Lscott
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Posts posted by Lscott
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10 hours ago, SteveShannon said:
Make it yours! Of course I haven’t gotten around to cutting a hole in my 4Runner but I find myself wishing I had done it years ago.
Modern vehicles use thinner sheet metal to save weight for improved fuel economy. What might have been in the past a minor adrenaline surge when the antenna whacked a tree branch now may result in some real damage to body sheet around the antenna mount. I would think a bit more about the usual advise to "just drill the hole" and mount the antenna.
- WRUU653, WSAM454 and SteveShannon
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4 minutes ago, WRUE951 said:
Getting them right is tricky but do it right, you have a decent good performing antenna
That's really the whole issue most of the time.
- WRHS218, WRUE951 and SteveShannon
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I did some quick screen captures of a Ham 70cm J-Pole simulation I had done some time back to show what people can expect. The radiation pattern of most interest is the azimuth one, perpendicular to the vertical element. As seen in the attached images there is some asymmetrical gain variation. The vertical, elevation, pattern is more complex and only of interest if the other station is at high angles , above or below, the perpendicular point.
- SteveShannon and WRUE951
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Some of the frequencies are in consecutive steps of exactly 100KHz too, so it's not even based on some standard channel spacing either.
My first guess is these were "test" frequencies used to "tune" the radio's PLL circuits. I know my commercial radios have a special bank of frequencies just for that purpose. The attached photo is from my NX-1300 for example.
- WRTC928, amaff and SteveShannon
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3 hours ago, MarkInTampa said:
Just got back to my desktop from a cruise. Here's a link to legacy licenses. It lists the license holder by zip, state and city. The list is a few years old but does give you the callsign and you can use the FCC license search to see if it's still valid or expired. I keep it bookmarked just in case.
https://www.thepeters.org/grandfathered_gmrs.htmlAh, that's a very useful link for this! The take-a-way is there are such grandfathered GMRS business users out there.
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38 minutes ago, 73blazer said:
But the Supergainer 7500 2m/70cm does much better even though is slightly less spec'd gain in it's design bands. SWR of 1.2:1 on all design bands as well as on 462/467 with a KG-UV980P mobile radio
What did you use to test the SWR?
I've done some testing myself using a Rigexpert AA-1000 and didn't get great results with the 7500. The comet CA-2xSR did reasonably well. My old Comet dual band CA-2x4MB is the best one I've had, but it's not manufactured anymore.
These antennas are sensitive to the type and location of the mount being used. Particularly the CA-2xSR.
I currently have the CA-2x4MB on my Mazda. The fold-over spring is weak so I have the antenna permanently taped so it doesn't flip over while driving. I have a spare brand new one still in the green plastic packaging. The antenna is about 60 inches tall so I have to be EXTRA careful where I drive.
https://forums.mygmrs.com/gallery/image/471-mobile-mount-with-antenna-rear-view/?context=new
https://forums.mygmrs.com/gallery/image/473-close-up-of-mobile-mount/
And this is when I had it on the old Jeep.
https://forums.mygmrs.com/gallery/image/259-ca-2x4mb-jeepjpg/?context=new
Antenna Scan Results (CA-2x4MB VHF Jeep).pdf Antenna Scan Results (CA-2x4MB UHF Jeep).pdf Antenna Scan Results (CA-2x4MB MURS Jeep).pdf Antenna Scan Results (CA-2x4MB FRS_GMRS Jeep).pdf CA-2x4SR VHF TRI MAG MNT.pdf CA-2x4SR UHF TRI MAG MNT.pdf SG7500A VHF Scan GND Radials.pdf SG7500A UHF Scan GND Radials.pdf
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9 hours ago, WSHE531 said:
What’s everyone think about the j pole antenna?
I think before that question it's important to understand what it is, and isn't. There is a good write-up at this link.
https://en.wikipedia.org/wiki/J-pole_antenna
Most of the issues with the antenna stems from it's radiation pattern. Depending on construction and installation the antenna may present some noticeable asymmetric gain characteristics.
One other important point is the antenna requires some kind of "decoupling" network for the connecting coax cable. That's typically done using some snap on ferrite cores very close to the feed point, or a coiled up section of the coax cable. If this isn't done then all sorts of weird highly asymmetric gain characteristics may occur along with high SWR readings, and even RF getting back into the radio causing distorted audio.
- WRHS218 and SteveShannon
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12 minutes ago, MarkInTampa said:
What is messed up is when there is a strong band opening, the Orlando 700 repeater users will complain about hearing DMR thinking it's coming from their repeater when it's coming from Tampa. The band doesn't open that strong very often though, maybe a few times a year.
Likely they would complain anyway if it was just FM and some real chatty users had the other repeater keyed up for long periods.
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1 hour ago, MarkInTampa said:
About all you can see with SDR are the headers at start of tx
One other course is if the repeater is located on a commercial, for rent, tower the owner of the tower may not want that repeater there if it's operating illegally.
If nothing else works then likely you may need to hijack the repeater unless it's locked down by the SU's, subscriber unit, electronic serial number or other access restriction method. It might not matter if the unauthorized traffic is encrypted or not from the hijacker. If it has to run encrypted chances are it's RC4, which is compatible with Motorola's enhanced privacy and other manufacture's 40 bit encryption.
I have my Kenwood NX-1300's enabled for it if I really need the feature.
https://forums.mygmrs.com/gallery/image/290-nx-1300duk5/?context=new
Some of the older Motorola radios have it enabled as a freebie on the HT's.
https://forums.mygmrs.com/gallery/image/261-motorola-xpr6550jpeg/?context=new
The idea is to use it enough to annoy the owner(s) to shut it down and move it. If the FCC isn't interested enough to do something about it they likely won't bother the people hijacking it either. While not ethical, and not legal to use DMR by the business or hijacking users, the FCC has invited the activity by their lack of rules enforcement.
Your choices and options are rather limited.
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14 minutes ago, MarkInTampa said:
It is not listed in the FCC database, at least by frequency. The local Motorola shop is one of those that filed a complaint. It has made .700 unusable in the area.
Hum.... If it's operating illegally then I suppose they really couldn't complain if it got hijacked by local GMRS users. If they did the FCC might take more of an interest in it and ask a lot of questions they would rather not answer. Their other choice is to shut it down and apply for a legitimate business frequency and move it there.
And SDR dongle with the decoding software, or one of those D878UV's using the digital monitor function, will show you all the color codes, slot numbers, talk groups and user ID's on the repeater. While the D878UV might not be that great of a radio the digital monitor feature is one of it's very useful one's for getting info on unknown DMR traffic.
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50 minutes ago, MarkInTampa said:
In my area there is a business operating a illegal DMR repeater and has been for a few years. It's been reported to the FCC by numerous folks, yet it's still there.
You sure it's really operating illegally? Remember before the 2017 rule changes business could get a GMRS license. So long as the business has maintained their license, didn't let it expire, they can continue to renew it and operate LEGALLY. The only way to find out is locate the business in the FCC's database, assuming it exists, and if so is their license still active.
- WRNU354 and SteveShannon
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6 hours ago, tcp2525 said:
Copper is so old school and outdated, especially on UHF. We now use platinum plated titanium rod.
The resistivity of platinum is far worse than copper. At UHF frequencies the skin depth of the RF is so shallow the underlying material doesn’t really affect things.
https://www.thoughtco.com/table-of-electrical-resistivity-conductivity-608499
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I'm guessing before the rule changes GMRS licenses could be assigned to businesses. That would have been the attraction for the dual 90/95 certification. Now with the new rules it's only for individual users, unless the business has a grandfathered license they kept current.
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9 hours ago, wayoverthere said:
The Part 95 certification combined with having the range to fully cover 70cm (as I had my eye toward my ham license at the time) was one of the big factors in choosing it
And found the ID, it's K6610354640
It's not fully side by side, but there's a thread on reddit where a user tested power outputs of a few popular MARS-modded ham handhelds on GMRS; the FT5D was one that was noticeably down on power on GMRS.
Thanks for the link. That's the very first radio I've seen that covers the full Ham band, 400-470 MHz split, with a Part 95 certification. Now that's way cool.
I have a collection of various Kenwood HT's, with the same split, but NONE have Part 95. The exact same model with the typical commercial frequency split, 450-490/520 MHz, do have it. I had always assumed if the radio covered 400-470 the FCC would not grant Part 95 certification. I guess my assumption was wrong.
Yeah the MARS/CAP mod at times isn't all that great if you can't get crap for power out. I ran across some power tests done on a Icom IC-706MKIIG with similar results, sort of sucked on GMRS.
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3 minutes ago, WRYZ926 said:
You can find adult trikes for as low as $220 on Walmart's website.
https://www.walmart.com/browse/sports-outdoors/adult-tricycles/4125_1081404_1230089_7538787
And it looks like you can get them on Amazon starting at $146 and up.
I want to check on that. I had a total knee joint replacement done a year ago last August. Wore out the joint, it messed up when I was on the leg press machine doing my usual full weight stack setting, meniscus was half gone per the doctor when I finally went in. I get around OK now and do about 30 minutes on the exercise bike 3 times a week, and weight lifting.
The trike might be a good option in case the knee gets a bit stiff and less likely to take a spill.
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"Let's have a moment of silence for all those Americans who are stuck in traffic on their way to the gym to ride the stationary bicycles."
Funny as heck to see people try to park as close to the gym entrance as possible to avoid walking more than necessary to get in. Then get inside and run for an hour on the treadmill like a hamster in a wheel for an hour. Never could figure that out.
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8 hours ago, TrikeRadio said:
I 3d printed a custom designed holder for my TD-H3 that I zip tied and fastened to my handlebar. I use a shoulder mic with it and a 771 antenna.
It works well, and I use it to communicate with others in our cycling group (usually 8 - 14 riders) to give turn instructions, check on safety and if everyone made the right turns or got through the last traffic light.
How much did the trike cost you? Looks much more comfortable to ride than a standard 2 wheeler. More room to mount stuff too.
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5 hours ago, wayoverthere said:
I'll have to find the FCC ID for it, but IIRC the Vertex Standard VX-4207 carried both 90 and 95 certification for both the 400-470 (g6) and 450-512 (g7) versions.
No luck with searches, so I'll have to find the ID for my g6 (aka dig one of them out). The g7 is FCC id K6610354740
If the G6, 400-470 split, has Part 95, it will be the first one I’ve seen.
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13 hours ago, WSFZ339 said:
From what I understand if you do the MARS mod you can get the GMRS channels. Anyone tried this?
You can, BUT Ham band specific radios MAY experience a significant power output and receive sensitivity loss outside of the official Ham bands. That's due to the internal band pass filters.
For example my old original Yeasu FT-817 QRP rig is modified. It's a nominal 5 watt radio on the Ham VHF/UHF bands. I'm lucky to get maybe a watt or so out of it on the 467 MHz GMRS repeater input frequencies. Hardly worth the trouble. I'm way better off using one of my 4/5 watt commercial HT's designed for either 400-470 or 450-490/520 MHz band split operation. With the 400-470 MHz band split I can at least use it on the full Ham 70cm band and GMRS.
Some of the older commercial grade radios are certified for Part 95, the 450-490/520 MHz band split, so they are legal to use with proper programming. I'm not familiar with the commercial grade base/mobile radios, I use mostly HT's.
https://forums.mygmrs.com/gallery/image/468-tk-370gjpg/?context=new
https://forums.mygmrs.com/gallery/image/263-tk-3170jpg/?context=new
https://forums.mygmrs.com/gallery/image/254-tk-5320-1jpg/?context=new
The commercial grade radios with the 400-470 MHz band split are not Part 95 certified from my experience, just Part 90, at least I've never seen one that was.
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2 hours ago, WRYZ926 said:
know that you definitely get a "DUI" on a bicycle and even on a horse in Missouri. T
Many Many years ago I had a buddy who got a speeding ticket on his 15 speed bike for exceeding 25 MPH on a residential street. Yeah, it really happened.
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3 hours ago, BoxCar said:
If I remember correctly, most states have laws against having both ears covered while operating a vehicle. That would depend on an officer classifying a bicycle as a vehicle which, technically, it is.
When I ran my IC-706MKIIG in a van I used a single sided head set with a boom mic for the exact above reason. The radio was setup for VOX for "Hands Free" operation.
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15 hours ago, WSFL951 said:
I wasn’t aware that you could do that. I believe it’s prohibited.
Yes you can.
Go to the FCC Manager Help page and scroll down a bit to the "Contact Information" section:
https://wireless2.fcc.gov/helpfiles/licensemanager/commonQuestions.html
Vehicle Antenna Placement??
in Technical Discussion
Posted
This guy has a few more.