Red's Engineering SRPT-03 Simplex Repeater

[WSFN703]

Background:  A friend has a 10,000 acre ranch in the middle of nowhere.  Cell phone reception is spotty at best.  We were looking for a reliable way to be able to communicate while at the ranch for quick status updates and for emergencies.  About 2/3rds of the land is fairly flat with the other 1/3rd being draws and ridges that limit line of site.  The challenge was threefold; 1) to find a location that allowed "line-of-sight" to as much of the ranch as possible, 2) to have a repeater located at said spot to "see" down the draws, and 3) to limit costs for an occasional use system.  

Equipment:

1. Red's Engineering Simplex Repeater - $61.00
2. Boafeng UV-5R GMRS radios - $31.00 (2pk)
3. A 15' pool cleaning pole - already had from previous project

The Red's Engineering Simplex Repeater features from the website:

• Web based configuration via cell phone
• Works with the Baofeng UV-5R radio
• DTMF detection, enable disable repeater
• Fox Hunt Transmitter Mode
• Periodic Station ID
• 45 second message record time
• Station Identification (Morse Code generation)
• LED Indicators show current status
• Shield type enclosure design
• USB Power / Charging
• Open source software
• OTA Firmware Updates (WiFi)
• Long battery life, ~12 hours talk time, ~10 month active standby

Set-up

After charging the repeater and radio, the set-up was straight forward and is easily done through the app.  You plug in the supplied cable to the repeater and radio.  On the initial startup you must press the reset button.  Turn on the radio and wait a few seconds, turn on the repeater, set the volume to about 50%, and you're ready.  Within just a few minutes I had the repeater programmed, connected to the radio, and bench tested.   In the app you can change the record time, toggle remote enable/disable function, program callsign and ID transmission, and a few other things.  Since we are very remote and the likelihood that anyone else would ever find the repeater is slim to none, I didn't go through some of the whistles and bells.  They may come into use later but I left most everything pretty basic.  

Real-world testing - Home 

After scouring Google Earth, Radio Mobile Online, and SCADACore line of sight generator I determined what I thought was going to be the optimum location for the "tower".  The furthest we would need to transmit and receive would be about 5 miles.  I unceremoniously duct taped the radio and repeater to a telescoping pool pole, ratchet-strapped it to the fence corner post at home and drove just over 7 miles LOS.  I transmitted on channel 5 and heard the repeater, well, repeat back my message.   Since 7 miles was well outside of the limits I needed I felt it was a good test and waited until the next trip to the ranch.  The radio was wearing the Abree AR-771 antenna that came with the radios.  

Real-world testing - Ranch

In a couple of weeks we went to the ranch.  Still using the high-tech duct tape and pool pole, I found the location I had identified and set up the repeater.  Over the course of two days, we tested the repeater at all the blinds we had around the ranch and routes along the way.  We found that the repeater worked as expected and better, hitting one blind that we were skeptical of hitting.  The repeater and radio were left up overnight and the batteries lasted both days.  We were not carrying on conversations, mainly just checking the repeater function and checking in with each other occasionally.  If we had 15 minutes of total talk time I would be surprised.  I was very impressed by the simplistic, but reliable, function of the repeater.  

Take Aways

This is a simplex repeater.  You must accept that you will, at minimum hear your own message repeated back to you.  In some cases, if you are in simplex range of the other radio, you may hear the original message and repeater message of both yourself and who you are talking to.  While some find this cumbersome, it is just the fact of a simplex repeater and if you know it is going to happen you learn to deal with it.  Personally, I didn't find it to be a problem for what we were trying to accomplish. 

For about $100 I don't think it can be beat for what we wanted to accomplish, basic communication for status checks and emergencies.  We also accept that there may still be locations that simply cannot be reached due to terrain.  That is why we stress that we let everyone know where we are going and when, within reason, to expect us back.  No amount of technology should replace a simple "flight plan".  

Future plans

I am now in the process of piecing together a weatherproof housing and solar backup.  The internal batteries will last about three days (not using any of the power-saving functions) at our communication frequency, maybe more.  In the event we are down there for more than a couple of days, solar will allow the batteries to remain topped off.  Additionally, I am looking at "tower" options that allow us to put the repeater up and down when we come and go.  I'm heavily leaning towards a 30' telescoping flag pole (staying with the limiting cost theme).  That will allow us to have a permanent location that is easy to run up and down.  All in I think I'm probably looking at about $300, radio, repeater, pole, solar, and bits and pieces. 

While I tinker with a lot of things, this is my first foray into repeaters, albeit very limited. The Red's Engineering gets my initial thumbs up.  I hope to be back with updates soon.

[WRXL702]

And At The End Of The Day - In My Opinion - (2) 50 Watt GMRS Mobiles With A Quality 5/8 Wave Antenna Will Work Just As Well, If Not Even Better.

[AdmiralCochrane]

4 hours ago, WRXL702 said:

And At The End Of The Day - In My Opinion - (2) 50 Watt GMRS Mobiles With A Quality 5/8 Wave Antenna Will Work Just As Well, If Not Even Better.

Providing one of the 2 radios is at the central "sees all" location.

[WSFN703]

7 hours ago, WRXL702 said:

And At The End Of The Day - In My Opinion - (2) 50 Watt GMRS Mobiles With A Quality 5/8 Wave Antenna Will Work Just As Well, If Not Even Better.

Undoubtedly 50 watt radios would work better, and at twice+ the cost, but that is not what I was trying to do.  That's like saying a backhoe works better than a shovel.  We needed a "shovel" as an occasional use, put up and take down, simple repeater for very limited TX/RX.  So far it meets our needs more than adequately.  

[WRXL702]

Agreed, But To A Limited Extent. Detailed Information On Elevations Is Not Provided For A True Site Evaluation. So For Me - I Would Still Prefer 50 Watt Mobiles For Simplex, Compared To The Limited Use Of A Lower Tier Simplex Repeater System, Just To Be Able To Use GMRS Potable Radios.

Not Trying To Slam Or Condemn Folks On Their Ventures, But Some Folks Always Want To Attempt To Win Their Point Of View, Or Argue It.

I Always Offer To My Repeater Users A Simple Bit Of Advice, Weather It Be Antennas, Coax Or Radio Choices - Application, Application, & Applications.

What Are You Attempting To Accomplish ?

That Should Be The Main Element For A GMRS Operator To Make The Right Decisions Or Choices For Their Particular Use Or Station Purpose.

Personal Opinions Such As Mine & Others Should Be Looked At As Comments & Nothing Else, Unless Asked.

WSFN703 - Good Luck On Your Simplex Repeater Station - Not A Thumbs Up For Me........

 

 

[SteveShannon]

On 1/18/2025 at 3:36 PM, WSFN703 said:

Background:  A friend has a 10,000 acre ranch in the middle of nowhere.  Cell phone reception is spotty at best.  We were looking for a reliable way to be able to communicate while at the ranch for quick status updates and for emergencies.  About 2/3rds of the land is fairly flat with the other 1/3rd being draws and ridges that limit line of site.  The challenge was threefold; 1) to find a location that allowed "line-of-sight" to as much of the ranch as possible, 2) to have a repeater located at said spot to "see" down the draws, and 3) to limit costs for an occasional use system.  

Equipment:

1. Red's Engineering Simplex Repeater - $61.00
2. Boafeng UV-5R GMRS radios - $31.00 (2pk)
3. A 15' pool cleaning pole - already had from previous project

The Red's Engineering Simplex Repeater features from the website:

• Web based configuration via cell phone
• Works with the Baofeng UV-5R radio
• DTMF detection, enable disable repeater
• Fox Hunt Transmitter Mode
• Periodic Station ID
• 45 second message record time
• Station Identification (Morse Code generation)
• LED Indicators show current status
• Shield type enclosure design
• USB Power / Charging
• Open source software
• OTA Firmware Updates (WiFi)
• Long battery life, ~12 hours talk time, ~10 month active standby

Set-up

After charging the repeater and radio, the set-up was straight forward and is easily done through the app.  You plug in the supplied cable to the repeater and radio.  On the initial startup you must press the reset button.  Turn on the radio and wait a few seconds, turn on the repeater, set the volume to about 50%, and you're ready.  Within just a few minutes I had the repeater programmed, connected to the radio, and bench tested.   In the app you can change the record time, toggle remote enable/disable function, program callsign and ID transmission, and a few other things.  Since we are very remote and the likelihood that anyone else would ever find the repeater is slim to none, I didn't go through some of the whistles and bells.  They may come into use later but I left most everything pretty basic.  

Real-world testing - Home 

After scouring Google Earth, Radio Mobile Online, and SCADACore line of sight generator I determined what I thought was going to be the optimum location for the "tower".  The furthest we would need to transmit and receive would be about 5 miles.  I unceremoniously duct taped the radio and repeater to a telescoping pool pole, ratchet-strapped it to the fence corner post at home and drove just over 7 miles LOS.  I transmitted on channel 5 and heard the repeater, well, repeat back my message.   Since 7 miles was well outside of the limits I needed I felt it was a good test and waited until the next trip to the ranch.  The radio was wearing the Abree AR-771 antenna that came with the radios.  

Real-world testing - Ranch

In a couple of weeks we went to the ranch.  Still using the high-tech duct tape and pool pole, I found the location I had identified and set up the repeater.  Over the course of two days, we tested the repeater at all the blinds we had around the ranch and routes along the way.  We found that the repeater worked as expected and better, hitting one blind that we were skeptical of hitting.  The repeater and radio were left up overnight and the batteries lasted both days.  We were not carrying on conversations, mainly just checking the repeater function and checking in with each other occasionally.  If we had 15 minutes of total talk time I would be surprised.  I was very impressed by the simplistic, but reliable, function of the repeater.  

Take Aways

This is a simplex repeater.  You must accept that you will, at minimum hear your own message repeated back to you.  In some cases, if you are in simplex range of the other radio, you may hear the original message and repeater message of both yourself and who you are talking to.  While some find this cumbersome, it is just the fact of a simplex repeater and if you know it is going to happen you learn to deal with it.  Personally, I didn't find it to be a problem for what we were trying to accomplish. 

For about $100 I don't think it can be beat for what we wanted to accomplish, basic communication for status checks and emergencies.  We also accept that there may still be locations that simply cannot be reached due to terrain.  That is why we stress that we let everyone know where we are going and when, within reason, to expect us back.  No amount of technology should replace a simple "flight plan".  

Future plans

I am now in the process of piecing together a weatherproof housing and solar backup.  The internal batteries will last about three days (not using any of the power-saving functions) at our communication frequency, maybe more.  In the event we are down there for more than a couple of days, solar will allow the batteries to remain topped off.  Additionally, I am looking at "tower" options that allow us to put the repeater up and down when we come and go.  I'm heavily leaning towards a 30' telescoping flag pole (staying with the limiting cost theme).  That will allow us to have a permanent location that is easy to run up and down.  All in I think I'm probably looking at about $300, radio, repeater, pole, solar, and bits and pieces. 

While I tinker with a lot of things, this is my first foray into repeaters, albeit very limited. The Red's Engineering gets my initial thumbs up.  I hope to be back with updates soon.

Nice job building something that meets your needs  and describing it. As long as it does what you want that’s all that matters. Fortunately there are many ways to do something. Your way is inexpensive and simple.

Thanks for telling us about it. 

[gortex2]

This is an ideal situation for the RT97 repeater. Add a battery and a little antenna and it will sit and tick away. 

[WRUI365]

2 hours ago, gortex2 said:

This is an ideal situation for the RT97 repeater. Add a battery and a little antenna and it will sit and tick away. 

Don't forget at least a 25watt solar panel to keep said battery charged

[AdmiralCochrane]

I still say the properly located simplex repeater is superior.  Wattage does not guarantee comms across blind ridges.

[WRHS218]

I enjoy working solutions like 703 did. Finding something that works for your needs on your budget. Sure there are other ways to do things but he got it done. I can see a use case for a simplex repeater like he put together.