Ideally you would want the dummy load to handle all the power the transmitter put out (and then some) in case of antenna failing, the transmitter could keep transmitting into the circulator with out even blinking. It would see close to a 1 to 1 SWR until the dummy load burned up unless you had an over sized dummy..
35 watt dummys will work just fine as long as your reflected power stays below what the dummys can handle. Some dummys have a thermal switch that you could wire to an alarm or kill the transmitter. tom > [Original Message] > From: Nate Duehr <[EMAIL PROTECTED]> > To: <[email protected]> > Date: 8/20/2008 8:36:04 PM > Subject: Re: [Repeater-Builder] Celwave Circulator > > Nevada Amateur Radio Repeaters, Inc. wrote: > > Ref: <www.telewave.com/pdf/TWDS-4015.pdf > > <http://www.telewave.com/pdf/TWDS-4015.pdf>> > > > > I looked at the Celwave dual stages circulator rated at 150 watts a dual > > stages with a 35 watt dummy load on each stage. I dont understand the > > design since I have seen and used two stage circulator with a 100 watt > > dummy load on the first stage and a 25 watt dummy load on stage two. > > What make two 35 watt dummy loads in series ok? What am I missing? > > I saw some weird numbers on some of these recently also when I was > trying to compare apples-to-apples. > > As best I could figure out, the 150W "rating" from some manufacturers > was how much power you could put THROUGH it from the transmitter port, > not how much power it was going to isolate coming back down the antenna > feed-line. > > You may want to see how many dB of "isolation" they rate it for and do > the math and see if that's 150W. I doubt it. > > That first load will just get really really HOT if you shove 150W into > the antenna side... heh. Probably burn it up. > > Of course, if you have 150W coming back down the antenna... you're on a > really wicked site. (Yeah, I know we've all seen that there ARE some > really wicked sites... usually power like that means you're right up > against a broadcaster of whatever variety.) :-) > > Nate WY0X > > ------------------------------------ > > > > Yahoo! Groups Links > > > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.138 / Virus Database: 270.6.6/1621 - Release Date: 8/19/2008 6:53 PM > ------------------------------------ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Repeater-Builder/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> 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/
