mbrun

As SWR is a constant topic in radio, and since it may be difficult initially to grasp the concept of, I thought it would be helpful to provide a link to an incredibly effective video that allows you see it in action. The video is 60 years old and was produced by AT&T labs. It is worth watching from start to finish. You will get to see standing waves, reflected waves, impedance matches, mismatches, shorts and opens. It does not get visually any clearer than this. Enjoy. Michael WRHS965 KE8PLM

And it is back. Learned that just within the last hour they got the software that allows it to work installed. Thanks Team! Michael WRHS965 KE8PLM

Today I lost the ability the use the TapaTalk app with the myGMRS. Anyone else having the issue? TapaTalk tech support says the plug-in that the web site needs for TapaTalk to operate is currently not running. Just looking to find out if I am alone in this issue or if others are experiencing the issue as well.

I am hearing that the long wait is about to come to an end. Yeh, I too hope that the next shipment is sufficient to cover the current backorders. Seems like there is a lot of interest in this radio. Michael WRHS965 KE8PLM

Here is a snap shot of my NanoVNA showing the resonance of the external GMRS at my home. The resonance can recognized by the sharp dip in the yellow LogMag trace. Since the impedance of the antenna (as depicted in the green smith chart) is also closely matched to the 50-ohm coax there is also a corresponding dip in the SWR. So this image shows that, in my case, the best SWR reading corresponds with the resonance of antenna. So, in part, how can you view the resonance of an antenna independent of SWR? Use a NanoVNA, perform an S11 measurement with the instrument set to display the LogMag trace. Hope this helps. . Michael WRHS965 KE8PLM

There appears to be an accidental typo in the GMRS frequencies listed. All GMRS frequencies begin with 462 and 467, none are 457. The issue of odd splits has been discussed. While some believe that there is nothing that prevents use of a odd split, so long as only the main frequencies are used, it most certainly is unconventional. The use of unconventional pair of frequencies, does have the side effect of limiting use of a conventional pair by another would-be repeater user. I don’t recall hearing anyone confirm that they are actually doing this. I do recall one reason folks consider during this is to make it more difficult for those that seek to cause intentional interference on the radio. It makes it more difficult for them get their kicks (but does not prevent it). Is the off-shore traffic sufficiently frequent that even with different PL codes, communications cannot reasonably occur through the repeater? If the interference is frequent and disruptive enough I would consider shifting frequencies. Just some thoughts. Michael WRHS965 KE8PLM

Yes, a change in cable and cable length can yield a different SWR. A higher loss and longer length cable will yield an artificially lower SWR when measured at the radio when contrasted against the same antenna but lower loss and shorter length coax. The greater the total loss in the coax, the lower the SWR. The LMR-240 has lower loss than the 8X, so assuming the same length of cable you could see a small increase in SWR because you are able to see and measure the antenna’s reflected power better. The integrity of the solder connection could be factor, as could the integrity of the antenna ground connection to the vehicle. Both are items to check. If possible, use the shortest possible coaxial length with your antenna until you confirm that SWR is where you want it to be, just to eliminate the cable length variable from the equation. Once it is where you want it to be, then you can use longer cable, and if done well, the SWR will stay the same or drop a smidge. Also, same antenna mounted in different vehicle(s) can yield different SWR values, as can the physical proximity of the antenna to other objects. Just some thoughts for you. Michael WRHS965 KE8PLM

In Cincinnati there is an informal net every Sunday evening. Listeners and active participation continues to grow. A good number the participants are licensed for both GMRS and amateur services. Others are licensed for only GMRS. Folks also know to monitor the repeater daily at a given time of day just in case an there is important information that needs to be shared with the community and an impromptu net is needed. Some folks want to participate but cannot get into the repeater that is used. To help, there are multiple people that monitor both amateur and alternate GMRS frequencies to receive check-ins and relay questions. That shows some real dedication in reaching out to the community and a conscious degree of collaboration and cooperation. The leader of the group, Hans, is all about spreading the experience thoughout the community. If there are no repeaters in your area, I see an opening for you. Put one up and share it with the community and put it to use in your daily routine. Traffic will draw traffic. I cannot say that I have experienced any arrogance in the local community at all. Ignorance perhaps (i.e. not familiar with) on both sides of the aisle, but no arrogance. Locally I see cross-pollination as folks licensed in one service see the other has just another communication option. I see hams getting GMRS license and vice versa. With GMRS you can do something that amateur-only folks cannot as readily and easily do: use radio to communicate with family without them having to study and pass a test first. Yet, you can achieve the exact same level of UHF FM communication experience as the amateurs can on 70cm. Michael WRHS965 KE8PLM

I am posting this for the benefit of newcomers to myGMRS. Folks entering the world of GMRS and repeaters often have early questions on this very subject and the question can often best be answered through the use graphics or video. I stumbled across the following video this morning that I found to be short, simple, and concise. So I post here for the benefit of new members of the myGMRS community. Enjoy. Michael WRHS965 KE8PLM

I remember back when I obtained my NanoVNA and was doing experiments with a simple 1/4 wave ground plane. It allowed me to not only see the resonance change as I trimmed the antenna down to size, but it also allowed me to observe the impact of length and descending angle of the ground plane radials had on the impedance of the antenna. Without it those factors are hidden mysteries. Michael WRHS965 KE8PLM

I don’t know what the issue is, but the first thing that is running through my head is ‘Is the transmitter output truly remaining constant or is changing too?’ If the transmitter power is in-fact remaining constant while the insertion loss of the duplexer is changing, then perhaps a cable to or connection within the duplexer is warming and changing impedance. If the radio is actually changing, then we know the issue is related to the repeater. If the SWR is located at the radio and the duplexer characteristics that are changing while transmitting, would expect to see some subtle movement in the SWR. Just food for thought. Michael WRHS965 KE8PLM

Resonance and SWR are two different things. Resonance speaks to how closely tuned the antenna is the wavelength of the frequency you desire to operate on. SWR speaks to how closely the impedance of the antenna is to the characteristic impedance of your feed-line (e.g. coax). If the antenna is perfectly resonant, its impedance is exactly 50-ohms and the antenna is connected to a good 50-ohm coax, then your SWR will be 1:1. Now, if your antenna is perfectly resonant but it’s impedance is 75 ohms, you will never achieve a real SWR of 1:1 using 50-ohm coax. You cannot achieve it because there is an impedance mismatch between the two. You can trim and lengthen the antenna all you want, but you will never get to a 1:1 unless you add sufficient extra coax to eat up and waste all your reflected power (a waste). Hypothetically though, switch to a radio designed for 75-ohms, use 75 ohm coax and you are back in business, 1:1. A perfectly resonant antenna will absorb (i.e. radiate) all of the power you send it using the frequencies for which it is resonant, assuming off course you send it from a source and over feed-line that matches that of the antenna. When tuning an antenna you will see a nice SWR dip where the antenna is resonant because the impedance of antenna drops at the point it is resonant. The miraculous NanoVNA can be your friend because it affords you the ability to calibrate to the point of antenna connection, then focus on analyzing the antenna itself to see what it’s actual doing, seeing what its real impedance is. Other analyzers can be just as useful. In using one of these at the antenna you can see the effect of every change you make, from moving it, mounting, nearby surfaces, lengthening and shortening. All in all, 1.6:1 to 1.7:1 are not bad at all. So, except for the learning you would achieve, I see no critical reason to fret about the values you have listed. Michael WRHS965 KE8PLM

Yes, it will. That is one of the major real-world functions that the lighting arrester serves. Contrary to its name, a lighting arrester does not protect you from damage from a direct lighting hit, but instead it shunts surges from nearby lighting and bleeds off static that occurs naturally during storms as well as other periods of high winds. BTW, welcome to myGMRS. Michael WRHS965 KE8PLM Edit: Here is a link to a document that explains how they work. https://www.polyphaser.com/News/DownloadFile?downloadGuid=52f23510-c294-40d8-889b-b63f1c6fdcb5

Absent test equipment, it would be through experimentation, which is how I did it originally. In the end, I tweaked the receive threshold value in the software until its predicted coverage map reflected the same edge coverage limits I experienced in the field. This was done after I had already entered the transmit side information accurately. I knew I had found the right value when I all the nuances I experienced within the coverage area showed up clearly and accurately reflected my personal experiences. That told me I had gotten the receive value in the right ballpark. While the radio manufactures do publish a sensitivity value, the only time that value means anything is in the lab. It is not usable for the real world range prediction. Once you hook up an antenna to the radio, the noise the radio sees from the area around it increase thus making the lab sensitivity value meaningless to use in the software. In the end, it is this effective sensitivity you would use as the receive threshold in the software (i.e. the value that you can reasonably reasonably expect to be required to open squelch on your radio in your area of concern and produce at least a minimally usable audio). In my coverage maps I had to use an effective receive threshold of about -85dBm to get its edge coverage to align with my real-world experiences. Once I had found that number I was able to vary antenna elevation, gain and cable loss factors to see realistical coverage changes to expect from my transmit location. The key thing for me was learning just how much more elevation I would actually need to achieve a given objective. Recently, I learned that could use my TinySA with its external antenna under some circumstances to get a ball park noise figure that could prove useful in establishing a baseline receive threshold for my radios if I were to go into another area. I also have acquired additional equipment too that affords me the ability to go into the field and conduct model-specific effective sensitivity measurements. Thanks to wisdom gained from interactions with Gman and RadioGuy. Hope this helps. Michael WRHS965 KE8PLM

Welcome to myGMRS. There are a lot of good folks here and a lot to learn. Enjoy your stay. Again, Welcome. Michael WRHS965 KE8PLM

You have to make sure the receiver figures are correct as well. Those are the hard-ones to get correct. Last summer I did extensive simplex testing around me, long before I found that program. Retroactively I modeled the coverage and when I got the receiver numbers adjusted the coverage pattern (good, marginal and no coverage) did end up being a good facsimile of all my results. The key learning item here was that spec sheet receive values and real-world effective receive values are different. Michael WRHS965 KE8PLM

Thought I would add that RT Systems has informed me they are currently working on programmer version for the 805G and they intend to make one available for the 905 in future. This does not help you Mac Guys, but it may be welcome news for the PC folks that read this. Michael WRHS965 KE8PLM

WyoJoe, I agree 100% that each person that transmits would need to have a license. I also believe that if MAC’s station is the one that would be actually transmitting, he would be fully and solely responsible for the legal use of that station. Consequently the burden would be on him to make sure each user is licensed to gain initial access as well as to make sure that the user looses their access immediately when their license expires. Michael WRHS965 KE8PLM

Good Day BoxCar. The rules changed in 2017. 95.141 no longer exists as originally written. In the 2017 that section redirects as follows: Old 95.141 ‘Interconnection prohibited’ replaced with 95.349, 95.1749 The following excerpts are from the 2017 rules. § 95.345 Remote control. Operation of Personal Radio Services stations by remote control is prohibited, unless otherwise allowed for a particular Personal Radio Service by rules in the subpart governing that specific service. See e.g., §§ 95.945 and 95.1745. § 95.347 Automatic control. Operation of Personal Radio Services stations under automatic control is prohibited, unless otherwise allowed for a particular Personal Radio Service by rules in the subpart governing that specific service. See e.g., §§ 95.1747, 95.2347, and 95.2547. § 95.349 Network connection. Operation of Personal Radio Services stations connected with the public switched network is prohibited, unless otherwise allowed for a particular Personal Radio Service by rules in the subpart governing that specific service. See e.g., §§ 95.949 and 95.2749. § 95.945 Remote control of a CBRS station. This section sets forth the conditions under which a CBRS station may be operated by remote control, pursuant to the exception in § 95.345. Operation of a CBRS station using a hands-free or other type of cordless microphone or headset authorized under part 15 is not considered to be remote control. (a) Wireless remote control. No person shall operate a CBRS station by wireless remote control. ( Wired remote control. Before operating an CBRS station by wired remote control, the operator must obtain specific approval from the FCC. To obtain FCC approval, the operator must explain why wired remote control is needed. See § 95.329 regarding contacting the FCC. § 95.1745 GMRS remote control. Notwithstanding the prohibition in § 95.345, GMRS repeater, base and fixed stations may be operated by remote control. § 95.1747 GMRS automatic control. Notwithstanding the prohibition in § 95.347, GMRS repeater stations may be operated by automatic control. § 95.1749 GMRS network connection. Operation of a GMRS station with a telephone connection is prohibited, as in § 95.349. GMRS repeater, base and fixed stations, however, may be connected to the public switched network or other networks for the sole purpose of operation by remote control pursuant to § 95.1745. Michael WRHS965 KE8PLM

The radio technically has 4 power levels. Low, Medium-Low, Medium-High, High. As a user you are in control of which of the two medium power settings you will actually use, but you do that in advance. Then, when using the radio you can press a single button on the microphone to cycle between H, M, L. Which power is actually used for medium then is based on your earlier decision. Every channel has its own power setting too so you can have some channels on H, some on M, some on L. It is your choice. Michael WRHS965 KE8PLM

Welcome to myGMRS! Enjoy your stay. Be sure and pass on the knowledge as you acquire it to help out all the newcomers. Michael WRHS965 KE8PLM

Be aware too that if you turn the feature on you likely have settings for choosing if the are sent when you press PTT, release PTT or both. Also, your radio may have a feature for turning on sidetones on so that you can hear these tones as they are being sent out. This can be helpful to let you know when it is clear to start talking. Michael WRHS965 KE8PLM

I suspect not, as long a suitable paint is used. But, in full disclosure, I have not done it. But if I were considering it, this is what I would do: Step 1: Measure and record the SWR of the antenna on your primary channel. Step 2: Using small diameter piece thin-wall plastic pipe or tubing, place it over your antenna (as small diameter as you can). Measure and record the SWR now. If SWR changes dramatically from step 1, that material is not ideal for this test. Try a different material or move on to a different option. Step 3: Paint that same piece of pipe/tubing, let it dry, then place it over the antenna as in step two and measure then check the SWR again. Assuming little or no difference in SWR between step 1 to 3 I expect I would be just fine. An alternative is to not paint it at all but instead use a length of thin heat-shrink tubing. With this method it can be removed it if negatively affects performance. The benefit of the heat-shrink tubing over the paint is that it eliminates risk of paint adhesion problems as the antenna whips around. (The ideal paint would not have an issue with this). The downside is slight increase in wind loading. Third suggestion, buy a black antenna [emoji23], which I did. Food for thought. Michael WRHS965 KE8PLM

No, not yet. So surprised too. Michael WRHS965 KE8PLM

For all practical purpose long-distance skip is non-existent in GMRS (UHF-FM frequencies). Oh yes you might experience an outlying case when under just the right solar conditions, but you are more likely to win the lottery than to experience that. You are likely to observe that your range expands and contracts locally from day to day though if you regularly work repeaters and simplex stations that are on the range fringe for you. Michael WRHS965 KE8PLM