yes I know -55db is I think around 399 microvolts which will flatten
any receiver,
I sure hope not; there are many signals coming down my antenna that are
that strong. In fact, my 440 repeater 13 miles away is at about that level
at my antenna connector.
Reminds me of a test I did with a GE MASTR Pro VHF receiver (stock - no
preamp - ER-41C) and a GE MASTR II PLL exciter (stock - 200 mW output)
and a tee connector. Receiver and exciter on each end of the tee (with
short cables) and antenna/service monitor on the center. As I remember,
the frequencies were about 6 MHz apart and the 'repeater' would duplex
reasonably well considering no filtering was used between the units. Of
course, I'm not saying there wasn't desense, but it worked - pretty well.
Obviously, the 200 mW was split into two paths and who knows how much
was hitting the input port of the receiver, but lets say half of it was
- 100 mW. That power level is +20 dBm. I can almost guarantee you
that transmitter side band noise is what created the desense - not the
shear power of the transmitter. +20 dBm is 2,240,000 ?V or 2.24 volts
of RF.
My receive antenna for the UHF remote receivers is top mounted across
the tower face beside the VHF stick. The VHF repeater runs 250 watts.
4 watts of VHF power appears at the splitter (in the shelter - including
feedline loss) which feeds the 4 UHF receivers. The splitter (old CATV
type) gets warm - you figure out how much VHF power is getting to each
UHF receiver <grin>.
Kevin Custer
