Re: Kpc3+ settings for APRSISCE

Robert D. York

IMPORTANT!! If you intend to leave the TNC attached to a computer, but will not be running an APRS or other terminal program on that computer, you must make sure that the INITKPC3.TNC and RESTORE.TNC files are modified to include "MON ON" and "MON OFF", respectively. And, before exiting from any terminal program, issue a "MON OFF" command.

In this particular circumstance, it is possible for the computer's serial port to tell the TNC to not send data. When the TNC's port buffer fills, the TNC may stop working. This problem has not been reported when the TNC is not plugged into a computer, or if the computer is actively listening to the TNC. In the absense of a connected computer, however, the TNC just sends the excess data off to the bit bucket. [Note: failure to provide a properly-sized bit bucket will require proper drainage, or sufficient airflow to allow for adequate bit evaporation]

On Mon, Jun 14, 2021, 12:30 PM Gil <gil.chapin@...> 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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