Model 253 Band Decoding Interface

I recently completed a band decoding interface for the TenTec model 253 Automatic Antenna Coupler. The 253 requires a voltage of +10 to +14 VDC at 3 ma on one of seven pins to select the preset tuning information for up to seven memories on each of four switch positions (28 memories). Originally the voltage and pin selection was provided by the TenTec transceiver (band information), but the OMNI-VII does not.

I used DXLab Commander to provide BCD via the computer parallel port to the (solder pads ABCD) UM BCD-10, the band is decoded (J1 1-9) which then pulls down pin 2 of the selected (band) 8L01 DIP Relay, which upon contact closure outputs +12 VDC on pin 14 of the relay to one of seven Band Select pins on the #86027-26 to the 15 pin Molex® on the rear panel of the model 253 tuner. Pins 6 and 8 of the 8L01 DIP Relay are at +12 VDC supplied by +VR of BCD-10. The UM BCD-10 receives +12 VDC from the OMNI-VII Power Supply.

Model 253 Operators Manual pages v, 2-4, 2-5
8L01-DIP-Relay-PDF page 27 ( (bcd1.jpg)

Gary Huber - AB9M

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