[Repeater-Builder] Tone squelch vs. carrier squelch
Ok, I know all the usual reasons for using input tones on a repeater, but I have more of a theoretical performance question. Again, I'm putting together a portable VHF repeater out of a pair of Icom mobiles (IC-F121) for search-and-rescue use. Since it's for temporary, emergency use, my primary concern is weak-signal performance, particularly being able to hear someone out in the field with a 5W handheld and a rubber duck. Here's my question: For the best chance of allowing my repeater to hear that weak signal, am I better off using an input tone and turning the receiver squelch way down (perhaps even all the way), or using no input tone and plain old carrier squelch (at a higher level)? I'll almost certainly end up using a receive tone on this thing anyway just to minimize interference potential, but it seems to me that doing so might help improve my ears as well. Comments? Brian K9JVA
[Repeater-Builder] Re: Icom portable repeater help
Just to follow up and close the loop on this thread, I got a Sinclair MR256 mobile duplexer, threw together a quick test setup and tested it on my drive to work this morning... it's kicking butt compared to what it used to do using two separate antennas. I'm now getting good audio from five miles away using a 5W handheld, and no real effort to optimize repeater site location (i.e. it's in my backyard). Thanks for the input, folks... Brian K9JVA --- In Repeater-Builder@yahoogroups.com, covertp9 [EMAIL PROTECTED] wrote: I would think you'd be best served by getting the duplexer ASAP. If your intent is to have a smaller, portable, quick to set up repeater... the duplexer allows you to eliminate one antenna feedline, sets up more quickly, and works immediately without antenna jockeying, tuning, etc. (assuming your duplexer is properly tuned). I have the IC221s combo up as a UHF repeater using a mobile duplexer. Until I got the duplexer correctly tuned, the desense made the setup unusable. However, now that it's tuned I get a 15-18 mile radius coverage from the colinear ground plane 18 feet above the back of my garage rrof. It works as expected. - WB2ULR --- In Repeater-Builder@yahoogroups.com, Brian Rau brau@ wrote: I'm putting together a portable suitcase repeater for our search and rescue team, using Icom F121 radios per this article: http://www.repeater-builder.com/icom/repeater-mod-for-icom-ic121-221-series.rtf I've got the two radios together and working, my question is: has anyone had success with this configuration using two separate antennas (no duplexer)? I've tried using two twinlead J-poles, one at the top of a 25' mast and one at ground level (tried both RX and TX at the top, TX at top seems to work better), I've also tried a home-built 1/4 wave with four radials at the top (TX) with a 1/4 wave magmount on a car directly below. I can hit the repeater with a 5W handheld from a good long distance away, and get the squelch tail for the programmed hang time. However, I don't get any audio repeated much farther than a half mile to a mile away. I can do handheld-to-handheld simplex a good deal farther than this. I have permission to use a 5.5 MHz split pair of frequencies in the 150 MHz range, which is what I've done all testing on. It sure acts like the TX is desensing the receiver. We ultimately may want to incorporate a mobile duplexer (Sinclair or similar) into the box anyway just to be able to use a single antenna, but I'm surprised this isn't working better with two antennas mounted directly above/below each other. Interestingly, Icom apparently offers this configuration (two F121 mobiles in a Pelican case) as a standard portable repeater product now, and the duplexer is an option, so I'm wondering under what circumstances this thing will work without a duplexer? Any comments or suggestions are appreciated. Brian K9JVA
[Repeater-Builder] Re: Icom portable repeater help
Nothing fancy... single-shielded RG-58U. That's an interesting thought that hadn't occurred to me. And with my vertical-separation setup with the TX antenna up high, that could certainly be a factor. - Brian --- In Repeater-Builder@yahoogroups.com, Ralph Mowery [EMAIL PROTECTED] wrote: --- Brian Rau [EMAIL PROTECTED] wrote: Thanks for your input, I was hoping to hear from someone who had experience with this kind of rig. I've been trying the vertical antenna separation tactic, which *in theory* puts the antennas in each others' nulls, but I think the reality is that there's enough pattern distortion, signal reflection, etc to make it unworkable. I just was looking for a sanity check before spending the bucks on the duplexer. Brian K9JVA Were you using double shielded coax or hardling ? If you run single shielded coax next to each other or past one of the antennas you usualy get desense. Need Mail bonding? Go to the Yahoo! Mail QA for great tips from Yahoo! Answers users. http://answers.yahoo.com/dir/?link=listsid=396546091
[Repeater-Builder] Re: Icom portable repeater help
Thanks for your input, I was hoping to hear from someone who had experience with this kind of rig. I've been trying the vertical antenna separation tactic, which *in theory* puts the antennas in each others' nulls, but I think the reality is that there's enough pattern distortion, signal reflection, etc to make it unworkable. I just was looking for a sanity check before spending the bucks on the duplexer. Brian K9JVA --- In Repeater-Builder@yahoogroups.com, covertp9 [EMAIL PROTECTED] wrote: I would think you'd be best served by getting the duplexer ASAP. If your intent is to have a smaller, portable, quick to set up repeater... the duplexer allows you to eliminate one antenna feedline, sets up more quickly, and works immediately without antenna jockeying, tuning, etc. (assuming your duplexer is properly tuned). I have the IC221s combo up as a UHF repeater using a mobile duplexer. Until I got the duplexer correctly tuned, the desense made the setup unusable. However, now that it's tuned I get a 15-18 mile radius coverage from the colinear ground plane 18 feet above the back of my garage rrof. It works as expected. - WB2ULR --- In Repeater-Builder@yahoogroups.com, Brian Rau brau@ wrote: I'm putting together a portable suitcase repeater for our search and rescue team, using Icom F121 radios per this article: http://www.repeater-builder.com/icom/repeater-mod-for-icom-ic121-221-series.rtf I've got the two radios together and working, my question is: has anyone had success with this configuration using two separate antennas (no duplexer)? I've tried using two twinlead J-poles, one at the top of a 25' mast and one at ground level (tried both RX and TX at the top, TX at top seems to work better), I've also tried a home-built 1/4 wave with four radials at the top (TX) with a 1/4 wave magmount on a car directly below. I can hit the repeater with a 5W handheld from a good long distance away, and get the squelch tail for the programmed hang time. However, I don't get any audio repeated much farther than a half mile to a mile away. I can do handheld-to-handheld simplex a good deal farther than this. I have permission to use a 5.5 MHz split pair of frequencies in the 150 MHz range, which is what I've done all testing on. It sure acts like the TX is desensing the receiver. We ultimately may want to incorporate a mobile duplexer (Sinclair or similar) into the box anyway just to be able to use a single antenna, but I'm surprised this isn't working better with two antennas mounted directly above/below each other. Interestingly, Icom apparently offers this configuration (two F121 mobiles in a Pelican case) as a standard portable repeater product now, and the duplexer is an option, so I'm wondering under what circumstances this thing will work without a duplexer? Any comments or suggestions are appreciated. Brian K9JVA
[Repeater-Builder] Icom portable repeater help
I'm putting together a portable suitcase repeater for our search and rescue team, using Icom F121 radios per this article: http://www.repeater-builder.com/icom/repeater-mod-for-icom-ic121-221-series.rtf I've got the two radios together and working, my question is: has anyone had success with this configuration using two separate antennas (no duplexer)? I've tried using two twinlead J-poles, one at the top of a 25' mast and one at ground level (tried both RX and TX at the top, TX at top seems to work better), I've also tried a home-built 1/4 wave with four radials at the top (TX) with a 1/4 wave magmount on a car directly below. I can hit the repeater with a 5W handheld from a good long distance away, and get the squelch tail for the programmed hang time. However, I don't get any audio repeated much farther than a half mile to a mile away. I can do handheld-to-handheld simplex a good deal farther than this. I have permission to use a 5.5 MHz split pair of frequencies in the 150 MHz range, which is what I've done all testing on. It sure acts like the TX is desensing the receiver. We ultimately may want to incorporate a mobile duplexer (Sinclair or similar) into the box anyway just to be able to use a single antenna, but I'm surprised this isn't working better with two antennas mounted directly above/below each other. Interestingly, Icom apparently offers this configuration (two F121 mobiles in a Pelican case) as a standard portable repeater product now, and the duplexer is an option, so I'm wondering under what circumstances this thing will work without a duplexer? Any comments or suggestions are appreciated. Brian K9JVA
