Radioguy7268

Ok... No argument with your interpretation. However, note the word repeater is never mentioned. Rather, they use the word transmitter. So, would that, by extension, allow any Part 90 compliant transmitter to be used in Part 95 service? Like as a base or fixed station? And, aren’t handhelds also transmitters?
 
BTW, Inalso found this in the FCC’s response to comments on the (at the time) proposed GMRS rules changes:
 
Several commenters are concerned that the proposal to prohibit combination radios would prevent GMRS licensees from using surplus Part 90 equipment in GMRS. See, e.g., Comments of Jerry Scott Parham at 3. This is not our intent. We will continue to certify equipment that meets the respective technical standards for Part 90 (land mobile) and Part 95 (GMRS) in both services, if requested. However, we are amending the language in new section 95.1761© to clarify the requirement in old section 95.655(a) that Part 95 GMRS radios will not be certified if they are equipped with the capabilities to operate in services that do not require equipment certification, such as the Amateur Radio Service.

For the price of that you can get a way better repeater. I purchase Motorola MTR2000's in the 100W full duty cycle version for 600 all day on ebay and run them at 50W. We use 7 of them on our GMRS network, and I have 4 more in the garage looking for sites. You can not go wrong since these devices have been used on public safety and commercial trunking systems for years and are still in use today. Great equipment for the money.

Just a note on channel capacity with the M1225 series. They were touted as having a capability for 20 or 24 channels. You could squeeze in 24 channels if you deleted certain features/functions on the radio. It's been too long, but I seem to recall that you would lose simple things like the ability to change the display backlight from amber to green, certain button functions, etc.
 
The reason that it sticks out in my mind, was that I do remember seeing problems as you would approach 20 channels and try to do things like priority scanning. It seems they were pushing the edge of the radio's capabilities to get to 20 + channels, especially if you had Alpha tags on each channel - and used all the characters on the display.
 
On a side note, I used to mess around with LTR trunking systems on the 1225 series before they came out with the LS models (and later on the PM400) - and a company named Scholer-Johnson made a plug in option board that would allow all types of features  - including the ability to do multiple zones of 16 (possibly more?) channels. The software wasn't user friendly - I remember that you did NOT want to Read radios with the option board - just Write properly defined setups. I stumbled across the 3.5" floppies with the install files the other day,  probably what brought this to mind.

Just a note on channel capacity with the M1225 series. They were touted as having a capability for 20 or 24 channels. You could squeeze in 24 channels if you deleted certain features/functions on the radio. It's been too long, but I seem to recall that you would lose simple things like the ability to change the display backlight from amber to green, certain button functions, etc.
 
The reason that it sticks out in my mind, was that I do remember seeing problems as you would approach 20 channels and try to do things like priority scanning. It seems they were pushing the edge of the radio's capabilities to get to 20 + channels, especially if you had Alpha tags on each channel - and used all the characters on the display.
 
On a side note, I used to mess around with LTR trunking systems on the 1225 series before they came out with the LS models (and later on the PM400) - and a company named Scholer-Johnson made a plug in option board that would allow all types of features  - including the ability to do multiple zones of 16 (possibly more?) channels. The software wasn't user friendly - I remember that you did NOT want to Read radios with the option board - just Write properly defined setups. I stumbled across the 3.5" floppies with the install files the other day,  probably what brought this to mind.

I agree with your comment about Digital emissions, the FCC has been pretty clear that GMRS is supposed to be analog voice in a clear & unencrypted state (foreign languages allowed - as long as your ID is in English or CWID).
 
However, when it comes to Part 90, I'm pretty sure that an FB6 private carrier repeater license can be used any way that a paying customer chooses to use it. I've never seen a single action from the FCC since the deregulation in 1980 for "casual communication" on Part 90 frequencies.  
 
I've got more than one licensed FB6 (and FB8) system, and I've never cared what a customer talked about. I also don't think the FCC ever asked to look at my books and see how much I was charging those FB6 customers. I think the definition of "Private Carrier" is fairly loose. I just told the Frequency Coordinators that I was planning to offer airtime service to my customers.

There's so much good stuff out there in the way of used Part90 Commercial gear.... I've got a couple PM400's, an XPR5550 (shop truck), an old TK-880, and an assortment of portables that run the range from Vertex through Motorola. I've always been a fan of the M1225 for starter gear. It's small enough, has decent specs, and the software is very easy to use. I've picked up units off eBay for under 25 bucks for low power (25 watt) 4 channel models. The 20 channel display units usually run higher, but almost always under $100 for clean working units. The M1225 series was also type accepted for Part 95, which calms some people's fears. 
 
I have to admit that having access to all the software and cables makes things pretty easy for me, but unless you're looking at current model top of the line stuff, the software is pretty easy to come by, and most of the mobile cables you can make yourself if you can follow a diagram on Batlabs or Repeater-builder.

There's so much good stuff out there in the way of used Part90 Commercial gear.... I've got a couple PM400's, an XPR5550 (shop truck), an old TK-880, and an assortment of portables that run the range from Vertex through Motorola. I've always been a fan of the M1225 for starter gear. It's small enough, has decent specs, and the software is very easy to use. I've picked up units off eBay for under 25 bucks for low power (25 watt) 4 channel models. The 20 channel display units usually run higher, but almost always under $100 for clean working units. The M1225 series was also type accepted for Part 95, which calms some people's fears. 
 
I have to admit that having access to all the software and cables makes things pretty easy for me, but unless you're looking at current model top of the line stuff, the software is pretty easy to come by, and most of the mobile cables you can make yourself if you can follow a diagram on Batlabs or Repeater-builder.

There's so much good stuff out there in the way of used Part90 Commercial gear.... I've got a couple PM400's, an XPR5550 (shop truck), an old TK-880, and an assortment of portables that run the range from Vertex through Motorola. I've always been a fan of the M1225 for starter gear. It's small enough, has decent specs, and the software is very easy to use. I've picked up units off eBay for under 25 bucks for low power (25 watt) 4 channel models. The 20 channel display units usually run higher, but almost always under $100 for clean working units. The M1225 series was also type accepted for Part 95, which calms some people's fears. 
 
I have to admit that having access to all the software and cables makes things pretty easy for me, but unless you're looking at current model top of the line stuff, the software is pretty easy to come by, and most of the mobile cables you can make yourself if you can follow a diagram on Batlabs or Repeater-builder.

There's so much good stuff out there in the way of used Part90 Commercial gear.... I've got a couple PM400's, an XPR5550 (shop truck), an old TK-880, and an assortment of portables that run the range from Vertex through Motorola. I've always been a fan of the M1225 for starter gear. It's small enough, has decent specs, and the software is very easy to use. I've picked up units off eBay for under 25 bucks for low power (25 watt) 4 channel models. The 20 channel display units usually run higher, but almost always under $100 for clean working units. The M1225 series was also type accepted for Part 95, which calms some people's fears. 
 
I have to admit that having access to all the software and cables makes things pretty easy for me, but unless you're looking at current model top of the line stuff, the software is pretty easy to come by, and most of the mobile cables you can make yourself if you can follow a diagram on Batlabs or Repeater-builder.

I agree with your comment about Digital emissions, the FCC has been pretty clear that GMRS is supposed to be analog voice in a clear & unencrypted state (foreign languages allowed - as long as your ID is in English or CWID).
 
However, when it comes to Part 90, I'm pretty sure that an FB6 private carrier repeater license can be used any way that a paying customer chooses to use it. I've never seen a single action from the FCC since the deregulation in 1980 for "casual communication" on Part 90 frequencies.  
 
I've got more than one licensed FB6 (and FB8) system, and I've never cared what a customer talked about. I also don't think the FCC ever asked to look at my books and see how much I was charging those FB6 customers. I think the definition of "Private Carrier" is fairly loose. I just told the Frequency Coordinators that I was planning to offer airtime service to my customers.

I use the Motorola M1225 mobiles in my vehicles and also have a pair for my repeater. They are great radios and you can find them for a decent price on Ebay.
Of course programming them can be a bit tough.
The correct model number for the M1225 is M44DGC90E2AA. This is the 450-470 and 40W model with 4 channels

And the hits just keep coming....  Apparently, there was video of the collapse as it happened. The video is grainy, but apparently shows that the workers knew something was wrong.
 
Shocking tower collapse video shows an erector just two seconds away from death.
https://www.youtube.com/watch?time_continue=88&v=oH-ER8yFJfs
 
More video, along with the story:
 
http://wirelessestimator.com/articles/2018/shocking-tower-collapse-video-shows-an-erector-just-two-seconds-away-from-death/

Update:
 
Inside Towers has an update on the outcome of the OSHA ruling.
 
https://insidetowers.com/cell-tower-news-contractors-error-caused-death-osha-reports/

Some people make things way too complex. Overanalysis = paralysis. 
 
As for CWID, yes, a repeater can and will transmit morse code on the output (462.xxxx) frequency. If you really read deep into the rules, I suppose that you can make a case that the mobile unit which transmits into the repeater on 467.xxxx should also be identifying.  A simple verbal call sign identification would serve that purpose, but I'm also not aware of a single case of the FCC ever taking action against some one who only identified on the GMRS repeater's output.
 
There are tone panels out there which will CWID based upon the tone/PL/DPL in use. In short, you can have different CWID's for different users, and pre-program them into the repeater based upon the user's PL tone. A pretty easy way to have multiple users identifying off a single repeater.
 
There are plenty of type accepted Part 95 radios out there, but they're not all being sold new anymore. Wanting brand new limits your choices, for sure.
 
There's also no FCC action I've ever seen that the FCC took against someone for using re-purposed Part 90 radios, and there's been a few letters and tacit admissions posted by the FCC where they realize that people are using surplus Part 90 radios and repeaters for GMRS. Does lack of enforcement = legal?  Probably not, but I'll still keep using Part 90 gear until such time as the FCC tells me to stop. Over the air, there's little way to tell what type of radio someone is using.
 
I guess some people like to know exactly who is talking & wish for an easy way to identify such. I view an automated CWID as being legal, slightly more anonymous, and a whole lot easier to use for my family. We don't need to spend 10 seconds identifying ourselves before we see if Mom wants milk on the way home. We let the automated CWID take care of all that after we're done talking. 

So much already written and available on this, yet every time we turn around there is a new post rehashing all of it. I think we all like helping others, but I can't frankly find the energy to do all that typing, bless you others for doing it. Some folks need to do a lot...a lot more reading before asking for the instant gratification answer. Not trying to offend anyone....just being direct. 

This is one of those extraneous bits of information that throws me off in these posts. Getting into the mobile repeater takes whatever watts it takes to get in. If you are relatively close enough and the propagation is good enough, it might only take a few milliwatts. BUT, in everyday use, it is merely the settings on the handheld used; low, medium, or high if ya got em. Low might be more than a few milliwatts but it's what you have at the time. Too much minutuae in some of this description is muddying the waters, IMHO.
 
Again, cross-band repeat would be simplest but we don't have that option in GMRS. So, a basic mobile repeater is the way to go. There is no need to reinvent the wheel. There is affordable used gear available right now to do it.

Ian. You titled this topic “A Beginners Repeater.” But, then you describe a very complex system that nobody here seems to fully comprehend. Then, when people suggest you simplify things, you respond that each suggestion offered won’t meet your beginner needs. Finally, you seem to misunderstand or misinterpret parts of Part-95 and in so doing, you seem to go in unsupportable directions and avoid other, much simpler, potential solutions.
 
At this point, I too will join the growing crowd watching from the bleachers, at least until you can provide a simple use case example that does not involve any discussion of how it should be done. Something like: “4 people are hunting in the woods and a 5th person is coordinating their a actions from a fixed location and they need to share their ideas for lunch.” Really, something that basic would be a good way to start getting the help you have requested.

Greg,
 
I fully agree with this, and I'll admit that I was trying to simplify something that just isn't so simple.  If the antenna has a high SWR, a wattmeter may not read correctly anyway, due to the reflected voltage not necessarily being at a half-wave point in the return path.
 
The main problem is that many consumer-grade RF power meters do not actually measure power.  They measure a sample voltage at a given point in the transmission line, and estimate power based on a low-voltage/high-current place on the line.  Reflected power, depending on the phase and time of arrival at the metering point will either add to, or subtract from, that representative voltage, giving a false reading.  For example, if your input jumper is too long, and falls at a voltage high point in the overall line length, and the reflected power from a mismatched antenna also falls at a voltage high at that same point in the line, your voltage-driven power meter may show 45 Watts output from a 25 Watt transmitter.  With a half-wave input jumper, you will start out with a known voltage low point. A mismatched load will still cause a false reading, but usually not as severe. - Your reading will be "less wrong".
 
I guess in summary, if you want to measure output power of your transmitter, use a known good terminating resistor - A.K.A. Dummy Load. I've seen good 50 Ohm terminators selling for less than $40.

The reading on a power meter will vary a LOT depending on where the meter sits in the overall total-length of coax cable.  To get an accurate reading, the meter MUST sit at an interval of 1/2 wavelength along the transmission line.  The only way to easily do this is by insuring that you are using a half-wave input jumper cable on your meter.
 
Cable electrical wavelength is figured by the Speed of Light (299,792,458 meters per second) divided by the frequency in Hertz, the dividend of which is multiplied by the velocity factor of the cable (look at the specs for the cable you are using).
 
For instance, if my meter's input jumper was made from RG-213u, I would see that the velocity factor for that cable is 0.66. (sometimes shown as 66%)
 
(NOTE: In this example, I have used 462.600 in the GMRS band as my desired frequency. 462,600,000 Hz)
 
Let's do the math: 299792458 / 462600000 = 0.6480597881539127 * Velocity factor of 0.66 = 0.4277194601815824 Meters.  That is a full-wavelength of cable, and we need a half wavelength, so cut it in half. So, your jumper cable into the meter should be about 21.5 centimeters long, or about 8.5 inches.
 
If you were using a smaller cable, like RG-58u with a foam dielectric, which has a velocity factor of 0.535, then you would need  .1734 Meter jumper, or about 6.8 inch jumper to correctly match the input of your meter.
 
If you are using just some random-length input jumper, particularly if it is over a full wavelength long, then you may not be even close to the half-wave point, depending on the length of the rest of the cable going to the antenna, and the meter will not read right.  If you use this calculated length of input jumper, accounting for its velocity factor, then whatever is on the output side makes no difference to the reading accuracy.
 
By the way, this rule goes for SWR meters as well as power meters.  If you set up your UHF antenna with a 3-foot truck-stop CB jumper going into your meter, then you are likely WAY out of 'whack'. These rules still apply at HF also.  It isn't as critical below 30 MHz since the wavelength is so long, but if you use a 4 or 5 foot long meter jumper at CB frequencies, it WILL be wrong. At 27.205 MHz, use a 6 inch jumper, or else a 9.6 foot one for accuracy.
 
Tech hint: I keep several different lengths of pre-made jumpers in my Bird watt meter case for different frequency bands that I normally work with, and have them all tagged as to what band range they are for.  The higher you go in frequency, the more critical this gets, and the SHORTER they get... sometimes TOO short, thus for 950 MHz, I keep a 15.6 inch jumper of LMR-400, which is 1.5 Wavelengths, but still on a calculated half-wavelength point in the line.  A 5.2 inch long LMR-400 jumper is too short to work with.
 
Long winded, sorry, but I hope this helps.
 
-Jones

Glad to help.  If you have any kind of jumper close to 7.5 inches or so, it will likely be close enough at 460MHz.  It may still show a difference in power levels between your different antennas, but not as drastic of a difference as your 2 foot jumper will show.  If you happen to hit it right on the half-wavelength mark, then there should be no noticeable difference between forward power level readings on any of your antennas, unless one of your antennas is bad -  then the transmitter might "fold back", or shut down for protection.
 
ALSO: If you want a true representation of the output power of your radio, don't measure it into an antenna, use a half-wave jumper into your meter, with a 50 Ohm dummy load connected directly to the output of your meter.
 
While I'm here, as long as reflected power is very low compared to forward, or if your SWR is less than 2:1, then it's close enough to work. If it's less than 1.7:1 then it's good. At 1.5:1, it's GREAT! Tweak it if you must, but the difference between 1.5:1 SWR and 1.1:1 SWR is not worth fighting for. In most cases, just follow the manufacturer's cutting chart.  ...and trying to fine-tune a quarter-wave stub at 460MHz is absolutely foolish.

Before anyone spends too much more time on this topic... note that, as seems to happen too often here, the OP has not logged in in 3 days (since Oct 8) and has, therefore, not seen any of these responses.

Depending on the exact location and situation - as well as the type of Duplexer you might be using, a Preselector is probably more of a Nice to have, as compared to a Need to have. But, if you're buying a used repeater, get one with a Preselector if you can - especially if the price is within $50 or so.  Buying a Preselector after the fact would probably run you @ $200 + tuning. 
 
If you have a really good duplexer (meaning a properly tuned 6 cavity bandpass/bandreject) the benefit you would get from a Preselector is minimal. If you were running a typical compact flatpack notch duplexer - the benefit would be amazing.
 
The front end (receiver) of an MTR2000 is worlds better than most any '2 mobile radio based' duplex repeater package out there. The MTR2K converts received signal into PCM (Pulse coded modulation) digital signal for all it's internal processing, and the internal noise level introduced by the machine is nearly non-existent. You get a clearly reproduced voice -- even with a weak input signal from a distant mobile. 
 
Trouble areas are minimal - but if you're getting one off eBay, be super careful. If you can wait on them, you will often find people selling off a batch of them as they part out an old UHF trunking system - recent pricing between $450 and $650. The power supplies can be troublesome on the 100 watt units - but I've picked some up for a few hundred dollars that had known power supply issues, and then turned around & grabbed a huge 26 volt DC rack mount power supply for $100 or less (plus the $50+ for shipping the beast). Nice way to eliminate a known problem spot & put a 100 watt repeater on the air for less than $500.
 
Motorola doesn't support them anymore, and many of the components are designed as "bricks" - so you can swap around a receiver, a power amp, a power supply module, but each component is sealed up & considered non-serviceable by Mother M. I don't think I've ever seen any schematics or break downs to component level. Software is a little old & cludgy, but I've still got a winXP machine that runs it well enough. The last time I programmed one - I realized it had been nearly 5 years since I'd touched one for a customer. A testament to the "set it and forget it" nature of those machines.
 
Basic single user repeater mode is pretty straightforward. If you try to run a multi-tone panel things get a little more complicated, but the method to do it has been well documented and doped out. 

IMHO, They dropped it to be compliant with their FCC grant. They only got part 95 certification for a 2 watt radio. 
Sent from my SAMSUNG-SM-G920A using Tapatalk

Depending on the exact location and situation - as well as the type of Duplexer you might be using, a Preselector is probably more of a Nice to have, as compared to a Need to have. But, if you're buying a used repeater, get one with a Preselector if you can - especially if the price is within $50 or so.  Buying a Preselector after the fact would probably run you @ $200 + tuning. 
 
If you have a really good duplexer (meaning a properly tuned 6 cavity bandpass/bandreject) the benefit you would get from a Preselector is minimal. If you were running a typical compact flatpack notch duplexer - the benefit would be amazing.
 
The front end (receiver) of an MTR2000 is worlds better than most any '2 mobile radio based' duplex repeater package out there. The MTR2K converts received signal into PCM (Pulse coded modulation) digital signal for all it's internal processing, and the internal noise level introduced by the machine is nearly non-existent. You get a clearly reproduced voice -- even with a weak input signal from a distant mobile. 
 
Trouble areas are minimal - but if you're getting one off eBay, be super careful. If you can wait on them, you will often find people selling off a batch of them as they part out an old UHF trunking system - recent pricing between $450 and $650. The power supplies can be troublesome on the 100 watt units - but I've picked some up for a few hundred dollars that had known power supply issues, and then turned around & grabbed a huge 26 volt DC rack mount power supply for $100 or less (plus the $50+ for shipping the beast). Nice way to eliminate a known problem spot & put a 100 watt repeater on the air for less than $500.
 
Motorola doesn't support them anymore, and many of the components are designed as "bricks" - so you can swap around a receiver, a power amp, a power supply module, but each component is sealed up & considered non-serviceable by Mother M. I don't think I've ever seen any schematics or break downs to component level. Software is a little old & cludgy, but I've still got a winXP machine that runs it well enough. The last time I programmed one - I realized it had been nearly 5 years since I'd touched one for a customer. A testament to the "set it and forget it" nature of those machines.
 
Basic single user repeater mode is pretty straightforward. If you try to run a multi-tone panel things get a little more complicated, but the method to do it has been well documented and doped out. 

Isolation between transmit and receive can be achieved if you have enough spacing between the 2 antennas. The trouble is, horizontal spacing requires about 300 ft to get 60dB of isolation in UHF, which isn't really enough. Vertical spacing only requires about 25 ft height difference for decent theoretical isolation in the UHF GMRS band. But, I'd still run a bandpass can on the receive side.
 
http://www.repeater-builder.com/antenna/images/vertsep.jpg