[RFI] Shielding a ground wire

[Roger (K8RI)]

On 4/28/2013 11:21 AM, Timo Toro wrote:
> I did fix my problems already. My antenna systems are not incomplete. Of
> course more and higher masts would be nice, hi.
>
> But if I run over 1KW to my 4el Yagi on 40m and my PC stops working, I
> have to fix that problem. I did not use the band aid either. Nowadays my
> ham shack is more like Faraday shield, hi. And lightning safe.

Sounds like what I had on 75 with a center fed half wave, sloping, fan 
dipole. SWR  at resonance is less than 1.1 : 1.  When I'd get to around 
a KW out, all the LEDs on the control heads in the station would light. 
To me that said, RF on the feed line which meant it was on the ground as 
well.

My first thought was a current balun.
http://www.rogerhalstead.com/ham_files/AntennaFeed1.htm
Not neat, but a very high impedance for common mod voltages.  It 
improved the situation but did not cure it, So I inserted another, 
similar choke where the feed line reached the tower and no more RF in 
the shack, feed lines, or ground.

I stopped the RF at the source.

An antenna may appear to have all its parts, a good SWR, and a good 
ground, but bear by objects, ground conditions under and near the 
antenna may leave you with an unbalanced system even though every thing 
looks good.  Matter of fact, it's extremely unlikely that an antenna 
will be truly balanced

73

Roger (K8RI)

>
> I still like to use word "grounding" meaning low impedance route to
> common point near earth potential.
>
> 73, Timo_oh5kw
>
>
> At 9:08 -0700 28/4/13, Jim Brown wrote:
>> On 4/28/2013 3:00 AM, Timo Toro wrote:
>>> Tuning the ground lead to series resonance on most problematic band,
>>> can help too. As was done in the example?, I sent earlier.
>>
>> This is NOT a solution, it is a "band aid."   The real CAUSES of the
>> problems you are trying to solve are with improper or inadequate
>> BONDING between equipment, and incomplete antenna systems.
>>
>> There is RF on that earth wire you are "tuning" because you are
>> PUTTING the RF there. That wire is a conductor, so it is an ANTENNA,
>> so it will radiate the current that you put on it and it will receive
>> noise.  That earth wire is a problem either because your antenna
>> systems are incomplete -- perhaps you have no counterpoise or radials
>> on a long wire, for example, so return current for the antenna flows
>> on that earth wire, so it is part of your antenna -- or because
>> failure to bond together all equipment and all grounds causes current
>> on that earth wire to couple into equipment.  To understand how this
>> happens, study the tutorial material on "The Pin One Problem," on my
>> website. http://k9yc.com/publish/htm  Almost all ham gear is built
>> with Pin One Problems.
>>
>> 73, Jim K9YC.
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