Here is the situation with the repeater I maintain that runs 300W on TX. Repeater antennas are at 1300 ft feed through 3/4 in 75 ohm line. The majority of the user base is 40 to 60 miles from the site. We have a remote input about 60 miles from the repeater to provide HT and mobile coverage for where the majority of the users are. With all the feedline loss and the distance from the users, we need the 300W Tx power to provide good coverage where the users are.
The repeater is also the primary skywarn repeater with wide area coverage of the state and users need to be able to hear the repeater well in adverse weather conditions. With 300W, I can hear the repeater from my house which is 50 miles from the repeater and I can get into it on the HT with the rubber duck using 200 mw through the remote receiver. With the repeater running 100W for TX, I can get into the repeater using the HT but can't hear it on the rubber duck. John Lock KF0M Wichita KS kf0m at arrl dot net > -----Original Message----- > From: Kevin Custer [mailto:[EMAIL PROTECTED] > Sent: Wednesday, November 03, 2004 8:09 AM > To: [email protected] > Subject: Re: [Repeater-Builder] Solid State VHF PAs (200+ watts of > power) > > > > RE: Excessive power. > > Neil McKie wrote: > > >I can only wonder why the need for what seems to me is excessive power? > > > > Most folks will agree that a repeater that is working properly (no > desense) having a receiver sensitivity of .35 uV (- 116 dBm) for 12 dB > SINAD, and a transmitter power of 110 watts will likely be fairly well > matched in receive/transmit coverage considering a modern 50 watt mobile > rig. > > Now, lets add a receiver preamp on the repeater and increase its > sensitivity by say 6 dB to -122 dBm. Considering the repeater still > operates properly, without desense, this same repeater would now require > 480 watts of transmitter power to be matched as above. > > That being said, 200 + watts of transmitter power doesn't seem to be > excessive to me, but it depends on what is there to hear the user. > > Kevin Custer > > > > > > > Yahoo! Groups Links > > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
