The power secret for General Mobile radio mobile and base installations. This is applicable to 70cm and 2 meter Amateur radio stations. Or, is it the dirty little secret.
Thanks, for the video! I agree with most of what you said, but I would like to make a few observations, if I may: 1 - Losses equally affect reception and transmission. Likewise, antenna gain improves reception as much as it improves transmission. 2 - No antenna actually increases the power out of the system. Antennas achieve gain by "squeezing" the radiation pattern such that energy that would be wasted in ineffective angles of radiation are redirected to useful angles of radiation - like towards the horizon, rather than up or down. You used the term, "effective radiated power" which is the correct term to refer to the improvement due to antenna gain. 3 - Less than 1dB change in signal strength is going to be imperceptible to most humans. And, a standard "S" unit on an S meter is going to be about 6dB - just to put the losses/gains into useful perspective. 4 - GMRS is a "line of sight" band. Therefore, increasing transmit power - or effective radiated power - is far less important than improving line of sight. Indeed, the increased gain from an antenna that is placed at greater height is going to be far more useful than increased transmit power. For example, a GMRS radio that has a transmit power of 50 watts connected to an antenna that is 20 feet above the ground is nowhere near as effective as a GMRS radio that has a transmit power of 5 watts connected to an antenna that is 100 feet above the ground - even with increased feedline losses considered.
@@oldolfmann8927 1 - You're just plain wrong. Radio waves don't care whether they're being received or transmitted, and neither do antennas care whether they're transmitting radio signals or receiving them. It is a stone cold fact that antenna gain is EQUAL in both directions. But, you go right ahead and do your level best to refute this, if you think you can - but, just saying that they aren't the same isn't going to cut it. 2 - Antennas are PASSIVE components in any radio system. They are incapable of adding power for transmission or reception. From where would an antenna get the extra power you seem to think they provide? From God? What an antenna can do is provide GAIN - which is not the same thing. An antenna can be designed such that it "squeezes" the radiation into a desired direction, while sacrificing performance in undesired directions. But, the total amount of power in the system remains the same. If you have an omnidirectional ground plane antenna and a beam antenna connected to an antenna switch with 100 watts being provided by the radio, both antennas will radiate a maximum of 100 watts. But, the beam antenna will squeeze those 100 wats of radiated power into a desired direction, while providing some rejection - along with decreased performance - in undesired directions. This will have the effect of providing a stronger signal in the desired direction, as compared to the ground plane antenna. On the other hand, the omnidirectional ground plane antenna will receive and transmit equally in a 360 degree pattern, with a nominal amount of gain directed toward the horizon, depending on its height above ground. The higher the antenna above the ground, the lower the angle of radiation toward the horizon and the longer the distance of potential contacts. But, the gain from the beam antenna will provide a stronger signal in whatever direction it may be pointing. There are advantages and disadvantages of both beam and omnidirectional antennas, which is why many radio operators like to have both types of antennas. Because, ultimately, the goal of radio is to make contacts, and each antenna can help you in different ways in that regard. 3 - Isn't that essentially what I said? The point I was making is that it makes no sense to go chasing a 1dB improvement in your system - because, no one is going to notice the difference. And, the radio doesn't care. I am still wondering why you would even say anything about this, except to just be obtuse. 4 - An antenna at 20 feet above the ground is DEFINITELY going to be subject to more potential obstructions than an antenna at 100 feet above the ground. And, no amount of extra power is going to be able to overcome the effect of those obstructions at GMRS frequencies - hence, getting your antenna higher above the ground is how you overcome the effect of obstructions. And, assuming that you do get your antenna above the obstructions, the difference between 5 watts and 100 watts is going to be nominal for the vast majority of contacts you might make on GMRS. Why? Because, most mobile and portable stations are going to be located near the ground with obstructions and lower power levels which is going to reduce their effectiveness in making contacts. And the increased transmitter power of a station with an antenna at greater elevation is going to be benefitting more from the higher elevation than the increased transmitter power. Of what benefit is there for the mobile and portable stations to be able to hear a station that cannot hear them? At the limit, though, the station who has an antenna at 20 feet above the ground in the desert with no obstructions is not going to be able to make contacts as far away as a station right beside it that has its antenna at 100 feet above the ground with no obstructions - because, the curvature of the Earth becomes the obstruction. Now, go ahead and argue some more.
@@richardowens9061 I have learned more in your two posts than I have in countless hours of reading on the internet. Thanks for putting it in simple and easy to understand terms that makes CLEAR sense and understanding.
@@wjf213 You're welcome. I'm glad I could improve your understanding of radio. Clearly, that you have spent so many hours reading on the internet indicates that you are also fascinated and intrigued with the intricasies of antennas and radios. For the best information on the subject I highly recommend the ARRL Handbook - all editions. You can learn very valuable information from the very first edition, as well as the most recent. The science does not change, even if the technology and the rules do.
Thanks for the informative video, just got my gmrs license and am looking into building a portable base station. This video had exactly what I was looking for.
i ran LMR400 in my mobile no problem. 21 Silverado 2500 Crew cab. through the dash, under the carpet , up the rear pillar, under the headliner to a NMO roof mount. Yes a Cut a hole in a $80k truck. running a Motorola XPR5550e in a custom mount. Laird BB4505CR antenna 5db
Now I was an old CBer from way back and I remember they had field power meters which had a little antenna connected to it. You could test the power of your CB radio by standing a distance away from the antenna and have someone else key the mic. You could see the power in watts that you were transmitting. I have been out of the sport for a long time but have become very interested in GMRS. Do they have such a device for GMRS and if so, would it measure the effective power of the system you described in your video and how many watts would it read?
Field strength meters are most useful in determining RF radiation exposure for higher powered systems, in accordance with FCC regulations regarding RF radiation exposure limits, as they are able to measure the "effective radiated power" or ERP of an entire system, including transmission power, feed line losses, and antenna gains. They're merely a novelty at CB power levels. The radiation pattern of an antenna is far more important to analyze in terms of actual performance, and that is something that can either be calculated from known antenna parameters, such as its length, configuration, and height above the ground using antenna modeling software, or provided by manufacturers of antennas.
@@oldolfmann8927 I'm sorry, if my post, above, went over your head. I've had an Amateur Radio Extra Class license - the highest you can get - for over 20 years. And, I have an electronics engineering degree. My reason for stating that they are for novelty use at CB power levels is because you will NEVER exceed FCC RF exposure limits at 27MHz and 4 watts transmitter power. You're better off measuring power delivered to the antenna at the feed point, which takes into consideration the losses through the coax, and calculating effective radiated power (ERP) based on the specified gain, as provided by the antenna manufacturer, or antenna modeling software, like EZNEC. But, you go right ahead and have fun playing with the field strength meter.
When you see this in a reply ---> "I've had an Amateur Radio Extra Class license - the highest you can get - for over 20 years." You know it's one of the Sad Hams NotaRubicon talks about in his videos, they think they know it all, and the main reason why I left the Ham radio hobby, they will try to run your station the way They see fit. Ignore Them.
Amen love proving them wrong even though I know they'll never admit. Like notarubicon has said if they start out with their degrees and you know everything thing else out of their pi hole is bs
Here is your Answer: Your radio uses standard SMA-Male connector. Your Yagi is a ??? If is optimised for GMRS ( basically 470 mhz) then cool You can sort of get by likely with a 70 cm yagi but that's optimised somewhere between 420-450 mhz. You didn't mention what connection is on your yagi It can be PL259/UHF(SO-239) standard connector. Or a better type N connector ( provides a far more water tight seal ) or even a TNC ( even better for keeping water out of your antenna connection ) If you are Asking What Connector to use on your Yagi.. Best is TNC Next Best ( and I use a N connector ) UHF ( which is also known as a SO-239 ) So.. Depending on what you already have hooked on your yagi..is what you will use on yagi end Then on your radio end prefibly install directly to the feedline a SMA-Male connector.. Or a converter to sma-Male ( but that will induce a loss.. though only a small/ tiny loss ) BTW.. For UHF ( Your gmrs ) I use Andrew's Heliax LDF7-50A Feedline ( extremely low loss feedline )
This is a really good easy to understand video. But, what wasn't covered was the effect on receive signal. Each 3dB of loss in the antenna/feedline system equates to about one S-unit less receive signal. And increasing transmit signal by 3 dB really only increases the signal at the receiving station by one S-unit. This may be really important if operating simplex; maybe a little less important if using a repeater. So, the best installation is to get the radio as close as possible to the antenna by being closest to directly underneath the antenna, use the highest gain antenna, and the shortest run of the best coax.
Back of napkin calcs based on what you explained mean that I can change the location of my new radio shack to a different room. More transmitted power, for less money and less labor for installation! Everyone wins.
You get less cable loss, which is significant, in the 440 & GMRS frequencies with a shorter run distance. Everyone wins unless the new room is the bathroom 😁 There are calculators on-line and in the App Store for helping with this.
I just installed the Midland MXT275 in a newer suv. when I key up the mic...i get a bad hum in the audio of the radio system the radio is plugged into to the cig lighter.... I am guessing its the amplifier of the radio. the Mxt275 is only plugged in and that is my poor ground. Ideas?
@@personalradiofun526 It is mounted on the front hood on the drivers side with the 2 supplied set screws. I have noticed over time that the "hum" appears to have lessened . but still there. It only is noticeable on the Car audio amplifier . Thank you
😷👍🏻 Nice explanation of dB logarithmic info & wire size. We mostly use 1/2” or 7/8” Heliax for UHF repeaters & RG400 or RG214 for general purpose jumpers & duplexer jumpers. Connectors are also pretty critical. Just say NO to CHINESIUM !
dB = 10 x Log10(multiplier) In Excel put a multiplier into cell A1. The formula in A2 will be = 10 * LOG(A1,10) A2 will be the dB. Quick check is if 3dB is a 2 times multiplier then 4dB will be more.
Antenna gain does not amplify radio power. To amplify output power you need an amplifier that use electricity. Antennas are passive units without any amplifying capability. So what is dB gain? - It’s a method of describing what the projected signal from the antenna looks like. A 3dB antenna projects more or less a doughnut shaped signal. A 6dB gain antenna projects a slightly flatter doughnut. And the same for the 9db gain antenna. The higher the gain the flatter the doughnut. The flatter the doughnut the longer the range.
Yes, coax is not friendly with GMRS frequencies. I was able to "gain" 7.3 db in a mobile setup by changing out the coax and antenna from a stock issued antenna. Made a sizable difference, but think that the higher gain antenna's height helps with mobile setups. The tip of the antenna went from 7 to about 9.5 ft, not much but that little bit clears a lot more stuff near the ground. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-rU-P1lq7hMI.html
That is a good idea. There are not typical base station radios for MURS. It is doable, but; not straight forward. What would you want your base station to be able to do?
@@personalradiofun526 If a manufacturer would produce a MURS base with a good S meter, all 5 channels. They would make some money. MURS frequencies are good in the woods. Great for camping, hiking, hunting, good camp base station. Dakota made the M538 base station which is not really set up for a true base station. The time is ripe for a listening manufacturer.
@@bulldogbrower6732 MURS is an Excellent Band. Using Portable..and to Also have GMRS band. Get a good 2 meter / 70 cm HT typically Very easy to open up transmitting on your MURS but to Also cover GMRS Plus ham radio HT's typically are much better units then either dedicated MURS or gmrs HT radios
Maybe instead of saying the antenna _increases_ the power, say the antenna _concentrates_ the power. And saying an antenna can increase power from 10W to 40W is just wrong.
@@richardowens9061 yep agreed, for that high of a frequency, only short runs of LMR 240, for example my long runs are LMR 600 but then when I need short jumpers and things less than 10 ft to reach to the radio, LMR 240 is pretty nice.
As a ham radio operator I do know the best way, usually, to maximize communication distance and maximize safety. 1. Most important, the antenna. It is the singly most important component of a radio system. Mounted as high as physically possible within limits of the FAA and FCC with the proper lighting and painting. 2. Coax. Get the one with the least amount of loss per foot for the highest frequency you will be using. Remember that, for the most part, repeater inputs on the higher bands are 5 MHZ or more higher. 3. Grounding. Most may forget this part or say they do not need it. Wrong on both counts. On the lower bands, it is essential for communications. On EVERY band, it is a MUST for safety. In the shack, a COMMON GND point is best with the largest conductor to a physical GND rod, or multiples of gnd rods. 4. Static discharge tube or similar device in-line with the coax. This is important to shed any currents in a antenna system that is not shunted to gnd. 5. Finally the radio, get the best you can afford, AFTER purchasing ALL the above. For a communications system to work, all the above MUST be observed. I have seen a 400 ft guyed tower for ham use. Required FAA and FCC approval. Required lighting as it was ABOVE the 200 ft limit by the FAA for unlit towers. Also needed the red and white alternating color scheme used by commercial broadcasters. This guy also had a repeater on the tower, was non-coordinated, and was used for testing. He used a self-contained repeater in a cylindrical container mounted ON the tower powered with 120 vAC, 50w with a short 5 ft length of coax. That repeater worked very well in the midwest, think ?0?? country. Programming was OTA. Because he had to light the tower, he used romex 10/3 w/gnd. This powered the lights and the repeater. Without having to run a 1" hardline up the tower, the weight savings was very good and the wind loading was reduced. This also allowed a lower powered repeater to operate as coax losses were negligible with only 5 ft used, most of which was used to make a de-coupling choke just below the antenna, which was a 4 bay shorted loop for 440mhz. I did not include the power-dividing coax assembly provided with the antenna in the coax length. This repeater setup could be used for GMRS to increase distances without increasing power past the 50 watt mark. 73 de N7TZQ
Shame on you, Sad Ham, for playing along with this clown. ERP - is a power rating, is it not? No antenna can increase power, because you can't make something out of nothing. dB gain on an antenna describes the focus of power, not amount of power. Also look up the NEC on multiple ground rods, you are providing DEADLY ILLEGAL advice. GMRSers are right, there are a lot of Sad Hams out there. No wonder CB is more fun than Sad Ham Bands. After decades of CB & GMRS use, I considered Hamming it up. Then I saw Sad Ham videos in which grown men were giddy about making distant contacts, and that was it. Their goal was to make as many DX contacts as possible, and that's it. So strict, and so boring. While Ham radio has a very useful place in the world of communications, it has got to be the most boring place on the dial. You can keep your 73s, GMRSers say "69s"!!
Thanks for the video, but loss on a 100 foot coax is meaningless in a mobile installation. Some of the best antenna mounting systems I have ever used are actually RG-174 based as the cable is easy to run and conceal in a vehicle. In a 10 foot run coax loss is nominal to say the least. Far more effective is to use a GMRS specific antenna centered on the roof of the vehicle to maximize height. And the better the ground plane the more the signal is compressed vertically making it extend more horizontally. The best results I have had with 2 meter or 70cm or GMRS is a mount in the center of the roof of my pickup.
Also, quit using pl-259 connectors. They were designed ages ago for lower frequencies. Anything above 300 mhz should be N or SMA. Pl-259 connectors have impedance bumps at higher frequencies and they get worse as the frequencies get higher. Don't use ham or cheap radios that have so-239 / pl-259 connections. Get N connections all the way through, and limit the adapters and pig tails, etc... People have no idea how big of a difference this can make, especially when combined with hard line or other very low loss coaxial cable that is short as possible
Very true. But, I would point out that the typical application for MURS radios does not lend itself well to using Yagi beam antennas. For example, if you have a group of MURS walkie talkie users with whom you wish to communicate who are constantly moving around the area, a Yagi beam is not going to be an effective way of communicating with them, as your antenna will not be pointing in the right direction most of the time. A far more effective type of antenna that can provide similar gain is a vertical phased collinear array. They achieve gain by squeezing the RF energy and redirecting it to the horizon, rather than up or down. The more collinear elements the antenna has, the more omnidirectional gain it will have toward the horizon, thereby increasing range and ERP. And, all of that gain is going to be in useful directions, not requiring that you aim the antenna at any particular station.
You are Not Exactly Right..but close. But No one who is Truly looking for a Home System ( especially for a 100 foot or greater run of feedline ) Will use any of those feedlines.. Example.. For HF ( I use for cb / 27mhz ) I use Heliax LDF5-50A For VHF & UHF ( GMRS is UHF ) i use Heliax LDF7-50A Coax feedline Though "genually" VHF and UHF is line of site That isn't always True ( antenna type becomes very important to achieve beyond line of site).. and Height is Might Yet.. I argue these points with plenty of people. But then heck i have Only been doing this stuff for 50+ years But i for sure wouldn't be caught dead using LMR-400 Even on CB /HF Frequency's And you are trying to state it's great for UHF.. That's a Big.....NOT !!!
Thanks for suggesting those great feedlines. At less than a 0.5 dB loss / 100ft. they are definitely less lossy than LMR-400. The main point of the video is to get people to understand that not all coax performs the same. So if you have a small budget then make the best choice that your funds can support.
@@personalradiofun526 Additionally Besides buying Andrew's Heliax from Andrew's and or a store.... So too one can get left over runs from cel phone cites installers ( and save Lots doing so plus these guys can install any type of antenna(s) if one isnt good at doing so themselves ( being inventive in how you buy and or install your equipment can make a huge difference enabling one to get better coax runs at huge discounts) I will admit though.. LDF5-50A & LDF7-50A is hard to work with for many people...yet well worth it. It is the types of coax feedline I use Along with Equally high end radios and power supplys That Enables me to get ranges well beyond a average user and to do so on a regular basis I cant tell you how often others with even 10 to 20k amps get Destroyed with my tops 135 watts output on hf and 20 to 50 on vhf/uhf ( I dont use amps-liniears ) but rather use of large high quality ground planes for HF and vhf/uhf antennas 57 ft up at base of antennas ( 81 ft at top of antennas) with nothing higher around for 1/2 mile around ( at least ) My point is The better equipment one gets The better they set it up The refusing to setting for half measures Once done One can settle in and enjoy the 2 way hobby quite well
With your calculations on the coax your right there is a loss with your calculations on the antenna you're totally wrong because you cannot multiply the wattage coming out of the radio with just your antenna that is a myth what your radio puts out is what your radio puts out the antenna will not give you more the only way you get more is with an amplifier sorry to burst your bubble
You are right. Its not magic. The multiplication of antenna GAIN is gotten by how the signal is focused in a specific direction. Effective Radiated Power (ERP) was not the topic of the video. If I said it multiplied the power out of the radio, then I stated it wrong. The correct statement is effective power coming out of the antenna.
