Retevis RT97 Portable GMRS Repeater 5W

[Extreme]

Retevis RT97 Portable GMRS Repeater 5W

 

I'm considering this for my 5th wheel that already has 400w of solar and 2000w inverter.

I expect it would not draw a ton of capacity from my battery 'plant'. 

 

Question I have is on antenna placement/mounting on a rubber roof.  Could I build a ground plane mount on the ladder or maybe a bracket somewhere else on top?

 

Next question:  How about dropping it on a bald/rocky mountaintop during hunting season.  Power:  can I use a mini-solar panel or would a USB power pack keep it going?

 

Looking for a link to a simple portable repeater build that this would work with.

 

Thanks

 

 

 

 

[gortex2]

So for the 5th wheel I would use a standard base style antenna. I run the Laird omni. Its only 20" tall and I use the provided brackets on my ladder on the back of the MH when i get on site. I have also used it on my fiberglass flagpole but found I didn't gain much range even going up 15'. Its the FG4500 below is one place that stocks them. 

 

https://www.theantennafarm.com/catalog/index.php?main_page=product_info&cPath=1096&products_id=1057

 

I have a 25' piece of RG213 that is N Male on both ends. I connect it to the antenna and drop it down behind the ladder. I run it to my compartment that has a GR1225 currently. It works really good at campgrounds and the NASCAR tracks I frequent. I used it at JJ2020 but other than me on it I never heard another jeeper. 

 

https://www.theantennafarm.com/catalog/index.php?main_page=product_info&cPath=342_343_1438_1411&products_id=6843

 

I really want to swap out to the RT97 mainly because I dry camp at the NASCAR tracks and the GR is a power hog. I pull the fan power when I am not on AC but still at 10 watts it uses more power than I want. My hope is to swap to the RT97 also so I can jsut wire it to a switch and power on, vs swapping from power supply to battery every time I use it. 

 

You could probably use the same antenna with a 3' jumper if you can carry it to a high place and strap the antenna to something to keep it up. An old camera tripod may be perfect for that combo. Not sure how much battery you would need. Remember the more you talk the more battery needed.

[MacJack]

I was ready to get a Retevis RT97 BUT my scope for a repeater has changed like your family need to be multi purpose.  So I just picked up a GR1225 for $300 and power it to 25 watts for family at home then move it to RV and Jeeping (your hunting use).  This new purchase can run on standby 12 volt battery and trickle charge off of 110v plus I have solar panel for charging in RV as well as an inverter that I will plug it into.  So I can do RV site and solar thus I when bigger and not RT97.  So I'm got a https://www.ebay.com/itm/GMRS-HAM-UHF-5dB-gain-Repeater-Base-Antenna-/112813555663 for the RV and Jeep and for the home base a https://www.commscope.com/product-type/antennas/base-station-antennas-equipment/base-station-antennas/itemdb404-b/

 

I'm open for comments as these items in the cart not purchased yet.

Thanks,

 

Jack 

 

Edit: kb2ztx can you power down your GR1225 to less than 10 watts?

[gortex2]

For your house the DB404 is an excellent antenna and will serve you for quite some time if installed and cabled correctly. Get decent RF cable. Try to stay away from LMR400. Depending on how long of a cable short runs of LDF can be found reasonable online. 

 

I'll be honest I'm not a fan of the home brew antenna's from Ebay regardless if it the Ed Fong or others. They are all good to get started i suppose, but i never had good luck with them. Some swear by them. For me for the $20 difference in price there are decent commercial antennas out there even on ebay. As said earlier for cable go with the RG213 version and not LMR for mobile use. 

 

The GR1225 is high and low power. Without the proper equipment and tuning your not going to get it below 10 watts. Your going to have loss in the duplexer anyway so just use low power and be happy. They are good repeaters for what you want to do. If it has the battery revert module installed you can run a new power cable directly to your house DC system and it will switch from AC to DC all by itself.

[MacJack]

Thanks for confirmation on DB404.  Yes the RV antenna is a Ed Fong.

Jack

For your house the DB404 is an excellent antenna and will serve you for quite some time if installed and cabled correctly. Get decent RF cable. Try to stay away from LMR400. Depending on how long of a cable short runs of LDF can be found reasonable online. 

 

I'll be honest I'm not a fan of the home brew antenna's from Ebay regardless if it the Ed Fong or others. They are all good to get started i suppose, but i never had good luck with them. Some swear by them. For me for the $20 difference in price there are decent commercial antennas out there even on ebay. As said earlier for cable go with the RG213 version and not LMR for mobile use. 

 

The GR1225 is high and low power. Without the proper equipment and tuning your not going to get it below 10 watts. Your going to have loss in the duplexer anyway so just use low power and be happy. They are good repeaters for what you want to do. If it has the battery revert module installed you can run a new power cable directly to your house DC system and it will switch from AC to DC all by itself.

[Radioguy7268]

The R1225 UHF repeater came in 2 versions. A Low Power model starting with model # M04GRC*****   and a Higher power version model starting with M44GRC*****

 

The lower power version will do 1-10 watts - and do it with nearly a 100% duty cycle. Those units have a smaller heat sink on the back of the transceiver, and rarely had problems with burning up, even with heavy use. Many people used those for on-site use with Portable radios, or for driving a power amplifier to achieve higher wattage power outputs with a higher degree of reliability in high duty cycle applications.

 

The high power versions were rated as being 50% duty cycle at 40 watts, and 100% duty cycle at "mid power" settings of 20-25 watts. Those units commonly burned up - especially if someone tried to run them at 40 watts with anything approaching 5 minute conversation times. The higher power models did have a much more substantial heat sink on them, but you still needed to have good airflow if you wanted to run them at even 25 watts for any period of time. I've seen those units burned up even when run at the lower power levels that were advertised as 100%. Motorola should never have sold the higher power version at any level above 25 watts, and they should have said even then that it was a 50% duty cycle IMHO.

 

I would be VERY careful buying a GR1225 off Ebay if I didn't know the seller or the source of the unit. Make sure it works and transmits with advertised power! Make sure the seller accepts a return if it doesn't. The amplifiers can be repaired, but its done wrong as often as it's done right. The cost to repair a burned up unit at the local radio shop would probably equal or exceed what you paid for it.

[MacJack]

You are confirming everything the seller said and is doing... Not a eBay purchase, which I only use to get hard to find spare parts.  Keep the advice coming.  putting unit on the counter top with the AC on.

Jack 

The R1225 UHF repeater came in 2 versions. A Low Power model starting with model # M04GRC*****   and a Higher power version model starting with M44GRC*****

 

The lower power version will do 1-10 watts - and do it with nearly a 100% duty cycle. Those units have a smaller heat sink on the back of the transceiver, and rarely had problems with burning up, even with heavy use. Many people used those for on-site use with Portable radios, or for driving a power amplifier to achieve higher wattage power outputs with a higher degree of reliability in high duty cycle applications.

 

The high power versions were rated as being 50% duty cycle at 40 watts, and 100% duty cycle at "mid power" settings of 20-25 watts. Those units commonly burned up - especially if someone tried to run them at 40 watts with anything approaching 5 minute conversation times. The higher power models did have a much more substantial heat sink on them, but you still needed to have good airflow if you wanted to run them at even 25 watts for any period of time. I've seen those units burned up even when run at the lower power levels that were advertised as 100%. Motorola should never have sold the higher power version at any level above 25 watts, and they should have said even then that it was a 50% duty cycle IMHO.

 

I would be VERY careful buying a GR1225 off Ebay if I didn't know the seller or the source of the unit. Make sure it works and transmits with advertised power! Make sure the seller accepts a return if it doesn't. The amplifiers can be repaired, but its done wrong as often as it's done right. The cost to repair a burned up unit at the local radio shop would probably equal or exceed what you paid for it.

[Extreme]

What kind of power would I need to place this temporarily on a mountaintop for hunting?  I know I'd get excellent coverage from the spot I have in mind, including back to my camp 1000' or more below.

 

Solar:  what size, amperage, etc.?

Battery:  Same question.

 

Would probably leave it in place for a few weeks or possibly relocate depending on coverage.

 

Obviously I don't want to pack a lot of weight 1000 yds up a very steep hill.  

 

Spit balling...

 

Thanks.

[MacJack]

You guys have been so helpful.  My mentors and coachs move me from a GR1225 to a VRX-7000 as they have this unit and will help me by programing it to my base and RV needs.

 

I will started with a Ed Fong rollup antenna for use on my RV but to start will use it at base.. Let's face it ... I have not found the perfect location on the house and need architectural approval (from my wife) to locate a DB 404 on top of my chimney which is the highest structure on the house, some 300 feet above ground (split level but only has two stories with a fake doomer third floor).

 

Keep in touch with suggestions.

Jack 

[mbrun]

What kind of power would I need to place this temporarily on a mountaintop for hunting? I know I'd get excellent coverage from the spot I have in mind, including back to my camp 1000' or more below.

 

Solar: what size, amperage, etc.?

Battery: Same question.

 

Would probably leave it in place for a few weeks or possibly relocate depending on coverage.

 

Obviously I don't want to pack a lot of weight 1000 yds up a very steep hill.

 

Spit balling...

 

Thanks.

There are a lot of factors to consider. Let’s start with the basics.

 

How much power does the repeater actually draw when transmitting. Although it is rated at 5 watt output, it may very well draw 12-15 watts or more power. You will want to confirm this as this identifies your worst case load load scenario.

 

You need to know how much power it draws when sitting idle, while powered on but doing nothing. This establishes your best case scenario.

 

How much time do you estimate the repeater will actually be transmitting per day? This value combined with the numbers above will then help you establish how much power is needed to keep you operational for 24 hours.

 

If you were packing in battery packs as your sole means of power, the amount of power needed per day can easily be used to calculate how much usable battery capacity to carry in.

 

Now, if you are going to use solar to recharge the batteries, you need to establish how long you anticipate (worst case) that you might be without useful sun for solar charging. This number of days multiplied by the watt hours of power needed to run the radios per day then helps you determine the minimum usable capacity of battery packs you need to bring in.

 

Now, the type of battery pack you go with will also be a factor.

Lead acid batteries should not typically be deep cycled routinely, although they can in a pinch. When designning a system that uses them it is pretty common to assume you would only ever use 50% of their capacity so you would want twice the needed capacity as its rated capacity. On the other hand, if you use one of the various lithium chemistries you will be able to leverage more of the batteries rated capacity before you must recharge.

 

OK, now that you know how much battery capacity you may need, now you turn to sizing your solar panels. You need solar panels that can deliver enough power during daylight hours to operate your repeater, with plenty of extra capacity to recharge the batteries from the previous night or past several rainy days.

 

So since all of the above factor in and we don’t yet know any more particulars, let’s start simply.

 

Let’s say your repeater actually consumes 15 watts. Let us be absurd and assume it would transmitting all day long. For the whole day the repeater would consume a total of 360 watt hours of power (15w x 24hr) or approx 30 Ah (1.25A * 24 Hr) of 12vdc power. A deep cycle battery with a REAL usable capacity of 100Ah has about 1200 watt hours +/- of potential energy.

 

From the above your can see that if you truly had 100Ah of usable capacity, with a 15w continuous load you could perhaps run just over three days on this battery. Now, if you drop your repeater transmission time to say only 5-10% of the day, then your battery will last you quite a bit longer.

 

Finally. If 360 watt hours is the worst case operating scenario, then solar panels capable of replenish this 360 watts daily, plus more for charging the batteries is in order. But, if your worst case daily usage is only on the order of say 50 watt hours, then you need much less in the way of solar panels.

 

Now it is all about the numbers. What is the specific scenario you are trying to satisfy? I think you will be able to do the math from here.

 

Hope this helps.

 

 

Michael

WRHS965

KE8PLM

[Extreme]

I'll dig into this.

 

Thanks!

[OldRadioGuy]

You hunters may want to read my posting from this morning on Simplex repeaters in the "general" section of the forum.

 

Vince