[TowerTalk] antenna FS measurements

Tom Rauch w8ji at contesting.com
Tue Jun 29 19:11:03 EDT 2004


> A technique to disable the AGC that works with many
receivers is to advance
> the AF gain to maximum and reduce the RF Gain untill the
S-Meter rises to S9 or
> more. You can acheive a linear dynamic range approaching
30 db using this
> method.

It would be much better to just use a step attenuator and
set the S meter to the same reading down low on the scale
then to depend on everything being linear with the AGC off.

Turning the AGC off and using some soundcard device to read
level is not a good method.

MFJ sells a surface mount step attenuator that is accurate
within a small fraction of a dB per step. Of course I'd
check it first. I have three or four, and they are within
.05dB per step.

73 Tom




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