I figured that I would ask here first because 1. you guys da bess and 2. I know we have a few packet folks here.
I picked up a KAM-XL for cheap that appears like new. I have wanted to play with 9600 packet and winlink, but our local 9600 nodes are down for a little while so it may be a bit before I can check out the 9600. I've got some experience with packet, mostly playing with myself, winlink, APRS, and our local packet node - all 1200 baud using mainly my KPC-3+. Radio is a Kenwood TM-v71a. No problems up to this point. Wanted to test out the KAM-XL, at least on 1200...
Now here's my issue: The KAM-XL seems to do just fine TXing. No issues on APRS, winlink, or the packet node getting heard on 5w or 50w. RX, however is a different story. The KAM-XL does fine with short packets from strong signals. Weak signals (as heard audibly) are not decoded well or at all. Short signals (ack, short data burst, etc) from the packet node (or logging in to the APRS digis) are fine, but longer bursts (i.e. responses from help, MH, or info commands) do not decode well, often times taking several retries to get the burst of data decoded. TX on my end seems to be fine, as I don't see any repeat requests from the other station, even at low power.
Trying to replicate the situation with the KPC-3+, I get much much better decodes on weaker signals like APRS mobiles, and the "long" packets decode just fine... no repeat requests or missed packets at all. This makes me think that it is not a radio, cable, or computer issue.
I went through the (incredibly long) manual for the KAM-XL, and have gone over all of the jumpers and set them in what I believe are the correct settings. I have also set the TX deviation (by ear) as I don't have a proper monitor for that, but again I have no TX issues that I'm aware of. There are no settings to adjust RX level or whatever that I can find. No potentiometers inside the TNC.
The only other idea that I have come up with is that the TM-V71a has a software setting to adjust the TX and RX sensitivity on the packet port. I haven't had a chance to fool with that yet, but I would think that if one Kantronics TNC worked, then the other would as well.
Any words of wisdom or suggestions? I'd appreciate help, especially from someone with experience with this TNC.
Edit:
Figure I'd add: Only V/UHF packet so far (and only 1200 now), no HF or other modes yet.