[BC] Part 15 LPAM Question?

[Robert Meuser]

It is the extremely high reactance that is the problem.

R


Dana Puopolo wrote:

>It's a gray area. I've installed several part 15 statems in colleges. They all
>pass FCC muster. In these cases the transmitter case was bolted to the
>structual members of the building. What's the 'ground lead' there? The length
>of the bolt (about 1/2 inch) or the four story gym?
>
>Has anyone used an emitter or source follower in a Part 15 transmitter to
>match the (very low) impedance of a short antenna? Yes, I know their gain is
>slightly less then unity, but the coil losses in a large network might be
>more. 
>
>-D
>
>
>
>------ Original Message ------
>Received: Sun, 10 Sep 2006 06:04:10 AM EDT
>From: "Richard Fry" <rfry at adams.net>
>To: "Broadcast List" <broadcast at radiolists.net>
>Subject: [BC] Part 15 LPAM Question?
>
>  
>
>>I'd put a 102 inch CB whip (with spring) atop the cabinet,
>>and stick the whole thing 25 feet in the air (preferably 25 feet
>>above a nice steel frame building that the mounting pole
>>is lightning grounded to with a nice wide strap).
>>No "ground lead" would be used.
>>    
>>
>_______________
>
>But in reality, conductors such as the building frame and the nice wide 
>strap connected to the tx chassis by a low-Z path will become part of the 
>Part 15 AM radiator length along with the 102" whip, and likely will 
>radiate more field than the whip, itself.
>
>So this system _would_ have a functional 25 foot ground lead, even if that 
>isn't recognized at first.
>
>RF 
>
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