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Author Topic: MY CB GO BOX  (Read 3447 times)

gil

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Re: MY CB GO BOX
« Reply #15 on: November 20, 2017, 05:57:28 PM »
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I will keep you posted!

Please do, thanks!

Gil.

cockpitbob

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Re: MY CB GO BOX
« Reply #16 on: November 20, 2017, 07:52:40 PM »
At a simple level I knew having different polarizations reduces reception, but I never knew any numbers.  Over at antenna-theory.com I found this little gem:  http://www.antenna-theory.com/basics/polarization.php

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In general, for two linearly polarized antennas that are rotated from each other by an angle , the power loss due to this polarization mismatch will be described by the Polarization Loss Factor (PLF):
 
Polarization Loss Factor

Hence, if both antennas have the same polarization, the angle between their radiated E-fields is zero and there is no power loss due to polarization mismatch. If one antenna is vertically polarized and the other is horizontally polarized, the angle is 90 degrees and no power will be transferred.

So now I have a rule of thumb and numbers I can work with.  I love numbers ::) .  I think the equation falls apart around 90degrees because it predicts zero, but in the real world, the polarizations are probably imperfect so even if the antennas were 90.00deg off, some will get through. 

But here's my big take-away.  At 45deg the power transfer is 50%.  That's only 1/2 an S-unit.  You could cant your 4-element Yagi 45deg and its 8dB of gain would only drop to 5dB gain.  You could do fine talking to both repeaters and SSB operators without having to fuss with the antenna.

NF822WNY

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Re: MY CB GO BOX
« Reply #17 on: December 07, 2017, 07:39:48 AM »
Well as i continue to test my go box i continue to run into some problems.  I have been experiencing some pretty significant RF feedback through the microphone when TX.  Basically, after the radio has warmed up when i transmit i am getting a small shock through the microphone.  This does occur more when i am using the amplifier than when i am not.  After my initial research it appears that a grounding issue is to blame.  My question and what i can't quite come up with a solution for would be how do you ground a go box? 

cockpitbob

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Re: MY CB GO BOX
« Reply #18 on: December 07, 2017, 01:54:51 PM »
Describe your antenna and feedline to it. 
My knee-jerk reaction is to put a 1:1 balun at the antenna.  You've probably got RF on the shield due to driving a balanced antenna (di-pole) with an unbalanced line (coax).