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[TowerTalk] Front to Back Measurements

To: <towertalk@contesting.com>
Subject: [TowerTalk] Front to Back Measurements
From: n4kg@juno.com (n4kg@juno.com)
Date: Thu, 13 Dec 2001 07:45:18 -0600


On Thu, 13 Dec 2001  "Bob Alexander" <realex@flash.net> writes:
> 
> Hi Kim,
> It is not possible to get an accurate F/B measurement (or any kind 
> of pattern measurement)from any rig that has the AGC turned on.

        HUH?  IF the S-meter is used as a fixed level indicator
        in conjunction with a calibrated external step attenuator
        there is no problem.  N4KG (Receiver Design Engineer)

        If you want to *hear* small differences, *then* you must
        turn the AGC OFF.

> Also, the  signal must be a constant carrier, not SSB.  I am not 
> familiar with the 756 but...
> 
> If it has an IF output available, turn off the AGC and use a scope 
> or RF voltmeter to measure the signal level as the antenna is 
> switched from 0 to 180 degrees.
> The voltages can be used to calculate the F/B of the antenna.

        This will work ONLY if you have sensitivity on the scope
        to see the weakest signal.  N4KG

> 73, Bob, W5AH
> 

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