> >I would have never considered a dual series RF Preamplifier
> >layout viable until I'd seen one demonstrated against the
> >single preamplifier version. The properly installed and
> >setup dual preamplifier layout with system gain well in excess
> >of 14dB clearly out preforms the rest of the bunch on the
> >same mountain top. I didn't invent it... but I've copied
> >the layout many times and it works killer (very well).
> Unless the engineering details of this "dual series RF
> preamplifier" system are provided, I'll stick to my
> original claim that anything over 14 dB gain feeding
> a single NBFM RX is a waste of gain & will only lower the
> system dynamic range.
The dual series preamplifier layout/operation is not first
directly targeted at increasing system dynamic range. It's
quite a bit about using the maximum practical gain possible
for a given situation, understanding, controlling the
hardware and conditions which would cause problems at high
input signal levels. Use of Gain Values above 14dB are
quite possible, often used and the demonstrated results in
many of our applications are quite impressive. Users can
reliably access dual series RX Preamp configured distant
repeaters with fractional watt power levels (hand held
radios on the lowest power settings).
You might remember reading my past story regarding a
karaoke mic we tracked down. The UHF band mic operated
fractional RF power from internal batteries, no real
antenna except the split mic body, inside a double walled
night club about 15 plus miles from the repeater site
and of course it was full quieting into the repeater
input during carrier squelch operation. Might never have
been a problem/noticed in a single preamp system and
of course the hand held (portable) radio access would
have been noticeably less.
The karaoke mic event has been the/our only experienced
(so far) negative result sourced back to using the dual
controlled series preamplifier layout. Hearing is
believing...
s.
