Buying Second-hand
you’ll find this under the small oval-shaped removable
cover.
To locate which pin is which, while you’re looking at
the connector from the front of the transceiver with the
connector on the left hand side, pin 3 is at the 3 o’clock
position and pin 6 is at the 10 o’clock position.
If you’re unsure of poking wires into the connector, then
you could get yourself a PC keyboard extension cable and
use this to plug into the set and link the wires on it, the
connector is exactly the same.
With the pins linked, simultaneously press the F key
and Tone key while you switch the set on. Then select
v.f.o. mode and tune to a 144MHz frequency, which you
can monitor on another receiver, or even better a radio
communications test set to measure transmit deviation if
you have access to one (or use a PC and monitor receiver,
read on in this month’s column).
Next press ‘MNU’ to select the adjustment mode, and
use the keys to select ‘DEVI’. Press the mic PTT and speak
into the mic, and use the rotary encoder knob to adjust the
transmit deviation until you get to the right level. You’ll see
the display will indicate a two-character level as you adjust
this. Once you’re at the right deviation level, ideally 2.5kHz
maximum deviation, press the ‘OK’ button to save this
adjustment level into the set’s memory.
Then press the MNU button to return the set into v.f.o.
mode. If you need to adjust the 430MHz deviation level,
you can simply tune to a 70cm channel to do the same
series of operations. The deviation level for v.h.f. and u.h.f.
i
s stored separately inside the transceiver. When you’re
finished, switch the set off and remove the wire short on
the connector.
The Icom IC-207
Next, I’m turning to the Icom IC-207, a set that provides
you a 50W 144MHz rig and a 35W 430MHz rig squeezed
into the same box, a ‘band’ button switching between the
two bands. Wide-band coverage is also available (see later
for this) the modification for this. The set’s case measures
a very small 140x40x185mm, so you should be able to fit it
in into the tiniest of available positions in a car.
The transceiver’s front panel offers a number of
operating knobs and buttons. A detachable microphone
cover reveals a fully-fledged
remote control system for the
set, with each button being
backlit for night-time use.
The microphone control
even provides Up/Down
volume and squelch controls,
as well as handy facilities
such as a reverse-repeater
monitor and transmit power
selection. There are 150
memory channels plus extra ‘call’ channels and the like
available for frequency storage and one-touch scanning.
A bright yellow back-lit liquid crystal display is used, with
the functions for the six push-buttons below the panel also
being shown on the display.
Along with the detachable front panel, a ‘separation
kit’ is also available, so the transceiver itself can be
mounted remotely with just the small display fitted in a
more easily-viewed position on your dashboard. Together
with a 1750Hz tone-burst facility from the microphone for
repeater access, the IC-207H also has full CTCSS (sub-
audible
tone) encode and decode built in, and ‘tone scan’
l
ets you check which, if any, sub-tone is being used on an
active channel.
For packet radio use, a 6 pin mini-DIN connector is fitted
to the rear panel, the transceiver accommodating both
1200 and 9600baud speeds.
On The Air
When I used the set, I found it was very easy to operate
and within a few minutes of switching on I was enjoying
a QSO on my local repeater. I found the set’s front panel
controls were intuitively very simple to use.
With the plastic cover in place on the supplied
microphone, it of fers a smaller number of controls, such
as you’d typically use for ‘normal’ operation, like Up/Down
frequency or channel change, VFO/memory switching,
band switching, and so on.
About the only awkward operation mode I found with
the set was that of generating a 1750Hz tone for initial
repeater access – this needed the microphone’s plastic
cover removed, with a sequential press of two different
buttons beneath the cover. I found this rather awkward in
practice, although if you know the CTCSS access tone for
the area you’re using the set in and pre-program it, this
isn’t too much of a problem.
This rig also includes a handy facility, which consists of
five ‘scratch pad memories’ for each band. Here, the set
automatically memorises the operating frequency every
time the p.t.t. is pressed, storing the last five frequencies
(including repeater shifts) on each band into separate
memory channels. Recalling these just needs a quick
press of the ‘M/Call’ button, the tuning knob then selecting
between them – very useful and especially handy when on
the move.
Operating from home, with the set connected to my
rooftop collinear, it showed a good level of performance
without a trace of the ‘typical’ intermodulation problems
I’ve learned to expect on 144MHz in my r.f. congested
location. Icom have also usefully incorporated an
automatic attenuator in with the squelch control – turning
this beyond around
the mid-way point
gradually adds
up to around
10dB of front end
attenuation, to
help guard against
strong signal
problems without
a lot of button-
pushing.
I found operating with the transmitter on high power for
long ‘ragchew’ periods did cause the heat-sink panel to get
very hot and I usually found I needed to drop down to the
‘next lower’ power level for this. However, programming
the set to keep the rear panel fan on continually helped, as
long as I didn’t mind the fan’s constant low-level ‘whirring’
noise on receive.
My lab tests back in the days when the set was
Practical Wireless, July 2010
32