Jump to content

Can a high wattage micromobile in camp act as a repeater between two handhelds?


Guest John Wright
 Share

Recommended Posts

I was a little surprised to see in a lot of reviews that with most handheld GMRS radios you can only expect about a one-mile range between the two handhelds when hiking in forested areas.  Does anyone know if a high wattage Micromobile Two-Way Radio like the Midland MXT400 that is back in camp can be configured to act as a repeater between the two handhelds to extend this one-mile range?  I am not sure if this question is worded clearly but would a high gain antenna mounted on a RV roof connected to a 50 watt micromobile GMRS radio back in camp serve as a repeater for the two handhelds on separate trails and extend the range between handheld 1 and handheld 2 beyond one mile.

 

Link to comment
Share on other sites

Good Day John.

 

axorlov is correct, you could do that with a human dispatcher that relays/echos the messages. That human effort and associated echo would certainly get old.

 

If you desire a duplex repeater setup you have several options.

 

First option is to purchase a purpose-built repeater, perhaps an all-in-one unit. There is an affordable fixed purpose unit like that sold right here on the myGMRS site ideal for just the scenario you describe. There are also higher priced commercial units available.

 

Second option is purchase a pair of standard mobile radios, plus duplexer, antenna and controller and assemble one yourself. If you consider this option, the Wouxun KG-1000G has features that simplify this a tad over say a pair of MXT-400. The beauty of this arrangement is then have the option to use the component radios independently when repeater operation is not required.

 

Third option is doing the same as above but instead some HTs. Some of have done this. I suspect you will find this works but will have the lowest performance of all your options. Plus your talk time will be limited.

 

The beauty of the all-in one is that you could you can perhaps hoist the repeater and antenna high into a tree (or use a push-up mast you take with you) to get some serious elevation. Elevation pays more in range dividends than any legal GMRS power will practically get you.

 

I was a little surprised to see in a lot of reviews that with most handheld GMRS radios you can only expect about a one-mile range between the two handhelds when hiking in forested areas. Does anyone know if a high wattage Micromobile Two-Way Radio like the Midland MXT400 that is back in camp can be configured to act as a repeater between the two handhelds to extend this one-mile range? I am not sure if this question is worded clearly but would a high gain antenna mounted on a RV roof connected to a 50 watt micromobile GMRS radio back in camp serve as a repeater for the two handhelds on separate trails and extend the range between handheld 1 and handheld 2 beyond one mile.

 

Michael

WRHS965

KE8PLM

Link to comment
Share on other sites

With a human dispatcher, yes, certainly. With a simplex repeater (seems to be not allowed by Part 95 rules), yes. To make a regular repeater one would need two radios, diplexer, repeater controller, etc..

I don't see anywhere in the rules any prohibition of a simplex repeater. Unless something is expressly prohibited, it is permitted.

 

Sent from my SM-T350 using Tapatalk

Link to comment
Share on other sites

Store and forward systems are prohibited. Simplex repeater could be interpreted as store-foward.

With that said, I admit to using Argent Data simplex repeater for the stated purpose. It's too damn useful in the woods.

 

I was just looking through Part 95 looking for such a GMRS exclusion. I found only two references to store and forward (e.g. Simplex Repeater). Both were prohibitions in non-GMRS services. FRS and MURs. One is 95.2733. The other is 95.987.d.

Since repeaters are allowed in GMRS, and since there is no express exclusion of S&F devices in 95e, I conclude they are legal for use, but only when using the 462 main channel frequencies.

 

BTW, I too own the Argent Data SR1. Nice little box. Actually bought it to facility one-man simplex radio testing. It is programmed to give my callsign both in CW and in Voice.

 

 

Michael

WRHS965

KE8PLM

Link to comment
Share on other sites

I was just looking through Part 95 looking for such a GMRS exclusion. I found only two references to store and forward (e.g. Simplex Repeater). Both were prohibitions in non-GMRS services. FRS and MURs. One is 95.2733. The other is 95.987.d.

Since repeaters are allowed in GMRS, and since there is no express exclusion of S&F devices in 95e, I conclude they are legal for use, but only when using the 462 main channel frequencies.

 

BTW, I too own the Argent Data SR1. Nice little box. Actually bought it to facility one-man simplex radio testing. It is programmed to give my callsign both in CW and in Voice.

 

 

Michael

WRHS965

KE8PLM

We actually discussed this here on this forum exactly a year ago, and I promised to find the wording. I still owe this to the community. One day (or night) when all booze is gone I'll do it. What I remember, is a specific prohibition or repeaters (with the word "repeater" explicitly used) for FRS, CB and MURS. But I also remember about store-and-forward not allowed either for 95E or for all of 95.

Link to comment
Share on other sites

We actually discussed this here on this forum exactly a year ago, and I promised to find the wording. I still owe this to the community. One day (or night) when all booze is gone I'll do it. What I remember, is a specific prohibition or repeaters (with the word "repeater" explicitly used) for FRS, CB and MURS. But I also remember about store-and-forward not allowed either for 95E or for all of 95.

Since you brought up the prohibition, it is now incumbent on you to back it up.

 

Sent from my SM-T350 using Tapatalk

Link to comment
Share on other sites

The other way is to get a Ham license and do a cross band repeater on 2M/70cm. 

Several mobile units and the Wouxun UV9? will do cross band repeat.  

Cross band repeaters do not require duplexers so much much easier and cheaper to do. 

 

I know - the problem is that your camping buddies and family don't want to get a ham license. 

That's why I have GMRS :-) 

 

A different way to address the problem is better antennas. 

I have a couple Nagoya 771 and Smiley Super Stick antennas for my Wouxun 805G's and they do help. 

 

Terrain is a huge factor so always good to be aware of it. 

Maybe have a look on Gmaps before going camping just to have a general idea. 

 

Vince

Link to comment
Share on other sites

The other way is to get a Ham license and do a cross band repeater on 2M/70cm. 

Several mobile units and the Wouxun UV9? will do cross band repeat.  

Cross band repeaters do not require duplexers so much much easier and cheaper to do. 

 

 

Vince

That particular type of cross-band is specifically called out as not permitted. Part 95 and Part 97 frequencies can't be intermixed.

Link to comment
Share on other sites

That particular type of cross-band is specifically called out as not permitted. Part 95 and Part 97 frequencies can't be intermixed.

To clarify you can't do cross band repeat on Part 95. It's done all the time on Part 97, particularly between the Ham 2M and 70cm bands. I think that's what the OP was trying to convey.

 

It's true you can't do direct cross communications between the two licensed services. Technically there is a way to do it using the right unmodified radios. However the way it could be done would violate rules that say Hams can ONLY communicate with other stations licensed in the armature service, and except for brief one way transmissions for testing for example, one way transmissions are prohibited.

 

I'm not advocating people do this but as a purely theatrical exercise it could be done as follows.

 

Many Ham HT's can do split band operations, TX on one frequency while RX on another in the same band much like repeater operations. In this case the TX frequency would be one in the legal section of the Ham 70cm band while the RX is set to one of the official GMRS channel frequencies. Thus the Ham would be TX'ing on a legal Ham 70cm frequency while ONLY RX'ing on a legal GMRS channel frequency.

 

Using the right GMRS radio that allows programming of out of band RX ONLY frequencies for monitoring and a priority RX function would be used. The GMRS radio would be programed to TX on the legal GMRS frequency the Ham HT is programed to RX on. The GMRS radio would have it's priority RX programed for the legal Ham's HT's TX frequency. The GMRS radio would then constantly monitor the priority RX frequency.

 

Both radios are now TX'ing on their respective legal frequencies while RX'ing on the others TX frequency effecting cross service communications with unmodified radios.

Link to comment
Share on other sites

Thanks for clarifying that I meant x-band repeater operation only within the ham bands. 

I was not suggesting to mix ham and GMRS signals.... which is not even possible with the radios I mentioned. 

Well, it's possible,  but not without some serious hacking. 

 

Vince

Link to comment
Share on other sites

Keep in mind this repeater can only operate on ONE of the GMRS repeater channels at a time This is due to the notch duplexer. It can ONLY be tuned for one TX and one TX frequency at a time. If you need to change the repeater channel the notch duplexer must be retuned. That requires equipment most people don’t have or a trip to the local commercial radio shop.

Link to comment
Share on other sites

  • 3 weeks later...
On 4/15/2021 at 4:47 PM, mbrun said:

First option is to purchase a purpose-built repeater, perhaps an all-in-one unit. There is an affordable fixed purpose unit like that sold right here on the myGMRS site ideal for just the scenario you describe. There are also higher priced commercial units available.

...

The beauty of the all-in one is that you could you can perhaps hoist the repeater and antenna high into a tree (or use a push-up mast you take with you) to get some serious elevation. Elevation pays more in range dividends than any legal GMRS power will practically get you.

@mbrun

Hey I'm new here & to GMRS, and it wouldn't let me post in this general forum when I signed in. Anyway, what models of these all-in-one repeaters exist, and generally how much do they cost? The idea of a base campsite with a repeater on a pole for better range seems like a great idea that I'd like to try out.

- Ben, WRML438

Link to comment
Share on other sites

On 4/17/2021 at 4:53 PM, Lscott said:

Keep in mind this repeater can only operate on ONE of the GMRS repeater channels at a time This is due to the notch duplexer.

I was rather surprised that the notch duplexer is fully capable of passing +/- 500kHz from the tuned center frequencies without all that much difference in performance. Yes there is some slight degradation, but not nearly enough to decrease operating range.

Link to comment
Share on other sites

On 5/8/2021 at 12:42 PM, Guest GMRSdude said:

@mbrun

... what models of these all-in-one repeaters exist, and generally how much do they cost? ...

- Ben, WRML438

Very likely, mburn was referring to this one: https://shop.mygmrs.com/collections/repeaters-and-accessories/products/retevis-rt97-gmrs-repeater-5w

Proper repeaters usually cost arm, both legs, and a firstborn. You can roll your own, and you may save money (but also, may not), however you'd need to invest in studying and experimenting. This one, in the link above, is much cheaper. But also you'd need consider limitations. For a campsite far from urban RF noise, with antenna up on the telescopic pole, it probably will do great.

Link to comment
Share on other sites

Very likely, mburn was referring to this one: https://shop.mygmrs.com/collections/repeaters-and-accessories/products/retevis-rt97-gmrs-repeater-5w
Proper repeaters usually cost arm, both legs, and a firstborn. You can roll your own, and you may save money (but also, may not), however you'd need to invest in studying and experimenting. This one, in the link above, is much cheaper. But also you'd need consider limitations. For a campsite far from urban RF noise, with antenna up on the telescopic pole, it probably will do great.

You are correct. There were forum issues originally when GMRSdude posted his question and I could not respond here, so I sent a private message answer instead.


Michael
WRHS965
KE8PLM
Link to comment
Share on other sites

On 5/9/2021 at 1:08 PM, n4gix said:

I was rather surprised that the notch duplexer is fully capable of passing +/- 500kHz from the tuned center frequencies without all that much difference in performance. Yes there is some slight degradation, but not nearly enough to decrease operating range.

It would be of interest to see just how much attenuation you actually get. Normally the filter is tuned to get as deep a notch as possible. These cheap Chinese notch duplexers  are only spec'ed for 70db or a bit more. The wider the bandwidth the less notch depth you get. Some of the more expensive band-pass band-reject filters have attenuation levels of 90db or more at 50 watts for example.

At 5 watts you "might" get away with it in a quite RF area whereas using the same filter with a higher power transmitter may not work. Remember one of the notch filters is used to keep any side bands, phase noise, generated by the transmitter from getting in to the receiver section. In fact knowledgeable people building repeaters stay away from particular models of radios because the transmitter section generates too much crap the filters can't eliminate.

Link to comment
Share on other sites

31 minutes ago, Lscott said:

At 5 watts you "might" get away with it in a quite RF area whereas using the same filter with a higher power transmitter may not work.

Our intended purpose is to use this portable repeater strictly in the field with an antenna height of no more than 20' to provide personnel to communicate within a relatively flat agrarian area of around 3 miles radius.

I am going to use my IFR-1200 Super S spectrum analyzer to create a receiver performance table for each of the 16 programmed channels.

Link to comment
Share on other sites

1 minute ago, n4gix said:

Our intended purpose is to use this portable repeater strictly in the field with an antenna height of no more than 20' to provide personnel to communicate within a relatively flat agrarian area of around 3 miles radius.

I am going to use my IFR-1200 Super S spectrum analyzer to create a receiver performance table for each of the 16 programmed channels.

I would like to see the results just to satisfy my curiosity.

Link to comment
Share on other sites

Join the conversation

You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use and Guidelines.