At 3/21/2007 18:24, you wrote: >Steve, > >It's on 2M, single Station Master antenna with about 400 feet of 7/8" >feedline. The duplexer is a BP/BR followed by a band pass can, then >the pre, then the radio side. All cables are RG-400. > >The radio is GE Exec II. The sensitivity without the pre is about >0.35 uV. The noise floor is pretty low, but the ARR pre was picking >up a bunch of garbage without the attenuator.
If the ARR preamp is nonlinear with a pass can ahead of it, it's probably oscillating. I recommend replacing it with an Angle Linear preamp (http://www.anglelinear.com). Chip's preamps are guaranteed to be unconditionally stable, meaning it won't oscillate just because there's a pass can ahead of it. And without that 6 dB pad in front of it, you'll reduce your system noise figure by over 5 dB! Bob NO6B
