Repeater set up issues

[WSAT974]

I bought a eBay retevis repeater consisting of 2 of those radios , power supply and a case here is the link https://www.ebay.com/itm/176430316639?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=MCH-9Ak_QBu&sssrc=4429486&ssuid=kQuvVT3uS1K&var=&widget_ver=artemis&media=COPY. I'm having issues, the power output is 30 watts on both radios not 40 and I connected and set up everything right using 2 antennas about 40 feet away and at a different altitude and when I test it here at home it is working putting out 30 watts on the watt meter but when I do a range test after half of mile it doesn't work anymore I can't figure out why it it doesn't make sense both base antennas match under 1.5 SWR and even using a high power mobile radio I can't reach more than half a miles I don't know if the issue with the tx antenna killing the received signal I'm going to try it with a duplexer I just received it today if not I'm going to return it, does anyone here have an idea why is that happening?

[SteveShannon]

3 minutes ago, WSAT974 said:

I bought a eBay retevis repeater consisting of 2 of those radios , power supply and a case here is the link https://www.ebay.com/itm/176430316639?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=MCH-9Ak_QBu&sssrc=4429486&ssuid=kQuvVT3uS1K&var=&widget_ver=artemis&media=COPY. I'm having issues, the power output is 30 watts on both radios not 40 and I connected and set up everything right using 2 antennas about 40 feet away and at a different altitude and when I test it here at home it is working putting out 30 watts on the watt meter but when I do a range test after half of mile it doesn't work anymore I can't figure out why it it doesn't make sense both base antennas match under 1.5 SWR and even using a high power mobile radio I can't reach more than half a miles I don't know if the issue with the tx antenna killing the received signal I'm going to try it with a duplexer I just received it today if not I'm going to return it, does anyone here have an idea why is that happening?

Is that 30 watts measured at the radio or at the antenna?

What are you using for cable? How long?

What antenna are you using? How high is it mounted?

What’s the surrounding terrain like? Are you in the middle of vegetation, like a forest?

How are you doing the range check?

[tweiss3]

You need the antennas to be 25' apart, one directly over the other, to achieve the isolation of a duplexer. That is 25' from top of bottom antenna to bottom of top antenna. If they are not directly 1 over the other, you loose your isolation. For horizontal separation, you need 2000'+ apart to get the same isolation as vertical separation, or a duplexer.

40' apart and at slightly different elevations is not enough, you are getting desense, which is 1 reason you are getting no range out of the repeater.

As for 30W vs 40W, the difference in the field is minimally noticed, you are still limited in range by height you get the repeater, not wattage. When figuring height for how far the repeater can reach, you need to use the bottom elevation of the bottom antenna. 

[WRYZ926]

I have to agree. you don't have enough separation between the two antennas. The average person is not going to have enough room for that and why using a properly tuned duplexer is a better option.

Remember that you will loose some output power when using a duplexer, that is just the nature of the beast. That being said, there is not enough difference between 20, 30, or 40 watts output from the repeater. Using the proper coax and an antenna with at least 6 dBd (8dBi) of gain will make up for any power loss at the duplexer. Make sure to get the antenna as high as you can get it.

We are using a Bridgecom repeater that puts out about 25 watts after the duplexer with the antennas about 400 feet above the ground. We get around a 35 mile radios coverage area with all the hills and forested areas here in mid Missouri. Yes there are some dead spots but that is to be expected with all of the river/creek valleys and sections of red cedar trees.

[dosw]

4 minutes ago, tweiss3 said:

You need the antennas to be 25' apart, one directly over the other, to achieve the isolation of a duplexer. That is 25' from top of bottom antenna to bottom of top antenna. If they are not directly 1 over the other, you loose your isolation. For horizontal separation, you need 2000'+ apart to get the same isolation as vertical separation, or a duplexer.

40' apart and at slightly different elevations is not enough, you are getting desense, which is 1 reason you are getting no range out of the repeater.

As for 30W vs 40W, the difference in the field is minimally noticed, you are still limited in range by height you get the repeater, not wattage. When figuring height for how far the repeater can reach, you need to use the bottom elevation of the bottom antenna. 

When you said 25' apart, one directly over the other, I wanted to confirm what you meant: You really meant a 25 foot vertical separation? That seems like a lot. But then I looked at this: https://www.repeater-builder.com/antenna/separation.html ...and it does seem that 20' is about right for 60dB isolation. Apparently that's measured at the center of the antennas, though. So if the antennas are 36", then the actual vertical space between them would need to be a minimum of about 17 feet. Am I understanding that correctly?

It does seem like using a duplexer is a more effective solution. Putting one or the other of the antennas 17 feet lower on a mast seems bad for range/reception. And a $150 duplexer isn't more expensive than two antennas with two feedlines.

[WRUE951]

1 hour ago, dosw said:

When you said 25' apart, one directly over the other, I wanted to confirm what you meant: You really meant a 25 foot vertical separation? That seems like a lot. But then I looked at this: https://www.repeater-builder.com/antenna/separation.html ...and it does seem that 20' is about right for 60dB isolation. Apparently that's measured at the center of the antennas, though. So if the antennas are 36", then the actual vertical space between them would need to be a minimum of about 17 feet. Am I understanding that correctly?

It does seem like using a duplexer is a more effective solution. Putting one or the other of the antennas 17 feet lower on a mast seems bad for range/reception. And a $150 duplexer isn't more expensive than two antennas with two feedlines.

you are better off getting a Duplexer and i recommend getting from  www.Buytwowayradios.com.  Make sure to have them tune Duplexer to the Ch. you operate repeater (otherwise you'll get one tuned to Ch 18)..  Also, make sure you are using LMR 400 or better cable...  Don't buy your cable from Ebay,,  get it from DX or BuyTwowaayradios.com  Connectors are also important, i prefer a quality (Times Fiber) UFF N-Type Crimp but you will also need the crimp tool..   (worth having)..    And the connectors need to be sized to your cable.  In other words.  LMR Connectors for LMR 400 cable, LMR 200 for LMR 200 cable.   etc...    Be patient, you'll get there.