[TowerTalk] 4-Square Configurations

[Tom Rauch]

> From: <K3BU@aol.com>
> To: <towertalk@contesting.com>
> Sent: Wednesday, August 16, 2000 1:25 AM
> Subject: Re: [TowerTalk] 4-Square Configurations
> 
> >
> > So it didn't happen, I was imagining it. Also S5 that was there and
> > warned them about it, was dreaming. What is your explanation for the
> > mushy and distorted signal, when their TX was producing clean signal and
> > amplifiers were linear?
> >
> > Yuri
> > Tesla RC

That's one of the MANY reasons I avoid small numbers of elevated 
radials Yuri.

The radial system radiates a considerable amount in the nearfield 
area, the strength of induction fields is very large around the 
radials. They produce strong electric and magnetic fields, the fewer 
the radials the stronger the fields near each radial.

Because of that, they induce lots of unwanted signal into any other 
conductor near the radials. If that conductor happens to be another 
antenna, and if the transmitter has poor output filtering, you can 
generate mixing products in the output device that re-radiate.

A second problem is common mode currents. As far as feedline 
currents, small ground systems on Marconi antennas really 
aggravate the problem. It often requires multiple chokes on the 
feedline to clean the system up. It doesn't take much common 
mode current to screw up a modern radio, in particular because the 
microphone grounds and keyer grounds are often not grounded at 
all at the case entrance of the radio.

***The same problems can occur center feeding vertical dipoles, 
where a single choke at the feedpoint often isn't enough. 

It doesn't surprise me that they had problems in a multi-multi.


73, Tom W8JI
w8ji@contesting.com

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