[App_rpt-users] URI active low?

mike at midnighteng.com mike at midnighteng.com
Wed Mar 2 09:48:05 EST 2016

I had made a interface to a cat1000 but from the PPort some years ago.
Don't use it anymore.

And I suggest using a transistor buffer in any case.
I doubt that the URI can sink enough current without it.

2n3904/06 work well.

I used opto-coupled transistors to isolate it. Can be overkill but limits RFI and
lightning/spike damage.


> Being pulled low enough is kind of what I was thinking and wondering if others have
> had that issue.  Its really the only thing that makes any sense to me in terms of
> what I am experiencing.
> A little digging shows this solution, which I will try this weekend once I dig out
> my parts.
> http://dmkeng.com/images/HIGH_CURRENT_PTT.pdf
>>I seem to recall some people having issues with the PTT output not being
>>pulled low enough, you might try searching the list archives for a similar
>>situation.  I recall several fixes from adding a reed relay,  inserting a
>>diode in line, or using a transistor buffer, might have been a jfet.
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