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Everything posted by Lscott
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Tx on one channel and Rx on different channel.
Lscott replied to WSCA349's question in Technical Discussion
How have you got your radio programmed up? -
Despite the government's denials, a cell phone kill switch, I'm sure in the case of some "domestic disturbance" cell phone use would be restricted or disabled completely by their order. After J6 if it didn't exist then I'll bet it does now. That's when you're likely to need your radio the most to coordinate with others to get out of an area to a safe place.
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I've tried installing my own connectors, wasn't easy, didn't turn out that well. Unless you've done a lot of it, and have the right tools, it's money well spent to just buy a cable with the connectors already installed. One less question mark if things don't work as planed.
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For a db or two that's true for most people. With a modest gain antenna the coax loses can be compensated for. For people on the very fringe of a coverage zone every db counts.
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You have to be careful about which models to get. For example the Kenwood TK-3180's come in two different band splits. Both will cover GMRS, but only one has Part 95A certification. The 450-520 MHz band split can be "pushed", enter out of band frequencies with a warning message, down below 450 MHz to get into the repeater section of the Ham 70cm band. https://forums.mygmrs.com/gallery/image/417-tk-2180jpg/?context=new Some radios, like the Motorola's, the frequency range is locked to the official one and out of band frequencies can't be entered like with the Kenwood's. You have to buy the correct band split version. Also they may not have Part 95 certification either. https://forums.mygmrs.com/gallery/image/261-motorola-xpr6550jpeg/ For example while the Motorola XPR6550 is a nice radio it's not FCC Part 95 certified. TK-3180 FCC Grant-2.pdf TK-3180 FCC Grant-1.pdf TK-2180_3180 Brochure-2.pdf XPR6550 FCC Grant 4.pdf XPR6550 FCC Grant 3.pdf XPR6550 FCC Grant 2.pdf
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I think LMR600 has lower loses, a bit larger than LMR400, and I think it's not much more expensive either. The loss at 450MHz for LMR400 is 2.7db/100 feet. The loss at 450MHz for LMR600 is 1.7db/100 feet. For somebody who needs to run between 50 to 100 feed of coax stepping up to LMR600 would makes sense. The chart frequency of 450MHz is close enough to GMRS at 462/467 MHz the extra loss at the slightly higher frequency isn't that significant. For 50 feet of LMR400 at 450 MHz the power loss would be about 27%. For 50 feet of LMR600 at 450 MHz the power loss would be about 18%.
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At a reasonable cost. There is better cable, various types of "hard line", but gets expensive real fast.
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What is the principle behind the "ghost" antenna?
Lscott replied to WRWE744's question in Technical Discussion
I’ll have to check that one out. Every once in a while I get asked about it. -
What is the principle behind the "ghost" antenna?
Lscott replied to WRWE744's question in Technical Discussion
I was under the impression they all required a ground plane. https://forums.mygmrs.com/gallery/image/428-stealth-dual-band-with-swr-scanjpg/ -
From the album: Misc. Radio Gear
I picked up a cheap no-name Ghost/Phantom antenna at a local Ham swap a long while back. I wanted to test one since some people swear by them. And from my results likely will swear at them. The testing was done with the antenna screwed into a magnet mount on a large sheet metal ground plane. These antennas are basically loaded 1/4 wave vertical antennas and thus require a good ground plane for proper operation. The sample I got I'm not impressed with it. The antenna is VERY narrow banded on VHF. The SWR on the Ham 70cm band isn't too bad, but on GMRS it's poor. -
Any updates on the mystery signal?
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I've seen this all before years ago on various CB Internet news groups. Same sort of logic. Always ends up in the same place.
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What would happen if.... This is starting to sound more like what turned CB 11M in to a garbage heap. I guess with the increasing popularity of GMRS it was bound to happen to this service sooner or later.
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FCC database shows them licensed for VHF only and using DMR. https://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=1210947 https://wireless2.fcc.gov/UlsApp/UlsSearch/licenseFreqSum.jsp;JSESSIONID_ULSSEARCH=3P97hIOEmzSE_jvaTR3pepbHCYvM_n-Mf1fkabwZDAB8YVFyLPLy!-1848806523!-1099177123?licKey=1210947
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Some basic info to get you started. https://www.brara.org/documents/presentations/The DMR Basics _ No Frills.pdf https://w1yca.org/tech/tips/dmrGuide.pdf
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You have a good start to your collection.
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Drooling.
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OK, you asked. https://forums.mygmrs.com/gallery/image/249-934916052_radiocollectionjpg/?context=new https://forums.mygmrs.com/gallery/image/259-ca-2x4mb-jeepjpg/?context=new
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Also NOT certified for GMRS. For new users to GMRS the recommendation is to get a radio with Part 95A, under old rules, or Part 95E under the new rules certification. Some of the older commercial radios are certified under Part 95A and perfectly legal to use on GMRS. Plus, with some effort, they can be used outside of their official band split to allow operation into the upper half of the Ham 70cm band where the repeaters are typically located. Not all commercial radios allow this. This is just one such example: https://forums.mygmrs.com/gallery/image/263-tk-3170jpg/?context=new The difference between a 4 watt verses a 5 watt radio isn't very significant. Some may recommend a higher power handheld radio. What you'll get is a much shorter battery life and a great hand warmer, burner, if the radios is used at high power for more than very brief transmissions. I've read where some people have destroyed their radio from heat, even at the 4 to 5 watt level, when used at high duty cycles.
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I've been monitoring 462.5325MHz here at the office. I'm only a few miles directly due east of that water tower. I am getting something on the CCR triband radio I use as a scanner. It's not real strong and just short transmissions, about a second or two at a time.
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My biggest problem with DMR is the ever changing repeater settings. Identifying new talkgroups, deleting old talkgroups, changes in which network the repeater belongs to etc. I think I have a radio setup then a few weeks/months later it's all in the crapper and I have to update the zone for that repeater. PIA. DMR is nice, but the frequent changes aren't, and trying to find the current info is a crap-shoot. This repeater example is one of the more messy and busy systems I've seen. N8NOE.pdf
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Stranger things have happened. Had a thought. If it's a trunking system then there is an input and output frequency. You should see at least two pips on the spectrum display during each transmission. The lower power signal is likely the input. That one might be easier to zero in on since the area will be smaller and help localize the source.
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I looked up the address. Surprise, It's not where I thought it was. The address listed in the FCC's database shows its across the street from the golf course on Evergreen. It's looks like it's almost across the street from the Southfield City offices, library, court house and jail on the east side. They just recently built a couple of round-abouts there I believe.