On Wed, 22 Feb 2006, skipp025 wrote:
> Don't go overboard thinking hard line is a must have. If your 900Mhz
> repeater system is a portable setup it might be better to have good
> quality flexible line (coax).
Hardline is a Must Have(tm). :)
> Forget the rg-58 at 900Mhz unless you want to numb up your receiver for
> no good reason. Use some better coax or feed line that might be rated
> for the higher frequency range. Even mil spec rg-214 or 9913 is much
> better than rg-58.
Yeah, I've got 1000 feet of RG58 here -- just the perfect length to run up
the 800' TV tower, and 150 feet over to the building. Then I can coil up
whatever is left over and hang it inside the building.
> Relative to the big picture, the addition filtering is nice but won't do
> a lot to help the crappy performance of any rg-58 feedlines you use at
> 900MHz. Deep six using the rg-58 idea.
The RG58 is used inside the repeater cabinet, not up the tower. And as
little as possible will be used, once I have some idea about where
everything will be in the cabinet.
> You've got to worry about a lot more than "only the tx eating up the Rx
> inside the box".
Oh, I dunno... 90W PA eating up a reciever with very little front-end
filtering, plus nearby paging and LMR transmitters...
The basic breakdown of the system (thus far) is antenna -> mobile duplexer
-> bandpass cavity -> RX and the TX side just goes to the mobile duplexer.
The mobile duplexer provides notches on the RX frequency and TX frequency,
then the duplexer provides the brick-wall on both sides to make up for the
missing front-end filters in the RX.
--
Kris Kirby, KE4AHR <[EMAIL PROTECTED]>
"BIG BROTHER IS WATCHING YOU!"
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