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PacSat users with 847 and EVM - Cable and software howto



I've been working on connecting my 847 to the EVM and using it to work the
9600, 1200AFSK, and 1200PSK birds.  I've taken a slightly different approach
than some of the other discussions and would like to share those result if
anyone cares.  I have an 847, evm, Tapr Enclosure.

To summarize, I wanted to keep the radio in 9600 mode all the time and not
have to worry about switching it back and forth between 9600 and 1200 (you
can't do that from software control, bummer).

Most will tell you that driving the Varactor directly is the preferred
method and also taking the Rx signal direct from the discriminator is also
the best.  With a bunch of circuits in the way when the radio is in 1200
baud mode, I couldn't do the above.  I also wanted to have one connection to
the radio for both FM and SSB.  Here is what I've come up with.

CABLE

a) get yourself a ps2 keyboard extension cable (make sure it has all 6 wires
connected on the mini-din 6 side).  Cut off the end that doesn't mate to the
847 and bring all the wires over to the evm/ri.  One note here, strip back
the outside of the cable on the evm side about 6-7 inches (you'll understand
why in the next step).   Next you'll need to pin out the cable so you know
what colors are connected to what pins on the mini-din side.

b) leave the wire that is connected to the 1200 audio from the radio long
and shorten the remaining 5 to connect to the DIN 8 on radio 1 on the
evm/ri.  NOTE!!!  There is a pin that has squelch status on it.  It is 5V
when the squelch is closed and 0V when open.  You don't need this, so
heatshrink it so you don't short it to anything on the evm!  - VERY BAD! 

What we are after here is a connection to radio 1 with the signals for all
the FM TX and a long single wire that you can connect to the radio2 port for
the rx of SSB audio

c) Wire up the single wire to pin 4 on the evm/ri for the SSB audio from the
radio (You will note that they 1200 audio from the radio is available on
both the data in/out port and a pin on the packet connector, they are the
same audio from the same source in the radio itself.

Ok, now you are done with the cable part, check your work and you should be
ready.  Make sure you have audio FROM the radio to audio IN to the EVM and
vice-a-versa.  ALSO make sure you didn't connect that pin from the radio
that has squelch status on it... You don't want 5V going to somewhere on the
evm that is shouldn't.

EVM

Remove the 1K pots on both radio ports on the evm, just jumper across the
audio path, you don't need to worry about the grounds, a resistor lead  or
something similar works just fine.  You can do this without un-connecting
the rear interface, but it's easier to solder if you unscrew it and turn it
over :-P

Also, make sure you turn the 10K pots on the RX side all the way clockwise.
I guess you could remove them as well, but I didn't go there.  We'll control
the RX audio levels in the software.

SOFTWARE

Ok, we're almost done.  For any that want to go to this extent, I'll be
happy to provide my parameter modified source for the G3RUH, PSK and FSK1200
code.  I've tweaked the parameters so that the deviation should be

G3RUH - 2.75 
FSK1200 - 3.75 (max I can get out of the source code)
PSK - 3.75 (what can I say, I could go more, but it's a good value)
On the PSK module you RX on the radio2 port and tx and PTT on the radio1
port.

The above seems to work pretty well.  There still is an issue with the radio
because you can't switch the 1200/9600 mode from software.  So, what I did
was program all the sat memories with 9600 and resave them.  Then regardless
of what sat mem you were in last, you'd have the right mode selected for
this code.

I haven't made any PSK mode contacts yet, but I've verified the G3ruh and
the FSK1200 stuff both in ground contract and in sat contacts.

I'd actually like to get a few others to test this with real setups (my
steerable arrays aren't up yet).  And with the ability to judge deviation
levels to make sure I got them right.  I can monitor them on my service
monitor, but I'm still curious.  If anyone would be interested and has
similar test equipment, please let me know.

Just thought I'd help.  I had to learn most of this the hard way.... BUT
huge thanks go out to Mike N1J... I never remember.  He got me started.  At
some point however, he stayed with parameters for 1200 mode and I went on to
9600.

If we are really lucky and Yaesu didn't change the radio much in production
runs, we should be able to create a version that works with any 847 cabled
as above.

Alan
ne1h@ne1h.dyndns.org

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