Re: Kpc3+ settings for APRSISCE

Lynn Deffenbaugh

The issue with the KPC-3+ has nothing to do with the MON command, but everything to do with a firmware bug and handshaking signals.  Please read and understand:

And especially the comment that says:

I was working with Kantronics support on this issue and I seem to have solved it by shorting the RTS and CTS pins together within my serial cable. (PINS 4/5 on DB25 and PINS 7/8 on DB9) I simply ran a jumper between the two. This appears to be an issue with how the APRS software and/or the AX.25 stack controls the RTS pin and shorting the RTS and CTS together prevents the software from holding the RTS pin low. If the RTS pin is at low voltage the KPC3+ will start buffering and does not get caught back up. I have been running mine for several weeks without showing this behavior again. Before I made the change it would happen after about 12 hours.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 6/14/2021 1:30 PM, Gil wrote:
Please check your KPC3+ (or KPC3) once you've got it in operation.  I have seen those TNCs delay packets for a significant amount of time before digipeating them.  They are sometimes delayed so long that the system thinks they're new packets - and repositions my mobile station accordingly.  I've seen my mobile beacons regurgitated by KPC3 digipeaters many minutes (and miles) after they were sent.  On a recurring basis, it makes the track appear to be bouncing back and forth from where it most recently was (as digipeated by other digipeaters) to where it formerly was (at a former beacon location delayed by the KPC3) - many miles away (I think astronomers call it "retrograde motion" when they refer to the apparent observed motion of some planets).  I have a problem with a KPC3 digipeater doing that right now (I need to try to contact the owner again...).  I can see my beacons showing up from it 5 or more minutes after they were sent from my station at another location.  It won't be obvious for a fixed station, but it sure shows up for mobiles.

Please just check that your setup is not doing that.  Monitor it for a while once you've got it going.  This is apparently a known problem for some KPC3s.  Lynn can probably provide information regarding what to do about it.

Gil Chapin, WB2UTI

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