Icom IC-756
PRO III
side by side with the Drake R8B
By John
Plimmer
The first thing
to look at is why would one who is a DX listener
only, want to buy a transceiver? Consider the price
of receivers today and what's available:
Icom IC-756 PRO III (above)
and Dreake R8B
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Winradio G313i
for US$1,000
The Drake R8B costs US$1,500
The AOR 7030+3 is around $2,120 with the noise blanker
and notch upgrade.
The Japan Radio NRD-545 is $1,800
Ten Tec RX-340 at $3,950
Icom IC-756 PRO III for $3,000
The 756 has 32 bit DSP technology and a 24 bit processor
against the oppositions 16 bit technology. It also
has a spectrum display that otherwise only the Winradio
has. I am not going into the detailed technical
descriptions of the above radio's as this has been
widely published in magazines, handbooks and on
the web, but there is general criticism of the 16
bit receivers inability to handle large signal environments
and their lack of capacity in close up operation
at the IP3 5 Khz spacing.
The 756 does not suffer from these close in signal
handling problems, so therefore it represents good
value for money for the performance and technology
it offers.
Sound
The Drake is renowned for
its excellent audio when played through an external
good quality speaker and provides a nice mellow
sound that you can listen to for hours, whether
that be listening to BBC orchestral's or static
ridden DX on MW and Tropical Bands.
Earlier Icom's on the other hand were well known
for poor audio sound delivery, but this is where
the 756 breaks with the Icom tradition, as the sound
is excellent with broad spectrum audio. I would
describe the sound as "clearer, crisper, tighter
and fuller" than the Drake, whilst not being
in the least unpleasant to listen to for hours on
end. A highly commendable effort by the Icom engineers
(an additional outboard speaker is required of course).
I ran both sets through my Icom SP-20 speaker that
allowed direct comparison.
The Drake has a tone control, whereas the Icom does
not have one (not an important issue for me).
On the 756, moving from AM wide to a narrow SSB
setting, and/or enabling the NR noise reduction
function seriously attenuates the audio output,
necessitating an adjustment to the volume control.
This does not occur on the Drake and I find it quite
irritating on the Icom, continuously having to manipulate
the volume control up and down.
Ergonomics
Larry Magne in his Passport
review of the Drake R8B says "the only ....
receiver tested that gets everything right",
and so it is. Everything comes easily to hand and
everything the DXer want's is there. But shame Drake!
that awful cheap plastic tuning knob is inexcusable
in a radio costing $1,500.
The Icom is roughly the same size as the Drake,
but a large portion of the fascia is occupied by
the large colour LCD display. This makes the numerous
functions available necessarily quite small and
cramped. The keypad is too small and sits awkwardly
right above the lovely large tuning wheel that can
easily be knocked off your frequency. The use of
the 756 requires quite a long familiarisation and
learning curve with the manual on your lap to get
to know all the numerous functions and the many
variables you may introduce into the operating setup.
Perhaps the most used control is an inner and outer
knob control labelled "Twin PBT" passband
tuning. It is used for narrowing the set filter
in small steps, but when rotated together acts to
shift the passband to the upper or lower sideband.
This is inconvenient and I would like to have seen
a separate knob, as in the Drake, for passband offset
only.
A nice touch for boosting your ego is that you can
enter your name or callsign permanently into the
LCD screen to remind you what a great guy you are
for purchasing such a high quality radio.
Filters
Here
the 756 comes into its own with its extremely tight
filters and the large number of settings you may
set and the way you can customise the defaults to
your own requirements. I will not go into the technicalities
of these filters as they are discussed in great
detail in Icom's own Technical
Report and also here.
The immediate observation is that they are much
tighter and sharper than the Drakes. A "sharp"
setting of 2.5 Khz on the Icom proves even tighter
than the standard Drake 2.3 Khz filter. On SSB you
can set only two filter width's on the Drake, vis
2.3 and 1.8 Khz, whereas on the Icom you can start
at a 3.6 Khz setting and then set them to any value
down to 250 Hz. This you can do by selecting three
default settings to speed up finding the width that
is most suitable for you. From the factory the defaults
come set in SSB mode for 3.0, 2.4 and 1.8 Khz wide,
but you can set these three defaults to any figure
you like within the range 600 Hz to 3.6 Khz. I have
set mine at 2.5. 2.0 and 1.2 Khz width. You can
then narrow a default even further in 100 Hz steps.
Very flexible and very effective.
AM mode is less flexible and doesn't offer infinite
narrowing of the filters on the 756. The three set
defaults for AM are 9.0, 6.0 and 3.0 Khz wide. The
3.0 Khz filter is too narrow for most usage, but
becomes useable when the passband is offset to the
upper or lower limit. The Drake has 6.0, 4.0 and
2.3 Khz width and 2.3 is useable by rotating the
passband offset to obtain the "sweet spot".
If you are a CW NDB beacon DXer, you will find the
756's filters sensational as they run infinitely
variable from only 50 Hz up to 1.2 Khz (or higher).
A characteristic of a lot of CW filters and add
on's is that as the filter gets narrowed the sound
starts to "whistle" and "rings",
as if it is tunnelling at you. This is not the case
with this Icom and you can comfortably set the filter
width down to 50 Hz when you locate that really
faint beacon. The Drake only has a 500 Hz CW filter
width.
In SSB and CW mode the filters width can be narrowed
as mentioned, but using the Twin PBT controls it
is possible to do this independently on the upper
and lower side of the passband non-symmetrically.
This is very useful. You cannot adjust the filters
on the Drake.
A further useful feature on the 756 is that the
filter width you have manipulated is always shown
on the display, and if you get "lost"
you merely press "PBT clear" to get you
back to the default setting. In addition you can
call up on the LCD screen a full diagrammatic of
the current filter and its width and offset settings.
Two shapes of filter can be set: "soft"
for a pleasanter sound, and "sharp" for
a clearer DX sound. In practise I use the sharp
setting exclusively.
In operation the filters on the 756 seem to have
deeper skirts than the Drake and thus consistently
render more marginal signals readable than the Drake
does.
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Passband
offset
On the Drake
you have one knob to manipulate this - it is uncalibrated
and suffers from the fact that it "floats".
However constant use allows you to quickly find
the "sweet spot" you are looking for.
The 756 on the other hand is much more sophisticated
in that the offset is calibrated and is even diagrammatically
shown on the filter screen if you call that up.
However, it takes a bit of a knack to manipulate
the two "Twin PBT" rotary controls simultaneously.
I would have preferred the Drakes single knob for
that function.
VFO's
The
Drake has two VFO's, only one of which can be seen
at a time. Whereas the 756 effectively has four,
as it has two VFO's plus two memories active at
any one time. The nice thing about the large Icom
LCD screen is that the contents of the two VFO's
and two active memories can be seen as you DX along
= useful. As the memories are fully tuneable you
effectively have four VFO's, a very useful feature
when the band is open and you are trying for as
many ID's as possible. If you manipulate a memory
in the Drake it immediately reverts to one of the
VFO's, so you still only have two VFO's on the Drake.
Tuning
around
The Drake's
tuning wheel is a little slow, but by various settings
and manipulations it is possible to move quickly
from place to place, although you often have to
revert to entering a new frequency into the keypad.
You can quickly tune the MW split band by leaving
a 9 Khz tuning step in the AM MW mode and a 5 Khz
step in the SSB mode.
The 756 is a little different. It responds to the
tuning wheel much quicker, so moving very rapidly
around the band is quite easy. For a MW DX run you
would have to set the 9.0 Khz step in AM mode and
then a 10.0 Khz step in the SSB mode. If you move
to the Tropical Band you would have to reset the
tuning step in both modes to a 5.0 Khz step, which
is a little cumbersome.
The Drake can be set to automatically revert to
a 5.0 Khz tuning step in the Tropical Band, so no
additional step resetting is necessary, and when
you tune down to the MW band, the Drake automatically
reverts to the default 9 or 10 Khz setting = convenient..
The Drake tunes to a minimum of 10 Hz - the Icom
tunes to 1 Hz when specially set. The Icom also
has a RIT function that operates at a 1 Hz tuning
rate.
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LCD Spectrum
display
The "piece
de resistance" of the 756 PRO series must surely
be the LCD screen and the frequency spectrum display.
If you have not experienced this, then it is something
very worthwhile to look forward to. Seeing the stations
around your chosen station and their relative strengths
is very useful. Finding weak stations in between
powerful ones becomes an easy matter. Watching a
thunderstorm create havoc on the band is also interesting
if futile, as there is still not much you can do
with the very heavy static generated by a lightning
storm. The bottom screen can be dropped and the
top VFO information displayed larger and in more
detail.
NR noise
reduction
On the Drake the notch
filter, being quite broad, does a good job of getting
rid of a lot of the white noise associated with
DXing. On the 756 though, we have a very effective
digital DSP noise reduction. The level and intensity
of this can be adjusted by turning a rotary knob.
It is very effective at removing all sorts of noise
and static on a band and actually enhances the audibility
without muffling or distorting the recovered audio
sound too much. Annoyingly though it attenuates
the audio output a lot and requires you to turn
the volume control upwards. That's fine, but you
must remember when you have your earphones on to
turn the volume down before switching it off, otherwise
your ears are going to be blasted with a high volume
level.
NB noise
blanker
I never found the older
Icom NB's very good and they also used to distort
the audio. The 756 is quite good though and is nearly
as good as the superb Drake NB. The major difference
is that whilst both eliminate ignition type pulse
noise, the Drake's NB also eliminates some lightning
static which the Icom's doesn't do. The Icom's NR
feature does that more effectively than the Drake
though. Neither of these radio's NB's distort the
audio.
Notch
The Drake
has an effective notch that is quite broad and easy
to tune - it is manual in operation and can therefore
only attack one het tone at a time. The notch on
the 756 is superb though, as in it's "auto"
form it will kill up to three tones at a time and
do this on the fly. It also has a manual setting
that will kill one single tone, but it is very critical
and therefore more difficult to use (others find
it easy and useful to use!).
Memories
I
have never been a big fan of too many memories,
and the possible computer control of both these
radio's allows for unlimited memories anyway. The
R8B has a massive 1000 memories against the 756's
100, more than adequate in my experience though.
Both allow for alpha numeric labelling of the memories.
In the Drake you can only see one memory at a time,
so unless you arrange these intelligently it becomes
quite difficult to see what you have in the memory
bank. On the Icom, you can call up on the LCD screen
the memory bank and display 7 or 13 memories at
a time, which you can then scroll through. Makes
memory management and finding something in the memory
quite easy.
If you want to manipulate a memory in the Drake,
it reverts to the VFO, thus loosing whatever you
had in that VFO. On the Icom though, you can manipulate
the memory without it going to the VFO unless you
instruct it to = handy.
Synchronous
detection
If you want
to listen for hours to the BBC promenade concerts
or music on AM, then the Drakes synchronous detector
gives a superb fade free sound that you can listen
to undistorted pleasantly for hours.
The Icom does not have synchronous detection and
it shows. Deep fading and multi path distortion
effects most signals, even from the most powerful
stations, and this distorts the audio unless there
is a very good sync detector controlling matters.
Unfortunately the Icom's audio output of AM and
shortwave stations is seriously marred by the lack
of a sync detector and the resultant sound can become
irritating after a while as the audio keeps distorting
and breaking up as the fading/multipath takes place
(playing around with the AGC settings may improve
this a bit). But you wouldn't buy a 756 PRO III
just for listening to the Beeb!
Other
comments
The preamp
on the 756 is very good and introduces virtually
no noise whereas the R8B's preamp introduces a lot
of hiss. The advantage of the 756 is very apparent
above 15 Mhz.
The Drake has a single 10 dB attenuator whilst the
Icom has a three stage attenuator down to minus
18 dB.
The AGC rates on the Drake are very well chosen:
off, fast and slow. The Icom has an AGC that is
infinitely variable from off, very fast and variable
through to very slow.
CW NDB
beacon DXing
I have described
above how the CW filter width on the Icom can be
adjusted all the way down to as little as 50 Hz
without ringing or whistling. There are other useful
features as well. PBT passband offset to find that
sweet spot of the signal, pitch control to enhance
the audio tone and CW reverse mode for when you
are trying to avoid that unwanted adjacent channel
beacon that is interfering with your desired signal.
The RIT function is also useful when critically
tuning a beacon on a filter width as narrow as 50
Hz. You can also turn the AGC off if you need to
and choose a very slow quarter of normal tuning
rate..
The 756 runs rings around the Drake as far as CW
NDB DXing is concerned.
MW mediumwave
mod
As it comes from the factory
the LF and MW band has been attenuated to 13 uV
sensitivity. My dealer reversed this and enabled
full sensitivity and assured me that the guarantee
was still good. This involved only a minor mod.
The 756 is now slightly more sensitive than the
Drake in "normal" mode, but the preamp
cannot be activated, whereas on the Drake it can
be (others have enabled the preamp 1 on MW on the
earlier 756 PRO's).
Unfortunately I am completely
non technical and was not present in the workshop
when the Icom techie in Johannesburg (1,200 km's
away) did the mod. However my friend Guy Atkins
supplied me with pictures and a schematic diagram
from mods he did and originally worked out by Dallas
Lankford for the 756 PRO.
The Joburg techie said he had
no problem and booked time of one and a half hours
workshop time for this mod including a lot of time
for disabling the transmit section.
He marked the 756 PRO III's schematic
diagram in case the mod ever has to be reversed.
All I can see he marked is bridging R801 to R803
and removing C802 to the earth connection. These
parts can be found on the reverse side of page 4
of the schematic diagram, at the top and about a
third of the way in. He said it was simple, but
when I queried this with him later, he conceded
that an amateur solderer without special lab equipment
might find it challenging. He said that sort of
thing was his everyday work and was easy for him.
Side by side with the Drake R8B
the 756 seems, if anything, slightly more sensitive.
You can see the tremendous
MW results I get by looking at the South
African DXpedition page so I am quite satisfied
that the MW sensitivity is where it should be and
that everything is working properly.
Performance
comparison
I tested the radio's on
the same RF Systems DX 1 Pro antenna which has twin
matched outlets through an Icom SP-20 speaker that
allowed instant comparisons.
- 81.5% of stations were better to much better on
the Icom 756 PRO III. That is, clearly more readable.
- 7.5% of stations were better and more audible
and clearer on the Drake R8B.
- 11% of stations were the same on both radio's
One of the questions hanging over digital radio
receivers is their ability to receive a weak signal
only 5 Khz apart or less from a powerhouse. I tried
this on several frequencies, the most notable being
Deutsche Welle on 11,945 which was putting out a
massive S9+60 signal. There was a much weaker station
almost hidden in the skirts of DW barely showing
on the spectrum display on 11,950. The Drake could
barely render the weaker signal readable, whereas
the 756 did a superb job and rendered the audio
quite readable.
I tried many stations from the LF CW beacon area
right up through to the top end of the HF band.
On CW NDB beacon chasing the 756 was head and shoulders
above the Drake due to its superb narrow filters.
On MW and Tropical Bands the 756 was again better
due to its sharper filters and outstanding NR noise
reduction circuit.
Higher up the HF band the 756 gets progressively
better due to its excellent preamplifiers, whereas
the Drakes preamp introduces a lot of hiss that
obscures the readability.
Minor
matters
The Icom comes poorly packaged
- a reputable dealer will repackage it in a stouter
box for shipment.
The Icom draws over 3 amps of power and thus runs
quite hot even in receive mode only. If you run
it on batteries on a DXpedition, you are going to
need big ones.
Cool
things
The spectrum display on
the 756, the sharp and tight filters and the ability
to set them anyway you like, and the very effective
NR noise reduction.
The R8B's superb synchronous detector for hours
long comfortable listening to shortwave programming.
Great ergonomics - everything is where you want
it with one touch of a button.
CONCLUSION
So, the bottom line is
this: is the Icom 756 PRO III worth double the price
of the Drake R8B?
I think the answer lies like this: If you are a
casual listener, like to get some rare stations
now and again but also like to listen to good music
and programming on AM and shortwave, then the R8B
will probably do very well for you and you may not
find the 756 much better for your purposes. The
R8B is a venerable receiver that has achieved awesome
results in the hands of serious DXer's over the
years.
But if you are a serious hardcore DXer and have
owned all the current offering of receivers, you
will find the latest technology in the 756 very
useful and with a performance that is top line.
I think you will be quite happy with this set even
though you have outlayed $3,000 on it. It offers
a better chance of IDing that very faint station
deep in the heavy static. The tools available to
do this are impressive.
The law of "diminishing returns" applies.
Although the 756 PRO III represents the very latest
in cutting edge digital technology, the improvements
over the Drake R8B are incremental, but nonetheless
significant.
Postscript
If you were thinking of
buying a Drake R8B or similarly priced RX, you might
like to consider a good pre-owned model from eBay.
The older 756Pro and 756ProII models should be looked
at, as they are very similar in operation to the
756 PRO III. In the USA, the 756ProII is currently
selling new for about $2100 new, and used for $1600.
A 756 PRO II at $1600 would be an outstanding DX
radio.
An excellent full size professional photo of the
Icom 756 PRO III can be found at the Icom
UK website.
Postscript
II, 18 months later (May 8, 2006)
It is now
eighteen months since I acquired the Icom 756 PRO
III and it has been on four serious DXpeditions
and is in continuous use at the home QTH. Things
have moved on since my original report and sadly
the Drake R8B is now off the market and no longer
manufactured. Pity, as it is a great receiver and
I still miss the wonderful easy to use ergonomics
and solid all round performance.
However I am more than pleased with the 756 and
if I shot from the hip and say what impresses me
most, it is:
# The sharp filters and nice clear cut sound in
SSB mode
# The flexible filter options and passband offset
# The awesome notch - the auto setting zaps out
hets one time, but the manual notch is really marvellous
for getting rid of all sorts of electronic interference
that the auto setting doesn't do.
# I can't really say that I am getting any more
exotic DX logged than on the old Drake, but I can
say that I am getting much better quality recordings
of exotic far off 13,000 kilometer/8,000 mile distant
MW signals than ever before.
# My chasing of NDB CW beacons has gone up exponentially
as the Icom's CW performance is really very impressive
with the wide range of filter options and enhancement
controls available. On the Drake my furthest beacon
was only 1,700 kilometers away, but with the Icom
I have now got beacons as far away as 6,000 kilometers/3,750
miles.
What I don't like and that irritates me:
# The cramped controls, some of the most used ones
like the VFO swap/change, and VFO to Mem are so
small that you need to operate the radio in bright
light in order not to push the wrong button, and
then you often do anyway.
# Also the fact that the NR noise reduction reduces
the audio output and also the recording level on
line out. This means on a weak signal you do not
have enough line out oomph to make a decent recording.
# The NR is good on strong signals and does a great
job of eliminating static, but when the going gets
tough and the signals are weak, the NR muffles the
audio intelligibility to such an extent that you
can no longer get a clear ID and have to switch
it off.
# During the day when DX is not present, I listen
to my favourite AM BCB and BBC stations, but I miss
the Drakes lovely sound and rock solid synchronous
detector. On the Icom I have to listen in SSB to
avoid fading, but the sound, despite eighteen months
of fiddling and trying to optimise it, is not very
good.
Overall though, I am very happy with the Icom, it
is a very satisfying radio to DX with, and it has
proved to be a substantial upgrade on my old Drake.
(published
on DXing.info on January 2, 2005,
second postscript added on May 8, 2006,
and one more paragraph added on July 4, 2007)
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