998cc wrote:
I am looking for ways to improve my receive for 2-meter SSB weak signal
work. I am running an Icom 706 MkIIG and a M2 5WL yagi. I understand mast
mounted preamps bring the signal up significantly.
Doe any one here use one for 2M SSB? What are your experiences?

Thanks
Russ


Russ- You may improve your senseitivity to a degree, with a preamp,
but it may (or may not) be worth the effort. As the mast mounted
preamp will establish your Rx noise figure, but, the ONLY advantage
from the GAIN of the preamp, would be to overcome the (Coax Loss,+
the Xcvr front end Noise Figure)-
This assumes that the preamp has a Noise Figure LOWER than the rig
, as Lower loss (hardline )coax might be more beneficial!
- the rest of any gain will only
make your receiver subject to front end overloading , from nearby
STRONG signals! Futher, you must have SOMETHING to delay the
transmitter from keying (a " sequencer"), or you may destroy your
preamp, by transmitting into it! Question? What is the Fastest
fuse you can get? Answer: a Transistor! Another way to increase
sensetivity, is to narrow your receiver band width . Halve your
Bandwidth, gain 6 dB increase in senseativity (X-4). And, as a
reliatively good test as to HOW MUCH the preamp will improve your
reception, try this test: 1) attach a 50 ohm non inductive
resistor to your antenna connector, and note your NOISE LEVEL/
S-METER. 2) Now replace your dummy load with your antenna.
Did the noise /or S-METER INCREASE? If so, you are most likely
receiveing at your maximum senseativity. (IF the noise level stays the
same, you MAY make an improvement to your system, tho, HOW much,
is hard to say! Hope this helps-- Jim NN7K