-
Posts
3529 -
Joined
-
Last visited
-
Days Won
104
Lscott last won the day on June 3
Lscott had the most liked content!
Profile Information
-
Unit Number
0
-
Interests
Design high power AC high frequency inverters for induction heating of metal parts. Have degrees in Electrical Engineering, Math with Computer Science.
Recent Profile Visitors
Lscott's Achievements
-
TrikeRadio reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
WRYZ926 reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
GrouserPad reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
It's all the wicked Wick's fault.
-
I have a few Motorola radios. The XPR6550 is a good choice. You can buy them for reasonable prices. They also use a standard SMA type antenna connector. The XPR7550 is a better radio, but they are expensive used and have a funky stud type antenna port. So, if you need to use an external antenna you want the XPR6550.
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
I paid close to $100 for mine at the Hamvention. Who knows, might have been due to the tariff crap then. R and L Electronics, which seemed to have the best price, was out of stock when I looked a while back. Plus they didn't have a booth at the Hamvention, which I though was sort of strange since they are one of the better known Ham gear vendors. This is a link to a photo I just added to my album with the testing results and a photo of the antenna in it's protective sleeve. Note the antenna is clearly marked as a NR240CA. I've seen the NR240C being sold. Not sure if they are the same or not. https://forums.mygmrs.com/gallery/image/613-nr240ca-roof-rack-mount-swr-and-photojpg/?context=new -
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
-
WRYZ926 reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
The antenna is a 5/8 wave design, and really does need some kind of ground plane to work. For whatever reason it seems to work rather well on my roof rack mount. I suspect there is some coupling, capacitive, through the mounting strap to the rail plus the metal roof on the vehical. A close up photo of what the mount looks like with an antenna installed on it. Note I use the UHF type mounts whereas most people like the NMO type. You can clearly see the electrical tape on the base of my old antenna since the fold over spring is worn out. I've been driving around like this for years. The mount is on the driver's side so I can reach it and unscrew the antenna when necessary. https://forums.mygmrs.com/gallery/image/473-close-up-of-mobile-mount/?context=new -
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
https://www2.randl.com/index.php?main_page=product_info&cPath=2_1240&products_id=76310 I got mine at the Hamvention last May from a vendor. I forget who it was, but the source in the above link has them. -
SteveShannon reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
The Diamond antenna is a bit different. There is a locking collar you have to unscrew to lift up the antenna to fold over. No spring to wear out like on the Comet design. Another reason to go with the Diamond antenna for those interested in it. -
SteveShannon reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
WRYZ926 reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
Good idea for anybody who is going to routinely use this antenna mounted up high. I picked one up at the Hamvention last May for mine for future use. I would install it if I planed on using the antenna at some point. Right now I have my old CA-2x4MB on the ride. That monster is about 60 inches tall. https://forums.mygmrs.com/gallery/image/471-mobile-mount-with-antenna-rear-view/?context=new The match on it is something else. This was done when I had it on my old Jeep. It looked better than the newer CA-2x4SR. The one on the ride the fold over string is shot, that's the black electrical tape you see, the antenna is at least 20 years old. I do have a new one still in the green plastic sleeve, never been outside of the house. I purchased both at the same time. https://forums.mygmrs.com/gallery/image/223-ca-2x4mb-jeep/?context=new https://forums.mygmrs.com/gallery/image/282-ca-2x4mb-scansjpg/?context=new I've been looking around for a possible replacement for it. After testing the CA-2x4SR and N240CA, on my roof rack mount, either one might be a good replacement, and they are only 40 inches tall. I might go for the NR240CA, yeah it's more expensive, but the SWR match looks a bit better over the ranges I'm interested in. One thing people don't talk about here, or elsewhere for that matter, what the match looks like in crummy weather, like moderate to heavy rain or fog. It's going to get worse to some degree. If you start out with a really low SWR it likely won't deteriorate nearly as bad in less than ideal weather. Modern radios are designed to tolerate SWR's up to 2:1 at full power. After that the radios, with SWR protection circuits, will start to fold back power to protect the output power stage. -
Lscott reacted to a post in a topic: What did I do wrong?
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
I picked up a no-name one at a local swap a long while back just for fun, it was really cheap. Tested it and I wasn't impressed with this sample. Likely better ones out there. https://forums.mygmrs.com/gallery/image/428-stealth-dual-band-with-swr-scanjpg/?context=new -
koni13 reacted to a post in a topic: What's missing from myGMRS.com?
-
WRYZ926 reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
SteveShannon reacted to an answer to a question: New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
Yup. The price is very reasonable too. -
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
Well I got around to doing an SWR scan of both the Comet CA-2x4SR and the Diamond NR240CA wide-band antennas the past few days. Both were tested on the UHF type roof rack mount I have on my Mazda. Both antennas are 5/8 wave design, thus they need a decent ground plane to work. I expected crummy results. However I'm absolutely shocked how well they matched up on the VHF and UHF bands!!! I guess there is enough "ground plane" under the mount, plus whatever capacitive coupling between the mounting strap and roof rack rail for a better coupling to the rack rail. The installation looks like this photo, but I have a different antenna on the mount at the time. https://forums.mygmrs.com/gallery/image/471-mobile-mount-with-antenna-rear-view/?context=new The attached photos show the match on the VHF and UHF bands. The results are very similar. Not uprising since both designs look about the same except the center loading coil. subjectively I think the Diamond antenna match is a bit better. -
My personal preference is to use the official factory software where possible. That's really important for commercial radios. CHIRP is nice, but for every radio it supports the developers have to reverse engineer the code plug layout and communications protocol with the radio. When it works, great. The one issue with Chirp is it may not always give you access to all of the radio's features. For that the only choice is the factory software.
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
You can always change it later. Once you drill a hole, well that's not going away if you change your mind. I had a buddy who messed up his measurement when he drilled a hole for his NMO mount in the roof of his old van. It got into one of the support beams on the underside. He ended up putting a plug in the hole he couldn't use and drilled a new hole over a bit. We kidded him for a while asking to see the Band-Aid on his Boo-Boo. Oh, if you do end up at some point drilling a hole. Be absolutely sure you use the right hole saw. The wrong one will really mess up the roof. -
Lscott reacted to a post in a topic: Long, Long Ago
-
Kraco CB's were the equivalent of GMRS CCR's today. They were the cheapest POS radio's you could buy.
-
New to GMRS Loving It So Far, Looking for Advice on Mobile Setup
Lscott replied to WSIK420's question in Technical Discussion
Looks like you've done a fair job of researching your options. Lets start with the antenna system. First off I wouldn't worry too much about a few extra feed of coax cable. Likely the mount you will use has RG-58 type cable. A few may use the thinner RG-316, noticeably higher loss, but easier to route through small holes and other tight spaces. With RG-58 the difference between 13 feet verses the typical 17 foot long ones isn't worth worrying about. More on that later. The antenna is where you shouldn't compromise. The same goes for the location on the vehical. Your usage case may justify two antennas. You would use a cheap quarter wave, about 6 to 7 inches tall, for local communications and repeater access. Then a much taller higher gain one for out on the highway traveling. Both would be better off mounted in the clear on the roof. The quarter wave is so short you could almost forget it's there, even when parking in a garage. While swapping antennas is a bit of a pain some of the folks here do it depending on where they are going to spend most of their time. Oh, the quarter wave is likely the best option when traveling in mountainous or hilly terrain. The radiation pattern gives much better coverage when two or more stations are at significantly different altitudes. About an extra connector or two and comments about extra losses. I see people frequently get two things mixed up in that area, SWR matching and power loss. Good quality connectors have very low losses when used within their design frequency range, about 0.1 to 0.2 db. The real issue is the typical SO239/PL-259 "UHF" connectors are NOT really recommended for use above about 200 to 300 MHz, but you see them all the time used on UHF, on the back of radios and on the ends of the coax from antenna mounts. The problem with those is the "impedance" doesn't match the coax impedance of 50 ohms. This results in a higher SWR. The more of these you have the worse the match gets. Myself I try to stick with "N", BNC or RG-8x mini type connectors. Those are all 50 ohm types, and have very low power loss. If you want to go down the rabbit hole with the antenna system design evaluation I did one for my current ride as an example. Most people don't do this, and likely wouldn't need to anyway. I did it just out of curiosity. https://forums.mygmrs.com/gallery/image/483-cx-5-antenna-system-analysisjpg/?context=new For antenna choices the CA-2x4SR from Comet gets mentioned frequently. It's a good high gain wide-band antenna. If you ever plan on getting your Ham license it's usable on the VHF and UHF Ham bands as is. The price is very reasonable. https://forums.mygmrs.com/topic/7914-how-is-the-comet-ca-2x4sr-antenna/ There is a very similar antenna now available from Diamond, of course more expensive. Be careful, I see two slightly different model numbers. I believe the one you want is the NR240CA. I see the NR240C sold too, which I think is tuned a bit different. I asked Diamond about this and never got a reply. The spec's for the NR240CA seem to show a slightly wider bandwidth than the CA-2x4SR. Now lets talk about radios. As mentioned a 25 watt radio would be good for most every day usage. A higher power radio would be a good idea if you had to communicate through heavy foliage, trail riding on your 4-wheeler for example. A lot of good recommendations for radios here by other members. Personally I stick with commercial grade radios. A number of the cheaper consumer grade types, including some modified Ham gear, I've played with suffered from poor sensitivity, and worse, poor selectivity and de-sense issues in moderate to high RF environments. The commercial grade radios tolerate the later two much better. I have a large collection of mainly commercial grade hand held radios if you have any questions on these I would be happy to answer them. https://forums.mygmrs.com/gallery/image/249-my-radio-collection/?context=new This is typical of some of the Kenwood mobile radios. https://forums.mygmrs.com/gallery/image/250-nx-820ghjpg/?context=new CA-2x4SR.pdf NR240CA.pdf