The maxtrac interfacing article on r-b by Scott
KB0NLY had information and photos. There are really
only two styles of logic board: those that have just
the masked CPU (one big chip) and no shield, and those
that have the CPU, an ASIC, an EPROM, etc, all in a
shielded area. Your 5173A should match one of those
two board layouts, I suspect it's got the shielded
area.
There's a row of feedthru holes inside the shielded
area, in the lower left corner, that will either be
all in-line, or with some offset. It doesn't matter;
the left-most hole is a signal called RX MUTE. This is
low when the radio is squelched and goes high when the
radio is unsquelched and passing audio. This means it
will only go high when the incoming signal has the
proper coded squelch and the MONitor button is set for
normal operation. If you press the MONitor button to
put the radio in carrier squelch, then the RX MUTE
line won't care about PL or DPL. Also, if you press
and hold the MONitor button to open the squelch, the
RX MUTE line will go high and stay there.
Use a 4.7k resistor and a common NPN transistor to
invert and buffer the RX MUTE signal. Bring the
collector out through the MIC jack on pin 1 and use
that as the COR signal for your controller. You can't
get a separate PL/DPL detect line; it's just not
available outside the microprocessor.
I've been modifying MaxTracs and Radiuses this way for
years and it works great for repeater use.
Bob M.
==
--- Jay Urish [EMAIL PROTECTED] wrote:
I just picke dup a few of these little gems and I
want to build a
temporary portable lunchbox repeater in case my main
machine croaks or
incase I am in a weak coverage area--
These have the HLN5173A logic boards-- I was on RB
and I saw a couple of
articles on how to bring the important signals out..
However, none of
the articles addressed my logic board directly.
I have the 5pin board and I think I want to make
this a sdown and dirty
as possible.. I will just cut one end off of a db-9
serial extension
cable and run it out the back hole of the radio.
I need the usual stuff-- ptt/cor/audioin-out and I
really want to find a
place for PL detect as well..
Does anybody have a pic of the board showing
where/how they tapped and
flipped the logic to make this fly?
--
Jay Urish W5GM
ARRL Life Member Denton County ARRL VEC
N5ERS VP/Trustee
Monitoring 444.850 PL-88.5
Give
spam the boot. Take control with tough spam protection in the all-new Yahoo!
Mail Beta.
http://advision.webevents.yahoo.com/mailbeta/newmail_html.html
