Hi Nate, Two or three people have already Emailed me direct so here goes...
> Nate Duehr <n...@...> wrote: > Nate Duehr, WY0X > I'd love to see how that gets properly measured, if you > ever have the time, Skipp. That one's outside of my > knowledge level, for sure. Can do: The measurements are probably best described by the dual series preamplifier layout set-up. The more common site hardware layout is as follows: Antenna - Pre-Selection (cavities) - Rx Preamplifier #1 - Variable Attenuator (later replaced by a fixed pad) - Rx Preamplifier #2 - n-way signal divider (splitter) - Receiver. In some systems we also use other configurations with trailing cavities, different n-way dividers, etc. *Note In this example the receivers are of the same type and or similar spec. Quite different receiver specs can be later discussed if their inclusion in the system setup is not obvious. Measure the site effective sensitivity: http://www.repeater-builder.com/tech-info/effectivesens.html Measure and record the 20dB Sinad of your as installed receiver. Set the center connected RF Attenuator to an initial 1dB value. Place a signal into the receiver system antenna input port, increase the RF Attenuator value until you see the receiver come out of limiting. The value of RF Attenuation can be - is also adjusted to/for the site effective sensitivity and becomes your fixed value pad number/value plus 1dB (typical) in place of the variable attenuator when you remove it. Many of the people I know running this configuration add at least an extra dB or two on the final fixed value pad value. More later... the boss is making me a very attractive offer to go for a late afternoon walk. back after this commercial break. s. > > There are Northern California site locations in operation > > where the Repeater Rx Antenna System contains the desired > > pre-selection, two series pre-amplifiers separated initially > > by an adjustable attenuator and later a fixed value. It's > > beyond the scope of this post (IE right now) to explain > > how the series preamplifier operation is dialed in with the > > attenuator. But the end results compared to a single preamp > > operation are dramatic and obvious.
