[Kenwood] TM-D710a GPS problem

[Steven Schultheis]

Hello All,

I'm wondering if any of you have any insights on my problem. I have a
TM-D710a that I bought new. I'm trying to run it with a Garmin Nuvi
350 GPS, connected by one of these Argent GTRANS cables:

http://tinyurl.com/244nvus

This "smart" cable translates Garmin's proprietary output format to
standard NMEA messages for the TM-D710a. It also translates 'Kenwood'
format waypoints, as output by the radio, into Garmin's waypoint
format for proper display on their GPS's screen.

When I connect my GPS to the TM-D710a and select 'gps' as input in
menu 602, I get no position information. Kenwood tech support told me
the "gps" legend towards the upper right corner of the display should
blink with each valid GPS packet received. It never does. Incoming
APRS messages are displayed with no 'arrow' in the position circle. If
I manually enter a location via menu 605 and set 'input' to 'off' on
menu 602 ,I do get the arrow and position information on received APRS
messages.

In menu 603, I have waypoint output enabled, and I _do_ get waypoints
displayed on my GPS. So output from the radio to the GPS is working.

I attached test leads from the GPS's 2.5mm cable to a serial connector
on my PC, opened a terminal program at 4800 baud, and saw this:

$GPGGA,191749,4302.3693,N,08928.0327,W,1,08,1.0,316.7,M,-34.3,M,,*77
$GPRMC,191749,A,4302.3693,N,08928.0327,W,0.1,184.0,090810,,*07
$GPGLL,4302.3693,N,08928.0327,W,191749,A*3C
$GPGGA,191751,4302.3693,N,08928.0327,W,1,08,1.0,316.7,M,-34.3,M,,*7E
$GPRMC,191751,A,4302.3693,N,08928.0327,W,0.1,162.0,090810,,*06
$GPGLL,4302.3693,N,08928.0327,W,191751,A*35
$GPGGA,191752,4302.3692,N,08928.0327,W,1,08,1.0,316.7,M,-34.3,M,,*7C
$GPRMC,191752,A,4302.3692,N,08928.0327,W,0.0,214.0,090810,,*07
$GPGLL,4302.3692,N,08928.0327,W,191752,A*37

[ ... etc ...]

So it seems that reasonable data is coming from the GPS/cable.

I borrowed a buddy's old GPS with RS-232 output and ran that into the
radio with the same result- no GPS data received. The old GPS (a
Magellan "Meridian Gold") has three software selectable NMEA 0183
format options: "V1.5 APA", "V1.5 XTE", or "V2.1 GSA." I'm not sure of
the differences (and I don't want to spend $350 for a copy of the NMEA
spec to find out), but in any event none of them work. I don't have
any other GPSs to try.

I'm beginning to suspect that the GPS input connector (or downstream
circuitry) is bad, although this seems unlikely with a brand new
radio. But I'm also reluctant to send it in for warranty repair until
I've exhausted my options. Since the radio is still under warranty,
I'm reluctant to rip it open and try to solve the problem myself. Even
if the connector itself is bad, I probably wouldn't be able to source
a replacement myself anyway.

If anyone has any insights or suggestions of things to try before I
send the radio to Kenwood, please let me know.

Thanks,

- Steve