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  #21 (permalink)  
Old 05-23-2017, 5:13 PM
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Originally Posted by paulears View Post
Quick report - so far the results are NOT encouraging. Kayn's prediction appear to be correct and the separation is not sufficient. In fact, so poor that I need a spacing of 11MHz before I get a system that would be usable. I had hoped that 8MHz would be acceptable but the repeater even on low power desenses the receiver far too much. I'm now on plan B. Kenwood repeater in a 4U rack, with a small fixed station duplexer, wrapped in foam in the 2U empty space, and a single antenna. Takes up far too much space, but appears to be a working solution.
If you have the ability/separation, I'd obtain a mobile duplexer. Epcom (El Paso Communications) has the best pricing I've seen so far on mobile duplexers...$215 before shipping. Getting it across the pond may be an issue though.
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Old 05-23-2017, 5:16 PM
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Originally Posted by paulears View Post
Quick report - so far the results are NOT encouraging. Kayn's prediction appear to be correct and the separation is not sufficient. In fact, so poor that I need a spacing of 11MHz before I get a system that would be usable. I had hoped that 8MHz would be acceptable but the repeater even on low power desenses the receiver far too much. I'm now on plan B. Kenwood repeater in a 4U rack, with a small fixed station duplexer, wrapped in foam in the 2U empty space, and a single antenna. Takes up far too much space, but appears to be a working solution.
I will suggest it again.

The Hytera portable repeater(you already own), with a mobile duplexer. If you need one, buy one of the Chinese ones, while they are a PITA to tune due to the screw and nut tuning 'rod', they will meet or beat the specs. of the Sinclair mobile duplexer they are a rip-off of.
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Old 05-24-2017, 2:42 AM
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The experiment with a duplexer does clearly show that I have to do it properly to get more than 400m or so range. My hope the split would add enough isolation was clearly wrong.

Is there a design difference that makes the mobile duplexers more expensive - externally, they appear the same, and I have a couple here, one UK built and one Chinese sourced that appear extremely similar. As the function of these and construction seems the same - has anyone cut one of the Chinese ones open to look at the engineering?
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Old 05-24-2017, 9:51 AM
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Originally Posted by paulears View Post
The experiment with a duplexer does clearly show that I have to do it properly to get more than 400m or so range. My hope the split would add enough isolation was clearly wrong.

Is there a design difference that makes the mobile duplexers more expensive - externally, they appear the same, and I have a couple here, one UK built and one Chinese sourced that appear extremely similar. As the function of these and construction seems the same - has anyone cut one of the Chinese ones open to look at the engineering?
I do not think so. The probable reason the Chinese ones are so cheap is the cost to make them. Like I said before, the Chinese ones tune up as good as the Sinclair ones they are a copy of. I have had them side by side on a bench with test hear. The big difference is the way the tuning rods are built. The Sinclair ones use a compression nut, where as the Chinese ones have a threaded nut on a screw.

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Old 05-24-2017, 3:12 PM
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Originally Posted by kayn1n32008 View Post
I do not think so. The probable reason the Chinese ones are so cheap is the cost to make them. Like I said before, the Chinese ones tune up as good as the Sinclair ones they are a copy of. I have had them side by side on a bench with test hear. The big difference is the way the tuning rods are built. The Sinclair ones use a compression nut, where as the Chinese ones have a threaded nut on a screw.

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The Chinese ones generally don't use silver plated connectors. Then again, some of the offerings from RFS (Celwave) don't either.


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Old 08-05-2017, 8:56 PM
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I sold the Pyramid and Vertex units. Both work. The Vertex is simple with a lower cost.

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Old 08-05-2017, 11:40 PM
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I actually just delivered two RF Technologies Eclispe 2 reciters in interop repeaters to a customer of mine. There's a new official mobile repeater based on the Eclispe 2 minus some features but will add the in-vehicle repeat capability for VRS operation. Originally I spec' d that job using Simoco SRM9005 radios configured for P25 repeat but they never would function properly in analog so they got swapped with the RFT options.

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Old 08-05-2017, 11:58 PM
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The Chinese ones generally don't use silver plated connectors. Then again, some of the offerings from RFS (Celwave) don't either.


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Oddly, I have seen the Chinese mobile duplexes tune up as good as the Sinclair mobile duplexes. Agreed on the silver connectors... a bit over budget for the chinese


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Old 08-06-2017, 9:31 AM
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Originally Posted by kayn1n32008 View Post
Oddly, I have seen the Chinese mobile duplexes tune up as good as the Sinclair mobile duplexes. Agreed on the silver connectors... a bit over budget for the chinese


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The irony, $100 more than a 50W Chinese notch duplexer (which is between $100-$150 less than an RFS or EMR) you can get a Made in Mexico notch only duplexer from El Paso Communications...with sliver plated connectors.
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Old 08-06-2017, 9:32 AM
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The irony, $100 more than a 50W Chinese notch duplexer (which is between $100-$150 less than an RFS or EMR) you can get a Made in Mexico notch only duplexer from El Paso Communications...with sliver plated connectors.


Interesting. Good to know.


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Old 08-06-2017, 12:24 PM
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I've used and tuned up dozens of Procom notch only mobile duplexers and to me are better quality and tune up smoother than a Celwave. I think their made in Denmark and can be had cheap used.
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Old 08-13-2017, 5:27 PM
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tacticalrf.com/tech/antenna_isolation.pdf

I found this H vs V isolation chart, don't know who to credit.
If you have to use dual antennas try yagis vertically stacked if you can get away with the unidirectional
pattern.
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Old 08-13-2017, 7:30 PM
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Originally Posted by mformby View Post
I sold the Pyramid and Vertex units. Both work. The Vertex is simple with a lower cost.

Vertex Standard | VXR-1000
The Pyramid SVR series and the Vertex VXR are simplex crossband repeaters to use as mobile extenders. They are not duplex repeaters like th OP is seeking.

You can make a duplex repeater, but you need either an in band mobile radio or a second SVR or VXR to do the transmitting. And yes you will need a duplexer either way you go for in band operation.

I have to wonder how these cheap Chinese duplexers handle shock and vibration. Hat to be down on the Chinese, but those damn cheap radios. What are they thinking?
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Old 08-13-2017, 9:59 PM
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Originally Posted by RFI-EMI-GUY View Post

You can make a duplex repeater, but you need either an in band mobile radio or a second SVR or VXR to do the transmitting. And yes you will need a duplexer either way you go for in band operation.
Almost be better off using 2 mobiles with a controller. Set it up so you have 5 watts out of the duplexer and put the 3rd mobile(that the SVR/VXR would be hooked to) on the link port. You would also be able to talk back before the repeater drops.



Quote:
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I have to wonder how these cheap Chinese duplexers handle shock and vibration.
I would loctight the threads and I imagine it would be no worse than the Sinclair mobile duplexer they are copies of.


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Last edited by kayn1n32008; 08-13-2017 at 11:34 PM..
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