maddogrecurve

Lets not give it too much credit. The VX-231 with it's stock UHF antenna was also making the trip to the repeater but just not as well. Here is an image showing the terrain. You can see how it is clearly not line of sight but the tall steep walls of the ridge lines clearly have something to do with the reception. The j-pole is good for cleaning up a weak signal at the edge of reception and or getting you out and over heavy vegetation on forest floors. I even tried it much further back with just the stock antenna and was able to kurchunk the repeater but the signal was too weak to make out anything. 1st image the the distance to the repeater from the camp. The 2nd image is an approximation of the path we took and where I was able to kurchunk the repeater from. Just prior to fording the river I was able to radio back and speak with someone.

Not terribly, but it's there. For me, it's the one place we use kind of like the lounge where the ragchew drifts from the normal weather/medical ailments without someone getting bent out of shape.

I have a question about reception with a mobile radio when driving.
Is it normal for a signal (when listening to traffic) to fluctuate when driving and not when stopped or parked?
I have a mag mounted antenna and a Radioddity DB25-G GMRS connected to a cig lighter. The recieve signal can go from 60-80 and all in between, is this expected when moving in a car, specific in a medium sized city with may trees and buildings.

This one is strange. 
After my Midland 275 install I tested all the channels (scan) and had no issues, drove around the block to test it. I took a road trip and after being on the freeway a few min (10 maybe) I got interference on 19. Scan would pick it up and just stay. Very annoying. Got worse to 18-20 all stuck. Tried turning up sq to max hoping it would skip it, no joy.
I moved the head a foot just to see if that helped, nada. 
After my trip took my handheld 905 with me, retested. Driving around w a cold truck no interference on the 905 or the 275. But once the truck is warmed up 10 min or so it comes back in on the 275.
I tried turning off/on AC, turning off the hvac, turning up down the hvac fan, turning off/on car play, turning off the stereo head all together. Nada. 
I'm taking a wild guess I have some power or ground interference that is popping up once the car is warmed up/the alternator is not charging from start up. 
I grounded the head on a factory ground in the cab, took power off the factory supplied ign hot lead (part of the auxiliary switch group). Rig is a 2021 Jeep Gladiator JT. I really like coming off the ign hot, but think I need to run a dedicated hot and ground. 
Thoughts? 

So first where is your antenna for the 275 ? I run the midland in both my JT and JK and have no issues. Do you have after market LED lights (headlights) by chance. on my JK ii bought ebay LED lights and it killed the 2 mtr band completely. 
 

Have never used one of these antennas, but came in to see what others had experienced. WRFP399's comment may make me buy a couple for hiking and camping use. Like that they are lightweight but can get out a bit. Have strewn wire into and between trees many times though.

I have two. Both are N9TAX. One I modified by removing the RG58 and replacing it with RG400. It it attached to my repeater (RT97). The antenna has been in a tree for about 2 years now. It does what I need. Once I get the repeater to a more permanent position I will switch out to a more traditional antenna. 
The second is again an N9TAX SlimJim tuned for GMRS. 16 feet of RG58. I use it when backpacking once we set up camp. It definitely helps extend the range. This summer I used it to get back into my GMRS repeater which was behind some heavy obstructions (think mountain). Its hard to see, but in the photo its in the tree to the right of the tent. The antenna itself is up near the top third of the photo. It was attached to a 5 watt Vertex VX-231. There was no cell service back here. This was our only means of reaching back. The repeater was about 15 miles away behind the mountain on the right side of the 2nd photo. I am sure being in the valley helped "tunnel" the signal through and/or we got some refraction over the top edges.

 

I have used the EdFong version for 2m/70cm ham, and 220 ham. They work pretty well if constructed correctly. My dualband is currently a scanner antenna, the 220 is going back up this weekend.

I own and have used both the GMRS and dual-band amateur versions. Both get used periodically and they will remain part of my radio tool kit. Although I have shack with external base antennae antenna at my home, the Ed-Fongs hang from plant hanger hooks near windows in other rooms. They provide better communications when using HTs in those spaces. I also grab them and put them into my radio bag when traveling.


Michael
WRHS965
KE8PLM

I have the N9TAX dual band slim jim antenna for 2m/70cm, and I've been using it for several years. I hung it from a ceiling hook in the corner of the room, and I've just left it there since. I really don't think about it much. It just works when I need it to. I've used it with several mobile and hand-held radios, and any issues I've had have always been radio related, not antenna related.

I use this antenna up in my attic. Much better than trying to use radios inside in the house. I'm going to get a 2m (amateur) version. I want to sell it, if you're interested.

For about nine months I used two different Ed-Fong roll-up J-Pole antennas for GMRS and amateur radio services in my home. I operated them at 5W using an HT. They can be used at higher power if you wish, but you should operate further away from them if doing so as @IanM pointed out. In my case, I hung them from existing ceiling plant hangers and curtain rods near the windows in a couple of rooms. Although I have external antennas feeding radios in my shack, those Ed-Fong antennas remain hanging in those rooms for ready and easy connection to my HTs when I want to use them. They are easy to take down, roll-up, pack and take camping as well.

Good luck on your endeavor.


Michael
WRHS965
KE8PLM

That all depends. I have a Ham buddy who built a special event repeater, for local marathons and bike runs, really cheap with some used radios and a good power amp. The way it was done is using cross-band repeating so the expensive cavity filters get ditched. Most Ham HT’s can be programmed to do split band operation. You RX on one frequency on one band, say VHF, and TX on another, UHF, when you press the PTT button. For Ham radio this usually ends up being the 2 meter and 70 cm bands. On the repeater side a simple diplexer is enough to work the VHF and UHF radios into and can be had for $50 to $75 new.
 
Then he takes advantage of the local high rise buildings. Through his contacts he has access to the roof tops. No need for an expensive tower and feed line. When you’re on top of a 10 to 15+ story building you get some decent coverage. Since the repeater can be located close to the temporary antenna you don’t need expensive feed line. And what you do use is fairly short thus keeping the losses down and thus the TX’er power required.
 
Granted his conditions are not the general case but if one looks around and takes advantage of the local resources you can save a huge amount of money and effort. 
 
However if one wants to build an in-band repeater, then yes it gets more complicated and likely expensive as you pointed out.

I just made a dual band antenna out of two coat hangers  Ended up scrapping it due to over-trimming the 150mhz band portion.   I the video I saw had the coax connected directly to the coat hangers via the terminal strip, but when I remake mine I am going to use jumpers and connect an SMA male connector onto it for my SMA female coax connector.
 
Anyhow, I just welded the stinger onto another groundplane antenna using brass rod that I bought to make tumbler pins for locks.  They are 12 inches long and I am going to install them full length, and run my analyzer on it and see where it resonates and trim it from there.  Just curious..
 
I do not know how well brass will work, but I have plenty of brass, so/239's, and coat hangers, so I can play..
 
WRMQ982

I just made this one!  GMRS resonant!  ugly, unlike yours, but it works!!!

I just made this one!  GMRS resonant!  ugly, unlike yours, but it works!!!

I built almost exactly the same thing using some old PCB type BNC connectors. All the wires were soldered on, no screws. Surprising how well a 1/4 works, and the bandwidth I got was from 430 MHz to 470 MHz at the 2:1 SWR points.

I think every ham should at least try building a 1/4λ ground plane like this and cut some dipoles.  GMRS users are obviously not in the hobby to experiment but I think being able to use stand alone antennas there seems value in understanding how they work and see first hand what impacts performance and issues.

Awesome!  I plan on making some J-Poles for portable use (like to rest on a tripod), and some copper pipe dipoles as well.
 

The antenna is almost always not supposed to use the coax shield, that would not make it not a shield anymore.  You go to great lengths to prevent this in fact with chokes.  Coax as feedline should not be radiating and the length should have no significant effect on SWR.
There are intentional exceptions to this, such as using coax stubs as impedance matching and there are designed coax antennas.
Usually when this will happens it's due to an issue such as the mount location not providing a sufficient ground plane (counterpoise).  The RF wants to complete the circuit and will find whatever return it can back to the radio.  This would be my guess as to your issue.  The mount isn't well grounded to the vehicle or you're using an antenna that needs a plane and you don't have one. 
You might make it work but it's not optimal.  For one the coax shield radiating will create local EMI.  This causes anything from irritating noise to potentially problems.  You might just get buzzing on your mic or you might reset your computers.  On the flip side if the shield is part of the antenna you open yourself to conducting radiation from the environment, you'll get bad alternator noise or cross talk from other radios or your cell phone. 
Shields work both way, to keep transmitted energy contained within the coax and to keep external noise out.  So in a vehicle having coax radiating is almost always bad.
BTW, regards to soldering PL259, it's kind of an art because heat will definitely melt the dielectric so it's about speed.  You want a good soldering iron with lots of mass.  You want the heat put into the outer shell fast, get the braid soldered in a second or two and get out.  If you have to sit there and hold your iron for tens of seconds then you're probably ruining the dielectric.  I have an old 100 watt leaded glass soldering iron I use for this although honestly I prefer crimp connectors much more.  In the case of PL259, though, I use solder center, crimp outer types.  I find the crimp/crimp have too long of a nose to always fit SO239s.  But any other type - BNC, N, SMA - I always crimp.

Yes, for the education and fun of it. I have made a few different 1/4 wave ground planes that I can use in a pinch on different services. But I am using commercially made antennas on the home and vehicle.


Michael
WRHS965
KE8PLM

Greetings!!!
 
Anyone make their own antennas for the field or for home?  I cut an old homemade dipole down to 470mhz and am using it as a scanner/gmrs antenna in my shop (stapled to the outside of my shop) right now but am gathering materials to make a copper pipe/pvc vertical dipole that I can raise over my roof.
 
WRMQ982

The factory most likely tests their antennas with a laboratory grade VNA.

Here is a photo I just took using a calibrated NanoVNA to check one of my 144-520MHz HT antennas. Not bad at all.

I can tell you that the results changed, but insignificantly, between holding the VNA vertical, horizontal, standing it on a table, laying it flat on a wooden table, laying it flat on wooden table with the antenna overhanging the edge of the table, and when touching and not touching the chassis ground of the VNA.

When comparing HT antenna performance, the best comparison of antennas is not going to be it’s SWR, but relative difference in signal strength at some given far field distance using some given amount of input power.


Michael
WRHS965
KE8PLM

Very true!  They also set up hospitals with radios and antennas, I saw 10 antennas on a hospital and wondered why it had all of those antennas.  I googled it and found out that Hams work with public health and safety to get them set up with coms on many bands in case of disasters.  I do not know how many people need to be licensed at the hospital, but I am sure that there is at least a few.
Hams are my hero, and soon I will be one of them LOL!!

Very true!  They also set up hospitals with radios and antennas, I saw 10 antennas on a hospital and wondered why it had all of those antennas.  I googled it and found out that Hams work with public health and safety to get them set up with coms on many bands in case of disasters.  I do not know how many people need to be licensed at the hospital, but I am sure that there is at least a few.
Hams are my hero, and soon I will be one of them LOL!!