DONE

2017 manual. That's the current standard and the one I just certified on last year. Scanning it??? It's 736 pages.... NO I ain't gonna scan it. 68P81089E50-C_Standards_and_Guidelines_for_Communication_Sites_R56.pdf

Dude, it really depends on your situation and install. Everyone is gonna tell you a 408 or a 420, and those are damn fine antenna's in certain situations, but NOT in others. So I am gonna ask a couple questions before I answer. First is what height is it gonna be mounted at? Second is what sort of tower is it gonna be mounted on? Third is what coverage footprint are you looking at/ And finally what repeater and duplexer are you gonna be running? Look forward to your answers and helping you out more.

Anything over 1/4 wave in length will reflect RF. Doesn't need to be anything real substantial. Because of what's required, the issues begin to manifest in the higher frequency spectrum, because more things are at least that size. While an apartment in Manhattan would certainly have this issue, it does show up in area's that are NOT nearly as congested as that. Road signs, other vehicles, metal poles, all are over 6 inches and therefore can create multipath. And the other part of it is the timing and wavelength for how out of phase a signal has to be. For AM radio, very low frequency, if this was even a thing the dead spots would be hundreds of feet in diameter, buy would require numerous HUGE objects to create the problem. When wavelength is much shorter, then the area's of phase attenuation due to multipath are much smaller, again typically within one wavelength of the signal you are receiving. Been through A LOT of this with simulcast radio systems where multiple transmitters were on the same frequency and their reference oscillators were referenced to GPS. Audio launch and PL launch times are also down to the millisecond to keep things working. With the systems I work on I am actually able to adjust the overlap area's of issue and put them in fields and other non-occupied locations and away from places that police and fire personal would need to use radios.

Ahh, go read this https://en.wikipedia.org/wiki/Rayleigh_fading Explains a LOT of what you are experiencing.

Yes, the applications are LIMITED for enhancing coverage through down tilt antenna's or fill antenna's for specific area's. It's mostly used in mountainous regions that have towers with a TON of HAAT (height above average terrain). If your repeater happens to be on a mountain top and it's the tallest around, and PART of teh area of interest is in the valley below then this type of stuff comes into play. But if you are JUST trying to serve the town at the bottom of the valley, then you put the antenna in the bottom of the valley somewhere on a tall structure and be done with it. I have heard of guys sticking MOSTLY ham antenna's way the hell up in the air on a tall tower on a tall mountain and can't understand why the coverage sucks. And what's funnier about that is the area that actually gets the best coverage is without any residents. It's forest, or wheat fields but NO PEOPLE. There was a time that even the commercial radio guys put the biggest antenna on the tallest tower if you want it to talk. And that is rarely the best option anywhere. 300 feet is about the max if you are in a flat area. And hilly terrain, you really need multiple sites with multiple repeaters to cover that topography. Nothing else really works. You either end up covering the hill tops, or you have a small footprint of coverage.

Here's the video. THis was posted on Facebook in the group. So some explanation. Think of an antenna's radiation pattern as a donut looking at it from the side. It looks a lot like to circles in side by side with the antenna in the middle between the two circles. This is the pattern of a UNITY (0 dB) gain antenna. Something known as an isotropic radiator. When you look at antenna gain numbers they will typically be listed in dBi. The i in there refers to this type of antenna. But the important thing here is the antenna radiates power in ALL directions almost equally with a null directly above and below it. So then we start talking about antenna GAIN. Gain manifests in a manner similar to crushing the donut equal distances from the bottom and the top. With the pattern being pushed out to the horizon at the cost of radiation both above and below the plain that the antenna is on. If you take this to extreme you CAN in some situations create a null at ground level under the antenna and out some distance from the tower. BUT you need enough height to make this happen. I actually know of a repeater that has this issue that is currently on the air at a local TV station. The repeater and antenna are located at 750 feet above the ground and the antenna is a DB-420 high gain UHF antenna. This repeater will talk to Indiana just fine, but you can't talk to it unless you are a minimum of 5 miles from it from the ground. The helicopter that it was setup to communicate with had no issues because it flew in the pattern of the antenna. So how does this effect your GMRS repeater and it's coverage??? It DON'T. Not unless you happen to have a VERY high gain antenna that is on a very tall tower or happen to be near the top of a high hill above a valley that is 700 foot down and inhabited with people you want to talk to. THEN and ONLY THEN does this come into play. I have a DB-420 antenna mounted at 180 feet up at the tallest point in the county. I have no issues with using it to communicate with locally and even from the tower lot. It works fine. Another thing you need to consider if you are looking at down tilt of an antenna. That being the UP tilt of the opposite side of the antenna. If you were to tilt your antenna DOWN to talk into a town or someplace below your antenna, then you tilt the other side of the pattern UP into space killing the ability to communicate in that direction at all. And frankly there are better ways of dealing with an antenna system that has this issue with local coverage. You add a second antenna and a power divider lower on the tower and if needed a yagi or corner reflector antenna to cover the area you need covered and only having a SMALL effect on the overall coverage footprint form the main antenna.

The biggest issue with what you are asking is finding an amplifier that will take the little bit of power that repeater puts out and amplifying it to 50 watts. One of the issues you will run into is the amp will need to be type accepted for GMRS and I don't believe there are any that are. Second issue is amp's typically don't have a 10dB gain number. Meaning 5 in for 50 out. it's less than that. Most of what I have seen in the commercial world was 6 dB of gain. which would be 5 in and 20 out. BUT 20 isn't bad with a good antenna, feedline and height of the mount for the antenna. Unless you are having specific coverage issues where the repeater can hear users that can't hear the repeater, the increase of output power does nothing except stroke your ego that you have 50 watts instead of 5 watts. And if the receiver in that repeater is not up to the task of hearing as far as 50 watts will transmit, then you end up with an alligator that's all mouth and no ears. Which leads to interfering with other repeater owners or prospective owners that can't use that pair because of interference.

Yeah, wall thickness is more about structural integrity than RF emission. If you look up 'skin effect' you will find that UHF rides right on the face of an antenna, not through the whole element. And the depth it rides in is far smaller than anything you are gonna find to make an antenna out of so I wouldn't be concerned with that. Now it was mentioned about the diameter of the antenna elements and how bigger diameters have a wider bandwidth. This IS important and can throw off the design a bit. So be aware of that.

Yeah, I like the idea of the linked repeaters. I seen it a bit differently in that if you put up a Linked repeater and there are no other repeaters in that coverage area, you should put up a stand alone repeater as well. I put up two stand alone repeaters first. Those being the 725 that was the first repeater on the tower. That one is under the call sign of the tower owner and he uses it to communicate with his family and some other folks and we use it for tower work. Then came the 675 repeater. I got licensed and had another repeater so I fired it up and put it on the air. Then I found this place, and the Midwest GMRS group and facebook page. And that looked REALLY appealing to me so up went repeater number 3, on the same tower and no same antenna system. My bigger concern is they will limit height on repeaters and I will need to drop my transmit antenna down 130 feet to 50 feet or something horrible like that. I really don't want to see linking go away, but if it does, I will just unlink the controller and and pull the Ethernet connection off it. It would suck doing it, but it wouldn't destroy me. I may decide to switch one of the repeaters to ham but outside that, it's not gonna be as big of a deal to me as it would be to others.

I don't disagree that things that are blatantly against the rules should NOT be encouraged. Equipment modifications are a no brainer for crap you don't do. And yes, the linking seems murky, but the linking seems to get people on the air. Which gets people to buy radios, get licenses and renew licenses. An issue the ham community is fighting with above 50Mhz currently and one they seem to be loosing. This leaves people that wanted to TALK on the radio (what a concept) bored and lacking enjoyment of the ham radio hobby. I realize that talking on the radio is PART of the ham radio hobby, but it's the most important part. Because at the end of the day when you have built some cool new antenna, or radio accessory, or even possibly a radio you want to test it and show off your accomplishment. And if there is no one to talk to about it, whats the point. Part of feeling accomplishment is recognition. Again, take that away and for many there is no longer a point. And while I agree with the statement that lack of enforcement is not a license to forget the rules and turn things into a free for all. I would NEVER encourage someone to do stuff like operate DMR or P25 on GMRS. But I sure would like to do it myself,,,, legally. Which of course isn't possible at this time.

Oh, I can't agree more. If you are looking for a relative measurement the cheap meters are great. And if they are 10% or even 20% accuracy, they are enough to tell you that you are squirting RF out of the radio and the SWR is close or way off. And I have some of that stuff too. I run an Anritsu 412LMR Master and a 50dB Connecticut Microwave 100Mhz to 1Ghz directional coupler for doing high power readings. And I am expected by both my employer and my main client to check the loss of the cables I am using and do my power calculations with those loss numbers in mind. In fact the client saw me doing it and when they ask what I was doing and I explained it, they required everyone else in the state to do the same thing. So my coupler is 50dB down from the actual signal level. So a 100 watt signal (50dBm) would register at 0dBm without that cable loss but at 800 Mhz that cable has 2.7dB of loss so it's significant, and will through the readings WAY off if not accounted for. Of course it all got questioned until I connected the 3 thousand dollar Roade and Swartz watt meter up in line as was within 1.5 watts of what I had on the paper for my reading. At that point they were all happy and rewrote the procedure for doing RF power readings at an RF site. Now I don't break all that out to check the SWR on a mobile antenna for a vehicle install. I use one of my Bird meters for that. And it's MORE than accurate enough to do that work. And maybe I was a bit harsh on my reply, but I thought my head was gonna explode when I read that. Not your answer to it, but that it's a topic even being discussed. But I get a LOT of that. I had one today, guy was wanting to know why his vehicle repeater was not working when he was driving down the street. I wanted to tell him because whoever installed it actually did it right. They are connected to the park neutral switch so they specifically DON'T work when you are in motion. That's what the mobile radio in the vehicle is for..... the one connected to the VRS (vehicle repeater system) that you talk through when you are on a fire ground and OUT of the vehicle. I honestly told my boss what was up and to explain that the system is designed that way to keep from causing interference while responding and driving past another working incident where they were also using a VRS to extend their coverage.

Why do I get the feeling that you are referring to the linking discussion here? And specifically me and something I have said here or elsewhere, it's just that reply just seems strange. Unless you are referring to my comments on another board about amplifiers that have the ability to exceed the power levels set in the US regulations for ham radio. If that is the case, remember, that is there and is about HAM radio, it is NOT here about GMRS radio and the two should be kept separate.

WiFi when you are using your call sign as your SSID and transmitting or exceeding the ERP allowed in part 15. You also have to be using the correct channels. This is a sticking point with MANY hams but the question has been asked directly to the FCC a number of times and they have said it was acceptable to encrypt data links that were ONLY supporting ham radio activities.

Well, I am a BIT higher. antenna height is 550 HAAT and 1560 above mean sea level.

Yeah, I don't expect that we will ever see encryption on GMRS. It's been deemed legal in certain situations on Ham, but the key has to be posted sort of removing the security of operating secure. I don't know that we will see digital modulation in GMRS in the future either. It's getting along fine without it and the number of license holders continues to grow. If enough people were to write letters requesting it be reviewed, it might get looked at but I doubt it's gonna happen. To the comment about linking. The regulation says the PSTN (public switched telephone network). Now that gets defined by the FCC during an enforcement action. Is the Internet (due to VoIP) now considered part of the PSTN? That would be for them to consider, and argue to a judge during legal proceedings. But there first has to be an enforcement effort to even begin to have the discussion. Leading back to the question of when was GMRS looked at for enforcement of any kind. Now the difference between 5 watts and 50 watts is 10dB. One S-unit is 6 dB of change from one level to the next, so it's actually less than 2 S-units. The height restriction. This is similar to the control station height limit spelled out in part 90. That states that a control station antenna, meaning an antenna for a radio that is communicating to a repeater and NOT another station, can be no higher than 20 feet above the highest point of the nearest structure. Now, a base station is defined as any fixed station that is NOT a repeater in part 90. Meaning a base station is setup to communicate SIMPLEX with mobile and portable radios directly without a repeater being involved in the communication. So again, what are they defining as a base station with GMRS, is it ANY fixed station that is not a repeater, or is it only a fixed station that communicates through a repeater? That is another double speak regulation that deserves a layman's explanation of the written regulation. Now here's a thought. I wonder if you could get an FCC attorney to write a layman's explanation of the GMRS regulations so that it was a bit more cut and dried and not so confusing. Lastly, ERP. there's where the rubber hits the road. If you were to stick a GMRS repeater on a tower. Have 10 feet of feed line between the duplexer and the antenna with 40 watt's of output due to losses in the duplexer with a 50 watt radio. Connect that to a DB-420 antenna with 8dBi of gain. Your ERP is 250 watts. Park that 200 feet in the air and you are legal in all aspects and talking for miles. But damn few are gonna do that. Maintenance on the repeater required a tower climb. Rigging and lifting the repeater and duplexer up there is gonna be difficult at best and the tower is gonna need to be sturdy enough to support the weight and wind load of the cabinet that it's in. If you put 300 feet of 7/8 line in there and locate the repeater in the building, you loose 2.4 dB of signal. Dropping you down to 144 watts of ERP. Which sounds like a bunch, but since I have an antenna at 180 feet and am only getting 20 watts out of the duplexer (actually a combiner which has higher loss) and it talks 30 miles, I don't believe it's that big of a deal. Now on some tower this is absolutely possible. But it's a pain to work on the thing. We discussed it and decided against it and have both the room and the tower to be able to do it. And that picture is ONE corner of the top deck taken from the center of the deck. And those posts are 6 feet apart.

God, I just found this by accident, and couldn't agree MORE. I posted earlier today on eHam about this very thing. Ham's seem to WANT to piss off all comers that are new to the hobby to the point they toss their equipment in a closet, and allow their license to expire in ten years, never really getting involved with the hobby because they came across this mentality and figured it wasn't worth the effort to remain in the hobby.

Well golly Gee.... it gets hot here too, and we don't have these issues with flex alerts or any of that stupidity. Can't say we have ever had a MANDATE to conserve energy here. And as far as cancer causing materials. Yep some stuff causes cancer. It's only regulated there, because state governments in other places expect their populace to be smart enough to not get over exposed to them. One one state feels like their residents are too stupid to understand that and create stuff like prop 65 to regulate it. Then again, interacting with some from that state, I can see why they would feel that way about it.

OMG is this REALLY a topic of discussion. The MOST common issue for a radio that is rated for 50 watts NOT doing 50 watts is it's actually NOT generating 50 watts. The second most common issue is line loss. And for the love of God, 49.37 watts is not 50??? Are you KIDDING ME?!?!?!?! This type of stuff is where the lack of ANY sort of testing of knowledge of subject matter to get a license becomes fully apparent. And drives guys that have a heavy back ground in RF systems up the damn wall. As Mark mentioned, there are a ton of singular reasons that power output can go down from what the spec the manufacture stated as being the 'rated output'. Any ONE of these can come into play, and it's typically a combination of them that will reduce power output. And these figures are generated by the designer NOT a test by the manufacture when the radio is built. And people need to have SOME small understanding of how much effect there is on coverage when you are down to 45 watts from 50 or even 25 vs 50. Becasue there is NO difference between 50 and 49 at ALL. Case in point. I loose 30 watts in my transmit combiner. So when my repeater is programmed for 50 watts, my power level leaving the building as measured at the surge suppressor at the cable window is 20 watts. The repeater talks for 30 miles in most directions and is only limited within that circle of coverage by topographical issues. Meaning I can't get RF to pass through hills, buildings and other structures. And that is a fact of UHF RF propagation and is consistent with all equipment operating on the frequency range. Nothing to do with 50 vs 20 watts. If I increased the power to 200 or even 2000 watts those locations would still be blocked from reception of the signal. Something as simple as a 3 foot cable being between the transmitter and the watt meter WILL decrease measured power. By at least a couple watts at UHF regardless of the cable type. And even the connectors have loss in them. So on paper the radio may calculate to have a power output of 50 watts but you will never seen that power level with an accurate meter due to something that simple. Another issue with not measuring the rated power of a radio is the radio and the meter used to measure the power. Good test equipment is expensive. A Bird 43 power meter is about 300 bucks new. The required element for it to work is another 150 bucks. And that meter is rated for an accuracy of 10 percent of the full scale indication of the element in the meter. Meaning if the element is 100 watts, that meter can be off as much as 10 watts and STILL be considered within spec. You are measuring a 100 dollar radio with a 20 or 30 dollar meter and expect the same level of accuracy. Yeah Right. I don't care if the meter has ability to indicate down to the hundredths (.01) of a watt. It ain't that accurate. I have a 40K dollar piece of test equipment that is coupled to a 700 dollar power coupler that is all sent off the be certified every year and calibrated. It ain't THAT accurate. And if you think that the meter you got from Amazon for 40 bucks is better than my 40K dollar piece of test gear, then YOU are the one living in a dream world and nothing I can say here is gonna change that. Hell I can make a measurement with what I have, disconnect the cables, reconnect them and they will indicate a difference in power of more than a hundredth of a watt. And that is just from cable placement and cycling of the connectors. And YES, ALL RF connectors have a finite number of connects and disconnects before they are deemed 'used up' and have to be replaced. For microwave testing, the adapters and connectors are rated for between 50 and 100 insertions. And cost 50 or 100 dollars a piece for a simple N female to SMA male adapter. And NO you don't check 6 Ghz microwave power levels with a Bird 43 either. That would be done with a HP watt meter that the POWER sensor is over 1000 dollars and the meter is around 10K. And the N connector is replaced on those every 2 years during calibration. Now that is getting into lab grade test equipment, which is NOT something that you are going to be buying from Amazon for 40 bucks. But it WILL measure accurately down to .01 watts and below depending on the power sensor used.

Or as my chemical spill response instructor and CERT instructor called it Methyl Ethel Bad Stuff. It's funny how the things that can kill you in one specific state are ok to posses in 49 other states. BTW, how are you handling the fact you can't charge you government mandated electric car while you have rolling blackouts? I wonder if the blackouts effect the folks that vote for liberals and the conservative voters equally.

I really don't see the linking efforts going away. What I DO think, and I have done, is provide a secondary repeater in my area with the same coverage footprint so that two or more users in my coverage area have a manner to communicate that they are not tying up 30 other repeaters in 3 states while they talk about nothing specific. To me doing that is a waste of resources. And I have the ability to run multiple repeaters for the same antenna system. Now the operating of digital modes, God I would love that. And encryption too. For specific applications, and situations. But not as a constant thing, unless it was a closed repeater. But I don't understand the idea of a club, or public repeater being legal and linking NOT being legal. If it's specifically meant to be family comms only, then limit the antenna height to 50 feet and the power to 5 watts and not 50. Because my power level out of the building is 18 watts and I can talk on the thing 30 miles away from it. And even at 5 watts with 180 foot of antenna height, I am not gonna have that much less coverage footprint. I guess the real question is this. Does the FCC even care what we do as operators and repeater owners if we are not interfering with other services outside GMRS? CB radio is limited to 4 watts AM and 12 watts SSB. But there are videos on YouTube of guys running so much power that they have corona discharges and maintain huge electrical arcs on their antenna systems and yet there are NO report and orders issued about anyone operating with increased power levels on 11 meters. And when was the last time you saw ANY enforcement issues with GMRS. I looked and I couldn't find a single one in the last 15 years. And has anyone actually contacted the FCC and gotten an opinion from them about using the Internet as a link path to do interconnect with? Now I will say that there are no devices that are specifically marketed to the GMRS community that are used for linking. I am not seeing radios with Ethernet ports show up that could be used as nodes to connect to an IP network for remote operation. So there is that. But is there a market for them and do the manufactures see it as being a viable market? I am not a lawyer, or an FCC field agent. Government regulations are typically written in double speak and are notoriously difficult for laymen to understand. So I will NOT question what John said or his stance on the legality of it. Many of us in the radio hobby have stretched the rules at one time or another. Done dumb stuff on purpose or by accident like putting GMRS frequencies in a 100 watt mobile and forgetting to turn the power down to 50 watts. But I don't personally believe that the linking thing is going to be a primary enforcement issue from the FCC either. Just like the discussions of type accepted radios. If they come at you for something else, and your radio ain't legit, they will throw that on top of what they came down on you for, but it's not a primary offense that they will come inspect you station for. And I have worked with the FCC directly in the past. Looking for malicious interference on an homeland security licensed frequency and about interference to a navigation radar system used by an International airport. They were equally serious about the enforcement of the problems but were very easy to work with. And at the time they wondered if I was the one causing the interference with the radar system due to dishes we had on the tower.

Some repeaters will generate CTCSS when they ID while others don't. Your configuration for TX PL/DPL and RX PL/DPL in some radios are separate, other radios will use either a single entry for both or rely on whatever the TX PL/DPL is set to for RX if nothing is configured. Try looking for a 'monitor' button on your radio. That will open the receiver regardless of the tone being received. See if you are hearing the Morse Code when you hit that button. Also, understand that the ID of the repeater is NOT going to happen every time you key it up. There is a timer in the repeater that if it hasn't transmitted ID in the time set in the repeater programming, typically 13 to 15 minutes, it will ID. If it has ID'd in the last 14 or so minutes it should NOT do it again. There is no requirement for a repeater to ID with the PL/DPL tone encoded. Ham's typically have this enabled so they can hear it to remind them to ID. Of course, some of them have talking repeater controllers that will babble on about where the repeater is, the frequency, call sign, time, temperature, how high the tower is, how much power it's running, club membership information, and a whole list of other nonsense that no one cares about. We have a ham repeater here locally that goes on for 15 seconds with this nonsense every 9 minutes rather or not it's in use. And for the love of God don't key the thing up after it's ID'd because then the secondary in USE ID will come on and it will ID again. If it's timed right you can get it to ID 3 times in about a minute. Hence the reason NO ONE uses the dumb thing. Personally I hate talking repeater controllers. The one on MIDWEST is fine. It runs once an hour, and has useful information. But if it was announcing crap every 15 minutes I would be unlinking my repeater. Anyway, I would be looking to see how your radio handles the PL/DPL configuration and see if you can disable the PL/DPL on receive to see if that helps. I am just guessing but I am willing to bet that the radio doesn't have some special filter to keep the Morse ID out of the receiver.

The repeater NOT generating tone during ID is usually a function of the radio and not the controller. And it's going to depend on where the PL is generated. If the controller is generating the PL and NOT the repeater, then the controller can be configured to NOT generate PL during ID. If the repeater is programmed to generate the PL and you key it via one line it's gonna generate the PL, if you are using mobiles as a repeater then this is also going to be the case. Again you have to control where the PL is generated. The problem with generating the PL in the controller and not the radio is the level of the PL. Wide band FM is 5Khz deviation at full send. The PL is generated at .7 to .8Khz deviation. So much lower than the intelligence. But the radio will typically have filters on the input that drop all audio below 300 Hz which is where the PL is. If your radio / repeater has a FLAT AUDIO input then you can send the PL up the audio line and it will be transmitted. But the level issue still exists. To set the levels, you about need a service monitor to get the levels right. If the PL is hot, then it's gonna be heard in the transmitter intelligence and people will ask what it is and complain about it. So lets go back to the i20r. What's wrong with it to begin with? Those were not exactly complicated and the failures were typically easy enough to repair. Typically they worked well unless they got hooked up wrong and a control transistor got huffed. Care to share the issues with it?

I can't stand that guy. He's the equilivant of the idiots that hit themselves with a hammer to get views.

Well, your right and wrong. The emmision for CW is indeed A1A. However, a repeater ID is NOT transmitted as CW. It's Morse Code as a tone transmitted on an FM carrier. The transmitter is legal due to this. NO one with an FM repeater gets an emission designator on their license for CW (A1A) because of this. Because they are NOT transmitting CW they are transmitting Morse Code. The CW emission A1A, is a modulation technique where the carrier is switched on and off as the method of modulating the carrier. If you were to hear a true CW emission on an FM radio it would be carrier being switched on and off. Basically it would sound like someone kerchunking the repeater and sending CW doing so. What you hear is an FM carrier that is modulated with a tone generator transmitting Morse Code intelligence on that carrier.

Where are you measuring this increase in SWR? At the radio or between the amp and antenna and what are you using for a meter to test it? If you are seeing an increase at the radio that means the input impedance of the amplifier is off. That's actually sort of common as there is little quality control in the manufacture of amplifiers for that band. If you are using an SWR meter that is designed for CB at a 'legal' power level and doesn't have an adjustment for calibration to the power level then it may be fine. You have to understand that if the meter is expecting 4 watts forward then a 1.5 SWR would be about a tenth of a watt. If you connect a meter like that to a 100 watt source, 1 or 2 watts of reflect would be that same 1.5 SWR. But 2 watts reflect on a 4 watt source is an SWR of like 10 or something like that. Short of that, you have a crap antenna or you are trying to drive a mag mount antenna and the capacitive linking to the car body for the counterpoise of the antenna is NOT coupling well enough and driving up the SWR. A properly designed antenna system should NOT change SWR with a change in power level unless the power applied is beyond the breakdown voltage of the components of that antenna system. And then it's actually failing and burning up, not changing resonance. Installation of a filter is NOT going to have any effect on the SWR if the filter is properly designed, and if poorly designed, it will INCREASE the SWR not lower it. I am gonna assume you are having issues with the RF interfering with other equipment and someone told you to use a filter? If that's the case, you need to do two things. First is quit driving the hell out of the amplifier and thinking that you need to get every last watt out of it by driving the circuit past saturation and linearity. The second is buy a better amplifier. RF gets amplified all the time. Radio stations run tens of thousands of watts and interfere with no one. So it's NOT a power issue.. it's a crap design issue. There's not exactly a set of regulations for spectral purity for amplifiers in that band as they are illegal. So stuff just gets slapped together with a cool name and flashy paint and it gets sold to unsuspecting guys that have no idea, they just want to get out better. And DAMN few CB shops have real radio technicians. Most of those guys got shown by someone it radio X that you cut this part, turn this adjustment and lie a lot to the radio owner. Collect his money and wait on the next mark. They get a bunch of old test equipment they have no clue on how to operate but it looks good to people that have no clue and put it on their work bench. The really dishonest ones will have a modified watt meter that has a hidden switch elsewhere that they flip after 'tuning' your radio to show you your 4 watt radio that has a 6 watt final in it is somehow outputting 10 or 15 watts. It's all bullshit. I lived that life for a few years. I watched co-workers screw people out of money putting 'kits' in radios that did NOTHING that were soldered into ground points and then after turning their mike gain back up and keying the radio as they would modulate and unkey as they stopped whistling get the watt meter to swing all over the place. And they did NOTHING to the radio to make it better. But it put money in their pocket. And you somehow are led to believe that they would sell you a quality amplifier. Sorry to burst your bubble there.... but thems the facts.