What to do with pesky delta tune pot.

[500kpot]

During testing of a freq mod on a Cobra 1000 we installed one of those small 20k pot and used the blank mounting for a dual pot connected to a svxo for "fine" and coarse". It provided 25khz of slide. Using 5MHZ crystals and taking control of the RX/TX signal provided a 80 channels + 2.5 channels where the new freqs are 26.575 - 27.495 with "A" channels included (So a bit more than 80 channels) using the stock PLL.

In this configuration it does require a 10.695 TX oscillator and the channel selector display doesn't match with the channel such as CH 40 is now 26.025 with the switch in low but its of no consequence as a frequency counter was installed in place of the clock. Switching to the "Hi" position the radio will end up on the "dimes" but it doesn't matter with the freq counter and svxo to slide to the "nickels".

So that was the idea behind of "What to do with pesky delta tune pot" - Get rid of the stock 10.240MHZ mangler and put in a "real" slider circuit with a freq counter.

Here is YT video of the unit.






Best to all

 

[144inBama]

When I installed the variable yesterday, I pulled the DT pot, made sure it was in the center position and wrapped it in 33 and tucked it away in the radio. I don’t ever foresee using it again but this way I know that’s one circuit I can pretty much dismiss if I encounter any problems down the road.