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The difference between 2and 5 watts is significan. Over 3dB assuming all else equal. That’s over half an s-unit, the unit of measurement on the signal strength meter.
 

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Discussion Starter · #42 ·
I got the parts I needed so I could test the power and SWR on my base radio and BTech U25 amp. SWR was 1.2 and 1.5 on the amp and radio I used . The GMRS channels I tested on was 19 and channel 4 . Channel 19 SWR was 1.2 . Power output on low was 20watts . The radio was a BTech V1 low power for it was 2.5 watts. BTech claims the U25 amp power output is 3 watts in =30 out I got 20watts. On both GMRS channels 19 and 4. Next was high power. The V1 GMRS on high was 5.5 watts . SWR was 1.5 . BTech says the amp with 4 watts in =35 out . I got 30 watts.
Do I thought I would try the Retevis RT76P GMRS radio . I tested it at 2.3 SWR on a couple antenna’s tuned for GMRS. Did not change the SWR . With that said I tested it on low got power out put of 2 watts . High power I got 6.5 watts with the Retevis RT76P radio . Now the U25 amp is supposed to at 6 watts put out 40 watts . At 6.5 watts I was only getting 34 watts . It might have been 35 -36 watts . The needle was close to either of those numbers . Close enough that it was hard to say.
Anyway my results today with the BTech U25 amp were better then some of the reviews say. I stopped testing there and started setting up to test the BTech UV-25 x2 mobile radio.
I only used the base antenna in this test. SWR was the first test. BTech UV-25x2 has high , low power . High power in vhf is 25 watts , low power is 10. UHF is high 20wats low is 7 watts . Now my SWR was 1.1 in low and high power. I did try vhf and my SWR went up to 1.5 -1.6. High power . Next I switched to UHF using GMRS frequencies.
I used GMRS channels 19,18, 22 and 5 .
Power in low was 10. High power in the lower GMRS frequencies 22 watts. So far I think I’m going to be happy .with my choice of radios. Soon I’m going to resume my range test . The first test will be the base radio to vehicle. As usual I will see what max range is going to be. Then I’m going to test range from base to vehicle using the back roads surrounding our area . I’m sure I’m going to be able to get the 5 mile radius around my house like I did with the BTech HT and once the foliage is gone for winter even further.
After that I’m going to test ranges of all the HTs in the wood around our home . That’s from HT to HT. Then HT to base .


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Only concern I would have is that swr over 2.0. Shouldn’t be high enough to blow anything, but I like numbers under 1.5, 2 is about as high as I like to run. Granted most of my stuff is running 100 watts.
 

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Discussion Starter · #44 ·
No range test yet . I have started a project for the BTech U25 amp . It’s going to take awhile for it to complete . I think what I’m going to do for it is make a power box and dedicate a HT to the amp . Then I have a fairly light weight & powerful field radio. The antenna I have selected is a N9tax roll up antenna.
As for my other test I’m going to start getting back on track . Then I will report the results and equipment used .


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Discussion Starter · #46 ·
My thoughts exactly . If everything in my build plan works out the way I hope it does. The power /amp go box the way I’m setting up I will be able to use any antenna that has a SO-230 connector


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Discussion Starter · #47 ·
Well this weekend I’m going to resume my range test with base radio . It’s only a 25watt radio . On UHF it’s only putting out 20 watts. It’s a BTech UV-25x2 using a Tram 1173 antenna tuned for 450-570Mhz. With a Tram 1460 UHF ground plane. My SWR is 1.1 . I will be transmitting to a Wouxun KG805G 5watt radio hooked to the BTech U25 amp. Paired with a U72G antenna. The SWR is 1.3 to 1.5. It’s kinda hard to tell with the way the needle is .
The amp hooked to the Wouxun puts out 35 watts. I know how far the amp will reach clearly. This test will concern the actual base radio.
I’m not sure what the weather will be on the day I get to test . I’m hoping for bad weather. That way I’m in less then ideal conditions. I can figure out what the range is in good conditions later this winter .


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