David Wilcox <Djwilcox01@...>
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If you want to read some very interesting information and research about portable antennas let me steer you to Myron, WV0H’s web site:
Look around. This guy has done a lot of understandable study with test results and lots of photos. He has a lot of stuff about the end feds and auto transformers among other things antenna related.
David J. Wilcox K8WPE’s iPad
On Feb 17, 2020, at 10:57 PM, Gordon Gibby <docvacuumtubes@...> wrote:
I'd like to see some LOSS DATA on that Hawaii endfed. It is an autotransformer design, but the concern that I have is that the toroid chosen is iron (type #2) permeability = 10. Using some online calculators, at 40 meters the primary would have about 1.2 microhenries and 50 ohms of inductive reactance. I think you'd rather see the self-inductance many times that of the resistive impedance desired..... Would want to see two built back to back, and losses measured. That test has been humbling to me at times.....
my 2 cents worth. If anyone has loss data, would be useful for me to hear....
On Mon, Feb 17, 2020 at 9:36 PM Ken Hansen <ken@...
+1 for EFHW if thTs an option.
I'm not a fan of that particular MFJ portable antenna - it's a series of compromises intended for a specific application, mounted on the back of a QRP Radio.
I'd suggest the 17 ft MFJ telescoping antenna, as well as The full-sized MFJ hamsticks, either one as vertical with a collection of ground radials cut to be resonant on the given band, or as a pair in a 'hamstick dipole' configuration.
Each of the above have 3/8" x 24 stud mounts.
If end-fed is an option, consider building the Hawaii EFHW described here:
They offer a kit, but construction is simple.
On Feb 17, 2020, at 12:27, KB9WOO <kb9woo@...> wrote:
New to the uBITX, kits, HF, and the group.
Looking for something small, easy, and quick just to get on the air so I'm looking at grabbing a MFJ-1820T single band antenna for 20m, which was designed for the FT-817. This antenna needs a counterpoise and the 817 apparently has a ground screw on the chassis that the counterpoise is connected to. I thought I'd just use a clip to attach it to the BNC elbow, or I might even use a small tripod instead.
Mostly just wondering if anyone has used one of these MFJ-18xx antennas with the BITX. There is also the multi-band 1899t.
Milwaukee, WI uBITX v6