Hi as do most european 6mtr repeaters, 500Kc split 73
Steve ----- Original Message ----- From: "Eric Lemmon" <[email protected]> To: <[email protected]> Sent: Friday, July 30, 2010 3:57 PM Subject: RE: [Repeater-Builder] Repeater transmit levels at the receiver? > Jeff, > > You did an excellent job of explaining the complex interrelationships > among > 2m repeaters. However, not all 6m repeaters have a 1 MHz split; my 6m > repeater on Tranquillon Peak follows the California band plan and has a > 500 > kHz split. The duplexer has four cans about 12" in diameter and five feet > tall. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Jeff DePolo > Sent: Friday, July 30, 2010 7:30 AM > To: [email protected] > Subject: RE: [Repeater-Builder] Repeater transmit levels at the receiver? > > > <snip> > > How many thousands of 2m repeaters are out there running 100 watts at 600 > kHz offset without desense? Let's be generous and say they have 100 dB of > isolation in the duplexer. +50 dBm TPO - 100 dB = -50 dBm transmit carrier > hitting the receiver. No big deal. And that's on 2m. The offset on 2m is > only 0.4% (0.6 MHz / 146 MHz), whereas on 6m, it's 1.9% (1 / 53 MHz), > making > isolation requirements that much more stringent on 2m. > > Now let's look at a 6m example. You have a 6m repeater on a 1 MHz split? > Let's say it's on 53.99-, highest channel in the band, putting your > receiver > on 52.99. Some other ham is working simplex on 52.525, using 100 watts > into > a unity-gain antenna, and he's 40 miles away. His signal into your > receiver, assuming unity gain on your end too, and line-of-sight, is -53 > dBm > (that's what the free-space path loss works out to: 103 dB for 40 miles on > 6m, check my math). Would you expect this guy 40 miles away talking on 525 > to desense your repeater? If so, then you should expect *every* ham who > transmits on 525 (or potentially any other frequency within 1 MHz of your > receiver) within a 40 mile radius of your repeater to cause you desense; > those that are closer than 40 miles are just going to desense it even > worse. > > <snip> > > --- Jeff WN3A > > > > ------------------------------------ > > > > Yahoo! Groups Links > > >
