maddogrecurve
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Posts posted by maddogrecurve
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On 7/28/2021 at 8:04 PM, WRNA236 said:
It doesn't get much more reasonably priced than a panel mount SO239 and some old copper wire.
Not withstanding the "this isn't ham radio" aspect in a couple of ham radio classes I've taught we built these 5/8λ mobile antennas in a morning as a group. The attendees got a kick out it and most of them ended up being put into actual service on trucks, this being members of my 4WD club, with good results. They aren't quite Larsen or Laird commercial but they're not bad and there's pride in being able to say "I built that" kicking tires around a campfire.
http://www.arrl.org/files/file/Technology/tis/info/pdf/8009022.pdf
Although for a home installation a J-pole makes more sense IMO. If you can find - and afford - enough copper pipe anyway.
I just made this one! GMRS resonant! ugly, unlike yours, but it works!!!
- WRNA236 and AdmiralCochrane
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LScott,
That is cool that you did this type of antenna with BNC connectors! I would have never thought of using anything other than SO-239.
I am not an Amateur operator, I have always been interested in it, and have been into C.B off and on for 34 years and antennas have always fascinated me. I am finally getting serious about getting my Tech license and after that may progress through the ranks, we shall see.
I have been listening to a couple of "nets", one at night and one in the morning and I love how disciplined they are ran and how polite everyone is! So much better than C.B.
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On 7/25/2021 at 7:51 AM, Lscott said:
For some people it isn’t about the cost. It’s the satisfaction of building something yourself and the knowledge gained doing it.
I’ve picked up cheap magnet mounts at swaps along with some generic whip elements that screw in to them. I wanted a cheap and quick 1/4 wave antenna for the Ham 1.25M band. Didn’t take much to trim one down using the antenna analyzer.
Also doing some simulations it looks like a 1/4 wave could be made to cover the Ham 2M band and the MURS channels.
The same with the Ham 70cm band and GMRS. The later I built using a cheap BNC circuit board socket and stiff bus wire. I can cover the frequency range of 430 MHz to 470 MHz with under a 2:1 SWR with a nearly 1:1 match at 450 MHz. I have one I use at the office on the top of a bookcase. Another one I used tie-wraped on the top of an old baseball type hat at the Dayton Hamvention a few years ago. Worked much better than the rubber duck antenna with the radio hanging on the waist.
Sure I could have purchased them, but where’s the fun in that?
Exactly!!!! That is where I am at! I have no one to talk to and am studying to get my Ham license so why not play with antennas! I love creating things and experimenting with design (also design and print 3D objects). I have a magnet mount antenna for my car and a fender mount as well, but nothing for my home yet, that is why I am playing with building them. My girlfriend probably would not let me hang a big antenna on the house so I have to be discreet.
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On 7/24/2021 at 6:15 PM, Lscott said:
If you like to experiment and design antennas some good simulation software helps.
I’ve used various versions of EZNEC+ up to V6 for a number of years. The software will be free starting in 2022. The guy who wrote it explains why, he’s turning 76 and wants to retire and doesn’t want to deal with it anymore.
Wow! That software looks way over my head! I am studying for my Ham license, but am not that far along LOL. I will look into it though, I think it is good to understand radiation patterns and all of that good stuff.
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On 7/24/2021 at 2:16 PM, AdmiralCochrane said:
Great success making VHF, UHF & GMRS J Poles and Slim JIM's. Not hard to do at all.
Awesome! I plan on making some J-Poles for portable use (like to rest on a tripod), and some copper pipe dipoles as well.
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On 7/24/2021 at 2:51 PM, mbrun said:
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
KE8PLMVery nice! I think it is more fun than talking on the radios! If I could find a job in an antenna factory I would be in Heaven!
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On 2/13/2021 at 5:41 PM, trickpony said:
I have a small problem, I live in the middle of nowhere. The animas valley to be exact in a place called windmill. I have a Midland mxt115 with a 3db stubby antenna in my truck the problem is if I want to talk outside of the area I have to hope the weather is right in order to reach the repeater which is line of site 43 miles I know this is right because I have connected to the repeater "jack's peak" and talk to tucson and Abq. I want to set up a base station and be able to connect to the repeater to talk to other people without having to rely so much and the right weather conditions any Ideas as to the type of antenna i should get. and maybe a good suggestion on a radio. any help would be appreciated.
thanks
Rick
WRKB393
Make yourself a dipole! Two wires some solder and a SO239 connector! Or you can use aluminum tubing or copper tubing as well. I am going to make one out of tubing because I have no trees to string wires up in. I have a small dipole stapled to the outside of my shop currently being used as a scanner antenna that resonates really well on the 470mhz band, though no repeaters in my area, maybe 70 miles or so is the nearest.
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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
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On 4/4/2021 at 2:04 PM, gothmog05 said:
New to GMRS and have a SWR question. I instaled a wouxun kg-1000g in my truck. I have been slowly checking everything along the way to make sure everything still works. I am using a midland mag mount with a midland 6 db antenna. With everything installed i was getting a 1.6 swr using a surecom sw-33 meter. The stock cable length was way to long so i cut about 15ft off leaving 3ft. After this i rechecked the swr and was getting 2.8 to 3.0 swr. So my question is am i needing to tune the antenna, or did i do a crappy job with my pl259 connector?
Thanks
Gothmog05,
We have to remember that the coax becomes part of the antenna! I do not understand it all really but the length of the coaxial cable does make a difference, but probably not as much as what you saw going on. I had a recent issue with SWR as well on a new antenna install, I put a new PL259 connector on my RG8 coax (I have put many connectors on) but the PL259 was not the right size for the RG8 so I had struggled to make a good solder joint on the center pin. I could not get the antenna tuned well at all and ended up cutting too much off of it for GMRS!
Long story short, I put a new connector on, and ended up trimming the antenna further down so that it resonates on Murs channels for that radio LOL>
Did your terminal fit the coax properly?
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21 hours ago, mbrun said:
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
KE8PLMMichael,
Very cool tool you have there! I have one in my Amazon shopping cart, just waiting to pull the trigger! Looks like you have the big one?
Anyhow, I do not have anyone to talk to, however I finally got the code to access a repeater so I have been testing my Nagoya magnet mount coming to and from work on the highway. So far 23 miles on this little antenna and to be honest that is amazing because the terrain is not easy to navigate! CB is blocked after about 10-15 even with my 102" whip and running my good radio. This area is in a gorge, high mountains and a windy highway, so the signal has to maneuver around the mountains to go anywhere.
I will try to test my rubber duckies in the morning, though i do not have much faith. For now I can reach the repeater from my office at work; I work in a food manufacturing plant and my office is upstairs, right in the middle of the building, I do have a window in my office, but not to the outside world, just to the open foyer area where the other windows are.
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On 7/20/2021 at 8:55 AM, axorlov said:
Yes, I said it before and will repeat again: testing SWR of HT antenna by simply plugging in SWR meter is meaningless.
How do the factories test them?
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On 7/20/2021 at 6:18 AM, Lscott said:
The main issue with testing HT antennas is duplicating the coupling between the radio and the users body. Yes, the users body is part of the antenna's ground plane, and it makes a huge difference.
I've done the experiments myself. Some of the antennas were screwed into a "SMA" magnet mount, yes they are around, then placed on a 30 to 40 inch square metal sheet for a ground plane.
On a few of the antennas tested the SWR was over 3 or 4 to 1. Removing the magnet mount from the metal sheet and placing it on the back of my hand reduced the SWR to under 2:1 in some cases.
The below links are what others have tried.
https://www.hamradio.me/antennas/ht-antenna-comparisons.html
https://reflector.sota.org.uk/t/antenna-testing-jig-swr/14791
https://www.ko4aje.com/ht_antenna_tests.html
I love that antenna test jig that the guy made! I have been thinking of something like that myself but wondered how I would make it simulate an HT. I guess that it would be difficult as the radios are designed to have us as the counterpoise. I suppose that we could touch the jig while we test the antennas maybe? When I have tested my antennas, I have laid them down onto plywood and tested them that way. Some have good results, some poor, the best SWR's are from the TwayRdio foldable 2M/70 CM antenna on GMRS and 2M/70CM. The stock antennas are horrid! But like it has been stated before, there is no real way to accurately duplicate what is going on with an HT antenna while it is hooked to a radio.
Thanks again for sharing the links.
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On 7/20/2021 at 6:18 AM, Lscott said:
The main issue with testing HT antennas is duplicating the coupling between the radio and the users body. Yes, the users body is part of the antenna's ground plane, and it makes a huge difference.
I've done the experiments myself. Some of the antennas were screwed into a "SMA" magnet mount, yes they are around, then placed on a 30 to 40 inch square metal sheet for a ground plane.
On a few of the antennas tested the SWR was over 3 or 4 to 1. Removing the magnet mount from the metal sheet and placing it on the back of my hand reduced the SWR to under 2:1 in some cases.
The below links are what others have tried.
https://www.hamradio.me/antennas/ht-antenna-comparisons.html
https://reflector.sota.org.uk/t/antenna-testing-jig-swr/14791
https://www.ko4aje.com/ht_antenna_tests.html
Thank you for your efforts! I wish that there was a tried and true method of testing HT antennae! I wonder how they test in the factory? I am going to purchase an analyzer and see how that works with the little buggers....
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On 7/3/2020 at 4:13 AM, berkinet said:
When discussing antennas commenters often refer to their antenna as "working great." However, while I am sure the observation is subjectively true, it is a whole different question as to how "great" the antenna is in objective terms. In other words. Unless you test the antennas in a well equipped and controlled environment it is virtually impossible to draw any concrete conclusions.
A big part of the difficulty in judging a UHF antenna's performance lies in the nature of how we observe them in use. It is pretty simple, do we get good connections to the stations we are communicating with? Given the nature of UHF, in most cases we are looking to contact stations relatively close to us and would probably succeed with a tuned coat-hanger. A secondary problem, especially for people coming from CB is that FM reception behaves quite differently than AM. AM tends to fade all the way to the point where the noise over-comes the signal. However, FM tends to go from intelligible to non-existent very quickly. Thus, if we receive the signal at all, it tends to be good enough for conversation.
There are also a host of other issues, like bandwidth and propagation pattern that may be important in some applications and irrelevant in others. And, finally, there are the mechanical factors ((like corrosion) that are usually only observed after a period of a few months or years.
All of which is to say, and this is strictly my own opinion: Unlike the ham low-bands where you can, and in some cased (low-power/QRP) must spend more on the antenna than the radio, for most GMRS uses, that is not the case. The perfect GMRS antenna is probably gong to be the lowest priced antenna that meets your basic communication needs* and is built by someone you trust to make quality products. Unfortunately, in GMRS there is no magic perfect antenna.
* terrain (elevation changes), distance, mobil, fixed or portable, power, etc.
Very wise words my friend! I love to test, test, test! I am having issues getting trustworthy HT antenna test results with an SWR meter however. I have to use a jumper between the antenna and the meter and from the HT to the meter which adds line length to the antenna, however I did hook up a super long foldable C.B HT antenna directly to the meter and tested it. Not sure how trustworthy the results were, but the SWR was at a 1.9 on 1 and 40, so I feel "Okay" about using it.
My little UHF/FHF antennas do not give me consistant results though. I have the two BF radios, one UV5R and one GMRS V1, and I purchased aftermarket "super long range" antennas for both of them prior to purchasing the radios.... Don't ask me why...
Now, where I live, I here FRS traffic all of the time, and I have no repeaters in my area, and only have made a few contacts. So I do not have a means to real world test these antennas. I did make a dipole for my shop "resonates on GMRS 467......" really well, but not well on FRS, and have two mobile antennas that I use. Still not enough traffic to even really test the bigger antennas.
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On 7/6/2021 at 5:21 PM, WRNA236 said:
Maybe I'm speaking out of turn but why duplicate efforts? Chattanooga and Tennessee generally have a pretty good amateur radio organization. Why not get in touch with them? Assisting communities with emergency communications is one of the key reason ham radio and clubs exist and not only legal but cited in the FCC rules that we are for that. They'll probably already have all the infrastructure in place, fixed and linked repeaters, portable power and mobile repeaters, periodic practice drills with willing sheriffs and counties EMS, etc.
https://www.w4am.net/local-ares-info/
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!!
- wayoverthere and WRNA236
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On 2/22/2021 at 8:12 AM, haneysa said:
Radioddity is selling pairs of UV-5X, Part 95E Type Certified HTs for $59.95/pair. It looks like when they created the Part 95 firmware for the UV-5r, the also created a WX alert function. The manual is not attached to the advertising page, so I am not sure if you can program multiple channels using the same frequencies. I know that UV-5r radios are of extremely poor quality, especially the front end, but giving people a cheap "rule compliant" option is a good thing in my opinion. There are also oodles of accessories available. What say you?
If it is like the UV-5R the receive will suck on it!! I love the B-Tech GMRS V1 though, the receive is twice as good as the UV-5R.
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On 6/8/2021 at 3:56 PM, DonErle said:
Seems to be some strong opinions on this subject, mostly folks that hate the feature. What are the pros and cons of using it? It's on just about every radio you see these days so I assume it's a feature that is needed. But I heard someone just a few days ago from an operator that simply asked for a radio check and he was berated for having it on.
I have keyed up my GMRS V1 made by B-Tech while listening to a cheap bubblepack radio and I cannot hear the unkey!! I may end up having to use beeps if people have a hard time knowing when I unkey (if I ever find someone to talk to that is).
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On 7/12/2021 at 5:22 PM, mbrun said:
In a number of posts on this forum I have mentioned my intent to side mount my amateur radio antenna on the same mast that I use for the GMRS antenna. I can now say that it is done and has been working for almost a week. As promised elsewhere, here are some pics.
The side mount bracket is home crafted and painted a color similar to the main fiberglass mast. The amateur antenna is currently about 6-1/2ft below the bottom of the GMRS antenna. There is about 21” between the amateur antenna and the nearest metal (the GMRS feed line).
I am using LMR400 feed-line for both antennas and have ferrite chokes installed over the coax. I have not yet detected any material interference or objectionable desense in the GMRS radio while transmitting on the amateur radio. I do however observe one bar on the GMRS radio’s meter flutter while transmitting at 50w UHF on the amateur radio, if the GMRS radio is receiving a usable low-level signal at the point I key up the amateur radio, just not enough to be of concern presently.
I will be operating both antennas at the lower height you see in the picture until I am ready to guy the mast at full height, which is about 16’ higher.
One of the inquires I received elsewhere is listed below along with my original response. Posted here to prevent derailing another thread.
I will be running 50w UHF and VHF, 50w GMRS.
I will let you know once it is operational. I may not have it installed for two weeks.
I do expect some desensitization of the listening receiver while I am transmitting on the other service, but nothing that I expect will affect my operations. I will have ferrite chokes on the GMRS feed-line to cut down on the noise and reduce ingress from the 2m/70cm since that line will be running parallel to the amateur antenna.
Michael
WRHS965
KE8PLM
Looks slick! I hope that the PVC will hold up! I live in a very windy area, but wish to try PVC as well, though I am fearful that the wind will splinter it like a darn toothpick!!
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On 7/12/2021 at 5:22 PM, mbrun said:
In a number of posts on this forum I have mentioned my intent to side mount my amateur radio antenna on the same mast that I use for the GMRS antenna. I can now say that it is done and has been working for almost a week. As promised elsewhere, here are some pics.
The side mount bracket is home crafted and painted a color similar to the main fiberglass mast. The amateur antenna is currently about 6-1/2ft below the bottom of the GMRS antenna. There is about 21” between the amateur antenna and the nearest metal (the GMRS feed line).
I am using LMR400 feed-line for both antennas and have ferrite chokes installed over the coax. I have not yet detected any material interference or objectionable desense in the GMRS radio while transmitting on the amateur radio. I do however observe one bar on the GMRS radio’s meter flutter while transmitting at 50w UHF on the amateur radio, if the GMRS radio is receiving a usable low-level signal at the point I key up the amateur radio, just not enough to be of concern presently.
I will be operating both antennas at the lower height you see in the picture until I am ready to guy the mast at full height, which is about 16’ higher.
One of the inquires I received elsewhere is listed below along with my original response. Posted here to prevent derailing another thread.
I will be running 50w UHF and VHF, 50w GMRS.
I will let you know once it is operational. I may not have it installed for two weeks.
I do expect some desensitization of the listening receiver while I am transmitting on the other service, but nothing that I expect will affect my operations. I will have ferrite chokes on the GMRS feed-line to cut down on the noise and reduce ingress from the 2m/70cm since that line will be running parallel to the amateur antenna.
Michael
WRHS965
KE8PLM
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On 5/3/2021 at 9:13 AM, OffRoaderX said:
We hear the same thing on the roads.. A lot of nothing and people that dont respond (probably using privacy codes)..
When offroading, the official GMRS channel is 16.. This a scientific fact because is "offroading" = "4 X 4" and 4 x 4 = 16 .. so this is the scientific answer to the question - it is explained in more detail in this video made by some Youtube clown:
Pretty sad! C.B is about dead also, I mean I can raise people, but it is not common like it used to be! Of course I don't talk much either, I mostly listen to audio books.
Where I live there are no repeaters for GMRS, there are two ham repeaters, but no one uses them, and I hear a couple of people speaking Spanish on a GMRS frequency during the day (I think it is a shuttle service). Other than that, I hear travelers and I cannot get responses like the rest of you.
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How cool! Radio is awesome isn't it? Never know what will work until we try it! I have an old dipole that I made for CB in 2011 with 12 gauge wire and a vitamin bottle for a center connector. I cut the wires to approximate length and stapled it to the outside of my shop and plugged my scanner in, it works great! I have not tried searching frequencies yet, but I will.
I plugged my GMRS into it as well and my SWR's are under 1.5 through all FRS and GMRS frequencies as well!!
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On 1/21/2021 at 4:02 AM, kb2ztx said:
You get what you pay for. If you have cheap radios then using a cheap meter isn't going to help much. Spend a bit more on the equipment you need to test and you will be pleased. Most likely youll also find all this cheap stuff is not going to perform well enough.
I bought the MFJ Grand Master meter! I have been impressed with it! I have a Dosy for C.B/HF and it's nice, but this MFJ seems easier to calibrate and more crisp.
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On 5/27/2021 at 3:31 AM, kb2ztx said:
Most of us use the Larsen NMOKHFUD NMO Mount. It isn't 100% waterproof but way better than the others. I normally slip a piece of self sealing heat shrink over the cable and I have yet to have one get water in them. My JK is at least 10 years old and still works fine. They work really well.
That's the one I have, I used an initial heat shrink tube, then spread silicon over that and shrunk another tube over that to really seal it.
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On 3/28/2020 at 8:25 PM, Jones said:
The straight answer is: No, a longer antenna will NOT help. An antenna HIGHER UP IN THE AIR will help tremendously.
Those guys walking around with a 19-24 inch long rubber antenna flopping around from the top of their walkie-talkies are on VHF ham bands, not GMRS. ...or else they are idiots.
BTECH will gladly recommend that you buy anything that they sell, if it makes you happy.
I have a foldable TwayRdio antenna in camo, I thought it would be a joke as it is long, too long, but I tested the SWR's and they are under 1.5:1 on all FRS/GMRS frequencies! The reception is way better than the 701-C, 771-C, and the stock (I have all of them). I cannot seem to find anyone to talk to for testing in my area, but when I do, I will use all my antennas and report back. I am leery about using the stock one or the 701-C anymore because the SWR is over 3 on both of those across all of the GMRS and FRS frequencies.
I Did by an external antenna and mounted it on my car, just waiting for the SMA connectors to come in. I bought the Browning antenna and mounted it to my fender!! Once that gets hooked up I hope to actually be heard! Also, I cannot access the one repeater in my area because my programming cable does not work, I have a new one coming (should be here tonight). I have no clue what I am doing, but should be hitting repeaters soon.
Cable Pinching
in Technical Discussion
Posted
Sadly, I just looked at my coax that is going under my hood! it has two nasty creases in it from me closing my hood onto it! I have a fender mount oand am running RG58 coax. I did not know that the foam padding made a difference at all.
I may need to notch my hood a little or re rout it?? The damage is done though, or can I try to re-fluff the insulation?
Any help would be appreciated please!
Jeff WRMQ982