[TowerTalk] Strong FM Station Impact on Antenna Analyzer Use in VHF

[N1BUG]

On 07/29/2016 12:14 PM, Jeff DePolo wrote:
> At 1/2 mile, the free-space path loss is about 70 dB at 100 MHz, so the 50
> kW FM would yield about +7 dBm using a unity-gain receiving antenna at that
> location.  I don't know those two specific devices well enough to know
> whether or not a signal of that amplitude (plus or minus the yagi's
> gain/loss at 100 MHz) that far off-channel would be an issue.

We found that none of three MFJ units could function in an 
environment where the free space path loss was about 50 to 60 dB 
from a 1 kW transmitter on 162 MHz. Not only could they not provide 
reasonable readings at 146 MHz, but they could not at HF either. 
This was without external filters of any kind. I am not certain this 
is relevant, but I measured the output of one MFJ 259B at 144 MHz 
and found it to be +8 dBm.

73,
Paul N1BUG