Lscott

They are going to be close to the antenna and in what is known as the "near field" so it couples into the driven element. That can booger up the impedance match, SWR issues, and the radiation pattern. It's not a guarantee you'll have problems but keeping the antenna away from from structures like that will at least avoid the potential for them. You read through the past comments over time here and you'll see this mentioned from various people.

If you don't have a GOOD ground plane for a 5/8 wave antenna, they really need it, don't waste your money on one. If it's a true 1/2 wave they don't need a ground plane so you can mount them just about anywhere so long as you keep it away from nearby vertical metal supports, like roof pillars.

The aluminum foil won't hurt the magnet at all. Don't worry about it. Sticking something magnetic on the back side of the foil the magnet can be attracted to is a good idea to hold the foil in place. The foil needs to be a rough square at lest 6 inches on a side or a circle about 12 inches in diameter. Put the magnet mount in the center.

I can verify that. https://forums.mygmrs.com/gallery/image/427-adapters-connectorsjpeg/?context=new

Good. I know a few who don't, and they are Extra's too. Sad.

Good points. Most Hams are "appliance operators" these days. Still the value is learning the rules. At least memorizing them is about all you can do so that part isn't any different. As for the rest, well, I guess experience is the real teacher. Maybe then the rest of it might start to make some sense.

You can ask questions with an in-person class. Can't do that with a YouTube video and get instant feedback.

You sure it wasn't due to a temporary "climate change"?

You need a few more zip-ties on the cable. I imagine that's to try and take the weight off the cable connector at the base of the antenna.

My experience with a similar type I picked up cheap at a Ham swap. On the Ham 70cm band it wasn't too bad. On VHF it was VERY narrow banded to the point of being mostly useless. The SWR on GMRS put it out of the running. Oh well I got a decent magnet mount out of the deal.

I think today will be one where Ham, GMRS and CB radio is going to get a bit of a workout. People driving around trying to beat out the traffic to find a good location to view the eclipse. With the weather forecast being crummy in some areas getting up to date viewing conditions is going to cause a lot of last minute scrambling to get to a better site.

It's not really a switch, but a coax relay. Plus it uses a 28VDC coil voltage. Not something easily available in a motor vehicle. I have a couple of coax relays but they use SMA connectors. Picked these up a long time ago for a project, but never got used.

That's mostly true. An effective antenna needs to be at least a 1/4 wavelength long so on 6M that would be around 57 inches long at mid band. The short helical antennas used on the radios are so inefficient that most of your power is wasted. It's the same story with those old "full power" 11M CB radio HT's. The range on them was poor. The only thing that comes close to a useful 1/4 wave antenna on an HT is on the UHF band, Ham 70cm or GMRS. On those bands a 1/4 wave antenna is only about 6 inches long, about what the usual HT antenna size is on an UHF HT. The antennas for 2M and 1.25M on an HT are also inefficient, but nowhere as bad as 6M. One other point. The 6M band usually doesn't see much activity unless there is a band opening. And when it does it's typically on sideband where you'll find most of the people. Some people claim that propagation on 1.25M is better than on 2M. I'm guessing it's due to a sort of a compromise between 2M VHF and 70CM UHF. Activity on the band ranges from nil to active depending on location. Not many people have equipment for 1.25M as it is. If you're into Ham digital voice modes there are currently only three radios I know of that can do a digital voice mode on 2M, 1.25M and 70cm bands. Two are Kenwood, TH-D74A and the TH-D75A, which only does D-Star. The other is the Anytone D578 series, which does DMR.

Here are a few more models. These antennas are a bit less common. The worse one to build and model was the 11 turn helix. I was looking at that for a satellite UHF down link. In the end I went with an 11 element Yagi from M2 Antennas. It was smaller, far easier to aim and the gain was about the same. The only thing lost was the circular polarization. https://antenna-theory.com/antennas/travelling/helix.php https://www.m2inc.com/categories/commercial/antennas/helical.html The rest are a bit more common. Corner Reflector: https://www.arrowantennas.com/solid/cr4501.html Eggbeater: http://146970.com/PDFs/Antenna Eggbeater-Revisited-English.pdf Turnstile: http://www.on5au.be/Cebik-2/SomeNotesOnTurnstileAntennaProperties.pdf https://www.qsl.net/g4hbt/dipole.htm The Turnstile model doesn't use the "typical" dipole phasing cable setup. Turnstile.EZ Eggebeater Rev 8C.EZ 90 deg 70cm Corner Reflector Rev 2.EZ 11 Turn Helix.EZ

If anyone is interested in messing around with antenna simulations the software is now freely available. https://www.eznec.com/ I've attached some models I've played around with in the past. Magnet Mount - Rev 2.EZ Magnet Mount Ham and MURS.EZ Ham and GMRS Magnet Mount.EZ GMRS J-Pole Rev 3.EZ GMRS 11 Element Yagi Rev 2.EZ FRS-GMRS Gnd Plane With Radials.EZ 4 Bay Anetnna MURS.EZ

OK. I simulated a simple magnet mount 1/4 wave MURS antenna. The frequency was selected to be about in the middle of the band. The results looks good. The match and radiation pattern look like what I would expect. The exact same antenna was then run at a frequency about in the middle of the GMRS band, between the simplex and repeater input frequencies. As you can see the match short of looks OK on GMRS, however most of the RF power shoots up at a very high angle uselessly into space. I guess if GMRS has satellites in low earth orbit it might be a good antenna. For normal ground work most of the power is wasted. This is what I was getting at in my prior post comments.

For "under the hood" and exposure to weather that's a good idea. On the inside of the passenger cabin, a home setting or a sealed enclosure the power poles are a good idea.

If you look at the photo and the specifications at the link the insertion loss is about 0.1db up to 500MHz for the example switch. That's only about 2.3 percent power loss, basically nothing to worry about. https://diamondantenna.net/cx310a.html

Anderson Power Poles are commonly used. I have just about everything I use outfitted with them. There is sort of a semi official configuration for them. Anderson Powerpoles - Standard for ARES and RACES.pdf ARES - RACES Standard 12 VDC Power Connector.pdf INSERTION - EXTRACTION TOOL FOR PP15-45.pdf

If he does that it will may look OK from an SWR standpoint but the pattern will look bad with multiple lobes likely giving crummy coverage. I wouldn't recommend it other than as an experiment.

You want a coax switch. Be sure you get one that is rated up pass the highest frequency you intend to use. Since you're stuck using SO-239 sockets on it you have to be careful to get the right insulator and socket design type. Most SO-239 sockets for CB radio or HF work may use the crappy red or brown Bakelite insulating material around the center pin. DON'T use those!. These will cause SWR issues. The better choice is when the material is white. That would typically be Delron or Teflon. While better than the above I would only recommend it for VHF and below. The best is where the center pin is supported by what looks like a spoked wheel design around the center pin. That gives the interior of the socket mostly air and results in a socket impedance closer to 50 ohms, matching the radio and coax, which will mitigate SWR problems. https://forums.mygmrs.com/gallery/image/431-coax-switchjpg/

Rumor has it that Anytone is buying Motorola's land mobile radio division too.

And Midland filed for bankruptcy. Production and shipping of all models has been halted.

They are. It depends are what point of view you take. The minimum length for a radiating element used as an antenna is 1/2 wavelength. Obviously a 1/4 wave alone won't work. That's where the ground plane come into play. The easiest way to understand how it functions is place your finger at a right angle against a mirror. You see a reflection of your finger so it looks twice as long. The same thing happens with a ground plane. It "reflects" the 1/4wave element making it look like a 1/2 wavelength long. By bending the radials it changes the feed point impedance so it's closer to 50 ohms, a good match to the 50 ohm coax cable. A true 1/2 wavelength dipole antenna is closer to 70 to 75 ohms with the feed point at the center. That results in an SWR of about 1.5:1, which is perfectly acceptable by just about any radio out there. A 1/2 wavelength antenna is used where a ground plane, or room for radials at the base of a 1/4 wavelength antenna, is not possible. The draw back is the antenna is now twice as tall and the bandwidth is reduced since a special matching section is required at the base of the antenna. Also high gain antennas are multiple sections of 1/4 and 1/2 wave elements with a "phasing" section in between the sections. Those are the small bulges or tiny single loops you see spaced along the length. The down side to high gain antennas is the gain is HIGHLY concentrated in a direction perpendicular to the antenna. Works great for relatively flat open terrain. Not so good in hills or mountainous areas. People who like to hit the trails often carry two antennas. A high gain one, these antennas can be rather tall, used when on the highway and a low gain, usually a 1/4 wavelength, when hitting the trails. https://forums.mygmrs.com/gallery/image/259-ca-2x4mb-jeepjpg/?context=new https://forums.mygmrs.com/gallery/image/268-ca-2x4sr/?context=new https://forums.mygmrs.com/gallery/image/338-cheap-14-wave-gmrs-antenna/?context=new