vhf reapter

[buddrousa]

Just so you know the local TACN sites were done with some LMR600. You also do not build repeaters out of walkie talkies but in his case it should work fine at 5 watts 50 feet.

 

[Wilton12]

I'm running 2 bafeng radio with sma female to pl-259 female adapters. The reapter control is one I bought of ebay that has a little black box and to cables coming out of it. I put a old dual band antana on the TX side and it got out about 1 mile but go 2 and all you can do it key it up but you can't get out on voice I scant get out that 1 mile with out a mobile antana

 

[KevinC]

Just so you know the local TACN sites were done with some LMR600. You also do not build repeaters out of walkie talkies but in his case it should work fine at 5 watts 50 feet.

I'd be willing to bet they aren't duplex.

 

[buddrousa]

I have not had trouble with low power LMR400 repeaters 20 watts or less. But is power goes up or length goes over 50 foot then 1/2 inch Heliax

 

[Wilton12]

I'm in the process of uploading a video to YouTube going over what I have set up. I will post the link shortly

 

[Wilton12]

https://youtu.be/oPeBFX6hrAs here is a link to the video I uploaded about my repeater

 

[12dbsinad]

I'm running 2 bafeng radio with sma female to pl-259 female adapters. The reapter control is one I bought of ebay that has a little black box and to cables coming out of it. I put a old dual band antana on the TX side and it got out about 1 mile but go 2 and all you can do it key it up but you can't get out on voice I scant get out that 1 mile with out a mobile antana

It sounds like classic desence. You might be able to key it up initially but as soon as the TX radio fires off it makes the RX radio completely deaf, hence the no audio passing thru.

The other thing to keep in mind (and not sure if you are doing this) is if you are trying to hear yourself talk thru the repeater with another radio that's with you, you will do the same thing, desence your receiving radio and you won't hear yourself. All tests should be done with a radio's far apart (and maybe you are doing this).

 

[nd5y]

diregard

 

[Wilton12]

What's densence mean? Im doing long range test as well as short range test. Today I hooked up my 2 otherbaofeng radios and got it on vhf and I was able to key up my repeater from 6 miles away (with a mobile ant) is it something to do with that box I got hooked up to both radios?

 

[Dog]

"desense" means it "hears" to much. It over loads the receiver. Imagine sitting next to someone yelling at you while you try to listen to a conversation in the other side of the room.

 

[12dbsinad]

What's densence mean? Im doing long range test as well as short range test. Today I hooked up my 2 otherbaofeng radios and got it on vhf and I was able to key up my repeater from 6 miles away (with a mobile ant) is it something to do with that box I got hooked up to both radios?

Desense means that the RX radio is being severely degraded by the TX radio while it's transmitting. This is because the sheer RF power overwhelms the RX radio that is trying to listen. It is the nature of RF and isn't specific to the type of equipment used or the controller. A duplexer is used to filter out and isolate the RX radio from the RF of the TX radio. It is a VERY critical part of a repeater.

 

[Wilton12]

I switch my radios out back to a vhf freqs just to do a test and I got out 7miles just keying up both on a mobile antana and a handheld radio but no voice. Either way I feel like im going to have to buy a duplexer. What kinda duplexer would you guys recommend

 

[12dbsinad]

A mobile duplexer would work. keep in mind that a duplexer is band and frequency specific. Meaning they are tuned to a specific set of frequencies and you cannot change that (without having it re-tuned within the band). They sell cheap china made ones that work OK, especially low power.

Before spending the money, I'd test the proposed repeater in simplex mode on GMRS hooked to whatever antenna you're going to use (which brings in a whole lot of other issues when using a repeater with said antenna) and test the range. You won't get any better range than that. That WILL be your optimal range if the repeater has ZERO desense issues.

 

[Wilton12]

Ive thought about ordering those cheap china ones but Ive also thought about if it would be easyer to buy 1 mobile radio and a simplex reapter control boxes and see if that will work any better

 

[Wilton12]

We tryed out vhf and uhf frequencys today and I unplugged the black box and my friend 3 to 4 miles up the radio was able to hear me and I could hear him clear as day and he was using a stock bafeng antana

 

[jeepsandradios]

OK. I just watched your video. First off you are trying UHF GMRS Channels Correct ? If so neither antenna is a real UHF antenna. Did you check VSWR on either antenna ? Additionally that much antenna cable with adapters on that portable will be alot of insertion loss. Most likely you have less than 1 watt hitting the antenna. As others have said you are most likely getting desense in the radios. I understand trying to experiment on the cheap and I have built a repeater such as this with a few different parts. First as others said get a cheap Chinese mobile duplexes. You can order one from china tuned on frequency for $75.00. Get 2 good RF cables, Short to go from the radios to the duplexer. Then get a decent UHF antenna. You can start out with a standard UHF whip on a base kit for around $50.00. This is a great starter antenna - http://www.ebay.com/itm/FRS-GMRS-FR...374383?hash=item3ac150642f:g:vgUAAOSwq19XCuvr

From there you should see some difference, however if you really dig into it you will most likely not see more than 2 watts on your antenna using the portables.

 

[farmerjack09]

I got my GMRS license about 2months ago and have changed freqs in my radio to Rx 462.725 TX 467.725 pl tone 151.4. I spaced out the antanas about 30feet and that seemed to work a little better. I don't have the money get to buy a duplexer. I just don't get what Im doing wrong. Im running RG-58 to both antanas. Would it be better to just do simplex? Im 19 and always wanted to build a reapter for along time but just don't understand what is going on.

RG 58 will cause a tremendous amount of lose in transmit and receive.You would be surprised the difference in running RG 58 compared to running 1/2 Andrews hard line it's like daylight to dark and you will immediately notice.

 

[12dbsinad]

RG 58 will cause a tremendous amount of lose in transmit and receive.You would be surprised the difference in running RG 58 compared to running 1/2 Andrews hard line it's like daylight to dark and you will immediately notice.

Although this is very true, the heart of the problem in this particular scenario is the close proximity of the antenna's (or at least a very good guess). Buying 1/2" heliax would not solve the initial problem.

 

[buddrousa]

Just a reminder this is a 19 year old with very limited funds. Not a City or County Government or a Rich Farmer. This is a young man wanting to get started and learn and build on a very basic start up repeater.

 

[cmdrwill]

https://youtu.be/oPeBFX6hrAs here is a link to the video I uploaded about my repeater

Wrong antennas, TX antenna is a TV receiving antenna, horizontal pol..
I see some not so good coax cable, another problem.
Very poor or no shielding in the radios.

Get some antennas that ARE for UHF 460 two-way radio.
You need lots of physical isolation not only between antennas but radios also.
Relocate your radios to each antenna location. You would only have the audio cable between the radios.

BTW, a duplexer and a better repeater antenna, even double shielded RG214 cable will NOT help, The radios do NOT have adequate shielding, very piss poor for repeater applications..