WRKC935

Lscott and gortex2 are both correct. But there is a bit of explanation that needs to be done to have a better understanding of it. First is receiver technology. Back in the day, and in the present, a standard analog FM receiver has a number of stages that the RF goes through as its stripped of it's intelligence (the voice communication) and presented to the user via the speaker. First is an RF stage, this is connected to the antenna and amplifies the signal (and ALL other signals it can hear) to be shipped up the line. These are typically fairly wide band amplifiers that will amplify much more than just the frequency range of the radio. Here's the first part of receiver degradation. That first RF stage has a design gain of X number of dB gain for the stage. So, lets say that's 10dB. If you connect said radio to a signal generator and feed it a signal level of -110dBm the output of that state SHOULD be -100dBm. An increase of the 10dB of the stage. BUT, if you feed that antenna with 2 signals from a generator that are different frequencies and also are -110dBm and look at the output of that stage, the signal level of each frequency will be -105dBm which is half as much as the single signal gain because the state can only generate 10dB of TOTAL gain. We are talking GMRS, so 462Mhz. But that RF stage exhibits gain at 140 Mhz too. To deal with out of band frequencies a GOOD receiver will have a band pass filter that will only let in 460 to 470 blocking the out of band stuff. Cheap receivers don't have expensive filters. And receiver sensitivity is measured with a SINGLE frequency in a controlled environment at the BEST measured level. Meaning they will sweep around and find where the radio performs it's very best and that's the spec. Second is shielding. Keeping the signals that are floating around in the radio out of other circuits in the radio requires shielding and isolation. Go find an old Motorola Spectra and take it apart, look at the designed isolation. Then take a part a kenwood TK860 or other radio from another manufacture of the same era. Spectra's were a BEAST for performance. Other's not so much. But you could buy 4 TK-860's for the cost of ONE Motorola Spectra. So stage two is the IF stage, a second signal is created in the radio and mixed with the RF. This mixing creates two frequencies. The sum of the two frequencies and the difference between the two frequencies, which is the one that's important here. Of course, what ever else has leaked through beyond the primary frequency of concern (what the radios actually tuned to) is also present and ends up converted as well. This is where the 10.7 IF frequency is created and passed to the IF amplifier. Stuff is cleaner now and more filtering happens. Then it's stripped of the intelligence from the IF and sent to the amplifier for presentation by the speaker. Digital processed radios. These are analog radios that operate in the digital realm. An SDR receiver if you want to think of it that way. Some of these directly take the RF into the digital processing chip and some operate at the IF frequency mentioned before. Because the RF is directly converted to a data stream it's now easily processed and can be filtered much better than even the best designed analog receiver could hope for. If it's not specific to the frequency of concern, it's simply ignored. And 'amplification' is as simple as changing the bit stream. All amplifiers can mix frequencies. so RF. IF whatever, mixing can occur. If there isn't any amplifier in the sense of a stage with an analog transistor that exhibits gain in the stage, then no mixing happens. Remember that the RF is now a digital stream of date, even in an analog radio. The SDR chip take the RF in and outputs the intelligence directly to the audio amplifier. All the A to D and D to A (analog to digital and digital to analog) happens in that chip along with all other signal processing. This allows for greater First RF stage gain, better filtering and error correction (something that CAN"T happen in an analog receiver at all) and a whole host of filtering that's done in the digital domain. And that's how we are seeing a huge increase in receiver sensitivity in these newer radios that are Digital and analog like the XPR Motorola offerings. They are barely analog at all. Doing all RF and IF processing in the digital domain while being 'analog' radios.

First thing that will be considered is the level of interference with legacy equipment. Since we are limited on bandwidth, FHSS is gonna be a no go. The popping it will cause in the analog receive of the legacy stuff and the fact it will effect ALL the channels not just the selected channel I just don't see it happening. The next logical thought IMO is DMR, using TDMA of a 25KC or 12.5 KC channel. Implementation would be simple enough in the channels could be designated with an A and B. Meaning CH 19 in digital would be 19A and 19B to split the two time slots per channel. The branded name for DMR of course is MOTOTRBO in Motorola speak, but there are a large number of manufactures that make DMR radios. This would basically DOUBLE the number of channels that could be accessed from a radio in the same allocated bandwidth for GMRS. But so would going to 12.5KC channel spacing. Mind you the range would suffer greatly with going narrowband, but the interstitial channels between the repeater allocations could then become full repeater channels if the FCC was so inclined to make that change. The other thing that's possible since we DON"T have the non-proprietary technology requirement in GMRS that the hams have, we COULD petition for some level of Tier2 DMR functionality like trunking for area's that have significant GMRS use. That would share 4 talk paths on 2 repeaters with a huge amount of possible group call designations (talkgroups). But planning and cooperation from ALL users of the system and the system owner would be key to getting that to actually work. But some level of a 'CLUB' membership with or without dues would almost be mandatory as the configuration of the subscriber radios and ID assignment for the individual radios would need to be controlled or it would simply be chaos. Tier 2 DMR allows for proprietary trunking methods like Capacity Plus from Motorola that will ONLY work from a Motorola radio. P25, which I would actually prefer, does NOTHING for increasing bandwidth allocation, unless you went to a Phase 2 APCO25 standard. But the requirements for that are radios that are thousands of dollars and back end equipment that would be in the tens of thousands. So that is a pipe dream. And linking P25 is FAR more complicated than linking analog or DMR. DMR linking is simple, other than every device on the linked system needs a specifically assigned ID. Call routing mandates this. But outside of that, a Motorola repeater that is DMR has an Ethernet jack in the back. You configure the repeater a certain way, and connect it to the Internet. There has to be a C-Bridge somewhere as there is a hard limit of 15 repeaters that can be linked together with out the C-Bridge, but outside that, you can route talk groups with the bridge to limit the number of active repeaters by the talk group being used. Meaning a TG (talkgroup) could exist for each state, region, or a nation wide group simply by routing the TG to the repeaters in the footprint of the TG designated area. Any of this would of course interfere with legacy analog equipment and communications in analog. There would almost certainly need to be some level of restriction of what repeater pairs could be used and how far they would need to be placed apart from current analog repeaters to minimize interference. DMR talks further, which increases the possibility of analog interference. And while I am all for it, and the conversion for ME is as simple as going to the tower and reprogramming my repeater (running an MTR3000 on the 462.675 machine) if you look at the coverage footprint of 675 on the map, running an analog repeater in that footprint would be near impossible as my transmitted output would tear the analog receive up for those operators.

Honestly, if you need the actual FCC regulation on the matter, then look it up on the FCC web site. If you are smart enough to get logged into this web site, you are smart enough to look it up. The regulation is pretty cut and dried, 50 watts out of the radio transmitter, amplifier or whatever the source is. That's the on paper FCC rule. Reality. If you are running a hybrid combiner network feeding three repeaters into one antenna, your losses in that combiner network will exceed 6dB. So if you are running 100 watts into the combiner, you are STILL only getting 25 watts out to the antenna feed line and then you have the loss of that line to contend with as well. My system is putting 18 to 20 watts out of the building. Feed line is 300 feet, and .817dB per 100 feet. So that's .817 X 3 or 2.451dB. Plus the .5dB loss per connector on the cable, the .5dB loss for the surge suppressor... Am I gonna tell you that I am pushing past the 50 watt maximum at the station, of course not. My station is completely legal. But lets have a different discussion. Lets talk about 12dB sinad, capture and minimum signal required to hold open squelch. The average MTR2000 will open squelch with a PL at about -120.5 to -122dBm. And requires about -118to -119.5dBm for a 12 dB sinad. That's a signal change of a very scratchy signal to a fully copyable signal with background static. For a full quieting signal you need to increase your input signal from -120 to about -105dBm. So about 15dB of increase. So what is that in terms of watts? specifically the power change. If you are running a 10 watt radio, and you are generating a signal level of -120 at the repeater input, to make that signal -105 would mean you increased your signal to 80 watts to achieve that -105dBm signal level. SO, does a 50 watt radio make a big difference over a 10 watt radio? It does, but not as much as you think. With my silly little 18 watts I talk 37 miles in some directions. Because antenna HEIGHT and gain is FAR more important than what your watt meter says your power out is.

While i don't mind net's for 'technical' and discussions that are SPECIFICALLY GMRS related, the ham add on's frankly make me turn it off QUICK. I fired up the radio a few weeks ago and heard a net starting. The minute they ask for 'emergency or priority traffic" on a linked system that NOT for emergency communications, I pushed the power button. I hear that on the local ham repeater every week. It's not a traffic net, it's NOT ARES (ham EMCOMM) and I honestly don't what to hear it. My PERSONAL thoughts are that if you want to use GMRS for SAR / EMCOMM/ whatever for YOUR group, then put up a repeater for YOUR GROUP and do whatever you want. But then again, WHY would anyone with emergency traffic of ANY kind wait for a net to start to pass that traffic or request assistance. So I am stuck on a mountain side, flat tire, broke down. Should I wait until the net starts to ask someone to make a telephone call to send me some assistance. If that's the case, I probably need to pack more crap because if it's Monday and the net is on Sunday night I am gonna be here for a week waiting on the net to start right???? Of course at that point I will have been eaten by a bear. These are MY PERSONAL opinions on the matter, you are free to agree or disagree. But I will not be joining ANY net on GMRS that starts off like a hammie ARES net.

Curious about the etiquette of linking a repeater to the different nodes across the US. I am going to be traveling to Fla at the end of the week and would like to have the ability to link back to my local repeater while I am down there. Of course I am in Ohio so it would be temp links while traveling, but is there issue with linking my repeater into 174 while I am down that way? Obviously I would need permission from teh local machine owners to access their repeaters, but is it an issue to link my repeater to 174 since it's connecting the stats I will be in for that period of time.

Well, geeze, if it's not a hobby, then there wouldn't be guys putting thousands of hours and tens of thousands of dollars into building sites and systems. And I certainly would not have put up 3 repeaters on the same site if they were ONLY for my personal communication. Of course, is my hobby building sites, or radio in general... I honestly can't answer that. I enjoy the site building more than the talking.

They would start hearing frequencies other than the one it was tuned to. Would get intermod, hear paging transmitters (High power but not overly close) And at times loose the ability to hear a transmitter on the tuned frequency. We figured this was due to the first RF stage being swamped with RF due to a total lack of filtering. Now scanners will do the very same thing, at least the inexpensive ones because they are designed to hear everything everywhere.

If you are wanting to have two or more radios on a single antenna you are out of luck..... you need two antenna's one for transmit and one fore receive... If you are willing to run 2 antenna's you can run a control station combiner that allows you to run as many radios as it has ports. 4 is usually the minimum but 8 is more common and they can be expanded to 32 ports which is the largest I have seen. With tow antenna's. Now the pricing isn't for the faint of heart, typically about a grand per port on the smaller ones and can get down to 500 per port on the larger units. Plus of course the two antenna's required. Signal loss though these is pretty high as well. Looking at 6 dB both directions. SO a 50 watt radio will have 12.5 watts out, but it's typical to turn the radios down to 20 watts so you are looking at 5 watts out. Incoming signal is also 6dB down so you need to be fairly close to the repeaters you are talking to.

OK, so part 15 and not 97..... I am good with that. To the statement about radio programming, I know at least one local city that has a law on the books that no one can have a radio programmed for their system. It doesn't limit ownership, just the programming in the radio. And I doubt they are the only place that's got that sort of law. And yes, I know the funky bowel (Baofeng) radios are crap and have crap signal. They 'work' in some applications. I do know that taking one 200 feet in the air even in a rural area, 30 miles from the nearest large city makes the receiver in them go bonkers. But, when your receiver will listen from DC to daylight, that's sort of what you should expect.

OK, glad to hear it's back up and running.

Final post on this, with results. Got the antenna jumpers run today from teh ground bar to the combiners. 725 and 675 are in the same combiner that is rebuilt as a hybrid. 725 is running 40 watts in and 14 out. 675 is running a bit more and getting 20 watts out 600 is in a different combiner, had to retune the isolators for that combiner. Will also have 442.775 in it. 600 is also at 20 watts out with about 35 in so that combiner is working better than the other, but it's not in a hybrid configuration. With 20 out the building and the line loss my realized gain on the antenna system is 6dB, so my ERP should be right around 80 watts. Plans are still in the works to swap the RX antenna from a 408 to a 420 but that's another project. Thanks to all those that gave guidance with getting this all working.

Yeah, I was getting that too. Is this a case of it did work and now it don't or is this a new setup and hasn't been connected before?

Naaa, I think we have similar jobs and see similar silliness. But, I think you were missing my point. If someone modifies a commercially sold ham radio that is 'type accepted' for ham use under part 97, and you cut the block out of it and transmit on some other service, be it commercial LMR, public safety pool or even GMRS, it's illegal because it's not a type accepted radio for that service. Service being controlled by another part of the FCC regulations. We are 95, ham is 97, commercial is 90.x for SMR and 90.y for public safety. Anything is pretty much legal on ham (part 97) as long as it's spectrally pure enough and below the maximum power level for the band it's on. Of course, GMRS and SMR are not that way, the radios have to be tested and accepted for the specific service they are operated on. GMRS there is little enforcement and there is a lot of lee-way. Not that the LMR is closely watched either, but there is more enforcement there than GMRS or ham.

Well, I have only be a ham for 20 years. Do I have an agenda, yes, I dislike stupidity and to a lesser degree, wackers, or wanna be public safety types. These aren't the average hams that want to do their part, pass traffic in a disaster situation and conduct themselves 'professionally'. I am referring to the clowns that have a light bar on their car, a big sticker about weather spotting, fake radar dish on the roof of their car and the mandatory ham radio 'police badge' further indicating their self importance. And the modification to the radio makes it 'illegal' under part 90, not part 97. The radio was never type accepted under part 90 so if it transmits there it's automatically in violation. This is regardless of any other regulation or stipulation in the rules that says any means at your disposal.... if you take a ham radio and transmit in another part of the spectrum that's regulated under a different part of the regulation, then the radio has to meet the requirements of that part of the regulation. Ham radios are NOT part 90 approved, therefore they can't be transmitting there. It's just as illegal to spin the dial on your HF radio down to the AM broadcast band and start transmitting there. Again, not because of the part 97 regulations, but because of part 73 that regulates AM FM broadcast. And the number of regulations they have to follow is FAR more strict than ham or even part 90. And that's a piece of the spectrum that WILL get the attention of the FCC if you go messing about in it. Here's the problem with all this. This lie has been being told to other hams for YEARS to the point it's common. The League refuses to set the matter straight, and tell hams to stop spreading this myth because it will drive away some part of the ham community as a whole that believe they need to be able to talk to the police or fire dispatchers directly 'just in case'. And the truth is a lot of those guys are one step away from getting a Crown Vic and turning it into a wanna be police car and ending up on the front page of the newspaper for being arrested for impersonation of whoever. Now all that being said, if you are stuck on a mountain top and you are in trouble, can't get down, or whatever the case may be. If you have a radio that will talk on the police, fire or dog catcher channel and you call for help, NO ONE is gonna fault you for that. And I seriously doubt you will end up with a fine from the FCC for transmitting a distress message. But there are limits to when it's acceptable. And with this specific situation, none of those limits were met.

The FCC in truth is partly to blame for this stupidity. Somewhere in the stacks of pages of FCC regulations there is a passage in the hammie law that states that A ham operator may use ANY means at their disposal to communicate an emergency. Now this has little clarification where it explains that if a General class operator can't raise anyone on the allocated frequencies of his license, he can move to the Extra class frequency allocations and and communicate there. But he HAS to remain within the allocated amateur radio bands. So the clowns see this as an excuse to remove the transmit block that keeps their 2 meter ham radio transmitting between 144 and 148 Mhz. And they cite this very regulation as the reason to modify their radios... so just in case they need to talk directly to the police or fire they can. I remember when Radio Shack brought out the HTX202 radios that would NOT even receive out of band. They were a kickass radio, worked extremely well but guys refused to own them because they wouldn't operate out of band. Had the FCC CLEARLY stated that the any means at their disposal within the allocated amateur radio bands, all this crap wouldn't be as common as it is. This goes back to the days of code requirements and 5 different licenses classes in ham radio. But it allowed a Novice license holder to use 2 meters in the case of an emergency. It was NEVER meant to allow hams to talk to police on their ham radios. And this stupidity is still prevalent in ham radio. I have heard numerous complaints that there is no radio that will connect to an 800Mhz trunked radio system that a ham can get. And they NEED it 'just in case" and have gone as far as stating that they need to have some public safety frequency available for them their ham radios will work on so they can advise of an emergency. Public safety communications is for the greater public good. Not the good on an individual. Meaning if the cell networks are down due to an earthquake. There is a building on fire with 30 people trapped and your father is having a heart attack, getting on the fire / ems frequency and calling for help will get you told to shut the hell up and ignored. The lives of 30 people are MORE important than that of a single individual. And they are NOT going to send resources for a single individual if they don't have them in reserve, which after a major earthquake, they are NOT gonna have. But getting on their frequency DOES put that group of people in greater jeopardy if they are communicating with you and not each other do rescue them.