Al & all, One of the purposes of a good receiver front end is to keep the LO and any other signals from going back up the antenna from the rcvr.
In WWII the Germans listen for the Allies receiver LOs. They knew their operating frequency (the freq the rx was tuned to) and knowing the receiver and IF they knew the LO freq. Most receivers at the time had no RF frontend amp so the LO when up the coax to the antenna and radiated. Think the TV boxes used by Nelson for getting TV ratings does this same thing...if they know the LO freq they can determine what channel you are tuned to...not necessarily watching. If a receiver is emitting its LO this at least says the receiver does not have much front end filtering. This is one reason higher freq 1st IFs are used. Image rejection is another, hi. Having a tight front end like a 5 cavity helical not only protects a repeater receiver from near by txs, but also protects others on the site from your repeater. 73, ron, n9ee/r >From: Al Wolfe <[EMAIL PROTECTED]> >Date: 2007/07/13 Fri AM 09:09:59 CDT >To: [email protected] >Subject: [Repeater-Builder] Re: Hamtronics > > Interesting report on Newsline this week. (Report 1560, July 6, 2007) >Seems the local oscillator of a Hamtronics R901 receiver in Bakersfield, CA >was putting out enough 406 Mhz energy to be a problem for NOAA's rescue >satellite system on that frequency range. > >Might be something to think about. What kind of energy does your >repeater receiver emit? > >Al, K9SI > > > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
