[TowerTalk] 40M rotary dipole and CM current

[Wes Stewart]

Yeah, but...

This thread started with a question about whether to just coil up some coax or 
to wind a balun at the feed point to "keep RF off the coax."
This sounded like a valid transmitting concern to me.  It then morphed into 
something else completely when the salesmen for CM chokes hijacked it.

Wes  N7WS

On 9/21/2017 5:43 PM, Drew Vonada-Smith wrote:
> Wes,
>
> For transmit, yes.  The note below was with regards to receive.
>
> Transmit CM issue - Unbalance of patterns, RF where it shouldn’t be, etc.
>
> Receive CM issue:  Noise pickup from non-antenna sources.  Common example - noise from sources in your home heard loudly when antenna not pointed there.  It's not because they are close to the radio, it can be because your cables pick them up and sends them around as CM.
>
> We have to be careful what aspect we are talking about...
>
> 73,
> Drew K3PA
> ------------------------------
>
> Message: 2
> Date: Thu, 21 Sep 2017 15:20:06 -0700
> From: Wes Stewart <wes_n7ws at triconet.org>
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] 40M rotary dipole and CM current
> Message-ID: <d9cfff41-03fa-9951-f48c-1607d735d133 at triconet.org>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> I thought the CM current in question came from the antenna in the first place.
>
> Wes? N7WS
>
> On 9/21/2017 3:03 PM, Drew Vonada-Smith wrote:
>> Doug,
>>
>> ...
>>
>> But, these common mode currents on the shield travel and radiate.  Therefore, they get to your antenna, and THEN they ARE on the center conductor.  You hear them.
>>
>> 73,
>> Drew K3PA
>>
>>
>
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