Base Receives 20 miles away but only Transmits 1 mile

[wqwx352]

I'm trying to test a GMRS Repeater Setup and the Base Station can hear me loud and clear over 20 miles away but I can't hear the Base Station even Key up within a few miles range. It seems like it's not sending the signal out over the Antenna.

Base Station
---------------------------------------------------
1 Surecom 683 Repeater
1 50W Duplexer tuned to 462.650 LOW and 467.650 HIGH
1 Baofeng Handheld Radio 8watts tuned to 467.650 RX Connected to HIGH Duplexer Connection
1 TYT-9800 Radio 50watts tuned to 462.650 TX Connected to LOW Duplexer Connection Set to 50W Power
1 30ft High Antenna - Four Band 29/ 50/144/430MHz Mobile Antenna for TH-9800 Quad Band Mobile Radio

Mobile Truck
---------------------------------------------------
1 TYT-9800 Radio 50watts tuned to 462.650 RX / 467.650 TX

I do have my GMRS License and I'm trying to test this out before I actually invest in a full base station compliant setup.
I'm not sure if it's the Antenna, Radio, or Duplexer. I bought the Four Band Antenna because the radio supports four bands so I can use them but I'm thinking that might be one issue.

What do you all think who have experience troubleshooting?

 

[n0nhp]

What is the SWR on the base antenna, I am betting the antenna is not happy at 460 causing the radio to drop it's power to protect the finals.
Check between the radio and duplexer and duplexer and antenna.
The folks playing with the nanoVNAs on YT have been having lots of fun looking at the chinese multi-band antennas and finding that they do not come anywhere near what they are spec'd on the package.

If you are seeing only low power, run the transmitter through the watt meter into a dummy load and make sure it is putting out near specified power. Sometimes the PA chip is not well fastened to the heat sink or other mechanical and electrical faults can happen to a brand new radio between the factory QC station and your hands.

Bruce

 

[wqwx352]

That Antenna is rated at 60W.
I have a Dual Band BROWNING BR-180 I am going to swap out rated at 100W just to see if it makes a difference and the TYT-9800 is 40-50W Output so it's still under.

I have to get myself a Watt Meter.

 

[KevinC]

I doubt too much power is the issue as the duplexer probably has at least 2 dB of loss (putting you around 31w out of it).

A couple of red flags are the antenna doesn't appear to be tuned for GMRS so we don't know how it will radiate on those freqs.

The other thing what is it attached to? It doesn't appear to come with any sort of mount. It will need a ground plane under it to properly radiate.

 

[Chronic]

Dont forget about coax loss

 

[N5XPM]

Might need to go back to the beginning. It is a little puzzling on the equipment at the base station, referencing a repeater, a mobile and a portable. I would consider trying a simplex configuration on 462.650 (TX and RX) at the repeater site (no duplexer, no CTCSS) to talk with the truck 20 miles away. If that works, add in CTCSS, transmit and receive and test again. If that works, try the repeater with the better antenna. It is possible there is a duplexer tuning issue on the transmit (462.650), if you confirm the CTCSS is fully operational. Seems like lots of new pieces put together at once. I have constructed many conventional repeaters and experienced variations of these problems at one time or another, so it does happen. Usually get everything working in the shop, then move the equipment to the site, reinstall and test again.

 

[n0nhp]

The antenna rating makes no difference, if it is not tuned properly and is reflecting most or all of the power back to the transmitter the protect circuits in the transmitter will shut the power down to protect it's self.
Trying to troubleshoot transmitter problems without a watt meter is like trying to repair electronics without a multi-meter. And a $20.00 CB watt meter is not going to cut it.
The modern receivers don't care what the impedance of the antenna is, to a point, so will receive well on an antenna not tuned for the frequency, that is not going to tell you where the problem is.
A watt meter and dummy load are going to let you know where the problem is and what you are going to have to do to fix it.
1. Is the transmitter putting out rated power into a dummy load?
2. Is the transmit power transiting the duplexer with nominal loss?
3. Is the antenna reflecting the power and not flinging it out in the air?

All diagnosed with a watt meter and dummy load.



Bruce
Wielder of wattmeters, dummy loads and service monitors for most of his life.

 

[rescuecomm]

See if you can hear the base with the repeater transmitter turned off. If you do, then the noise floor with the transmitter on is too high (desense). Most repeater receivers have full metal enclosures with feed through capacitors that filter the control signal paths. This prevents the transmitter from overloading the receiver with local noise. The duplexer will do the RF separation only if the receiver can't hear the transmitter noise through the radio's plastic cases. As far as the antenna SWR goes, the duplexers are normally tuned into a 50 ohm dummy load. Any SWR will add or subtract to the tuned frequency. You need a better built receive radio to begin with.

Bob

 

[ko6jw_2]

So many issues:

The TYT radios are not type accepted for GMRS.

The Surecom is an audio interface box. It is not a repeater. There were designed as cross band interfaces, not single band. Might work with a duplexer though.

The antenna is designed for ham radio. It probably has a high SWR at GMRS frequencies. Some Asian antennas are made for the 430-440 UHF band used in Japan for example. It needs a ground plane to work even at ham frequencies.

Baofeng receivers overload easily.

Who set up the duplexer? You really need a spectrum analyzer to do it properly.

As said above check the coax and connectors.

Check myGMRS.com for repeaters in your area. There are some I can see.

 

[wqwx352]

I doubt too much power is the issue as the duplexer probably has at least 2 dB of loss (putting you around 31w out of it).

A couple of red flags are the antenna doesn't appear to be tuned for GMRS so we don't know how it will radiate on those freqs.

The other thing what is it attached to? It doesn't appear to come with any sort of mount. It will need a ground plane under it to properly radiate.

Here are some photos of the setup I did but I have since raised it another 10ft and I'm running 50ft of LMR-400 Coax. I'm using Poles I found at Home Depot with different widths inserted into each other that are Galvanized and dug a hole and put about 3 ft into the ground.

 

[wqwx352]

The antenna rating makes no difference, if it is not tuned properly and is reflecting most or all of the power back to the transmitter the protect circuits in the transmitter will shut the power down to protect it's self.
Trying to troubleshoot transmitter problems without a watt meter is like trying to repair electronics without a multi-meter. And a $20.00 CB watt meter is not going to cut it.
The modern receivers don't care what the impedance of the antenna is, to a point, so will receive well on an antenna not tuned for the frequency, that is not going to tell you where the problem is.
A watt meter and dummy load are going to let you know where the problem is and what you are going to have to do to fix it.
1. Is the transmitter putting out rated power into a dummy load?
2. Is the transmit power transiting the duplexer with nominal loss?
3. Is the antenna reflecting the power and not flinging it out in the air?

All diagnosed with a watt meter and dummy load.



Bruce
Wielder of wattmeters, dummy loads and service monitors for most of his life.

I'm purchasing a Watt and SWR Meter. Will this one work?

Amazon.com: SWR / Power METER for CB Radio 100 Watts - Dual Meters - Workman SWR3P: Sports & Outdoors

Buy SWR / Power METER for CB Radio 100 Watts - Dual Meters - Workman SWR3P: Fixed-mount CB Radios - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Dummy Load

Amazon.com: Mcbazel Surecom 0014-0086 N Male Plug DC to 3.0GHz 50w Watt Dummy Load 50 Ohm Rf Coaxial Terminal: Gateway

Buy Mcbazel Surecom 0014-0086 N Male Plug DC to 3.0GHz 50w Watt Dummy Load 50 Ohm Rf Coaxial Terminal: Connectors & Adapters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[N9JCQ]

That SWR meter will not work. Simply, the frequencies it covers, Frequency range 1.7 to 30 MHz. is considered the HF bands. You want one the will work in the UHF range. You appear to want something that includes the 462.000 MHZ range. Make sense?

 

[Skypilot007]

That antenna needs to go. A quad band mobile antenna for a repeater was a very poor decision. Look for a band specific 460-470MHz antenna. You may have issues with the LMR400 also, not real good for repeater applications. Antenna and feed line are the two most important factors for repeater performance followed closely by duplexer tuning. you may be able to salvage something from what you have, get the correct diagnositc tools as mentioned above and see what you're working with. Good luck.

 

[n0nhp]

I am not too impressed with any of the watt meters I see on Amazon but would probably trust the MFJ 842 cross needle the most out of the selection.
The dummy load will be fine

 

[mmckenna]

...and I'm running 50ft of LMR-400 Coax.

One issue with LMR series coaxial cable….

The outer shield is a tinned copper braid over an aluminum foil.
It's fine if it stays -perfectly- dry. But add some moisture, water, rain, condensation, etc. and the two dissimilar metals can corrode and create a non-linear junction which will create interference when transmitting. When used in repeaters, the noise created when the transmitter is going will wipe out the receiver.

This may or may not be all or part of your issue. Usually using LMR series cable in a repeater is not a good idea unless you can guarantee that no water/moisture will ever reach the inside of the cable. For a short run, Heliax cable is recommended. I've got a few 10 watt UHF repeaters at a very remote work site and I use FSJ1-50 cable. It's a small diameter flexible cable that is easy to work with and reasonably priced.

Your antenna needs a ground plane, and I agree, you need a base antenna that is specially designed for the GMRS frequencies.

As for the receiver...
Ditch the cheap Chinese equipment if you want this to work. The cheap Chinese radios are well known to be problematic in all but very quiet RF environments. Making it your repeater receiver is going to lead you to chasing your tail in circles trying to fix this.

 

[wqwx352]

Thanks for all the feedback! I'm learning and although I started out with cheap equipment, without doing so, I wouldn't know the difference. I ordered the Meter and Dummy Load which arrive today and I'm researching Antenna's but I don't plan on making it a full time repeater and can't find a Dual Band Antenna that says it will work for GMRS as a base station too. The radio supports quad band so it would defeat the purpose of using a radio with all those options. Anyway, down the road I will look into base station radios but I'm just going to gradually upgrade the equipment and work with what I've got for now.

Today, I tried out a few different Mobile Antennas that were interesting.

I turned off the repeater and left the duplexer and radio connected and trasmitted in simplex mode (still using the quad band antenna 30ft high) at Home because I can't get that down until this weekend.

My truck has the same TYT-9800 50w radio with a Dual Band Tram Antenna.
This is the one I bought years ago I've been using all this time:

Amazon.com: Tram 1180 & 1237MUHF Amateur Dual-Band NMO 38 inch Antenna VHF 144-148 & UHF 430-450 MHz for Mobile Radios with Magnetic Mount Mini-UHF: GPS & Navigation

Amazon.com: Tram 1180 & 1237MUHF Amateur Dual-Band NMO 38 inch Antenna VHF 144-148 & UHF 430-450 MHz for Mobile Radios with Magnetic Mount Mini-UHF: GPS & Navigation

www.amazon.com

It worked great and is Loud and Clear on both sides over 20 miles away in simplex mode TX/RX on 462.650!

I also wanted to try a smaller Tram Antenna I've had that is low profile for my truck.
Here is the one I bought:

Amazon.com: Tram 140MHz-170MHz + 430MHz-470MHz Dual Band NMO Antenna: Sports & Outdoors

Buy Tram 140MHz-170MHz + 430MHz-470MHz Dual Band NMO Antenna: Antennas - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

With the smaller Antenna, base station can here me loud and clear but I can't hear base at all, so the taller Antenna is needed for RX.

So, I don't know why with the repeater on, the Base Station Radio will not TX far but I'll test the Power and SWR tonight!

The duplexer I bought is here and I ordered it tuned for the GMRS Channel 5 on frequencies 462.650/467.650:

Amazon.com: Wishring UHF 380-512MHz 50W DUPLEXER for Two Way Radio repeater N/M/BNC connector: GPS & Navigation

Amazon.com: Wishring UHF 380-512MHz 50W DUPLEXER for Two Way Radio repeater N/M/BNC connector: GPS & Navigation

www.amazon.com

 

[ko6jw_2]

Rule number 1: Don't order radio equipment from Amazon.
Rule number 2 : See rule number 1.

A repeater is a radio that can operate full duplex. That is, it can transmit a receive at the same time. Surecoms cannot do this.

I don't want to sound negative, but your set up will not ever work well. The SWR meter and the dummy load, while needed, do not alter the fact that this set-up is not a repeater as we would commonly define one.

Good duplexers cost many times more than the one on Amazon. There is a reason for this. You cannot tune a duplexer without a spectrum analyzer. At least not well.

Do you have an amateur radio license? Talking to other hams about repeater design would be helpful.

 

[wqwx352]

Rule number 1: Don't order radio equipment from Amazon.
Rule number 2 : See rule number 1.

A repeater is a radio that can operate full duplex. That is, it can transmit a receive at the same time. Surecoms cannot do this.

I don't want to sound negative, but your set up will not ever work well. The SWR meter and the dummy load, while needed, do not alter the fact that this set-up is not a repeater as we would commonly define one.

Good duplexers cost many times more than the one on Amazon. There is a reason for this. You cannot tune a duplexer without a spectrum analyzer. At least not well.

Do you have an amateur radio license? Talking to other hams about repeater design would be helpful.

I understand it's a cheapo system but for learning, it's helping me get familiar with how this all works with a smaller budget. I have a GMRS License which is my screen name and I'm studying for the Technician License. I originally bought the surcome repeater and duplexer to create an Ammo Can portable Repeater but the duplexer was too big so decided to use it as a base station instead. I'll most likely be taking your advice and buy better equipment one step at a time and swap things out as I go. The next purchase is an GMRS Antenna but I'm thinking now I might need some sort of switch or duplexer to use multiple Antennas with my Quad Band Radio or it would be useless for anything else.

 

[wqwx352]

Ok, so I have my Watt and SWR Meter and I'm confused about the results.
Unfortnately, I have no adapters so I had to run the test through the Duplexer.
I ordered adapters that will arrive later today.

So with the duplexer connected, the Watt Power is very low.
My radio on High 50 watts is only reading
23 watts and 2.09 SWR with antenna connected with 50ft LMR400 cable.
21 watts and 7.53 SWR with antenna connected without the cable.
15 watts and 1.02 SWR with Dummy connected.

I'm waiting for my adapters so I can bypass the duplexer.

Do you all test without the duplexer?
Is the duplexer really reducing the power that much?

 

[wqwx352]

I have to test with duplexer until my adapters come in.