Tom, You mentioned in an earlier posting that you had a six-cavity duplexer. Most six-cavity duplexers will have an insertion loss of about 2.25 dB, which means that with 70 watts in, you should see about 42 watts out. If you actually were measuring 45 watts out with 55 watts in, your duplexer has an insertion loss of only 0.9 dB. If your measurements are accurate, the duplexer tuning seems to be way off. What make and model duplexer is it? What instrument are you using to measure RF power?
73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of W3ML Sent: Monday, October 05, 2009 7:54 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Radio for repeater use Response to Tom's comments Thanks Tom, Yes, the advice is all good and I have tried several of the suggestions and most, if not all, did help some. Tomorrow, I will turn it up to 70 watts out, which should give me 60 out of the duplexer, if it works like it does not at 55 and 45 out. Then we will see what happens. In fact I did hook it up to another antenna on an adjacent tower. It worked worse than the G7. Funny thing is when I hook the G7 to a regular 2 meter radio and transmit on simplex, it works really well, hearing stations far a way and putting out a solid signal. 73 John --- In Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> , Tom Parker <t...@...> wrote: > > Well then, that's what everyone on this group is here for. All you have > to do is ask, and you've done that. All the advice tonight is valid, so > now you need to make some measurements. You definitely need an iso-tee, > and good watt meter, i.e., Bird or Telewave, and a service monitor with > at least a spectrum analyser would be a good start. Read the RB page > and follow the suggestions. We actually had a couple of Mastr II > mobiles rigged as repeaters, but we didn't de-rate the PA's. They saw > heavy use with zero problems for over ten years before we replaced them > with stations. Of course the tower building was a constant 74oF in the > Texas sun and the A/C ran most of the winter. It's a shame there's not > another antenna on the tower you could "borrow" for a few minutes. > > thp > > W3ML wrote: > > > > > > > Thanks Tom, > > > > Getting help around here is the hard part. I am the most experience > > and that is mostly from book reading and now a little playing around > > with the radio. No one else knows anything about repeaters either. > > > > We are just now getting into the repeater stage for our club. > > > > 73 > > John > > > > --- In Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > > <mailto:Repeater-Builder%40yahoogroups.com>, Tom Parker <thp@> wrote: > > > > > > Mastr II is a good radio. Likely not much wrong with it. They're a > > > great deal better than most of what you buy today; however, we're > > pretty > > > impressed with the Kenwood TKR's in our shop for mid tier units. Our 22 > > > trunk sites are made up of Micors, Mastr II's, Johnsons, and one > > site of > > > MSR 2000's and one site of R1225's with Henry amps. Most are five > > > channel and up. The TKR's are in stand alone situations or conventional > > > users who own their on. > > > > > > You ought to stick with what you have and work out the problems or get > > > some help. > > > > > > thp > > > > > > W3ML wrote: > > > > > > > > > > > > I probably will turn it up more to see what happens. When I had it at > > > > 5 watts out we had no problems at all. > > > > > > > > Over the 10 watts is when the noise was really bad. Now at 55 it > > works > > > > and then it doesn't and then it works again. > > > > > > > > So, yes I still have something wrong and maybe one of these days I > > > > will get another grant and convince the club to buy another GE Mastr > > > > II and and a new antenna and coax. Maybe that will fix it. > > > > > > > > People we got radio from are not answering. > > > > > > > > John > > > > > > > > --- In Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > > <mailto:Repeater-Builder%40yahoogroups.com> > > > > <mailto:Repeater-Builder%40yahoogroups.com>, "Chuck Kelsey" > > > > <wb2edv@> wrote: > > > > > > > > > > I'd suggest turning the power up more. You have it set at about 50% > > > > and the > > > > > transmitter may be intermittently spurious at that level. > > > > > > > > > > Watch the wattmeter when things act up and see if anything changes > > > > when you > > > > > notice the desense happening. You can also pull the TX ICOM when > > the > > > > problem > > > > > is happening and see if the receive clears up on the local speaker. > > > > > > > > > > There are so many things that could be at fault - loose > > connector, bad > > > > > antenna, problem with transmitter, problem with receiver, intermod > > > > issue, > > > > > etc. > > > > > > > > > > Ask the people you got the radio from if they had the same problem > > > > with it. > > > > > > > > > > Chuck > > > > > WB2EDV > > > > > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > > From: "W3ML" <w3ml@> > > > > > To: <Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > > <mailto:Repeater-Builder%40yahoogroups.com> > > > > <mailto:Repeater-Builder%40yahoogroups.com>> > > > > > Sent: Monday, October 05, 2009 8:33 PM > > > > > Subject: [Repeater-Builder] Re: Radio for repeater use Response to > > > > Tom's > > > > > comments > > > > > > > > > > > > > > > > Hi Tom, > > > > > > > > > > > > > > > > > > > > > > > > I did crank up the power to 55 watts out of radio and that gives > > > > me 45 out > > > > > > of the duplexer. Decided on this wattage until I can figure the > > > > problem > > > > > > better. It is working better than before, but still having > > trouble. > > > > > > > > > > > > So from what you said about power coming out duplexer, the > > > > duplexer must > > > > > > still be okay. > > > > > > > > > > > > However, during the day today there were 3 hams talking and > > they said > > > > > > (later) that all of them were loud and clear. But, when I got > > home > > > > and > > > > > > tried to call one of them, he was covered in noise. > > > > > > > > > > > > Later one of the others called in and he would be clear, then the > > > > repeater > > > > > > would cut out and his signal would be gone, then it would come > > > > back with > > > > > > noise on his signal and then clear again. > > > > > > > > > > > > Then the other one came in with a lot of noise, then he would > > come > > > > in with > > > > > > a little noise and then no noise at all and then back again > > > > through this > > > > > > cycle. > > > > > > > > > > > > This cycle of noise and then no noise is driving me crazy. > > > > > > > > > > > > The set up is this: > > > > > > > > > > > > GE Mastr II VHF mobile running into a 6 cavity duplexer set to > > our > > > > freqs > > > > > > with a service monitor prior to bringing it here. > > > > > > > > > > > > There is a bandpass filter on the receive side after the > > duplexer and > > > > > > before the radio. > > > > > > > > > > > > We have used 1/2 inch hardline going up to the used G7-144. > > > > > > > > > > > > Then only thing I can think of is the radio is bad, the > > antenna is > > > > no good > > > > > > and the coax is shot. > > > > > > > > > > > > Now, the radio was given to us by a group that had used it, but > > > > decided to > > > > > > replace it with a Kenwood. > > > > > > > > > > > > I am thinking that they had the same problem and that is why they > > > > gave it > > > > > > away. > > > > > > > > > > > > Any advice would be greatly appreciated. > > > > > > > > > > > > 73 > > > > > > John, W3ML > > > > > > > > > > > > > > > > > > - In Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > > <mailto:Repeater-Builder%40yahoogroups.com> > > > > <mailto:Repeater-Builder%40yahoogroups.com>, W9SRV <tgundo2003@> > > wrote: > > > > > >> > > > > > >> Ok- > > > > > >> > > > > > >> 1. Where are you checking the swr at in the chain? Make sure you > > > > bypass > > > > > >> the duplexers to check the antenna, the cans can throw off the > > > > reading on > > > > > >> some meters like you describe using. If you are less than > > 1.5:1 I > > > > would > > > > > >> not worry too much more about it, any reflected power will get > > > > eaten up > > > > > >> back in the cans. If you are really concerned about protecting > > > > the TX put > > > > > >> a circulator in-line with it. > > > > > >> > > > > > >> 2. Make sure all the interconnecting cables are good shielded > > and > > > > not > > > > > >> foil/ braid type. RG-213 and RG-400 are good choices, though > > > > there are a > > > > > >> few more. > > > > > >> > > > > > >> 3. Terminate into a good dummy load. Set you output power to > > > > 80-90W. Then > > > > > >> run thru the duplexer and check the power coming out of the > > cans. > > > > You > > > > > >> should see something like 60-70w, depending on the spec of the > > > > duplexer. > > > > > >> If your seeing much less than you may have a duplexer tuning > > issue. > > > > > >> > > > > > >> Figure out the real problem, let the radio run at a real spec > > power > > > > > >> output, than absorb the title of "far lord" as every one thanks > > > > you for > > > > > >> giving the repeater twice as many s-units. (then be prepared for > > > > the next > > > > > >> round of complaints that become your problem) > > > > > >> > > > > > >> Tom > > > > > >> W9SRV > > > > > >> > > > > > >> Sent from my iPhone > > > > > >> > > > > > >> On Oct 4, 2009, at 5:46 PM, "W3ML" <w3ml@> wrote: > > > > > >> > > > > > >> No, except when it was at the 2o watts the swr was almost 1 and > > > > someone > > > > > >> said that was the problem causing the de-sense. So we were > > afraid > > > > to run > > > > > >> it higher. > > > > > >> > > > > > >> Like you said guess it was only a problem from running too > > little of > > > > > >> power. > > > > > >> > > > > > >> > > > > > >> Thanks and 73 > > > > > >> John > > > > > >> > > > > > >> > > > > > >> --- In Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > > <mailto:Repeater-Builder%40yahoogroups.com> > > > > <mailto:Repeater-Builder%40yahoogroups.com>, W9SRV <tgundo2003@> > > wrote: > > > > > >> > > > > > >> You answered your own question : > > > > > >> > > > > > >> "So it appears that this radio, which is a GE Mastr II mobile, > > > > doesn't > > > > > >> like to run at the lower wattage of 10 to 20 watts out." > > > > > >> > > > > > >> 110w radio will not be stable at 10-20w. If you look at your > > > > output on a > > > > > >> spectrum you probably have spurs all over the place. Any > > reason you > > > > > >> cannot run it at least 1/2-2/3 power? > > > > > >> > > > > > >> Tom > > > > > >> W9SRV > > > > > >> > > > > > >> Sent from my iPhone > > > > > >> > > > > > >> On Oct 4, 2009, at 4:46 PM, "W3ML" <w3ml@> wrote: > > > > > >> > > > > > >> So it appears that this radio, which is a GE Mastr II mobile, > > > > doesn't > > > > > >> like to run at the lower wattage of 10 to 20 watts out. > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > >> ------------------------------------ > > > > > >> > > > > > >> > > > > > >> > > > > > >> Yahoo! Groups Links > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > ------------------------------------ > > > > > > > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
