Most ham gear made in the past 15-20 years tunes use some sort of rotary encoder. These encoders generate digital pulses that are fed either directly or through some sort of buffer to the rig's microprocessor, telling it to tune up or down. I purchased an Alinco DR-610T at a hamfest and found that the tuning via the main tuning knob was very erratic. I would try to increase (or decrease) the frequency (or memory channel) and it would bounce up, then right back to the same frequency or, in some cases, it would decrement instead of incrementing. Playing with the tuning knob repeatedly might finally get the frequency set where it was supposed to be. I decided to investigate the problem and see if a fix was possible.
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