Interfacing The KPC3+ And The Davis Weather Station/APRS




This will make the KPC3+ into both a digi and weather station for APRS.

Items needed:


1. Kantronics KCP3+ [V9.1] TNC fused  @1/2A

2. Davis Weather Station, # 6152c,VantagePro2-Cabled,

    # 6540 Weatherlink-APRS,

    # 7720 Heater [for ice in West Texas]

3. Ericsson GE  344A4210P2 40W VHF [radio] /144.39 MHz/fuse 7.5A [fast t/r switching and efficient/6 1/4A @ 40 watts]




1.Radio cable to TNC / DB-9


DB-9/TNC to radio                                                               


1.         Mic---------to mic circuit                           

3.         PTT--------to ptt                           

5.         Rx----------disc [open sq] use circuit below [pl3 /pin3 GE ]                            

6.         Gnd--------gnd                                                                             


Cable pulled out of radio at the SO-239.                                  




     c = .047 uf                              De-emphasis Circuit

   cc = .15 uf                     GE                                                                   db-9 to     tnc

   rrr = 6.8k  ohms           radio [pl3 / pin 3]   >---cc----------rrr--------->       pin 5 

                                                            [disc.]                                 |




2.Computer to TNC cable


DB-9(computer)                    Db-25 (TNC)


2.         Data in  --------------------   3.         Data out

3.         Data out  ------------------   2.         Data in

5.         gnd   -----------------------    5.         Gnd


3.DB-25/TNC to Davis comes with Davis # 6540


DB-25 [on the KP3+] will be the computer hook-up and the Davis Weather Station.




J1 on               batt. use 9v

J2 off               batt use 9v

J3 off               for 10k rx audio

J4 on               no equal

J7 off               RESET

The rest of the jumpers can be left at factory settings.


KPC3+ [V9.1] Software Settings:[Use hyperterm Windows @ 9600 baud 8/N/1]________


1.Restore / back to factory spec.[J7]           * Set time,Daytime-' Da mm/dd/yyyy hh:mm:ss'

2.Mycall: N5SOR-2                             info : * '?command'=help

3.Intface:  TERMINAL                                    *to get out of GPS mode :' ctrl c'

4.Cd : SOFTWARE [ for open SQ ]             *set dev. to 3.25 khz & use 'cal' &'+ / -' to adj. mod

5.Hid : OFF

6.Uidwait : OFF

7.Uiflood : TX,30,ID

8.Uitrace : WIDE,30

9.Uidigi : ON WIDE4-4,WIDE5-5,WIDE6-6,WIDE7-7

10.Unproto : APN391 VIA WIDE

11.Monitor : OFF

12.Cmsg : DISC

13.Ctext : REMOTE WX / APRS STATION @ DM70xv , BYE!

14.Btext : MT.McELROY / TX/ APRS WEATHER @ 6654FT. / DM70xv

15.Beacon E  20

16. Blt 1 E 00:30:00 START 00:00:00

17. Blt 2 E 00:30:00 START 00:00:15 CLEAR

18. Blt 3 E 00:30:00 START 00:15:00

19. Blt 4 E 00:30:00 START 00:15:20 CLEAR

20.Lt 1 !3054.55N/10403.82W_PHG6860/A=006654ft / MCP/W4/ HIGHEST APRS IN TX/MT.McELROY/DM70xv/1

21.Lt 2 [leave blank--wx /(128 chrs.)]

22.Lt 3 !3054.55N/10403.82W_PHG6860/DM70xv/ W4/ TNX WTC,INC + INTERTIE,INC./DM70vx/3

23.Lt 4 [leave blank--wx/(up to128 chrs.)]

24.Ltp 1 APN391 VIA WIDE3-3

25.Ltp 2 APN391 VIA WIDE2-2

26.Ltp 3 APN391 VIA WIDE2-2

27.Ltp 4 APN391 VIA WIDE3-3

28.Gpshead 2 @

29.Gpshead 4 @

31.Rtext : xxxxxxxx        [ keep private ]

30.Myremote : xxxxxxx   like 'W5EX-15' [keep private(call sign)]

32.Txdelay :27     [270ms]

33.Sl 8                  [slottime = 80ms]

34.Int GPS


After the above command [# 34] you must turn off the TNC or send reset to make it go into the GPS mode which the weather station uses. The TNC DB-25  is now the Davis weather input. Assemble your Davis weather station and check to make sure it works. Then shut it down and plug in the "data logger" in the back of the weather display. It takes a bit of pressure to put it in. Then insert '3' c-cells [battery back up] in the back of the display and connect the weather station to the AC. DO NOT PLUG THE LOGGER IN WITH ANY POWER ON OR YOU WILL BE BUYING A NEW ONE ! Connect the RJ-45 from the logger to a DB-9 adapter [Davis supplied] into your computer comm port (1). Load the software up [Weather Link 5.5.1] and run "setup comport". Set the baud rate at 9600 to match the TNC [9600]. Then run "config streaming data logger" and answer all the questions. Then take the RJ-45 and plug it into the [Davis supplied] DB-25 adapter and into the KPC3+ / DB-25. You should be up and running! Also, this setup will run as a digi/weather station/and with the new Paradigm W-4 [with the above setup].


KP3+ Extra Aux. Input/outputs


Remote KPC3+ AUX. INPUT/OUTPUTS with its own beacon!


1. [Input] 0-5v, An0 [J8, pin 1] goes to P1 [radio port] pin 4.  SW to DB-25, pin 18/J8, #2


2. [Input] 0-5v, An1 [J10, pin 1] goes to P1 [radio port] pin 8. SW to DB-25, pin 11/J10, #2

A [output] pin 4 on='ctrl A on',  off = 'ctrl A off'.  A & B can be pulsed too.

B [output] pin 8 on='ctrl B off', off = 'ctrl B off'.




'TEn' =  [n x 10 sec ] to beacon, i.e., ['TE1200' = beacon every 20 min.]

Read analog 0 = 'An0' Use 'myremote' command then send 'an0'.

Read analog 1 = 'An1'


More input/outputs on the KPC3+ [normally only 2 hook ups] can be made by hand wiring more off the KPC3+ circuit board.




Range command=Ra 0-255 /i.e., 0-255 range for # '0' with a 12 VDC scale='Ra 0-12'


Remember no voltage over 5 VDC, so use a voltage divider!


Two things that will be used above will be to monitor battery [back up] voltage on the station and shack door open/closed.




Dink, WA5LNL




Revised: 11/27/08 09:00 PM by KC5PIY, B. B. Stanfield, Webmaster

Copyright 2008 by Intertie, Inc. All Rights Reserved

No use of these symbols or phrases is allowed without the express written permission of Intertie, Inc.