Re: IRLP COS is not operating

David Cameron - IRLP

What happens if you swap the polarity of the COS (from L to H), does it work in reverse? What I would also try is applying the ground to the COS polarity jumper and then "flex" the board in various directions. It may be as simple as a cold solder joint.

The polarity and the lockout jumpers must be in place and have good connectivity for the COS to work at all. The Logic Select is not as important.

The circuit is just a voltage comparator. COS voltage versus voltage from the Logic Level circuit (either 2.7V or 1.0V). There is a dual comparator on board, one for logic high, one for low. The output from that is put through an AND gate with the PTT.

I have had people send in boards for repair with similar symptoms, but it always ended up being something in the wiring and not the board. Usually it is that the ground potential of the radio and the computer were significantly different, and the comparator would not work because the logic represented swings like +10v to +6V, or the voltages would show as negative to the COS.

If you want to send the board for repair, the way it works is send me the board with $30US or $40 CDN. I will try to repair it, and send it back, or if not repairable give you the options to get it back as is, or provide you the $40 off a new one. Contact me directly for more info.

Dave Cameron

On 02/12/2019 1:19 a.m., Rtech.ralph@... wrote:
Version 3. Purchased 2016. & I have tried running a jumper to ground from the COS pin with the jumper in the low position. No change. Can not light the COS light

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