If you look at the atmospheric noise on HF you will find its much
stronger there than it is on VHF so you can't make use of .01 uv
sensitivity on 160 meters. Because the quiet noise levels will be
upwards of a microvolt. 30 or 40 db above the receiver noise...
What are you using for a signal generator? Many at VHF aren't that well
shielded and leak fractions of a microvolt. Which leads to misleading
attenuator readings especially on ssb or CW receiver modes.
On any band you need IF gain only to the point that the front end noise
(or antenna) noise sets the threshold. Any more gain and you run into
worse intermod problems in mixers and broad band first IF stages.
Can you measure 3rd order intermod and blocking range on the 847?
73, Jerry, K0CQ
FAQ on WWW: http://www.qsl.net/k7on/yaesu.html
Administrative requests: yaesu-REQUEST@contesting.com