(Automatic .RF Band Decoder

Marc van Stralen

Marc (DK4DDS), is offering a selective RF band switch for the amateur HF bands (Automatic .RF Band Decoder). Devices such as the Flex 1500 and many other transceivers are often not equipped with an interface which is able to switch automatically (or to toggle) the low pass filters relays of an external Mosfet or Transistor PA (linear amplifier) when the amateur is changing band with his TRX from one amateur band to the other The FlexSelect is a good and simple solution without the use of a computer, etc. The device will be easily connected via a Coaxial T split connector, in the coaxial cable, between the TRX and the linear amplifier. During transmission the PIC processor on the Flexselect PCB measures continuously the RF transmitter output frequency and is switching very fast the correct relay input for the related amateur band to earth. The output will remain in this position also when there is no HF anymore if the user goes over in to receive modus. Only when you go in transmit mode on a different amateur band it will switch automatically very fast to a depending other output. The Flexselect has 6 (max. 12 V DC) outputs and is automatically dialing the, depending on the transmitter frequency, correct band range : 160m, 80m, 40m, 30 / 20m, 17/15 m, 12 / 10m and switches the correct depending inputs to Earth. The 6 inputs must be connected to the relays of the different low pass filters r in the power amplifier. If one of the 6 outputs are switched to ground the connected relay will be activated. Versions available: Flexselect PCB; Complete assembled & tested printed circuit boards for self installation in the amplifier, TRX or enclosure. More info at Marcs web site www.imdes.de