decided that I needed to get into my local repeater
(Newburgh, 146.430 RX [on my radio], 147.435 TX, 71.9PL)
from the office or wherever using my laptop or
smartphone. In addition, there are a few members
of the Orange County Amateur Radio Club that cannot
easily get into the repeater at all times. So....I
have an old laptop of my son's that works, so I rebuilt
the operating system and installed Echolink on it to run
in Sysop mode. Interfacing was fairly simple, and
it works well. To the right is the Echolink screen
during a QSO with KC2VTJ connected to the W2TRR-R
Right now, this is a
"private", by invite, node to connect to.
This is the
schematic for the interface between the computer and the
Yaesu FT-1802M radio. The computer being used does
not have a com port, so I am using a USB to RS-232
adapter. I have the Echolink program set to output
PTT on the Request To Send (RTS) pin, pin 7 on the DB-9.
When Echolink wishes to key the radio, RTS goes high.
The resistor in series with the RTS pin is to limit
current into the transistor. The resistor from
base to ground is to hold the transistor off when RTS is
not active. When RTS goes high (becomes active,
which is actually a data 0 - RS-232 levels are -12V for
a data 1, +12V for a data 0), the transistor turns on,
taking the collector of the transistor to ground,
connected to the emitter. This takes the PTT pin
on the radio to ground causing it to transmit.
I am using
two transformers to 1) isolate the computer from the
radio and 2) to drop the audio levels. The top
transformer takes the audio output of the computer and
drops the voltage, and sends the audio onto the mic
input of the radio. The bottom transformer takes
the audio output of the radio, drops the voltage, and
sends the audio onto the mic input of the computer.
I have the FT-1802M in a
carrying case which I use as a portable APRS rig for remote operation.
|This is the
experimental interface. The Echolink setup is
presently set up temporarily. Once I determine
where it's permanent home will be, I will neaten up
the interface and "make it real". Bottom line
is you don't need a fancy, expensive interface unit
to put together an Echolink node. The total
parts cost was about $20. I had the radio and
antenna. And I had a laptop kicking around.