Very useful especially during the contest, this simple decoder can read data from the Yaesu Band Data port and activates the corresponding relay. It 'was designed exclusively for the contest bands (10, 15, 20, 40, 80, 160) and' it is very easy to buiild. There are few components and easy to find.

The CD4028, binary to decimal decoder, reads binary data from the Yaesu Band Data port (A, B, C, D) and enables one of the outputs corresponding to the decimal code. In this condition, the transistor connected to, goes in conduction driving the relay.

You can use this decoder to drive a remote antenna switch so you can change antenna when you change band, automatically and with only one feed line. Another application is to change band filters automatically when you change band, and it is possible to do this simultaneously with the antenna change !!!

Instead the Yaesu Band Data port, the parallel port can be used to control this decoder. Many contest logger software (CT, DX4WINN, WRITELOG, QARTest, etc.) are able to emulate the Yaesu Band Data port trough the parallel port (read their own instruction manual). In this way, any radio (Yaesu, Icom, Kenwood etc..) connected via CAT can handle this Band Decoder. I hope it will be useful during your next contest.


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