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Old 04-08-2017, 1:52 AM
JimVK2JHG JimVK2JHG is offline
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Join Date: Apr 2017
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Default taobao bg7sgm DMR linear

Hi Bill

The text on the taobao website (Chinese equiv to eBay) can be translated using Google translate. After crunching the Chinese text I found most of it is marketing hype rather than technical detail. Some technical information is available re the Mitsubishi RF module from Mitsubishi's tech data sheets.

The bg7sgm is not aimed at amateur use, the sales pitch in Chinese is to travelling salesmen who rely on 400mHz DMR handhelds for sales. In short it says why miss a sale if you are out of range, when the bg7sgm can give you 20% more coverage!

Below are some performance figures logged by our local DMR repeater when using this amp with an Anytone 858. Results at line 1 are for barefoot Anytone and at line 2, with the bg7sgm DMR amp operating in line (fitted with the Minikits 450mHz lpf across the amp output):


06:35:48.303 Feb 3 4.3 VK1RBM VK2JHG Jim VK 505 -102.3 VK-TRBO 0.0%
06:34:13.503 Feb 3 4.3 VK1RBM VK2JHG Jim VK 505 -93.5 VK-TRBO 0.0%

The 6th column shows the signal strength received at the repeater. The bg7sgm gives approx 9dB improvement (suggesting approx =32W output). However, I am running it at only 12V using a LiPo 3S battery so power out would likely be higher with higher voltage psu.

Note the bg7sgm includes a RX low noise receive pre-amp so is probably best installed as close to the antenna as possible.
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