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Author Topic: APRS Chronic failure  (Read 2510 times)
W4XKE
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« on: January 11, 2003, 05:36:11 PM »

Well, if at first you don’t succeed…  I have been trying to get an APRS station up and running for a little over 1 ½ years now without success.  The equipment consists of a Kantronics KPC 3 +, a Yaesu FT-50RD,  a Radio Shack HTX-202, Diamond omni antenna at 25 feet and various computers.  I registered a copy of WinAPRS and am running that on a 1.2 GHz, Windows 98 SE, 40 Gig HD, 256 Megs RAM machine.
Everything runs fine except nobody can decode my packets.  The red transmit light comes on, the HT sends out a packet (I can monitor that on a different HT) but all it amounts to is a burp of noise.  The only way I can know for sure what the problem might be is to observe my signal on a spectrum analyzer or to check the deviation with a deviation meter (both are specialized types of test equipment that not even the Tennessee Technology Center has ever had access to).
   I am left with trying hundreds of different settings on the KPC-3+ as a kind of “shot in the dark” approach to hitting the right combination.  So far, in going on 2 years now, I haven’t accidentally hit the right settings.  
When I listen to packets coming in on 144.390, I notice that mine sounds different, but without being able to see the signal, there’s not much any way to determine what is out of adjustment.  The same situation exists with both the Yaesu Ft-50 RD and the HTX-202.  The TNC was successfully operated with a Kenwood 261A mobile at last year’s field day, but the HTs have not worked for the most part.  Two days ago, one fellow acknowledged one of my packet messages, but he was one of 3 people who have ever been able to see my station on their display.  Try as I might, it didn’t happen again.  (Must have been a fluke) I’m not quite ready to buy a $12,000 piece of test equipment to set the configuration on the TNC, so I guess I’ll just play around with it from time to time when there is nothing else to do.  HI HI.  I would advise anyone considering APRS not to invest heavily in it unless there is someone around locally with some nice test gear to get it properly adjusted unless you are content to just listen and observe the activity that is going on.  73, Johnny W4XKE
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KB9YNB
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« Reply #1 on: January 12, 2003, 05:17:45 PM »

This sounds like it could be an RF power output issue.  How far away from other receiving stations are you?  a 5 Watt HT doesn't have all that great a range, even into an antenna at 25 feet.  Can you borrow someone else's TNC to hook up to your other HT to decode packets at your QTH?  The fact that people have been able to receive your packets (however sporadically) and that your TNC worked with a higher power radio would lead me in that direction first.  

Or, can you buy/build/borrow a directional antenna to point at another known APRS station to see if your signal is received more often?

Finally, since the output deviation is corrected in software on the KPC3+, you might think about doing a  reset to restore the factory settings.  Most everyone I know has been able to use the factory settings with success with these devices.  I have used mine with my FT50 without changing any settings.

Don't give up, and good luck.

Ryan, KB9YNB
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N3EOP
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« Reply #2 on: April 28, 2003, 02:27:35 AM »

At first reading, it sounds like your TXDelay is set too short.

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K4SDI
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« Reply #3 on: June 06, 2003, 08:23:40 AM »

Sounds to me like your audio maybe be too loud out of the computer.  It's very easy for this to happen.  That would make the packets distorted and unrecognizable.  Also, I'm kinda worried that in all that "tweaking" the TNC may be way out of wack.  Try using the sound card approach. Its a heck of a lot cheaper that a TNC.  


Mark
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