Retevis RB91 Digital Repeater

[WSDU214]

Hi there folks, I am new to GMRS radios. I wish to expand the range of my GMRS 9R radios to my area of interest that has a slope downhill on the way back uphill. Not getting any signal after .75mile.  Once a get to the bottom of the hill, there is a nice size lake. Versus other areas I get over a mile range. Will this repeater assist with it & what type & size antenna I should get?  Thank you in advance for taking time in your busy day to answer my question.

[SteveShannon]

The radio plus repeater setup in the pictures is not GMRS and will not support GMRS radios. 

[WSDU214]

@SteveShannon, thank you for the response sir. So I gather the RT97S is the choice to make?

[SteveShannon]

53 minutes ago, WSDU214 said:

@SteveShannon, thank you for the response sir. So I gather the RT97S is the choice to make?

It’s one choice. There are others and without a basic familiarity with your situation I would not make a recommendation. 
What exactly are you trying to do?

[WSDU214]

@SteveShannon, I live a mile away from a lake called Lake Hollingsworth in Lakeland Florida. I use it to exercise around the perimeter which is about a 5K loop. I wish to be able to talk to my wife via radio for any emergency while I am in that area. Let me share with you information on the area.  https://www.tripadvisor.com/Attraction_Review-g34373-d4723284-Reviews-Lake_Hollingsworth-Lakeland_Florida.html.  

Can a specific repeater help me accomplish this task? If so what name & model#? Would the RT97S with a 5Ft Antenna on my roof do the trick? I am using the BAOFENG GMRS-9R, I like it since its water proof/wish to leave my cell phone home since may times it rains. Do I need to get a better GMRS radio for this on top of the repeater? If so which make/model?

[BoxCar]

No, a repeater is NOT what you need. Just a 20-25W radio set up in the house with an antenna 15-25 feet above the roof.

[WSDU214]

@BoxCar, thank you sir for this feedack. Much appreciated. What make/models you suggest?

 

 

[BoxCar]

They are all about the same. The fact about FM is that all radios using analog FM are compatible. Don't overpay, but don't skimp either. The Radioddity 20W is good along with any other in the price ($20) range is what I would recommend. The Radioddity brand was provided as only a start, not necessarily recommendation. You will need coax with PL-259 connectors, LMR-400 quality and an antenna. Your situation, where you're talking only a few miles requires just a J-Pole style and my recommendation here is not an Ed Fong but an https://www.jpole-antenna.com/shop/462-mhz-land-mobile-gmrs-j-pole-antenna/,

[WSDU214]

@BoxCarI appreciate you. Thank you for your feedbacks

[WSDU214]

@BoxCar, please confirm if these items will work for my set up from amazon. 

https://www.amazon.com/dp/B096533TR6?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY_2

https://www.amazon.com/dp/B09CKJ2RXS?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY

https://www.amazon.com/dp/B097Y67XQ3?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY_1

Again thank you for taking the sime to give me feedback. 

[pl4tinum]

On 7/21/2024 at 11:27 AM, BoxCar said:

No, a repeater is NOT what you need. Just a 20-25W radio set up in the house with an antenna 15-25 feet above the roof.

If OP needs to reach his wife, she would only hear a base unit if she is right there in the room containing the radio.  With a repeater she can carry a small HT while she move about the house or steps outside.  A repeater would also give a little more placement flexibility vs needing the radio in a specific location inside the house, and potentially less antenna feedline meaning less loss.  Personally I would probably still use a repeater.

 

OP, it matters most what type of terrain is between your home and the lake and how clear the line of sight is.

[pl4tinum]

8 minutes ago, WSDU214 said:

@BoxCar, please confirm if these items will work for my set up from amazon. 

https://www.amazon.com/dp/B096533TR6?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY_2

https://www.amazon.com/dp/B09CKJ2RXS?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY

https://www.amazon.com/dp/B097Y67XQ3?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY_1

Again thank you for taking the sime to give me feedback. 

I know I'm not who you are asking, but I have a DB20G and it's a very nice radio for the price.

I am partial to Ed Fong DBJ antennas and I usually order one from him with an N-type connector on the antenna, and then get a custom Messi and Paolomi UHF to N-type cable as n-type has better water resistance.  And/OR you can seal up the connection with silicone tape: https://www.amazon.com/Proxicast-Pro-Grade-Weatherproof-Self-Fusing-Electrical/dp/B00K5GW67O/

[WSDU214]

@pl4tinum Thank you sir, I am thinking about the repeater honestly since I will be spedinig about $150 less with the other cost effective option. I have a line of sight of houses & trees straight from my house ending on the lake a mile later exactly. If I use a large antenna on the radio at home & my redio from the lake at that point I get somewhat signal but not steady. The lake ends down a small hill. Now once on the lake property its 5K in circumference all open ground in all directions. Here is the URL on the proerty so you get on idea: https://www.tripadvisor.com/Attraction_Review-g34373-d4723284-Reviews-Lake_Hollingsworth-Lakeland_Florida.html.  

Please advise at your earliest convenience

[pl4tinum]

7 minutes ago, WSDU214 said:

@pl4tinum I have a line of sight of houses & trees straight from my house ending on the lake a mile later exactly.

Sorry could you clarify a little bit, are you saying you can see the lake from your house?  Or that you only see houses and trees that are in the way?

When you say "If I use a large antenna on the radio at home" do you mean a large external antenna on the roof or a longer antenna on the handheld at home?

[WSDU214]

@pl4tinum Be happy to. The line of sight its a straight mile to ending on the lake. Due to a small downhill can't see it otherwise I would see the lake from here. The antennas, are on the handheld radios. The GRMS 9Rs come with foldable large antennas you can switch to sir. 

[BoxCar]

43 minutes ago, WSDU214 said:

@BoxCar, please confirm if these items will work for my set up from amazon. 

https://www.amazon.com/dp/B096533TR6?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY_2

https://www.amazon.com/dp/B09CKJ2RXS?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY

https://www.amazon.com/dp/B097Y67XQ3?psc=1&ref_=cm_sw_r_cp_ud_ct_1BN20CJ4QYEDNZDJAAXY_1

Again thank you for taking the sime to give me feedback. 

They are fine with the exception of the coax. I recommend https://thewireman.com/product/cq-rg8-low-loss-4xl-lmr400-equivalent/ for coax ($1.80 per foot). If you order from the Wireman, you will need 2 PL-259 connectors and 2 installations. The connectors are either $3 or $6 each and there is a $5 install charge for each. The Wireman also charges for shipping so that's an added cost. I use coax from this vendor for my own site.

[pl4tinum]

If you do decide to go the repeater route, or may use a repeater in the future, you want an all-copper feedline to reduce the likelihood of "duplex grunge" aka PIM  distortion (passive intermod distortion).

Typically you'd want something super high end like andrew heliax but there are some good all-copper coax by Messi and Paolomi.  You can order custom cables from them and you probably want ultraflex 10 (ultraflex 10 and broad pro c 50 are the only ALL copper cables).  If you go with them get the UHF Male PL259 EVO connectors.  If you can get the antenna or repeater in an n-type connector, get the appropriate amount of n-type ends on your cable as well.  RT97S for instance only comes with a UHF connector not n-type.

https://messi.it/Calc/ordine.aspx?l=EN

They are in Italy but shipping speed and price is reasonable.  You can also find their cables pre-made in common lengths from gigaparts and buytwowayradios.  Just make sure it's ultraflex 10 or broad pro c 50.

Whatever route you choose, a base station unit or repeater, just getting the antenna out onto the roof will make a big difference.

[WSDU214]

@pl4tinum much appreciated sir. Semper Paratus!

 

[BoxCar]

18 hours ago, pl4tinum said:

If you do decide to go the repeater route, or may use a repeater in the future, you want an all-copper feedline to reduce the likelihood of "duplex grunge" aka PIM  distortion (passive intermod distortion).

 

i believe you are dismissing the Shannon Effect in stating you need solid copper core coax. The Shannon Effect (not our Steve's notes) states the higher the frequency, the electrons move closer to the surface of the conductor. That's one reason some coax has steel or aluminum cores and just a copper shell. The key figure to check in the cable's specs is the velocity of propagation along with the cable's loss.

Edited July 24 by BoxCar
incomplete

[WSDU214]

Folks, inccidentally. I noticed that these radios come with the Chirp USB cable. I dowloaded the software to my windows OS but I don't see the model# for my radio on the options to dowload the radio. Checked the manual it came with and now information. I am trying to program it with CHIRP. Any ideas or resources on the Baofeng GMRS 9R that I like a lot? @BoxCar,   @SteveShannon @pl4tinum

[amaff]

17 minutes ago, WSDU214 said:

Folks, inccidentally. I noticed that these radios come with the Chirp USB cable. I dowloaded the software to my windows OS but I don't see the model# for my radio on the options to dowload the radio. Checked the manual it came with and now information. I am trying to program it with CHIRP. Any ideas or resources on the Baofeng GMRS 9R that I like a lot? @BoxCar,   @SteveShannon @pl4tinum

just because it comes with a cable doesn't mean the radio is Chirp supported. What radio are you talking about? The thread's about an RB91 digital repeater, ostensibly. I doubt that's what you're trying to program in Chirp....

[SteveShannon]

1 hour ago, BoxCar said:

i believe you are dismissing the Shannon Effect in stating you need solid copper core coax. The Shannon Effect (not our Steve's notes) states the higher the frequency, the electrons move closer to the surface of the conductor. That's one reason some coax has steel or aluminum cores and just a copper shell. The key figure to check in the cable's specs is the velocity of propagation along with the cable's loss.

That’s true, and unfortunately no, it’s not me.  It’s possible it was a relative, but I don’t really know.

The effect @pl4tinum was talking about applies to layering mixed metals in the shielding of coaxial cables.  True LMR400 has a copper braid over an aluminum foil layer which some people claim forms tiny semiconductor elements at the points where the two “incompatible” metals touch.  That’s different from the copper cladding over aluminum on the center conductor, which genuine LMR400 also has, but which nobody I know warns against.

Are the deleterious effects of these spontaneous semiconductors real or myth?  I don’t know.  The warnings also say that these effects only cause an issue when full duplex transmissions are occurring, not the half duplex we do with our base and mobile stations.

[WSDU214]

@amaffI am using BAOFENG GMRS 9R

[pl4tinum]

On 7/24/2024 at 7:49 AM, SteveShannon said:

The effect @pl4tinum was talking about applies to layering mixed metals in the shielding of coaxial cables.  True LMR400 has a copper braid over an aluminum foil layer which some people claim forms tiny semiconductor elements at the points where the two “incompatible” metals touch.  That’s different from the copper cladding over aluminum on the center conductor, which genuine LMR400 also has, but which nobody I know warns against.

Are the deleterious effects of these spontaneous semiconductors real or myth?  I don’t know.  The warnings also say that these effects only cause an issue when full duplex transmissions are occurring, not the half duplex we do with our base and mobile stations.

Correct, and I'm not an expert on RF theory but did a lot of research to select an appropriate feedline.  There is a good writeup here https://www.bridgecomsystems.com/blogs/bridgecom-official-blog/how-to-select-feedline-for-a-repeate which is primarily what I based my selection on.

The article recommends against any LMR-### or LMR-#### for duplex service, and to instead use Superflex, Heliax, RG-214, or RG-393 on the antenna side of the duplexer.  I don't know if a copper clad aluminum core will be an issue but something like M&P UtraFlex 10 is a good alternative to heliax and not much more expensive than a quality cable of the types listed above.

I've experienced duplex grunge testing an RT97S with a Nagoya UT-72 antenna which is about 15 feet of PL-259 edit: RG-58A/U.  I believe that coax is a copper clad aluminum center and copper clad aluminum  edit: tinned copper braiding.  After releasing PTT there would be a low pitch screech which would sometimes continue activating the repeater for a few seconds.

Edited July 25 by pl4tinum
Typing too fast, made some errors

[amaff]

14 minutes ago, WSDU214 said:

@amaffI am using BAOFENG GMRS 9R

Try this: