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We’re here to help.
1  what program do you use for rt81
Do you mean software ? If so , here to download --- http://www.retevis.com/resources-center/
2  When trying to read the radio a message appears "invalid port number" I use a Baofeng programming cable. Do i need another cable?
1.Ths suited one is : http://www.retevis.com/2-pin-programming-cable-for-revevis-h777-baofeng-kenwood
2. Please check if you open the radio after connecting to your PC.
3. Did you upload the USB Driver Firstly ?
4.There is a blog may helps -- http://blog.retevis.com/retevis-radio-frequency-programming/
3  How do I set my radio to analogue rather than digital ?
Hello Richard Holman-Baird, Thanks for your question.Digital Radio can switch to Analog channel,please do it as a the photo. You need download RT81 usb driver and RT81 software from Retevis official website: http://www.retevis.com/resources-center/ Regards
4  Hello, Here I bought the RetevisRT81 in October 2016 or I noticed that it was not compatible tier2, it pulls on the 2 slot at the same time. Retevis ma say that a firmware update was planned for the beginning of 2017, that is my question or in es this firmware that fixes this bug Thank you for answering me Receive my greetings
It is still in processing . Hard to tell which part to fix this bug .
5  Good evening... My rt81 use both 2 slots ... it is possible? When I transmitting in slot 2 (for example) the radio use slot 1 and 2 ... Firmware problem?? Thanks. Kris
There is only slot 1 available to use for now .
6  I am looking for a Battery Eliminator (12v) for the RT81. Which is the correct one ?
Hello Lawrence Williams, This is RT81 original Eliminator link:http://www.retevis.com/original-12-24v-car-charger-battery-eliminator-for-retevis-rt8 Brgds
7  Hello there, is it possible to adjust the TX-Power for example to 2,5 W to get common with local/national law? best regards Mario
RT81 only have two levels power , low as 5W ,high as 10W.
8  Hi. I'm trying to program an analogue channel, but DCS setting for D212N is missing from the programming software. Regards.
It is not missing . It just doesn't have .