The Packet Radio
“
2 N 1
”
Handbook
by
Buck Rogers
K4ABT
Section 1
;
Packet Radio “The Basics
”
Section 2
;
The X1J4 System Node Operator’s (SNO) Handbook
ILLUSTRATION SECTION Charts & Node Drawings
TheNET
X1J4 System Node Operators Handbook
__ Page 45
APPENDIX “A”
FINAL NODE “CHECKLIST:”
When installing your 9600 baud nodes back on-line, and if you are using the small “rinky-dink” wall supply to power the
TNC/NODE, then check the power from the small wall type supply to be sure the supply is supplying over 14 volts. When
it is attached to the TNC, the voltage will drop to around 12 to 13 volts under load. If the supply is not delivering sufficient
power (voltage) to the TNC, the node will not perform properly and may not decode 9600 bauds. The same scenario
applies to the 1200 baud TNC and supply.
At my installations I chop the wall transformer wire off about 3 inches from the transformer/DC supply and attach it to the
12 volt DC power source that is used to power the radio for the node.
Usually the wire with the small “white” tracer on it
is the positive lead, however, I’d ring it out with an ohm meter to be sure that the TNC center pin is connected to
“PLUS” (+)12 volts.
The TNC needs less than half an ampere at 12 volts to make it work, so the load to the supply for the
radio should carry the extra load of the TNC well.
A low voltage problem may be experienced with the 9600 baud nodes more often than with the 1200 baud nodes. The
reason is; The 9600 baud node has the added load of the internal 9600 baud modem piggy back board. It adds to the supply
load with extra power requirement of the 9600 baud modem, and this is where I have some beef with the supplier.
CAVEATE ; In some recent mail and truck deliveries to my QTH, I have seen...(HEARD) rattling inside the TNC’s prior
to opening them. Seems the carriers uses them for base ball practice, and toss them hard enough to make the EPROM pop
out of socket U 23. This same scenario may be occurring with other deliveries of TNC and nodes to you. If you have any
problem at all, remove the (4) screws from the cover of the TNC/node and check all the IC’s to be sure they are inserted
securely into their respective socket.
ONCE YOUR TNC IS BUILT INTO A NODE; At the rear of the TNC/NODE is a set of 8 switches, called a inline 8 DIP
switch. DIP switch number
5
determines the baudrate of the
RS232
port(s). Make sure both nodes have DIP switche(s)
number 5, in the
ON
position. Remember that some older TNC have the DIP switches
UP =ON
and DOWN=OFF. On
some of the later (most) “C” versions, the DIP switches are
DOWN=ON
and
UP=OFF
. The principal idea is to make sure
the TNC/NODEs are talking between the 1200 and 9600 baud NODE ports (GATEWAYING) properly.
DIP switch number
8
is “ON,” on the
9600
baud node.
DIP number
7
is ON on the
1200
baud node. This is the switch
that determines the
RADIO
port speed.
So; here is what you should have:
the
1200
baud TNC/NODE;
DIPs
5 &
7
are ON
..
all others are OFF.
the
9600
baud TNC/NODE
DIPs
5 & 8 are ON
..
all others are OFF.
The following apply to both 1200 and 9600 baud VHF & UHF nodes:
Be sure you have the “UMBILICAL” cable is connected between the 1200 and 9600 baud RS232 ports.
The
BLACK
(HF/VHF) button on the rear of
all
MFJ-TNCs is
OUT
= OFF.
Make sure power is connected and
ON
; the
RED
button (Off/On) is
ON
= IN.
VISIT the
SEDAN
Packet Radio Networking Pages at:
http://www.PacketRadio.com
BucK4ABT
