[Antennas] Mobile Antennas - which shoots best, is strongest?

[Jack Painter]

Hi David,

The problem with any whip including of marine design mounted on or alongside
a house is the lack of ground plane. As Doc put it so well, the need for a
counterpoise is almost as important as any antenna choice, as they all
require it. This in spite of various design promises.

Besides omitting radials (the #1 mistake from most accounts), another common
problem when trying to residential-mount a marine whip is failing to place
the coupler/ATU right at the feedpoint of the antenna.

Using identical equipment, a small vessel with the whip mounted anywhere
generally does poorer than a large vessel with the whip mounted anywhere. I
have never seen comparisons of how the shipboard mounting location affects
the efficiency and radiation patterns, but we all have examples of the small
(motor) vessel getting poor-mediocre performance no matter how it was
mounted. People then try to mount that same marine antenna on a "small
house" (relatively speaking), use no radials, mount the ATU wherever
convenient, and then wonder why the thing won't work on 160 meters!

Cheers,

Jack

-----Original Message-----
From: David J. Ring, Jr.

Hello Doc - you don't give me a short name in your signature, so I'll use
this!

Thirty-three foot - the shorter version of the Marine thirty-five foot whip?
How neat - it would work 40 meters without a tuner.

That sounds like a great install.

Did you bury the ATU?  I guess you'd have to put it inside a vented box and
put a rubber hose to a descrete place so you could fill pressurize it with
nitrogen and keep the moisture out.

My fallback plan (more visible) was a Hy-Tower and a base mounted SAILOR
marine ATU-1500 tuner.

You know what I noticed?  I had several antennas on my ship, so I used a 35
Sheakespere whip fed with coax and ran it into my cabin, and I tuned it with
a small MFJ tuner.

One Christmas, I was near Singapore and I really wanted to get a phone patch
home - K4HAX ran a 4 element 204BA HYGAIN yagi with a National NCL-2000 amp
running off of a pole pig - but he said I was S-3.

I really wanted to go talk to my kids.  I'd been away from home too long!

So I went into the R/R and turned on the HF transmitter and used the Harris
ATU to resonate the remotely tuned transmitter whip for 14,320 kHz and then
took a 20 foot length of RG8/U as a jumper cable and put one end in the ATU
input and the other, I ran to my stateroom.

Now with my Ten-Tec Triton 2, I was S-7.

Same length of antenna, but this appeared to be the efficiency difference of
matching the antenna at the base, as opposed to running 30 feet of
mismatched RG213/U to my stateroom and then using a small MFJ tuner.

Do you think using the vacuum variable in the Harris ATU and matching the 35
foot marine whip directly at the base could account for all that difference?

Have you experience anything like that?

I liked the system your running (the same as on the ship) but I found the
bandwidth and matching really touchy below around 2.5 MHz.  It was super
touchy down around 1650 kHz.  Some of the guys had a big egg-beater top hat
so they could use it all the way down to 410 kHz - "in theory" it was
supposed to be efficient there, but it was several S units down from a
standard "Twin-T Marconi" or an Inverted-L antenna.

I'm sure Jack Painter, would love to get his finals on that system you have!

73

David Ring, N1EA