Dak IX extra front switch question

[darticus]

Dak IX extra front switch question
I know these switches were placed to switch to new added channels. I never used this feature but does anyone know how it worked. The switch has only two positions. In the up position it seems like regular channels 1-40. I don't know what it would be if I put the switch in the lower position. I don't hear anything when in the lower position. How many channel should it be with the new ones? The wire on the switch does goes to a green wire in the pll circuit so its probably for channels. I do notice that if I change REGULAR channels it seems like I have to turn the set off and than on again to get it to receive on this channel. This could be another problem. ANY INPUT TO THE OUTPUT? Email [e-mail] Thanks Ron

[2600]

The MC145109 chip used in the Mark 9 has over 500 channel codes possible for it. Only 40 of these are used by the stock channel selector.

Bad news is that there are a lot of different ways you can rewire the PLL chip's input pins and no way to tell how yours was done.

The PLL circuits wrapped around the chip are not capable of staying locked in to all the channel-code combinations that you can feed into the chip. A code that puts you above the highest frequency that it can stay locked on to will just cause it to shut down. Same goes for a frequency below the "lock-in" range of the radio's PLL.

There were some Mark 9 radios we saw back in the day that would not stay locked in for a full 40 channels. You could set the VCO slug to cover any 20 channels you wanted. The fix turned out to be a small disc capacitor installed across a cut made in one pcb trace.

The only way to tell what your setup should do is to trace where all the wires go on your switches. I don't think there's a lot of detailed info on frequency mods for a radio this old. Should be some info in the old "Secret CB" series of books. They are all posted at www.cbtricks.com/pub/secret_cb/index.htm . Might be worth taking a look. At the upper-left corner of the page there is a link to an index by radio model. Who knows, maybe that's where your extra-switch setup was copied from?

73