[AMRadio] Ground(Or Lack Of)?


John Coleman wa5bxo at pctechref.com
Tue Feb 15 19:29:47 EST 2005


Hi Bob,	
	A true Dipole is a balanced antenna that works in space or on earth.
The proximity to earth or any reflective surface changes the balance and /
or the radiation resistance.  That's enough said on the ant working, but the
reflectivity of the earth and the grounding system can greatly effect the
radiation patterns and how much RF is floating around on the wiring and
metal stuff in the housing community.  This RFI can be a big problem on AM
at 100 watts or more!  I once, in a cramped location, had to operate an Eico
720 and home brewed modulator, with a RF hot D104.  I could talk to people
but when I touched the Microphone it was HOT and the modulator started
squealing.  Some modification of the MIC circuit and a shorter cord got rid
of the squeals but the whole rig was hot with RF.  This didn't go away until
I changed the orientation of the dipole and did some ground wiring changes.


73
John, WA5BXO

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of Bob Macklin
Sent: Tuesday, February 15, 2005 5:05 PM
To: GlowBugs; AM Radio
Subject: [AMRadio] Ground(Or Lack Of)?

Back to my 4th floor apartment problem. This building has plastic
plumbing(which seems to leak at tleat once a month). This morning I pulled
the plate off one of the wall plugs. The building has plastic conduit also.

So the only ground is the third wire and who knows where or how it runs.

The antenna will be made to a full 40M dipole. What kind of problems should
I expect from the crappy ground?

Bob Macklin
K5MYJ/7
Seattle, Wa.

"REAL RADIOS GLOW IN THE DARK"
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