Repair Notes of Ten-Tec Corsair 560 Digital Readout

  
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The Digital Readout of the Corsair 560 is just above the tuning knob. On this particular radio these six digits bounced around, often doubling the frequency indication. The reading was so unstable, it was difficult to know what frequency the radio was tuned to. Below is a picture of the display after the repair. It is fairly solid down to the gree
Repair Notes of Ten-Tec Corsair 560 Digital Readout - schematic

n 100 Hz digit. Once the radio is warmed up (usually about 30 minutes) the green LED digit pretty much stays put. One of the reasons the readout is so stable is that I modified the grounding inside the Digital Readout module. I did so partly to make it easier to gain access to the two circuit boards, but also I wanted to tie the two boards together in a way that would reduce RF and logic level noise. Ten-Tec Corsair 560 Digital Readout module with the top cover removed. The upper circuit board is the bottom side of the TIME BASE 80974 Rev A board. The housing wall ground straps were removed, and a single tined braided strap added near the left edge of the board. Also re-routed is a short green grounding jumper. This replaced a longer edge routed ground jumper. The wooden dowel acts as physical support for the right edge of the board. Ten-Tec Corsair 560 Digital Readout module with the top cover removed, showing the connector board between the upper TIME BASE 80974 Rev A board, and the lower COUNTER LOGIC BD. 80973 board. On the right side of the back edge of the TIME BASE 80974 Rev A board, an RF ground strap ties the two board ground references to gether in a low impeadance manner. This reduces noise, and aids stability. The other path is now a low impedance ground strap near the connector board. This is a better method of grounding for two reasons. Firstly the wide flat physical form of the ground strap is better suited...



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