coryb27

same here. 100W machines turned down 3min TOT.  MTR's will run 24/7 @ 100W w/no problem.

Great follow up! I was hoping this topic would generate some conversation. I personally don't own any repeaters that are less then full duty cycle and I dont use time out timers on the repeaters. We link several machines together using VOIP and at times the conversations can get long winded with many users engaging I have seen them go for 45 min or longer. In the beginning we set the TOT for 2 min and had different machines resetting at different times causing lots of missed conversations etc. After a year of that we went to a system wide TOT of 5 min and that's been working out great as all the machines will reset at once. As far as the repeaters, we only use Motorola MTR2000's of the 100 watt configuration. At full power these machines are designed for 100% duty cycle, so at our allowed 50 watts they are hardly breaking a sweat.

What does “duty cycle” mean?
 
I bring up duty cycle every time I hear somebody talking about making a repeater out of cheap Chinese mobiles and worse any type of handhelds. Duty cycle is the maximum time an amplifier may transmit within a five minute interval, expressed as a percentage, to avoid overheating. Suppose a mobile amplifier is rated at 30% duty cycle. This means that it may transmit for no longer than 1.5 minutes and must remain off for not less than 3.5 minutes. Some people forget that a repeater is transmitting for 2 or more people, duty cycle will be reached quickly if you get into conversation. More people in the conversation just amplifies the issue.
 
Once a radio reaches it's thermal design limits it will no longer be able to adequately cool the output transistors. Even if a radio is not hot to the touch the transistors are, in part because of the inefficient transfer of heat to the units housing or internal heat sink. The longer you exceed the duty cycle the more heat builds on the transistors, surrounding electronics and heat sink effecting it's ability to remain on frequency without spurious emissions. Exceed duty cycle long enough and you will need a new transmitter or radio.
 
I have tested a few Baofang and TYT radios on my service monitor without great results. All of the radios started deviating outside of the allotted channel bandwidth after simulated conversation at 50% duty cycle, the longer I allowed this the worse if got. Testing was done using an Aeroflex 2975 IFR recently back from the calibration lab. 
 
GMRS is a tiny sliver of spectrum surrounded by the commercial land mobile part 90 service. It is important that any repeaters that are built or re-purposed are held to the highest standards and operated as to not cause any interference inside or outside of our allocated spectrum. I wont get into the part 90/95 debate but i do stand firm that non certified import equipment has no place on GMRS. 

Good explanation Corey. Its also important to note that even repeaters have some form of duty cycle and that the duty cycle can change depending on output power. A great example is the motorola 1225 series repeater. At full power, 45 watts, the repeater is limited to a 50% duty cycle. In low power, 25 watts, they are 100% cycle.

Luckily, good repeaters have protection in the form of a Time Out Timer (TOT) and usually a ReSet Timer (RST) When set up correctly, the TOT should cut off the TX BEFORE the duty cycle is reached, and the RST should prevent transmissions until the appropriate rest period has passed. This helps extend the life of the repeater even when your not there to monitor it.

Almost ALL radios now-a-days have a TOT as well. Typically I set mine for 2 minutes which is more than I need to transmit for, but is less than the duty cycle permits thus protecting the transistors.  I've had people tell me its dumb to do as no idiot would want to talk non-stop unless they are in a net or special operation. That's when I give them this story:
 
A while back when I was on the first aid squad, I was getting ready to go to sleep. Turned out the lights, laid my head on the pillow, then came the sound of a soft moan from a woman. Now, this would have been great, if there had been a woman in bed with me. The moaning continued and a bit confused I began looking for the source. Didn't take long to find my squad radio was receiving, and after turning it up a little, yep you guessed it. Turns out, the LT's portable radio had fallen between the bed and the night stand and as they and their lover were going at it, it was all transmitted quite clearly to the repeater, then retransmitted for the ENTIRE COUNTY to listen to. To make matters worse, the radios all had ID numbers so we knew whos radio was transmitting, and even worse, the LT had shut their phone off, so calling them to tell them their private session was public was not doable. Finally, the radios did not have TOT's at the time and so for a good while (I just shut my radio off but a friend at the county said they heard every minute of the 15+ minute incident. When the portable finally cut out, either from overheating or a dead battery or from falling loose of the PTT button, there wee quite a few catcalls to let them know everything was public including a few repeats of nick-names used during the session.

So folks, learn two things from this story. A: TOT's work, especially when a mistake is made or you don't realize the transmit button is pushed, it will work and save your radio from damage and possibly you from some embarrassment. B: Someone is always listening, so keep in mind what you say or do on the radio, especially if you work for a public safety organization because if you say the wrong things you could find yourself in quite a bit of trouble.

The MXT400 is narrow band and overall is not a great performer. I get 10 solid miles simplex on the highway using a Motorola XPR 5550 and a 1/4 wave thru mounted in the roof of a 2015 GMC pickup. The MTX400 and others in the lineup have been discussed in the equipment review section of this site.
 
http://mwgmrs.com/mygmrs/truck3.jpg

What does “duty cycle” mean?
 
I bring up duty cycle every time I hear somebody talking about making a repeater out of cheap Chinese mobiles and worse any type of handhelds. Duty cycle is the maximum time an amplifier may transmit within a five minute interval, expressed as a percentage, to avoid overheating. Suppose a mobile amplifier is rated at 30% duty cycle. This means that it may transmit for no longer than 1.5 minutes and must remain off for not less than 3.5 minutes. Some people forget that a repeater is transmitting for 2 or more people, duty cycle will be reached quickly if you get into conversation. More people in the conversation just amplifies the issue.
 
Once a radio reaches it's thermal design limits it will no longer be able to adequately cool the output transistors. Even if a radio is not hot to the touch the transistors are, in part because of the inefficient transfer of heat to the units housing or internal heat sink. The longer you exceed the duty cycle the more heat builds on the transistors, surrounding electronics and heat sink effecting it's ability to remain on frequency without spurious emissions. Exceed duty cycle long enough and you will need a new transmitter or radio.
 
I have tested a few Baofang and TYT radios on my service monitor without great results. All of the radios started deviating outside of the allotted channel bandwidth after simulated conversation at 50% duty cycle, the longer I allowed this the worse if got. Testing was done using an Aeroflex 2975 IFR recently back from the calibration lab. 
 
GMRS is a tiny sliver of spectrum surrounded by the commercial land mobile part 90 service. It is important that any repeaters that are built or re-purposed are held to the highest standards and operated as to not cause any interference inside or outside of our allocated spectrum. I wont get into the part 90/95 debate but i do stand firm that non certified import equipment has no place on GMRS. 

What does “duty cycle” mean?
 
I bring up duty cycle every time I hear somebody talking about making a repeater out of cheap Chinese mobiles and worse any type of handhelds. Duty cycle is the maximum time an amplifier may transmit within a five minute interval, expressed as a percentage, to avoid overheating. Suppose a mobile amplifier is rated at 30% duty cycle. This means that it may transmit for no longer than 1.5 minutes and must remain off for not less than 3.5 minutes. Some people forget that a repeater is transmitting for 2 or more people, duty cycle will be reached quickly if you get into conversation. More people in the conversation just amplifies the issue.
 
Once a radio reaches it's thermal design limits it will no longer be able to adequately cool the output transistors. Even if a radio is not hot to the touch the transistors are, in part because of the inefficient transfer of heat to the units housing or internal heat sink. The longer you exceed the duty cycle the more heat builds on the transistors, surrounding electronics and heat sink effecting it's ability to remain on frequency without spurious emissions. Exceed duty cycle long enough and you will need a new transmitter or radio.
 
I have tested a few Baofang and TYT radios on my service monitor without great results. All of the radios started deviating outside of the allotted channel bandwidth after simulated conversation at 50% duty cycle, the longer I allowed this the worse if got. Testing was done using an Aeroflex 2975 IFR recently back from the calibration lab. 
 
GMRS is a tiny sliver of spectrum surrounded by the commercial land mobile part 90 service. It is important that any repeaters that are built or re-purposed are held to the highest standards and operated as to not cause any interference inside or outside of our allocated spectrum. I wont get into the part 90/95 debate but i do stand firm that non certified import equipment has no place on GMRS. 

What does “duty cycle” mean?
 
I bring up duty cycle every time I hear somebody talking about making a repeater out of cheap Chinese mobiles and worse any type of handhelds. Duty cycle is the maximum time an amplifier may transmit within a five minute interval, expressed as a percentage, to avoid overheating. Suppose a mobile amplifier is rated at 30% duty cycle. This means that it may transmit for no longer than 1.5 minutes and must remain off for not less than 3.5 minutes. Some people forget that a repeater is transmitting for 2 or more people, duty cycle will be reached quickly if you get into conversation. More people in the conversation just amplifies the issue.
 
Once a radio reaches it's thermal design limits it will no longer be able to adequately cool the output transistors. Even if a radio is not hot to the touch the transistors are, in part because of the inefficient transfer of heat to the units housing or internal heat sink. The longer you exceed the duty cycle the more heat builds on the transistors, surrounding electronics and heat sink effecting it's ability to remain on frequency without spurious emissions. Exceed duty cycle long enough and you will need a new transmitter or radio.
 
I have tested a few Baofang and TYT radios on my service monitor without great results. All of the radios started deviating outside of the allotted channel bandwidth after simulated conversation at 50% duty cycle, the longer I allowed this the worse if got. Testing was done using an Aeroflex 2975 IFR recently back from the calibration lab. 
 
GMRS is a tiny sliver of spectrum surrounded by the commercial land mobile part 90 service. It is important that any repeaters that are built or re-purposed are held to the highest standards and operated as to not cause any interference inside or outside of our allocated spectrum. I wont get into the part 90/95 debate but i do stand firm that non certified import equipment has no place on GMRS. 

We are using Asterisk as the server (running on a raspberry pi 3) and the RTCM made by micro-node. Cheaper hardware solutions vs the RTCM are available but require other configuration. I have not used any of the other hardware so I wont touch on that. I chose the RTCM for its single unit design and application specific properties. The interfacing with the RTCM is rather simple, I went with the MTR2000 repeater for reliability, full duty cycle and used market availability. 
 
Our group hosts its own local node server (Asterisk running on a raspberry pi 3) with 6 repeaters connected to it. This local node also allows us access to the MyGMRS national linking network hosted by the owner of this site. By entering commands in Asterisk or using DTMF,  links to other systems can be connected or disconnected on the fly. Things like usage counters and the visual map show links with red lines as well as what site is transmitting by changing its marker from green to red, all of this in real time.
 
Its not as hard as it sounds, Rich from MyGMRS was a huge help, you can also find a linking thread in the private section here. Along the way I found a company that was able to build a custom cable for interfacing the MTR2000 with the RTCM, it provides a reliable solution that's repeatable and works flawless. The MTR2000 repeater can be configured to work with the RTCM rather simply using the repeaters wire-line card to handle the audio and the 96 pin J5 connector to pull ctcss, core, ptt and power.
 
We are using the RTCM and MTR at 6 sites with a stand alone MTR at a 7th and could not be happier. These machines are worth every penny, its not 2 mobiles in a box its a true full duty cycle, commercial grade repeater. Due to the simplicity I have several more RTCM / MRT2000 combos ready to go I just need to fined a few more tower sites with internet.
 
Hope this answers a few questions.

well i actually ended up getting 2 radios, a tk-860 and a tk-8160. both work good. the 860 is my base and the 8160 my mobile.i stayed away from midland.
did allot of reading before i ordered. decided old kenwood commercial radios (which i've always enjoyed) would be a good fit for me.

We are using Asterisk as the server (running on a raspberry pi 3) and the RTCM made by micro-node. Cheaper hardware solutions vs the RTCM are available but require other configuration. I have not used any of the other hardware so I wont touch on that. I chose the RTCM for its single unit design and application specific properties. The interfacing with the RTCM is rather simple, I went with the MTR2000 repeater for reliability, full duty cycle and used market availability. 
 
Our group hosts its own local node server (Asterisk running on a raspberry pi 3) with 6 repeaters connected to it. This local node also allows us access to the MyGMRS national linking network hosted by the owner of this site. By entering commands in Asterisk or using DTMF,  links to other systems can be connected or disconnected on the fly. Things like usage counters and the visual map show links with red lines as well as what site is transmitting by changing its marker from green to red, all of this in real time.
 
Its not as hard as it sounds, Rich from MyGMRS was a huge help, you can also find a linking thread in the private section here. Along the way I found a company that was able to build a custom cable for interfacing the MTR2000 with the RTCM, it provides a reliable solution that's repeatable and works flawless. The MTR2000 repeater can be configured to work with the RTCM rather simply using the repeaters wire-line card to handle the audio and the 96 pin J5 connector to pull ctcss, core, ptt and power.
 
We are using the RTCM and MTR at 6 sites with a stand alone MTR at a 7th and could not be happier. These machines are worth every penny, its not 2 mobiles in a box its a true full duty cycle, commercial grade repeater. Due to the simplicity I have several more RTCM / MRT2000 combos ready to go I just need to fined a few more tower sites with internet.
 
Hope this answers a few questions.

We are already doing it http://link.mygmrs.com
 
Corey

Does anyone know?

This whole thread hurts and is an absolute waste of time for the actual results. You would have more loss in the phasing harnesses than you would gain.
 
Put up the DB420 and enjoy the hell out of a kicka** antenna.

Now this is a phased array! It is the infamous "Duga Woodpecker" in Russia.

I would not even concider this a mid tier radio, mostly sold on Amazon and eBay its nothing more then a kids toy. For starters it has no ability to do repeater offsets, or programmable tones. A closer look at the company's website and its an Alibaba store front with the typical rebranded TYT, HYT and Baofang offerings as well as some new Chinese junk I have not seen before. I lookup the website registration and it was recently re-hosted and the ownership records updated in January of this year.
 
I would not waste a single cent on this junk, I will stick to my Motorola gear.

1 for the most part GMRS is intended as a Family radio service.
2  cost. I have $$$ into 3 machines. my time, my $$, it is at my digression to let others use it.
3  people can be idiots. you want to act like a fool on my machines I shut them off.
4  this is not HAM
as to being a member, you would have to ask permission and/or seek out the groups repeater you wish to use.
given your location you should/could be hearing machines in LI possibly  a couple of NYC machines.

I just want to know where all these people willing to pay a 100 per year to use the repeaters are! Lets face it, my network covers 3 states and several 1000 sq miles and we have 51 users. Anytime I have needed help with climbers or manpower its always my same core group standing in the driveway. What you are talking about is basically a part 90 community repeater service not GMRS. Again as i stated selling tones is not legal...nor welcome.
 
I would like to hear Pastor Gary's thoughts?

What is the emoji for Nauseated? 

It seems to me this has come up a few times over the last year . I always used the donation approach. I have alot of money invested in repeaters, antenna and cables. If folks want to donate great, if not its on me to cover the costs. I didn't put them on the air to make money, I put them there to use. If others can use it and can afford to help with electric or repairs great. If not its up to me. What your proposing is a LMR system. I for one dont believe in not letting folks use it if they can't afford it. 

I guess everything I have ever learned is wrong, guess I should sell my Areoflex and Sitemaster.

Trouble is most people dont understand what S/N ratio, insertion loss, return loss, impedance, noise floor, velocity factor etc even are. The Yagi example has noting to go with gain at all. I have shown countless people using calibrated industry standard equipment RX gain is nothing more then S/N. If you take a 3dB Yagi and a 18dB yagi, mount them in a fixed position at a fixed signal the uV level received by the test equipment is going to be the same. This is why filtering, pre-amps and attenuator's have a place. Simple really, a filter to reduce the S/N ratio and provide adjacent channel rejection, pre-amp to boost the signal and proper attenuation to lower the noise floor.

Antenna gain is selected based on the site and required coverage area. It is a total misconception that more gain is better. Depending on the antenna height and terrain you can do more damage then good with higher gain. Site engineering is an important part of any system, science and methodology will always provide the best results over what one may think. Unless you are stacking UHF Yagis you will gain nothing by phasing omni's together, you would be better off setting them up diversity using power dividers but this involves its own engineering and the proper test equipment. Co phasing omni's was and still is popular for 10 and 11 meter but that is HF AM not UHF.
 
I currently have several DB-420, DB-411, DB-408, DB-404 and a single Sinclair SC329-HF2LDF in use at different sites both part 90 Commercial and GMRS. Each one selected for the installation and desired coverage. The antenna is the biggest factor in any radio system with the coax the second, trust the science. I have and still do see allot of people wasting money and being unhappy with system performance over bad antenna selection.
 
Just my $.02 
Corey

I just want to know where all these people willing to pay a 100 per year to use the repeaters are! Lets face it, my network covers 3 states and several 1000 sq miles and we have 51 users. Anytime I have needed help with climbers or manpower its always my same core group standing in the driveway. What you are talking about is basically a part 90 community repeater service not GMRS. Again as i stated selling tones is not legal...nor welcome.
 
I would like to hear Pastor Gary's thoughts?

I just want to know where all these people willing to pay a 100 per year to use the repeaters are! Lets face it, my network covers 3 states and several 1000 sq miles and we have 51 users. Anytime I have needed help with climbers or manpower its always my same core group standing in the driveway. What you are talking about is basically a part 90 community repeater service not GMRS. Again as i stated selling tones is not legal...nor welcome.
 
I would like to hear Pastor Gary's thoughts?