[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" 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 > > >
Re: [Repeater-Builder] Re: Icom portable repeater help
On 2/14/07, Brian Rau <[EMAIL PROTECTED]> wrote: > 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. Usually putting the TX up high is "backwards"? Any particular reason you went that way? Unless you have other receiver sites, putting the TX higher just makes the machine a bit of an alligator... and now you have to run your power past the receive antenna in the cable, as mentioned by Brian. Nate WY0X
[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 Q&A for great tips from Yahoo! Answers users. > http://answers.yahoo.com/dir/?link=list&sid=396546091 >
Re: [Repeater-Builder] Re: Icom portable repeater help
--- 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 Q&A for great tips from Yahoo! Answers users. http://answers.yahoo.com/dir/?link=list&sid=396546091
RE: [Repeater-Builder] Re: Icom portable repeater help
Brian, I very familiar with those radios (small ICOM Land Mobile Dealer) one solution is to try a small preselector on the receiver . I have two F121s in the back of a fire dept rescue vehicle with antennas about 3 feet apart and it works fairly well. The FD has told me they can be several miles from the truck and still hit the repeater full quieting. The split is a little over 5MHz. I do have a Sinclair FP20401B-2-1 preselector and I separated the radio from each other with a heavy sheet of stainless steel between them . If I hook them up any other way the transmit will completely squash the receiver. E-mail me directly I may be able to help you further John [EMAIL PROTECTED] -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Brian Rau Sent: Tuesday, February 13, 2007 11:22 AM To: Repeater-Builder@yahoogroups.com Subject: [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 <mailto:Repeater-Builder%40yahoogroups.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 <mailto:Repeater-Builder%40yahoogroups.com> , "Brian Rau" 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 <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 > > >
Re: [Repeater-Builder] Re: Icom portable repeater help
At 2/13/2007 08:22 AM, you 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 I agree with using a duplexer as opposed to split antennas. As Adam pointed out in a previous posting (at least in the order I'm getting them from Yahoo), sufficient vertical separation in a portable operation is difficult, & while with enough coax or split sites you may be able to get enough horizontal separation, you'll need a lot more real estate to pull it off, or will need to use directional antennas so as to get a null between the two. I did this a long time ago on one of my first repeaters, a 2 meter system using a tube-type radio (clean TX, reasonable RX dynamic range), 1 pass cavity & a directional antenna & omni. The problem was I only had usable coverage in the direction the beam was pointing (~90 degrees away from the omni), plus I was constantly tuning the TX (about once every week or two) to keep the noise out of the RX. Using a duplexer will give you the maximum possible coverage from your limited antenna height & space. Bob NO6B
[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" 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
--- In Repeater-Builder@yahoogroups.com, [EMAIL PROTECTED] wrote: > > At 2/12/2007 09:45, you wrote: > > >Hi, > >from the experiments carried out here in the U.K. on in-band and > >cross-band portable and mobile repeaters vertical separation is > >nowhere near as good as horizontal.This also offers the chance > >to get the recieve antenna in a "null" from the transmitter. > > I assume you got your "horizontal" & "vertical" reversed in the above > statement, otherwise we're in for some spirited debate. > > Bob NO6B > Hi Bob, you have a very valid point but for portable "lash-up" which has to be man-portable to remote points i.e. post crash at Lockerbie (Flight 103) it has to be lightweight and only horizontal separation is viable.Also the authorities in the U.K. are not as liberal as the F.C.C. is where you are,and since money for kit is in short supply we have to use our day-to-day radios with the add-on interface units (look up CAIRO radio interface on the web) you can imagine the horrors that can result.We just have to engineer our way out of it,if you look up that web-site it will explain the philosophy much better than I can but it will also explain why in emergency service for us here accross the pond it has to be horizontal. Regards Adam (G8UMX)
[Repeater-Builder] Re: Icom portable repeater help
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" <[EMAIL PROTECTED]> 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 >
Re: [Repeater-Builder] Re: Icom portable repeater help
At 2/12/2007 09:45, you wrote: >Hi, >from the experiments carried out here in the U.K. on in-band and >cross-band portable and mobile repeaters vertical separation is >nowhere near as good as horizontal.This also offers the chance >to get the recieve antenna in a "null" from the transmitter. I assume you got your "horizontal" & "vertical" reversed in the above statement, otherwise we're in for some spirited debate. Bob NO6B
Re: [Repeater-Builder] Re: Icom portable repeater help
ensemble953039 wrote: > > Hi, >from the experiments carried out here in the U.K. on in-band and >cross-band portable and mobile repeaters vertical separation is >nowhere near as good as horizontal.This also offers the chance >to get the recieve antenna in a "null" from the transmitter.Also >it might be better to use a crystal-controlled rig for this work >due to noise generated in the Tx signal providing there isn't a >requirement for too many channels too far apart (less than 1%) of >the centre frequency. > > Adam G8UMX Whoops-got that backwards, Adam. Horizontal is not as good as vertical for the reasons you cited. Happy Monday to you too ;cD -- Jim Barbour WD8CHL
[Repeater-Builder] Re: Icom portable repeater help
--- In Repeater-Builder@yahoogroups.com, "Brian Rau" <[EMAIL PROTECTED]> 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 > Hi, from the experiments carried out here in the U.K. on in-band and cross-band portable and mobile repeaters vertical separation is nowhere near as good as horizontal.This also offers the chance to get the recieve antenna in a "null" from the transmitter.Also it might be better to use a crystal-controlled rig for this work due to noise generated in the Tx signal providing there isn't a requirement for too many channels too far apart (less than 1%) of the centre frequency. Adam G8UMX
