Topband: Getting Started

[Jim Brown]

On Mon, 26 Oct 2009 11:25:08 -0500, Trent Fleming wrote:

>I tried unsuccessfully to use my G5RV as a Marconi on 160m this weekend.
>Following the G5RV and tuner instructions, I did the following:

Dead wrong instructions. 

The right way:

1) Prepare some form of radial system or counterpoise. This can be anything 
from "pretty" radials to multiple runs of wire on the ground. The rule of 
thumb is that more is better, longer is better, and more copper near the 
feedpoint matters more than having long radials. 

2) Tie both sides of the balanced feedline together at a point that is as 
close as practical to the point where your radials/counterpoise converges. 
Connect the center conductor of a piece of coax to the antenna feedline and 
the shield to the radials/counterpoise. 

3) Feed that coax into an UNbalanced input of your antenna tuner. 

A variation of this that I used in Chicago with a 80/40M loaded dipole fed 
with 75 ohm KW twinlead (long discontinued) and a second floor shack was to 
tie both sides of the feedline together, connect them to the center 
conductor of a coax input of the antenna tuner. I ran some radials from the 
shack, and I also ran big copper down to a big wrought iron fence that ran 
around my front yard, and tied that combination to the chassis of the 
tuner. It wasn't pretty, but it worked, sort of, and I had a lot of fun on 
160M and 80M with it. 

The important part of this is #1 -- a Marconi isn't a Marconi until it has 
either radials or a counterpoise under it, and it won't work very well. 

73,

Jim Brown K9YC