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By Michael Stevenson Port Macquarie, NSW, Australia January 2004 |
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By Michael Stevenson Port Macquarie, NSW, Australia January 2004 |
MAIN FEATURES
Because this version of the
R75 is for the USA market, covering 30 kHz up to 60 MHz without
gaps, the Australian version has a couple of links installed to
limit coverage to 30 kHz to 29.999 MHz, and 50 to 54 MHz for the
Amateur band. The receiver is all-mode with USB, LSB, CW, RTTY,
AM, S-AM (Synch AM detection) and FM. It has a fairly large orange
backlight LCD display which has a fully adjustable brightness
from zero up to very bright (for seeing in full daylight), it
displays a signal strength meter from S1 up to +60 dB over S9
in bar graph, a large digit frequency display with readout to
1 Hz with fully selectable tuning steps of 1, 10 Hz, 0.1, 1,5,
6 25, 9, 10, 12.5, 20, 25 and 100 KHz and 1 MHz quick tuning step
all controlled by the large tuning knob which is weighted with
an adjustable clutch for very free spinning or tighter for no
spin. It also has a lock button so that the frequency setting
cannot be accidentally moved if the tuning knob is bumped
A single clock and timer on/off is also displayed but both frequency
and clock cannot be displayed at the same time which is a bit
of a disadvantage, the Sangean 909 displays both clock and frequency
at the same time and also has the choice of displaying world time
in most major cities around the world! The Kenwood 2000 is like
the ICOM, you had to turn a knob to see the single clock but then
the Kenwood has a small fluoro display (unlike the R5000 which
displayed frequency and two clocks at the same time). The ICOM
has a single one event timer (very easy to set) like the Kenwood
R2000 (the Sangean has three timers). The display also shows,
at the same time as frequency, the memory channel chosen and its
status (programmed or empty), whether one is using VFO or memo
at the time, as well as the operating mode and whatever else is
being used at the time, DSP noise reduction or auto notch filter,
pre-amps, attenuator, AGC, noise blanker, antenna 1 or 2, filter
selection etc.
The R75 has a headphone socket on the front (which disconnects
the in-built speaker or an extension speaker if one is used) and
on the back there is a recorder remote switching socket, line
out for recording, an RS 232C to connect to a PC so most things
on the front panel can be controlled from a computer, a CI-V remote
control for use with a transceiver, an external speaker socket,
a mute control jack (for use with a transceiver), cheap plastic
red and black push terminals for connecting a wire antenna and
earth and a PL-259 socket for connecting a 50 Ohm antenna and
finally an 11-16 V DC power socket.
CONTROLS
| A power button which you push momentarily for on and hold for two seconds to turn off | A dual knob with the inner being for audio volume level, the outer for a dual purpose RF gain / squelch control |
| Two buttons to the right of that with the upper button for antenna 1 or 2 select as well as for entering a menu mode for selecting and setting of the RF gain / squelch | The beep (every time a button is pressed) off or on |
| Another dual knob to the right of that is for the twin pass band tuning (or IF shift) | The volume level of the beep |
| The S meter peak hold | The beep level limit |
| Scan resume time | S-AM mode of manual or auto |
| Scan speed | CW pitch control from 300 to 900 Hz |
| AM noise blanker on or off | Recorder remote on or off |
| Blank channel indication | Speech option language and speed as well as for speech level |
| CI-V address to distinguish the type of accessory equipment (transceiver or receiver) | Speech current time |
| CI-V baud rate | RTTY mark frequency and shift width |
| CI-V transceiver | LCD backlight brightness or off |
| CI-V with IC-735 | Auto tuning step which selects how fast you want to change the frequency in the selected tuning step when spinning the tuning knob. |
All the knobs and buttons are below
the LCD display Another row of buttons below this right on the
bottom left of the receiver is left to right...... preamp select
for 1 or 2 or off, a 20 dB attenuator, a NR button which brings
in the optional UT-106 DSP module (if it is installed) to give
a selectable range of audio signal processing much the same as
the bhi NES10-2 DSP speaker I have, ANF which is an auto notch
filter which also only works if you have the optional UT-106 DSP
module fitted, NB or noise blanker which works reasonably well
at reducing or removing pulse type noise and an AGC switch for
fast, slow or off.
To the right of the LCD display and above the large tuning knob
are switches for AM, SSB, CW/RTTY & FM as well as for the
filters you want to select (wide, medium or narrow) and when held
can go into filter options if any optional filters are installed)
and finally another button for selecting the tuning steps. To
the right side of the radio at the top is a keypad with numbers
for direct frequency entry and for setting the clock and timer
as well as having alpha select of writing names to the stations
locked into the memory bank which has 99 normal memories and two
others for the scan edge feature. Below the keypad are buttons
for selecting VFO or memory, MW for memory write, CLR for clearing
a memory or if you make a mistake as well as for select memory
on or off and for selecting the memory name, a button for scanning
and below that is an up and a down button for selecting the memory
channel, below that is the lock button for preventing the tuning
knob from changing frequency
On the left top corner is the front facing speaker, it is only
50 mm in size with limited audio quality and volume and I personally
would recommend using the built in speaker for portable or mobile
use only if you did not want to carry an external speaker with
you, it certainly does not sound as good as the 75 mm speaker
in my Sangean 909 and of course the ICOM's audio frequency response
has been tailored to suit communications and not hi-fi sound.
Even with an external speaker, there are only two Watts at 8 Ohms
of power available with a frequency response that does not extend
much below 100 Hz or above 3 kHz.
I have to say though, adding an external speaker is the best way
to go, even a large speaker (provided it is of high efficiency
such as musical instrument or guitar speakers) will sound very
good and especially if the wide IF filter is chosen. I personally
have selected a small 3 inch speaker from an old two way radio
as well as a larger 5 inch speaker that has come from an old National
Panasonic portable radio and the 4 inch speaker which is part
of a Tandy amplified speaker (CAT # 32-2040) but I have the amp
disconnected because it was hissy, these three speakers are connected
with switches to the external speaker out on the ICOM.
On the tape record or line out I use the bhi NES10-2 DSP speaker
which is also switchable through the other 3 speakers, so, I have
a lot of options to choose from as to which speaker will do the
best job at the time.
WHAT IS THE
R75 LIKE TO OWN AND OPERATE?
It is quite easy to operate
but not quite as easy to remember all the adjustments and functions
that it has available, especially on the ones that are not used
all that much and it requires the odd reference to the instruction
manual when one forgets. The instruction manual in my opinion
is written quite well but does not go far enough in explanation
of how to operate some of the more advanced controls and features
to get the most out of this rig when DXing. Anyone owning an R75
or is contemplating buying one should become a member of the excellent
R75 group on Yahoo groups at http://groups.yahoo com/group/ICOM75/
There are a lot of friendly people on there with experiences,
tips and modifications to help everyone get the best out of their
R75 and would also be of help to experienced DXers.
Once you become familiar with the way the R75 works, the wealth
of tips and information regarding this receiver will allow you
to gain maximum benefit from it, after all, a receiver is only
as good as the operator who knows how to get the best out of it,
this applies to any radio I love the ICOM R75, it is a powerful
and wonderful receiver and once you get used to all the multi-function
buttons and controls, there are a load of tools available to you
to be able to dig out that difficult DX or just make listening
to programs that much better. Using a better and larger external
speaker, I find the audio very pleasant and it is very good for
being able to understand what is being said even under very difficult
noise and QRM conditions. Some of the buttons require to be held
for two seconds to activate them, this might sound like a long
time but it seems to happen a lot faster than two seconds to me,
more like one second, so, using the controls and buttons is easy
and convenient most of the time.
This receiver is very sensitive especially when switching in one
or both of the pre-amps and if noise is a problem then switching
in the DSP noise reduction which is adjustable to be able to get
a good compromise between noise reduction and audio quality will
work wonders in any mode, there is also the auto notch filter
which works on AM or SSB and will track up to three heterodynes
at once and reduce them or eliminate them. I also find that two
DSP's are better than one, under very bad noise conditions, switching
in the ICOM DSP and also using the DSP speaker I have is of a
huge advantage, voices just seem to rise out of the noise like
magic to a fairly well understood level. This receiver has Synch
detection however and unfortunately, it is available only on AM.
An awful lot of debate and opinions have been expressed about
the way AM Synch detection is implemented in the R75, most say
it just does not work and they cannot tell the difference, some
say if works sometimes but is not very good. I have no past experience
of Synch detection so I can only give my personal findings on
this particular R75.
Apparently, and especially on slightly weaker signals, synch detection
is suppose lo reduce fading and tries to hold the audio at a more
constant level. When I switch to S-AM on the ICOM which I have
set to manual mode, and, providing there is no co-channel splatter
around, the synch detection certainly does improve the fading
and during deep fades in particular, it hangs onto the voice or
audio so that it can still be understood, it also tends to help
on some moderately strong signals too. When I find the S-AM actually
worsens what you are trying to listen to is when there is co-channel
QRM in the form of splatter, it whistles and distorts and generally
won't settle down. I do not know if this is what happens to other
receivers using synch detection or not. Kiwa Electronics in the
US have a mod kit out for the AGC and synch detection for the
R75 (which come from the modifications on the R75 YahooGroups)
for a low cost which improves the S-AM to working all the time
so, I guess this is one mod I will have to do in the future.
There is also the usual noise blanker which reduces impulse noise
such as from car ignition systems, the NB in the R75 seems to
work reasonably well on most of those types of noise including
someone switching on and off an appliance The twin pass band tuning
which are dual knobs work a treat, especially when narrow fillers
are selected and especially when using SSB or CW. This receiver
is so stable that under severe QRM conditions, it is better to
switch to SSB or CW when listening to an AM broadcast station,
with 1 Hz tuning, one is able to zero beat easily and it stays
locked on. You have the choice of LSB or USB to get away from
the QRM or with a slightly different outcome, sometimes better
than SSB is to switch to CW, you either have normal or reverse
CW to choose from and you have a choice of beat frequency of between
300 to 900 Hz, this means that you have to tune up or down by
say 300 Hz to zero beat and this gives even more of a chance of
getting away from the offending QRM with addition of the pass
band tuning. Not only that, but having twin pass band controls
gives you the chance to effectively narrow the bandwidth even
more than the standard narrow filters that are switched in, wonderful
stuff.
An example of this was trying to tune into Radio Prague at 0800
UTC on 9880 - it was a weak signal and Swiss Radio via Julich
was booming in on 9885 splattering all over 9880, the Sangean
could not even reveal that there was a station on 9880, even with
its Kiwa narrow filter switched in and tuning 2 kHz down, the
splatter was all that could be heard. Turning to the ICOM and
trying AM narrow and tuning down 1 kHz revealed Radio Prague,
weak but with understandable audio. Switching to LSB and using
the pass band tuning made the audio much better and reduced splatter
even more, switching to CW reverse and tuning down to the maximum
of 900 Hz to zero beat, then cleaning up a bit with the pass band
tuning was even better again, it would have been easy to take
notes of the program and send a reception report in.
With the Sangean ATS-909, I was unable to hear if Radio Prague
was even on air or not, too much splatter completely wiped it
out! I am sure that the Kenwood R2000 would have been able to
detect Radio Prague on 9880 too but because its narrow filters
are not as narrow as the ICOM's (2.7 kHz on the Kenwood as compared
to 2.4 on the ICOM and narrower with the pass band tuning). I
don't know if the splatter would be reduced enough to be able
to understand the program, I no longer have the Kenwood to be
able to do current comparisons with. Needless to say, tuning and
listening to SSB is a breeze with the ICOM, being very stable
helps a lot (and ICOM themselves have an option available which
will make it even more stable!)
TECHNICAL SPECIFICATIONS
It is a triple conversion
receiver (like the Kenwood R2000) with IF's at 69 MHz, 9 MHz and
455 kHz. With the stock standard IF filters, wide is 15 kHz at
9 MHz and 455 kHz, medium is 15 kHz at 9 MHz and 6 kHz at 455
kHz, narrow is 2.4 kHz at 9 MHz and 2.4 kHz at 455 kHz. These
filters can be swapped around in the advanced filters settings
menu to suit preference, there is also a large amount of different
filter options available for your own choice The sensitivity is
quoted as being 1.6 microVolt for 10dB S/N on AM with preamp 1
switched in and 0.16 microVolt for SSB under same conditions from
1.8 to 29.999 MHz. On MW, the R75 has been attenuated to reduce
possible overload to shortwave, it is an easy mod to remove this
and have the same sensitivity from 0.1 to 1.8 MHz as well Just
to say a little about the RF gain control which also acts as the
squelch, the 7 to 12 o'clock position is for RF gain with maximum
gain at 12 o'clock, turning this control further to 1 o'clock
then brings in the squelch control with receiver mute usually
at 2 o'clock or more depending on noise.
The RF gain is like the one I used to use on the Drake R-4C in
that as you reduce gain, it moves the signal strength meter upwards
and whatever the S meter is set on then most noise on signals
below this setting are then cut off, this way, the gain is reduced
and also helps to cut out the noise which can be used to advantage,
doing this on AM especially helps reduce fading and noise especially
if S-AM can be used, makes some signals sound like a local station,
very good for program listening as well as for certain types of
DX especially by reducing the gain and turning off the AGC. In
closing this review, I am extremely pleased with the performance
of this stock ICOM R75 receiver, reminds me of the fun I had with
the Kenwood R5000, the ICOM is a better receiver because it has
more tricks up it's sleeve to reduce or eliminate noise and interference,
has better audio than the R5000 (but then, so did the R2000!)
and is a receiver that just sits there begging you to use it,
and, so I do (not as often as I would like to though!)
CONCLUSION
I am very happy to have saved
a fair amount of money by importing and to have the DSP unit included
as well, I now have a receiver that will probably outlast me and
shortwave as we know it, I presume the R75 will be able to pick
up DRM with modification and probably computer software, I guess
this will come to light as or is DRM ever going to be the future
of shortwave. Best of DX to you all!