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Idea for building Part 95 compliant repeater


commsprepper
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I am new to GMRS and have been looking to get or build a part 95 compliant repeater.  My build idea would use the following, would this make a compliant unit?

 

1. Part 95 Midland MXT115 (15 watt) or MXT400 (40 watt) mobile to server as the transmitter ($150 or $250 respectively)

2. HamTronics R306 UHF receiver (http://www.hamtronics.com/r306.htm) $230

3. HamGear ID-O-Matic controller (http://www.hamgadgets.com/ID-O-MATIC-IV) $40

4. Mobile imported band reject duplexer $125

 

Concept here is to use a Part 95 certified radio as the transmitter and then use low-cost items to complete the build.  Final price would depend on which mobile is used. $545 for 15 watts and 645 for 40 watts.

 

Comments welcomed.

 

 

 

 

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I am new to GMRS and have been looking to get or build a part 95 compliant repeater.  My build idea would use the following, would this make a compliant unit?

 

1. Part 95 Midland MXT115 (15 watt) or MXT400 (40 watt) mobile to server as the transmitter ($150 or $250 respectively)

2. HamTronics R306 UHF receiver (http://www.hamtronics.com/r306.htm) $230

3. HamGear ID-O-Matic controller (http://www.hamgadgets.com/ID-O-MATIC-IV) $40

4. Mobile imported band reject duplexer $125

 

Concept here is to use a Part 95 certified radio as the transmitter and then use low-cost items to complete the build.  Final price would depend on which mobile is used. $545 for 15 watts and 645 for 40 watts.

 

Comments welcomed.

 

I think that any of the new Midlands would be a poor choice for this. You'll want to verify this, but I would be surprised if they're rated for any more than 5% talk if that. In repeater use, they will overheat rapidly and probably fail early on. They just don't have the heat sinking that commercial or professional grade radios have.

 

For $150 or less, you can find a good used Motorola M1225 that will hold up much better than the Midlands, especially if you lower the power out a bit. There are other Part 95 mobiles that would work comparably well.

 

You'll still want to provide extra cooling. A muffin fan works well.

 

I think your HamTronics receiver is overly expensive for what you get. It doesn't even come in case, and you have to purchase the coax separately. You can pick up any number of different commercial grade mobiles for around $100 that will perform equally well. Remember that the receiver does not have to be Part 95 certified.

 

Regardless of your choices, you still need to add in the cost of a decent power supply plus the transmission line and antenna.

 

The ID-O-matic is OK I guess. If it was my project, I'd use a pair of Motorola M1225's and a repeater interface from Ebay seller mre1032. I'd program up the radios identically so that they could be swapped if there's a problem. The two radios would cost barely a half to 2/3 of what you're suggesting, and will perform much better and longer.

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I think that any of the new Midlands would be a poor choice for this. You'll want to verify this, but I would be surprised if they're rated for any more than 5% talk if that. In repeater use, they will overheat rapidly and probably fail early on. They just don't have the heat sinking that commercial or professional grade radios have.

 

For $150 or less, you can find a good used Motorola M1225 that will hold up much better than the Midlands, especially if you lower the power out a bit. There are other Part 95 mobiles that would work comparably well.

 

You'll still want to provide extra cooling. A muffin fan works well.

 

I think your HamTronics receiver is overly expensive for what you get. It doesn't even come in case, and you have to purchase the coax separately. You can pick up any number of different commercial grade mobiles for around $100 that will perform equally well. Remember that the receiver does not have to be Part 95 certified.

 

Regardless of your choices, you still need to add in the cost of a decent power supply plus the transmission line and antenna.

 

The ID-O-matic is OK I guess. If it was my project, I'd use a pair of Motorola M1225's and a repeater interface from Ebay seller mre1032. I'd program up the radios identically so that they could be swapped if there's a problem. The two radios would cost barely a half to 2/3 of what you're suggesting, and will perform much better and longer.

The M1225 won't hold up much better. Too small of a heat sink compared to its predecessors. There was a reason the R1225 was in a GM300/Radius chassis with appropriate heat sink compared to the predecessor repeaters and even it was known for failing.

 

As far as the hamtronics receiver goes, on average they have 40 dB better adjacent channel rejection…so yea the have a lot going for them over a $100 mobile radio.

 

 

 

 

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As far as the hamtronics receiver goes, on average they have 40 dB better adjacent channel rejection…so yea the have a lot going for them over a $100 mobile radio.

Count the number of crystal filters used to achieve such robust selectivity. This would be ideal for any high RF noise environment, but probably overkill for a SHTF repeater... ;)
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UHF Motorola Maxtrac 16 Pin radios are all over now. The PA wasn't the worst of the bunch and the last 2 I picked up were under $50 each. Being GMRS is wide band and most folks can't use these for much else they make great GMRS repeaters. I have 4 set up in different area's and while none are used alot they all function and are easy to setup and build. MY last unit cost jsut under $300 for 2 MAXTRACS, a mobile duplexer and a power supply. 

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UHF Motorola Maxtrac 16 Pin radios are all over now. The PA wasn't the worst of the bunch and the last 2 I picked up were under $50 each. Being GMRS is wide band and most folks can't use these for much else they make great GMRS repeaters. I have 4 set up in different area's and while none are used alot they all function and are easy to setup and build. MY last unit cost jsut under $300 for 2 MAXTRACS, a mobile duplexer and a power supply. 

 

The problem with the Maxtrac, the PA actually backs down in power based on a timer in the logic board. The GM300 on the other hand used a thermistor to control power. 

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