Specifications

4. Install
a .l mF capacitor between
pin
3
and
pin
1 of the channel element.
5. Locate
pin
I I
on Jl-this
is
the
plug
on the front of the radio. Make
your
receive audio connection
there.
You
shouldn't need to make any mods
to the
receiver.
(If
you
don't have any
real
good
test
equipment, don't make
any receiver mods-it will work okay.)
6. Install a.lmF
capacitor between
pins
I and
3 on
receiver
channel
element.
NcnB:
At
Jirst,
set
your
TNC's TXD
ar9ument to 200m5. If
all
works well, start lowering the
TXD
value-you'lL
probably
end
up with
a TXD of 7, or 70m5. The
capacitors
on the
channel elements'
pins
recLlly don't uJ-
fect
9600 bps operation, but they do reduce
the
local
oscillator
leak
that emits ottt of these
radios which is
about 20
dB
(very
important on hilltops).
TEKK KS.gOO
For
the TEKK KS-900, the needed
transmit
level
is in the 50
mV range;
the
level adjust is fairly sensitive
in
this range, so it may
be desirable to use a resistive divider to reduce the level from the 9600 bps
modem
board. This is
simply a 410W resistor in series
and a 39W
resistor
across
the TEKK's transmit input and
ground.
YAESU FT-211-RH
(courtesy
of Chris Lorek from
SMC)
The FT-2 I IRH
has been shown
to be
suitable lbr
9600 bps
packet
operation. Jr,rst.
two shielded leads arc
required,
one
fbr receive
audio and the other lbr transmitter audio. They are connected as lbllows:
Receive:
On the RX IF Unit
(sub
boar-d
F2869 104),
connect Lhe shielded
inner conductor to thc TKl0420
IC,
pin
9,
with
the shielded
wire
to
pin
15. Caution should be taken to solder these
if
they
are to be sol-
dered to the underside of the board.
Transmit: On the rear
of
the main PCB is
a small
potentiometer-this
is
the
peak
deviation adjustment
pot.
Unsolder the leg nearest to
the
rear
of the
set,
then connect the
inner
conductor
of the shielded TX
leads to this point
and the outer shield to the circuit
board's
ground
plane
adjacent to this
point.
To ensure
that the
9600
bps modem is
terminated with the required impedance, it's
essential that
a sllitable termina!
ing resistor be
placed
across the shielded lead inner/outer
(such
as a 560W resistor); this can be done
at the
FI-2 I IRH's
potcntiometer
connection.
YAESU FT-726
(courtesy
of Rick Meuse, NI HlD)
Tap
off between R45 and R96 fbr
the
receive,
and between R22 and Cl6 for the transmit end.
You'll have
to change the
receive
filter to a wider one
(CFW-455D)
which
I haven't done
yet.
YAESU FT-736
(courtesy
of
James
Miller,
G3RUH)
These notes tell
yoLr
where
to
get
at the
FM
receive audio direct fiom the discriminator and where to
modu-
late the FM TX varactor
directly. These mods arc nondestructive and take no more than a i'ew minutes.
The
signals
bypass the
"DATA"
socket fbr high-grade FM
operation.
The receive mod is suitable fbr:
.
UOSAT-D 9600 bps downlink and terestrial links
.
1200
bps
AFSK/FM
standard
packet
The
transmit mod is suitable for:
.
FO-2O/PACSAT
uplink
(1200
bps Manchester FM)
"
UOSAT'-D 9600 bps uplink
direct
FSK
and terrestrial
links
.
1200 bps AFSK/FM
standard
packet