DX Engineering Thunderbolt antenna includes a means to resonate and match the antenna using a series inductor and a shunt inductor. *It does not require a balun*. See the manual: https://static.d
I refined the DX Engineering Thunderbolt EZNEC model to be exactly like the actual antennat by changing the capacity hat wire size. It is resonant at 1930kHz. 2.15uH of series inductance tunes it to
David, the capacity hat does cancel some radiation. Think of RF current going up the mast and down the top hat wires. The magnetic fields partially cancel. Without the capacity hat wires the 55' mast
60 + j19 does seem off. Is this ground mounted or with elevated radials? An EZNEC free-space model reports *36 +j227* at 1800kHz. On perfect GND it reports 166 +j306 ohms. 10' above 0.005/13 GND it r
The radiation pattern plot shows the dipole end on. Rotate azimuth 90 degrees and the two antennas show the same gain at 30 deg elevation. Dave KH6AQ _________________ Searchable Archives: http://www
The antenna becomes a ground mounted vertical having elevated feed. The wire from the ground radial system to the base of the vertical becomes a radiating portion of the vertical. The vertical has in
Kenny, your model might have a problem with the acute antenna between the two vertical wires. I ran EZNEC simulations to test this and compare against a single vertical wire T reference antenna. Your
Hi Mike, your inverted-J in EZNEC shows a radiation resistance at 1850kHz of 10 ohms. It is resonant at 1800kHz. With the 50' vertical wire removed it is resonant at 2.7MHz and has a radiation resist
Rudy, N6LF, wrote a great article on his elevated radial experiments. https://www.antennasbyn6lf.com/2012/02/elevated-radial-ground-systems-some-cautions.html Rudy says, "1) Use at least 10 to 12 rad
For me 6dB RL is fine. That is a VSWR of 3:1. https://www.amphenolrf.com/vswr-conversion-chart Dave KH6AQ _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
John, here are EZNEC results for your downward sloping inverted-L and your T-vertical. Inverted-L radiation resistance = 8 ohms T-vertical radiation resistance = 12 ohms How the radiation efficiency
It isn't the feedpoint impedance that matters, it is the antenna radiation resistance that matters. For example, if we take a quarter wavelength vertical having radiation resistance of 36 ohms and ad