How to have a 13 watt APRS radio

that's only 2.75"x4"x1.5"

 

Let's start with the BNC connector on top.

For the BNC, I just remove the top nut on the press-fit antenna base (it's Loctited,
so heat it before removing) then unsolder the tab from the circuit board and knock
the mount out the back of the plastic.  Then I enlarge the hole and put the BNC in.
 

Now comes the really hard part...



For connecting to your TNC:
1 = Transmit audio (you may have to turn
      it down at the TNC - it's a low level input)
4 = PTT
5 = Ground
8 = Receive audio (it's push-pull and you'll
      get half audio, but it's enough)

Power connections are to the bottom battery plate area.  Be sure to leave
the fuse in!!!  By cutting up a dead battery and using it for a power adaptor,
you can still use the radio as a portable tracker radio with the correct battery,
as well as powering the TNC and GPS if you run a power lead out of the
radio.  I usually bring it out on pin 11.

If you remove the front cover, you'll find a small trimmer capacitor under a hole
in the shield near the top of the radio.  Watch the current on the ammeter while
adjusting for 13 watts.  If your current increases but the power stays steady or
drops, you've gone too far.  Use an insulated tuning tool to do this!

I had one of these putting out 16 watts, but turned it down...it has been in
continuous use at 13 watts for over a year with no problems, and draws
the usual 2 amps on transmit (considerably less on receive though - about
50 mA squelched!!!)  Just remember...turn DIGIPEAT off, and don't try
to use it as a WIDE!

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