Hi Al,
Both Telewave and Sinclair make tower mounted preamps,
but you'd better do much planning and engineering to
get the design/order right the first time.
As we saw with Alex in the South American VHF trunking
System. Many "out of the box" offerings can cause more
problems vs how much they help.
In short, the tower mounted preamp should have twice
as much pre-selection as you would normally see supplied
with the basic device. Else you introduce a nightmare
into your rx antenna system...
Looking at your basic site description, you're going
to need a serious combination of both a very tight
multi section band-pass window filter network along
with serious - out of the main rx window notching on
the paging frequencies.
As a general rule with Telewave boxes, bypass relays
are included and the system is fed operational voltage
right through the feedline (no external power wires
required).
The advantage of the Phempt Device Preamp is the mo'
betta "third order intercept" value. A change to a
phempt type preamp will improve the overall system
performance as described in the Dubus UHF preamp
project at: www.radiowrench.com/sonic
You didn't say how far away the pager antennas are
from your main rx antenna..?
Regardless of where you buy it, the phempt preamp
is much better choice. As I've mentioned in the
past... there is no free lunch.
cheers,
skipp
> "Al Wolfe" <[EMAIL PROTECTED]> wrote:
>
> Speaking of UHF preamps, does anyone have any
> experience/recommendations for tower mounted
> preamps? I have a receiving only site at 425
> feet AGL, DB420 antenna, 7/8 line, that feeds
> five receivers at present. Tried an ARR on the
> ground before the splitter but it seemed to
> overload from UHF paging transmitters a mile
> away. The frequecies I need to receive cover
> 449 to 455 mhz. with the pagers at 452 and 453.
> Also, 50 kw FM station on tower at receive site.
> In ages past I used a home-brew gasfet and just
> a 1/4 wave stub in front of the gasfet and it
> worked very well. Then came the pagers. Have had
> some luck with notch filters on the pagers.
> I'm curious as to whether an Angle Linear or
> another preamp would servive this kind of
> service. How do they fare with lightning? PITA
> to change something 400 feet up in the air.
> Coaxial bypass?
> Merry Christmas,
> Al, K9SI
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