Application Notes for Amateur Radio Products
RX-TX switching of DB6NT transverters
To switch a DB6NT microwave transverter from receive (RX) to transmit (TX), there are two possibilities.
The first: switch the port "PTT" of the transverter to ground for TX.
The second: supply +3 … 12 V DC to the core (center conductor) of the IF cable for TX.
This (second) method saves an additional PTT cable between transverter and transceiver.
A suitable control circuit is already included in the transceivers YAESU FT-290R (old model) and ICOM IC-402. They provide +12 V DC on the coaxial output connector (core) at TX.
The YAESU FT-290RII (new model) does not provide this function, but it can be modified. The modification is described on G4DDK's homepage: www.g4ddk.com/Techstuff
Modification of the ICOM IC-202
ATTENTION!The ICOM IC-202 provides +12 V at RX! So when you connect a DB6NTtransverter to a IC-202, then the transverter will switch to TX.Therefore, a small modification is necessary (see picture below). Withthis modification the IC-202 will provide +12 V at TX.
Modification of the YAESU FT-817
The YAESU FT-817 must also be modified for transverter operation. Peter Vogl, DL1RQ, has written a small tutorial how to do this modification: www.bergtag.de/technik_18.html
A further description for the YAESU FT-817 is written by Pedro M.J. Wyns, ON7WP.
Everybodyuses DB6NT transverters above 1000 MHz. These babies need a positivevoltage on the coax middle pin in order to switch into TX mode. As alotof microwavers have FT817 radios so it would be nice to have a "lazyham interface" for these fine little Yaesu radios.
The picturesare self explaining. Cut the wire going towards the SO239 antennaconnector on the rear. Insert instead of the wire a parallelconfiguration of 1 and 10 nanofarad capacitors. Connect a 1200 ohmresistor to the center pin of the connector, the other end to afeedtrough 1 nanofarad capacitor (or something alike)mounted/solderedto ground and connect the other side of this feedtroughwith a (red) wire to the solder pad on the PA module.
Pedro M.J. Wyns ON7WP (AA9HX when abroad)
Thanks to Pedro, ON7WP, for hisdescription and the photos!