ICOM IC-756
PRO II (2) DSP HF Transceiver |

I
give the "Now Long Discontinued" ICOM IC-756 PRO II (2)
a luke warm "Thumb's Up" for "Shortwave Listening"
use due to it's fair to poor receive audio quality. Even the JRC
NRD-545 receiver pars better with audio quality. The matching
power supply and speaker fare even less . But as a hybrid DSP set
for the Amateur who will be transmitting as well as receiving,
the PRO II is a good deal in my view. Be aware that the LCD
display has seen it's share of problems , see the text below for
more information. I have not used or tested a PRO III version (or
above).
( ICOM Japan
Picture )
This
report also includes the ICOM "PS-125 Power Supply"
review including KK5DR fan modification notes and the
discontinued ICOM "SP-21 Speaker" .
Discontinued
Product
Model
: ICOM IC-756 PRO II (2)
Country Of Manufacture : Japan (Osaka)
I was able to use a IC-756 PRO version for certain comparisons in
this report. I have NOT tested or used a PRO III (3)
version or above and have no plans to do so.
Icom's "Hybrid DSP" Amateur Transceiver IC-756 PRO II (2)
has same coverage as the old IC-756 PRO , that is HF thru 6
meters . Sorry, no 2m / 70cm as some would have liked, perhaps
the new lower cost IC-746PRO model might be of interest in this
case as it includes 2 meters with "Hybrid" IF DSP over
the IC-746 (neither tested). But this set of course does not have
the fancy display or dual watch receive.
A
Different Kind Of A Report Here...
Is ICOM's 3rd try around with this style box a winner ?? We are
going to have a look at it here, but on the side of the fence
with use of monitoring
general SW/HF broadcasting stations. So if you are looking for
a detailed report with amateur radio TX/RX use, you will have to
look elsewhere . However, I will cover a few topics on the TX
side of the fence as well, but not in any huge detail. You will
see me make reference to the Japan Radio Co. NRD-545 DSP receiver
and the 2 samples of Icom IC-R9000 that I have owned over the
years in the text below.
So you are not a Amateur Radio Operator, eh ???
I have heard of a number of IC-756 PRO's sold to pepole that will
never transmit on it. Yes, SWL's and alike. With the manufactures
curtailing tabletop receiver production, I think this will be on
the increase. And you can usually get a better deal with more
features in a Ham transceiver....... well not entirely as it is
not all red roses for "SW Broadcast Monitoring" when
say compared to a JRC NRD-545 (lack of bandwidths and sync
detection to name 2), which uses the same Analog Devices DSP IC
as does the PRO, PRO II and PRO III. But I'm sure many "PRO
II's" already have been sold to non-hams, like it or not.
So What's The Draw For a SWL Type To The PRO II ??
LCD Display Problems Reported !!
It has gadgets that others miss totally. The biggest draw is the
real nifty "Spectrum Display" that allows for viewing
of a chunk of the HF spectrum up to 200 Khz max. This works well
and really helps from missing signals as you zip across the bands.
You might fall in love at first sight with this one.
With ICOM's IC-R9000 beast now no longer sold, this is the only
way to get a HF NEW receiver with a "Good" spectrum
display of this type. Many used R-9000's that are around these
days have excessive burn on the CRT displays, so be careful. This
is one where the PRO II's will not have a problem with CRT burn
as it uses a TFT LCD (CCFL backlighting), and it's full color to
boot. The "Band Scope" width above 30 MHz the R9000 was
pretty much useless anyway, too narrow for VHF-UHF uses. And
being I'm not into VHF-UHF monitoring..I never used the spectrum
scope above 30 mhz on my R9000's when I had them.
The last IC-R9000's that were made (the "L" version)
used a "backlit" LCD display. It's monochrome only, and
I hear the resolution was really poor as it is NOT a TFT type.
The only down side is that we have a florescent tube in the back
of the "Sanyo" LCD display (CCFL). This will be a royal
pain when it burns out, or other problems that can and do arise
with the display (see the updated text below). You will see a
nice black screen if the backlighting goes out, like driving on
country road with no headlights in total darkness. At time of
writting a replacement display was over US $ 500.
You would think by now they could use some of the new white LED's
that are now around for the LCD backlighting (finally...LED
backlighting is now used in the IC-7600) ?
LCD Display Problems Reported with the IC-756 PRO II |
| I have not experenced this
with a PRO II myself, but from info via emails direct to
me and newsgroups etc, there has been quite a number of
owners having problems with the LCD. One is where the
backlight either fails totally or takes awhile to "pop
on". Another is where major color lines/bars creep
up after a few weeks or months of use. I have edited out
some of the names with "xxx".
Dave N9EWO. "I brought the rig
home and plugged it in. The radio wouldn't cycle up and I
turned it off. After turning back on it finally started
the 10 second process. After making a few contacts and
leaving the room I came back to listen around the band
and looked at the screen which was blank except for lines.
I turned the rig off and restarted. After approximately
10 minutes the same thing happened. I called GigaParts
and advised them I would be returning the rig for an
exchange. After returning to GigaParts, the service tech
plugged up the rig and after 5 minutes the display went
south again." A note to me from Gerd W2ISB on his 3 that he has tried so far : "I got rid of a perfect Pro I to get my first Pro II back in Feb. of this year (2003). The display failed after a few months with a green vertical line about 3/4 of the way across the display. I sent it to Icom Bellevue and after two months of getting jerked around, with help from xxx, I got xxx involved. He sent me a new one out 2nd day air, a letter of apology. The second one lasted about 3 months with a red vertical line about 1/3 of the way across the display. It went back to ICOM for repair. In the meantime I've bought my third Pro... for a backup. I'm expecting a blue line on my next one to wrap all possible combinations. By the way not a screw was turned on either rig... no hands inside, period, not even the expanded coverage. In the meantime I've bought my third Pro... for a backup. They are great radios, it appears ICOM may gotten a batch of crappy displays." "Has anyone
experienced the same problem with the display as me, the
display takes up to 1 minute to be active if the radio
has not been used for 1 week or more. If the radio has
been used within a day or two the display comes on within
20 seconds. Cure ? OZ8CY" "My PROII has exhibited that behavior for about for about 5 of the 9 months it. And it seems to me the delay-on-lite-up time has slowly been increasing during that time frame although I have no empirical data upon which to base that thinking. I spoke with Icom Tech Support three times, different people more or less gave me the same advice: If you think something's wrong, send it back to Icom for repair. It was a frustrating exercise in that Tech Support would neither acknowledge that the delay-on-lite-up is a problem nor agree that's it's typical and acceptable behavior. Steve" "The display on
my IC-756ProII would take 20 to 30 seconds to illuminate.
Icom tech support suggested I return it for service
before the warranty ran out. The repair read as follows
" DC to DC converter ok, replaced backlight bulb
" seems ok now. It appeared to gradually
happen to the point that the radio would have completed
startup calibration for 10 to 20 seconds before the
display would light. N1FDX" |
Pulling
It Out Of The Box
Icom's weak shipping box construction continues with the PRO-2.
It just simply does not cut it for the weight in it. It's a weak
single wall box with no major protection. At least they are still
using styrofoam inserts. But if a dealer does not pack the set
properly with another double wall outside box and PROPER use of
foam peanuts..it could very easily get damaged. My sample almost
got whacked by UPS totally as the dealer I ordered mine from did
not really pack it correctly . They only used a single wall outer
carton and did place any stryo-peanuts on the floor of the box.
If it was not for the large styrofoam inserts inside the PRO II"s
box, it would have not made it. If it needed to go a bit further
it would have been damaged for sure .
A pretty silly oversight for a $3000.00 radio I think. JRC does a
much better job on shipping box protection of the NRD-545 with a
much heavier box.
The LCD had a screen protect "peeley" over it's lens to
prevent it from being scratched during production, good idea and
JRC should do this too. My one R-9000 I purchased new also had
this.
Best way to remove the PRO II from the carton for me was after
removing the cardboard tray with the mic and power cord on it...was
to carefully lay the open box on it's belly with the top of the
set on the top etc....and "slide" the set out on the
stryofoam inserts. On a clean safe open surface of course (hey
clean that ham shack up first..hi hi). I would not try and
attempt to grab it straight-up out of the box. It would have been
a bit awkward that way, at least it was for me.
Everything looked and felt good out of the box with one exception.
The RIT/TX knob was scraping on it's cabinet as I rotated it......humm
?? After pulling the knob off, the problem stuck out like a huge
wart on a pin up girl's face. Apparently when the knob was molded
a small bit of plastic spittle was left remaining on the back
side of the knob (chunk sticking out and was not cleaned off) ,
after removing this small little plastic waste..it was just fine.
Outside Observations /Meter Lighting / Spectrum Scope /
No Rubber Feet
No more "yellow" markings on the "real" s-meter
(PRO has yellow on it's meter face). Now uses 2 white LED's to
light it, with a white background. This is good thing indeed...no
light bulbs and Icom did it right here, but has a lighting
problem when the backlight switches brightness setting is turned
to value 5 and below. If the LED (again called Backlight Switches)
brightness is turned to 5 and below and no other panel LED's are
lit, and when one other panel LED does become activated..the
panel meter behind the LED's will dim a bit. Weird is right, I
just keep mine set a 7 and is not a problem. Being up all the way
(8) is too bright for my eyes. The actual meter pointer
is a step back however, as it is a dark gray color and overall
the meter pointer is a bit harder to really see vs the old PRO.
The LCD display is simply breathtaking. As I compared to a
standard PRO model, is indeed sharper with the same settings.
Perhaps a caveat for all PRO 2 owners with a setting? When I
adjusted the "horizon" setting all way to max, it made
the display "twitch" a bit. But one would never keep it
this way as it makes the display very blurry indeed. It seems
that on the old PRO this was not a problem (as I checked this out
on a PRO sample).
I have found that a good 30 mins is needed to give full
brightness for the LCD back lighting. The JRC NRD-545 is the same
way. Yep, this is normal for the florescent elements (CCFL) that
are used for backlighting in these devices.
| Dave's LCD Settings "Display Set" For The ICOM IC-756 PRO (2) II (updated) |
| Backlight (Switches) : 7 (no less than 5 ....see text) |
| Horizon : 3 (no more..see text) |
| Bright (LCD): 40 % |
| Contrast (LCD) : 65 % |
| Display Type : E |
| Display Font : Classic |
Dont touch any display setting for a good 30 mins from a cold start, it will take this time for the LCD backlighting to become stable. This is totally normal, it will look very dark when first turned on. The NRD-545 is the same way, but does not take quite as long for full brightness. The settings listed above are with display type E and "Classic" style font, with others it will indeed vary. I have found the "horizon" should not be touched on any, always leave on 3.
| Display
Update : Here is a observation that may be a sample to
sample thing and your set may not even show this at all
or perhaps just unable to notice it. Let me say that this
is a VERY MINOR point here that I'm going to pass along.
So for many this will be of little moment...but "for
the record" again. After a good 30 min warm up, and beyond..the far right side of the display (say 1 inch in from the right side and all the way down) shows a shade, and I mean a shade...."darker". So is showing a bit of inconstant lighting across it's surface along this edge. I can really see this well while the display is warming up. During this peroid the right side really shows this inconstant backlighting of the display. It becomes less noticable after 30 mins (but still there). Again this is a very minor point but nevertheless one I feel needs to be made. I do not run my display all that bright, but that is beside the point. With the sample tested , this did vary with the type of font used and on the larger ones was less noticeable. Anyway it's a point that still nags with me on the display backlighting. |
Spectrum
Scope works very well indeed , even showing the weakest of
signals. Perfect widths for peering at the HF spectrum. The scope
"att" (attenuation) feature is most handy when the band
is noisy. The peak hold feature allows you to show signal
activity and strength on a certain frequency over a time period.
The case / bezel color as compared to the older PRO model is a
bit different. The PRO is a darker gray, where the PRO II is
black.
We have no rubber type feet on the bottom of the PRO II (just
hard plastic). Even with it 21 lbs (9.6 kg) of weight, it still
slides around in use depending on the table surface. This one is
a dirty shame, but many may find a work around without
eliminating the front rise feet. Perhaps some sort of a stick on
add on might work (or a rubber cap) ??? The R9000 had nice rubber
type feet on all 4.
Variable Control's / Encoder Feel / Push Buttons /
Painted Knobs
This
is generally good here overall with all controls, however we must
cover a few points here.
The optical encoder used for the "main tuning" is very
good. It has a generally very smooth feel to it with no play
either when rotating (no rotation play) from one direction to
another. Also "zero" amount of up-down/side to side
play as well. Great to see this. I had to touch up the knob drag
a bit with it's screw adjustment as it was a bit tight to me as I
prefer it about as free as you can get it. It's not quite as
smooth as the encoder used in the NRD-545's main tuning encoder,
but close.
Here is where it's not quite as sweet as it could have been. The
"smooth" mechanical encoder (# on schematic EVQ-VCJF0324B)
that was observed on my sample used for the RIT/TX adjustment has
a slight weird feeling as I rotate it. You can lightly feel the
encoder's internal contact(s) engaging. This is a hard one to
explain, but so far has no ill effect and just seems to be the
way it is. Many will be pressed to even notice this one. But
again this is of real little moment and was also noted on the
briefly tested standard PRO version as well.
The stacked analog "pot's" used for the AF/RF/SQL and
BAL/NR have a bit of a "feel" issue I will cover here.
The top part of both of these (VOL and BAL) not only rotate a bit
stiffer than what I would like, but to make matters a bit worse
have a slight amount of the dreaded rotation play. That is as you
go from one direction to another, you feel a gap before you
really start to go the other way. But I guess this is tolerable
being just the volume control with the PRO II .
A ham friend has indicated to me that the tightness of these
controls will loosen up in time with use??
On the push button front with the PRO II, I guess it's passable
to my standards. But is not one of my favorites. The keys on and
around the "numeric" entry area (also F1 to F5 and the
mode buttons below these) all have a "stiff" feel and
takes more pressure than it should to activate in my view. JRC
NRD-545 wins big here, as the ICOM also makes it more of a chore
to enter a frequency. Not only do you have to push a button to
begin to enter a frequency directly, you also must enter the
"." (dot). So you are forced to enter
a MHz frequency (or you can enter 2 extra "00's instead).
JRC allows either Khz OR MHz with out the extra buttons. So again,
2 extra buttons you have to hit on the ICOM. But this is a Icom
trait that continues to be handed down, and was ditto on the R9000
as well.
Perhaps the stiff buttons were done to improve the life and wear
......time will tell ?? As least we do not have the rubber
variety at the surface of the button that ICOM did use for a
number of years on some other sets. So it could be worse.
The stacked mechanical encoder that is used for the "TWIN
PBT" adjustment is a "click type" and has a good
feel to it with no problems (only slight play that does not
bother me only being the PBT control).
Icom as does JRC, makes use of "painted" push-on
plastic knobs. As I have have indicated elsewhere in this site,
this is not a real good idea as this paint could indeed wear off
with use. Oh humm....when we see this one go away ??? Save the
paint and leave them "bare" as JRC did on the old NRD-525.
Even with the direct keyboard entry not so easy, I find the ICOM
IC-756 Pro II to be a very pleasant set to use with good
ergonomics. The screens on the LCD make it a real enjoyable trip
around. Enough buttons for easy access for all functions.
Certainly night and day to the AOR AR7030 receiver "nightmare"
box.
DSP Detection / Bandwidth and AGC
The JRC NRD-545 (also discontinued) used the same DSP chip as
does this PRO II and sold for a good $ 1800. (USA). Even with the
same DSP chip being used which is of a true 32 bit type, of
course the DSP software is not going to be the same. But most
important that D/A and A/D converter (Digital/Analog) scheme is
much different with these 2 sets. The JRC uses 16 bit (in
practice) and Icom 24 bit converters. On paper the Icom should
win here, and with no weird DSP "burps or ticks", this
could have indeed helped here ??
But here is where the JRC wins huge is with bandwidth filtering
choices. On AM mode signals with the PRO 2, you only have 3
choices, 3, 6 and 9 khz. Now this in general is more than what
many non-DSP SWL receivers have, some even only give you one
voice bandwidth filter. But this sure limit's the boat doesnt it.
SSB is much better with the ICOM with bandwidths up to 3.6 khz,
but still very limited as compared to the JRC.
But as you can read on my JRC NRD-545 page ,the JRC
suffers from weird sounds that exist within it's DSP and
associated circuit's under certain band conditions. So it's
tradeoff, as the DSP in the ICOM does not suffer from this
problem at all. No weird sounds..no kidding.
At least Icom chose to include a 9khz filter with use on AM
signals when signals permit...a B-I-G whew indeed !!!!
It is not a fast easy job adjusting the filters with the Icom.
With the JRC is just a turn "one knob" affair. Icom
forces you to drop into a menu and push buttons and turn the main
tuning knob, a chore. You do have 3 bandwidths presets as you do
with the JRC ,but adjusting to other filter bandwidths in a split
second is where the chore is.
Having detection done within the DSP is a big plus.
| Audio
Recovery : "Is the Pro II the best set around for pulling the audio from a very weak signal in the mud (using manual ECSS ) ??" I wish I had better news here, and you would think that using a more advanced DSP scheme that you would have excellent audio recovery, as a good DSP system is used with detection in the PRO II. Well it is most certainly is not the top dog to my ears. Mind you it's not a total wash out either, it is an improvement over sets that do not use DSP in detection. First to achieve the same sensitivity level of other sets (i.e.: WJ-8711A / HF1000A, JRC NRD-545 etc.), you must have "pre-amp 2" on. This increases the noise floor greatly, where as the other sets I have tested with DSP like this are much more quiet with the same sensitivity level. Running side by side tests on extremely weak broadcast signals using the manual ECSS mode, the JRC beats out the PRO II in the audio recovery area due to the added hiss produced along with a cleaner sharper sound from the NRD-545. It's not a night and day thing here between these 2 sets, but lets face it.....the JRC NRD-545 won in my view. Turning off the AGC on the PRO II can indeed help quite a bit, but did not help bring my rating up. So this goes to show you, as far as the DSP goes in these sets, It's not only the DSP scheme and IC used that is important, but the software and other circuits over the entire set play in thes weak signal capture output. Of course the AGC circuit's have a big part in this too. |
DSP
AGC is another great item to have as it also can help the audio
recovery , and both the JRC NRD-545 and Icom use this scheme. The
Icom being MUCH more adjustable and can also use it on AM mode
signals (JRC you cannot). I found turning OFF the AGC on the PRO
II can be a huge plus digging out the weak ones. Turning off the
AGC on the JRC NRD-545 on a extremely weak signal is a big waste
of time and usually make it worse (so AGC off on the NRD-545 is
really worthless). But overall the NRD-545's AGC performs better
for SWL work.
| Dave's
AGC Settings on SSB and AM Modes (from default) |
SSB | AM |
| FAST | 0.1 | 0.3 |
| MID | 1.2 | OFF |
| SLOW | 3.0 | 2.5 |
I
changed my default AGC settings in SSB and AM to help with weak
signal reception, all just seems to be a way
too slow using the defaults. Switching off the AGC for really
weak signals will help greatly in audio recovery,
like closer to the
Finmeccanica / DRS / Signia IDT / BAE Systems / Watkins Johnson
HF-1000A/WJ-8711A. You access "off" on the AGC set up (push
and hold the AGC button) screen and can be toggled on whatever
settting you wish it in (slow-med or fast ). However, even the
slowest AGC settings do not help the excessive receive distortion
in SSB modes. Of course with the AGC off you will have to use the
RF Gain control to keep the level at bay for excess distortion.
Yes...you
can indeed change the filter slope on SSB and CW modes on the
"2" version. However when I switch to "soft"
on SSB , I'm hearing some sort of excessive distortion that
creeps in (audio line out or the speaker). "Sharp" is
where I'm leaving mine set. I threw this question to "Icom
America" and they did not come up with any answers for me (no
real surprise here...eh). See the update below for more on
this.
1 hz Tuning AND Display and a .5 ppm TCXO installed
Standard / Runs on the Hot Side / No Excessive Fan Noise
Here is something where JRC just cannot get it right. The PRO and
PRO II both have 1 hz tuning but most important "Displays
the 1 hz tuning" as well !!! This is a big plus for tuning
in "DX" AM broadcasting stations using manual ECSS (in
USB or LSB modes). One usually for "premium receivers"
that cost at least $1000. more.
The Icom IC 756PRO II has unusually consistent frequency accuracy
across it's tuning range needed with having with a 1 hz digit.
The 2 samples of the IC-R9000 were not as good here. However the
PRO II's display was off about 50 hz (high) out of the box. Good
news is that the Icom has a nifty little adjustment hole on the
right side of the cabinet to tweak this and was a cinch to get
corrected. This is a great idea and do not have to remove the
cabinet to accomplish. The R-9000 also had this, so another good
Icom trait passed down to another set.
| Tip : When "tweaking" the TCXO in the IC-756 PRO or PRO II down to the 1 hz digit, use a strong WWV signal on 20 Mhz . Use SSB mode and set at max. bandwidth (3.6 khz). Set so that the USB and LSB sound....EXACTLY the same. It will indeed be more touchy the higher you go, but will allow for dead on accuracy. Allow the set to reach total "hot" temp, a good 2 hours or more. This adjustment might be required down the road again, as the TCXO and other parts will age and will of course affect the total TX/RX frequency. This is a real easy chore on the Icom with the side adjustment (cabinet stays on too), where as the optional TCXO in the JRC NRD-545 (CGD-197) is a royal pain in the rump to touch up for 1 hz accuracy. |
Icom
includes (just as it did on the PRO) a .5 PPM TCXO time base osc.
as standard. You don't see many manufactures that do this one,
usually this is a option just as it is on the JRC NRD-545 (another
$ 100.00).
From my own testing, you really need to run operate the set at
least 2 hours before any adjustment is made or for absolute
accuracy.
Being on for a couple of hours and only in receive mode, we find
the PRO 2 to run on the hotter side of the fence indeed . No so
much on the top side of the cabinet, but underneath on the left
side. Another trait that the old R-9000's I had did. Another hot
spot is on the rear just left of the power plug. But in
comparison the PRO II certainly runs cooler than the 9000 ever
did as it uses a external power supply. As many know the AC power
supply in the IC-R9000 ran so hot as to burn (no kidding) your
fingers if you were touch the rear power supply heat sink.
Icom did the fan operation right in the PRO/PRO II. With the huge
heat sink area, and thermostatically controlled fan, it never
comes on in receive. Fan's that run in a set (or power supply) in
receive mode at ANY TIME (that has not been put in TX on cold
start) is totally unacceptable to me. This is getting to be more
rare these days. Thank's Icom for this one.
Anyway, I would not block the set in or stack anything on it ..allow
plenty of room around and behind it to prevent heat stress and
you should be just fine. But it is a very warm running set even
in a receive only mode.
Internal Antenna Tuner Problem ..Fixed ??? Receiver
Sensitivity / No Weird DSP Gremlins or Other Noises...
Problems with the auto antenna tuner (dropping slowly out of tune
in voice modes and not working correctly on 6 meters) that
existed on some "PRO" samples, seems to have been
cleared up on this new "PRO II" model ???
For the moment let me say that it appears that the PRO 2 is a
very sensitive set with lots of receiving power. The DSP makes no
weird noises so far like the JRC NRD-545 emits. So far...It
appears that the DSP is a big overall winner. Has many ICOM
traits that my 2 IC-R9000's had (and hopefully down the road....does
NOT have as explained below).
| Advanced Sensitivity Update : I ran much closer side by side test on sensitivity with the JRC NRD-545, I have to say now with more testing, as the JRC NRD-545 does show a tad beter sensitivity overall. And yes...this is with the ICOM's Pre-Amp 2 on..same antenna's. The Pre-Amp 2 on the Icom also places the noise factor in there too ,it's much more hissy. But for the PRO II to compare at all with other sets ,you need at least Preamp 1 on or otherwise it's pretty deaf. But in general the set does perform OK in this area, it just does not reach the above average area for sensitivity. |
Manual
ECSS tunes great on the PRO II
Something of course this ICOM lacks but the JRC has and works
well , is a Auto-ECSS (Exalted Carrier Selectable Sideband)
circuit. You can also call this just "Synchronous Detection".
Two issues are improved using this method receiving a AM mode
signal, but can vary on performance depending on the circuit. The
first is that the general fading distortion can be reduced or
even eliminated on a AM signal. The second is that depending what
sideband is used can reduce of eliminate interference while still
using a wide filter (if the set will allow this). Using the one
further away from the offending station. The JRC NRD-545 has a
ECSS that automatically lock this circuit in and allows for even
use of the max. filter bandwidth (10 Khz).
Of course on the Icom we have no such critter. But not all is
lost. You can still do a what's called a "Manual ECSS"
selecting USB or LSB on a AM mode signal and zero beating it.
Good news is we have a excellent 1 hz tuning and display with
rock solid stability (after warm up). The maximum bandwidth we
can select is only going to be 3.6 khz. So actually is easier to
tune than doing manual ECSS on the JRC (which is rarely needed).
You can use the "Twin PBT" to additionally tune out the
interference along with actually narrowing the bandwidth to help
even in very ruff conditions.
Most stations will be on frequency, right down to the 1 hz digit.
But some are not, so you will have to select the 1 hz tuning step
and fine tune it. Another reason to tweak the reference
oscillator as covered elsewhere in this report. Use WWV on SSB
mode and adjust for the same identical tones between LSB and USB
(after warm up of course). Be sure and use 3.6 khz bandwidth.
Probably best that Icom has not tried ECSS in another set at this
time, and you don't see this in transceivers much (I guess the
old Yaesu FT-1000 MP had it but worked very poorly ?), Icom of
course really blew the "sync" with the audio really
getting killed on the circuit in the IC-R75. Also not a
selectable sideband circuit, it's double sideband sync only. So
best to forget it Icom, until you can improve your circuit here.
But would be great to see a good ECSS/Sync circuit in a
transceiver someday.
The only fly (more like a snake) in the oatmeal is the general
audio quality in SSB and narrower AM modes. Read on for the sour
details.
Front End "Bandwidth" Preselection As Good As It Can
Get / Good Dynamic Range, But Not Perfect !!!
The IC-756 PRO II has a excellent front end stage of passband
filters. Also spurious signal rejection is also superb. So
perhaps for a few little small very minor gremlins that creep up,
if this set is hearing a signal......more than likely it's really
there.
A problem that the IC-R9000 had tuning in the SW part of
the spectrum was with dynamic range. It would overload fairly bad
at night in the 41 and 49 meter broadcast bands on a good antenna.
Gee, not good what was a $8000 + receiver. The PRO II fairs much
better but is still not at a sterling standing. This is more true
with preamp 2 on, and even with preamp 1 on, but not as bad. To
be fair, I have not had a problem in receiving any broadcast
stations with overloading....none, but at very strong
local HF ham signal I was (only blocks away with a bit of power
as well). But this is really a super test being pushed here, so
the dynamic range is actually quite good , but not up to any
professional standards (the NRD-545 actually shows better dynamic
range at my location, which as many know is only fair). Again it
does better than the R9000 ever did.
Pre-Amp Kicks Out on MW Band / Poor LW (and below) Sensitivity....
Many already know this from older and even the latest
Icom offering in the "receiver" area, and sadly the
trend continues....the pre-amp does not operate in on signals
below 1600 khz. I don't really see a point here, as in the area
that is left in the MW band that we are able to tune with the
preamp active, that is 1600 to 1700 khz area, it works great
without any ill effects that I can tell even with Pre-Amp 2 in
use. I'm no MW expert, but it seems that the area that lacks the
pre-amp, sensitivity is lacking big time. This will not be the
set for MW Dx'ers, unless some can come up with a mod to allow
operation of the preamps in the MW section ???
And also because of this, LW (and below) sensitivity is not good
at all when you compare it against the NRD-545. The JRC blows the
ICOM into the next planet in this area.
"Dual Watch" Receive
Here is a feature that might be of use for many,
provided you don't go too far apart from each other. We have a
function called "Dual Watch" and this can also be found
on other Icom sets.
As long as you are able to use the same mode and within the same
'"front end" filter range (say within a couple of Mhz
or so from each other), yes you can listen to 2 frequencies at
the same time. The "bal" control did take me awhile
getting used to. The newely added "BPF" board in the
PRO II has changed the ranges a bit over the old standard model,
but if you stay within the BPF range , sensitivity will not be
too bad on the second frequency (below the main).
Audio Quality on SSB Has Excessive Distortion / No Hiss
At All / Line Out Level OK / "Beep" Appears At Line
Output
| Important Note on Receive Audio Quality : For most amateur radio applications the RECEIVE audio quality issue that I'm about to cover below will be of little moment and most will never notice it. But connecting the PRO II up to a good audio system with proper speakers via the line audio output, it really shows it's drawbacks. All sets that I report on are treated 100% equally in regards to audio quality...no favoritisum. |
Audio
quality will of course depend what external speaker is used, and
as I commented elsewhere..this set really must have one..no
exceptions. By the way..AM has 3 bandwidths (wish it had a few
more) 3, 6 and 9 Khz. As you go narrower the distortion increases
using any mode, and this is a normal trait of all receivers.
But in the case of the PRO II it's takes a dive into the black
hole !! If you use the 9.0 Khz filter on AM or the max SSB filter
width on SSB (3.6 Khz), it's tolerable (but not by much).
Going into the narrower filters the distortion jumps at you like
a mad bear in the woods. It's really gets excessive. The JRC NRD-545
in these SSB modes is clearly the "Huge" winner !!!
Nope, it does not matter how the AGC is adjusted, even at the
slowest settings...it's still in there just as bad. Adjusting the
PBT (center only on AM signals) to either side can really help of
course when using the AM 6.0 Khz filter.
| Audio Distortion Update: I have now had another real good listen to the PRO II's receive audio and compared it to a later standard PRO sample. In the Icom AD's, it indicates that "the PRO II's receive audio is improved" and this is most true, because the standard PRO's RX audio on SSB signals is even worse (totally unacceptable to me in fact). Loaded with tons of general distortion, even with the AGC set to max. So I guess it could be worse !!! So the PRO II does have improved receive audio over the old PRO to my ears...if that's saying anything. It still is not the greatest when compared to say a Ten Tec RX-340 or other top receivers. Again for amateur radio use this should not be an issue as much ?? But keep the SSB set to the "sharp" DSP filter setting, read below....Dave Z.... |
Another
gremlin with the audio, when "Sharp" DSP filter
selection is used for the SSB modes, The excessive distortion
eases up a bit (but only a bit however). So again, this is not
good....so keep it in "Sharp" and it's a bit less. Not
sure what is going on here at time I wrote this , but is a most
definite problem for pepole that plan to make archive recordings
and such off the airwaves.
The overall audio output is much more punchy as compared to the
JRC but is also on the bassy side (line output too). It does not
exhibit the "running out of volume control" problem
that plagues the NRD-545. Very good news is that we have no hiss
at all either at the speaker or line outputs. Totally clean for
any hiss. But overall receive audio, even with the JRC NRD-545's
lousy virgin AM modes audio and DSP issues....it clearly
wins over the Icom IC-756 PRO II set.
It's audio recovery (distortion and all), I do find to be in the
above average realm with the AGC "OFF", so has good
weak signal "pulling out of the muck" power . But it
does lack the crispness of the NRD-545.
Anyway...to tie a recording device into the PRO II you have to
make a cable tied into the ACC 1 socket (pin 5 and ground).It
seems to be a bit louder level as what my older R-9000's were. R-9000's
were a bit anemic, and struggled to give a correct audio line
level. The PRO II is much better level wise. SSB on the wider
bandwidths when tuning via ECSS, the audio is going to be much
lower and could be a problem on stations with weak transmitted
audio.
Another similarity to the old IC-R9000, the keyboard "Beep"
appears at "line" audio output. So if you have a
recording going...don't touch a key or it will show up. You can
toggle the keyboard beep off in the set up menu's to get around
this. The JRC NRD-545 has none of this nonsense, only irks from
the speaker.
Digital Noise Reduction / Notch Filter
The digital noise reduction (NR button) works much better on the
PRO II, vs the (joke) NR button on the JRC NRD-545. It really can
be of use with only a moderate "in the tube" sound.
With the JRC, it sounds like all "in a tube" and no
signal.
However the JRC's notch auto mode (called the "Beat Cancel"
button) does a bit better job for use on wider AM signals. Even
the manual does a tad better. But not to say either notch is no
slouch on the Icom either (AN or MN), it works very well indeed
and is most useful and deep.
Only 100 memories, Accessing a Bit of a Pain / Band
Stacking Memories / Notepad Memories
For many 100 memories will be just fine and will not be a problem.
Actually having a smaller amount will make them more useful and
less confusing. Especially when used in the Ham radio realm what
it was really made for. But for SWL use it could be a issue. I
find 100 to be OK considering the lack of a EASY way to access
them.
Yes, accessing the memories is a bit of a pain the rump. There is
no "spin wheel" for zipping through them. Instead you
are forced to use the up down arrows on the keypad, or direct
entry (yep, have to hit an extra button as well), even the
buttons on the mic will allow you to surf the memory channels. I
guess this works OK, but it would have been nice for a dedicated
spin wheel encoder knob.
You can view a chunk of the memory channels on the LCD and add a
10 character alpha to each memory. Another trait to the R9000
again. I like the way the list is laid out and displayed. But
unlike the memory layout, you cannot copy and paste which I kinda
miss. Not a biggie here however.
If you are tuning around the Ham bands, the Band Stacking
Memories will store your last 3 entered entries. Can be most
useful and as I do the Ham thing too...this was most useful.
But even more useful are the "Notepad Memories". You
can store 5 or 10 (user defined) of your most used or hunting for
in the DX world, and these are very easily accessed. Great idea
here...
Digital Audio Recorder, Useless : Too Short Of Time (15
sec max)
The Icom IC-756 PRO II features a Digital Audio Recorder which
allows recording of the off air signal up to 15 seconds (in 4
chunks), or your voice onto the air for up to 90 seconds
total.
As for any use for SWL signals, this is just about totally
useless. On the PRO II you can continually record in a 15 min
loop for 30 min total. Then can capture the last 15 seconds buy
just hitting the button (in case you missed a word or 2). Connect
another device for any real recording.
Why Icom did not allow the 4 receive channels to be combined for
a total of 1 min is beyond me. They blew it here !!!
Audio quality from this recorder while being OK for most ham
applications , does degrade all a bit however.
Good Transmit Audio
and Quality
As I had made a comment at the top of this report, I will not be
covering the Ham Transmit side of this radio in any detail . But
with the tests I have made at time of writing it was very good
and clean with 3 different transmit bandwidths available. No
excessive relay's clicking when the set is put into transmit. The
mic EQ settings work very well indeed. The included HM-36 hand
mic is a real treat, very good responce, holds in the hand well
and has great tactile feedback. This is getting to be a rare one
indeed.
"Icom-itus"..lets hope not !!!
As I have indicated on my Master List Page, The IC-R9000 can
suffer from the nasty trimmer capacitor failure problem (I use
the term "Icom -itus") that plagues many other Icom
sets engineered in the era (such as the IC-745 / IC-751 / IC-271
/ IC-275 / IC-970 etc).
| Unacceptable Customer Service From Icom America In the Past !!! |
| I have not had so
good customer service from the folks at Icom America a
few years ago. I cannot say if this has changed over the
years , but for the record...I must cover this one...read
below. I made a $ 1500.00 purchase of a "Brand New" Icom radio a few years back. It died only 18 days after being pulled out new from it's box. The dealer would not replace it being it was a bit over 2 weeks old, so off to Icom America in WA for repair it went. It returned a couple of weeks later, with it still not working correctly..but even worse...they had taken a PERFECT CONDITION "Brand New" radio and gouged up the top cover + plastic front bezel / noze piece along with the front of the tuning knob BAD !!! The tech and or other pepole at Icom America did not give a hoot for sure..... This never got resolved either, only received the royal "run-a-round" a number of times, and the female service manager at this time quitting right in the middle of the affair. So as you might understand, I was quite a but sour with Icom after this for many years. I felt that this set should have been REPLACED with their botched repair and more importantly the general destruction of a brand new set by "Icom America" (in WA) from someone who could care less !! Nope, just received the cold sholder if you know what I mean. Enough ...off the soap box on this subject....but lets hope we NEVER have another bout like this one if service is ever to be required ?? Caveat Emptor !!! |
Great
Set , But Fair to Poor Receive Audio Quality Overall /
Construction and Parts Quality Not Up To JRC Standards
I find the Icom IC-756 PRO II to be a very nice set and I give it
a "luke warm" (for SWL use) thumbs up. It has many
functions that no other set manufacture has even begin to touch.
It does it's DSP business with no weird strange noises or burps
and without exibiting poor ultimate rejection that plauges the
JRC NRD-545 superset.
Downside is that you will have to find a nice hefty +23 Amp power
supply to get this one to work (if you use it for transmit as
well). A non-switching one if you want to stay away from RF noise.
Better add the cost of a good external speaker if you don't
already have one around. As I have indicated below, the matching PS-125
power supply and SP-21 speaker are not the best ones to go with
in my view .
You are paying a pretty penny for the fancy display, but I find
as many will this is one of the main reasons the one desires a
Icom IC-756 PRO II. If it fits the budget (ouch) and needs and
receive audio quality problem is not a issue (for most amateur
radio applications it will not be)...go for it. But as with all
sets it has it's share of good points/bad points and I hope that
I have covered these in this report.
The build quality and parts used are not in the same leauge when
compared to the JRC products in my view. It's not poor either...but
when one really compares.....JRC was on the top for
quality of construction and parts used. The PRO II also lacks the
ECSS mode, and the JRC NRD-545 really gave overall better audio
on all modes provided it (ECSS mode for AM signals) has not gone
into DSP overload mode (burps/ticks). Also the JRC gives a better
way to access bandwidths and gives more of them, but this could
be the flaw why it has the DSP overloading problems "trying
to do too much" too..who knows ??
But on the other side of the coin, JRC has not done well in the
amateur transceiver market. The now discontinued JRC's JST-145/245
ham transceivers via reports covered here on the internet have
suffered from nasty internal power supply and PA module failure
problems over the years and this makes the Icom IC-756 PRO II the
better transceiver (if you are to compare these 2 in the transceiver
area).
The real problem for SWL use with this set is the receive audio
quality. It simply does not cut it to my standards in this area.
If you are very sensitive to receive audio distortion...better
look elsewhere. Or perhaps treat the set as your 'Ham Radio"
TRANSCEIVER, with a perk to your SWL activites using the spectrum
scope to help hunt out the new stations,.and use another set for
the actual recording, and you could very well find a IC-756 PRO
II in your future.
I have covered the matching PS-125 power supply and SP-21 speaker
below.
(Please
Note: I no longer own this model. Also, I do not plan to purchase
or test the IC-756PROIII [3]. The JRC NRD-545 is also a
discontinued product.)
Discontinued
Product
Dave
N9EWO
© N9EWO
ver 5.9
| Icom PS-125 Switching Power Supply |

The Icom PS-125
is a switching type power supply that is rated to work with the
IC-756PRO and PRO 2 / 3 versions (25 Amp).
Can be used to work with newer Icom Transceivers (that have the
new 4 pin plug) with an aftermarket plug adapter.
As many already know the old PS-85 was an awful electronic
RF noise box, with a fan that just about drove you out
of the room and ran at no load (ran all the time..LOUD). This old
model did not have enough current rating to properly run the
older 756PRO in full TX power and was not even listed in the
brochure. What a D-O-G it was !!!
The PS-125 has a fan that does not run all the time
while the set is in receive mode. Tony D. informs me with this
info on the new switching supply,and yes the fan does indeed have
a thermostat, but it's still a very expensive power supply at
about $ 400.00 US street price . I personally think that a fan in
a power supply should NOT come on at all in receive only mode. Oh
well , at least an improvement over the old PS-85 (but not by
much):
"Yes, the fan will occasionally cycle on when the radio
is in receive mode. (cold start) I have come home, turned the
unit on , then the radio, and initially the fan does not engage.
After maybe 7 or 8 minutes, then fan will then come on for 1 or 2
minutes, then go silent. I think that the cooler your environment,
the less often it will come on when you are just receiving. In
any event, the noise from the fan is very low, and I do not find
it to be objectionable at all."
Tony is most most correct here on the fan operation.
But let me say while that it is true that the fan does not run
all the time now, but I think it's noise still way too
excessive. It
even runs when no load is connected to it.....ice cold !!! And
when it does run , it's way too loud to my ears. So for me it is
indeed overall a unacceptable power supply due to this awful fan
noise . I would have not been bothered in transmit...but in
receive as much as it does run....I don't think so. I
say buy a B-I-G analog supply (even a 50 amp one say
from astron) and be done with it.The PRO and PRO 2 /3 all draw a
good 3 amps in just receive...so don't skimp..buy "over-big"
and any heat issue will not be there.
Just about all
switching power supplies will
emit some "RF noise" somewhere within the HF spectrum,
and the PS-125 is no expection. Appears to peak very nasty around
12~13 Mhz or so and , yes is another gremlin I was not happy
about. But to be fair it's an improvement over the old PS-85. But
if your antenna's are a distance away from the PS-125, this
should be of little monent ?? But you still have the nasty fan
noise in receive mode.
The PS-125 is a very well made made supply. It also has a AC cord
that uses the standard 3-pin socket that computers use. Yes you
can disconnect it. But I would pass this one up if you are
sensitive to either one the gremlins above. It actually can be
used with the newer 4-Pin Icom transceivers by use of a aftermarket converter
plug. UPDATE :
Fan noise is much reduced with the KK5DR fan modification (see
below).
Dave N9EWO
© N9EWO
ver 4.1
********** N9EWO tries the KK5DR PS-125 Fan Modification ********** |
|
| Matt KK5DR came up with a
great and very simple modification to the tame down the
noisy internal fan in the Icom PS-125 power supply. We tried it and I must say the fan
is much more quiet and no excessive heat either with my
phone ONLY operations. Not to say that it totally cures
the noise (it dosen't) , but now I can actually put up
with the PS-125 fan noise. Does not sound like a jet
airplane taking off anymore. As usual, TRY THIS AT
YOUR OWN RISK !! Click on the link above for more
information. Hardest part is to take it apart (properly)
!! Should work for the PS-126 as well (not tested) ?
|
Icom SP-21 External Speaker |
You will need a
external speaker when using the PRO / PRO2. My PRO 2's sample has
a internal speaker in it that buzzes so badly to be totally
useless. It's one of the worst internal speakers that I have ever
heard !!! Not to say that internal speakers in any set are of any
real use (99% are not), but this one really stunk on my
sample.
But like the PS-125 power supply, the matching SP-21 External
Speaker (color scheme matches the PRO not the PRO 2) is another
"Thumb's Down" for me as well. Not as strong of a
downer as the PS-125... but I would pass on it. Find some other
speaker and try it. Certinally will almost be cheaper and sound
better.
It's extremely light (not a steel cabinet...made from pop can
material) and has a very small "low end" speaker
element with a very small magnet. Not so much that it's small
size but what's in the speaker's cavity which will of course have
an effect on sound quality. But the cheap element used does play
a part.
It nevertheless gives a "bonky" sound with it's "loaf
of bread" shape. It could indeed work for many, but I went
with another speaker with a bit bigger element and magnet that
sounds better to my ears. But if you just "have to have the
matching speaker", it will work without any weird buzzie
sounds that the internal one had on my sample.
© N9EWO
(NOTE : The SP-21 is a discontinued product)
Other information :
| Users Input (from old IC-756 PRO Model) | ICOM's answer with IC-756 PRO II |
| IMD problem. | Improved 3rd IMD characteristics. |
| The sensitivity of 50MHz is not good enough. | Changed the RF circuit for 50MHz and used SSB-SOFT filter. |
| The voice recorder/player
works for SSB only. When the recorder/player is in use, other features cannot be used at the same time. |
Added a new button for
recorder/player, which can be used not only for SSB but
also for other modes. Added an interface for the external logic to control the recorder/player. |
| NB is not effective in some situations. | Added a level control for NB. |
| Special ROM. | Added a DSP set mode that allows the user to change the filter shape on the fly. |
| AF volume know is touchy. | Improved the AF volume resolution. |
| With NB on, the signals are distorted. | Improved. |
| The output level of the headphone is not loud enough. | Improved. |
| The VHF users commonly use USB side for CW (CW-R) | Got it user-customizeable. |
| The receive frequency is shifted when the mode is changed. | Added an option that keeps the receive frequency even when the mode is changed. |
| The repeat interval of the memory keyer should be set longer. | The repeat interval can be set from 1 to 60 seconds. |
| The power meter swings stickily in the CW mode. | More Smooth |
| The key-speed knob is not easy to handle. | Exchanged the positions of the key-speed and delay knobs. |
| The narrow BPF does not work for SSB. | The narrow BPF is available for SSB, too. |
| The filter settings for DATA should independently be controlled. | The user can settle the filters for SSB and DATA independently. |
| The 1/4 function is not available for SSB. | It is available for SSB, too. It is effective for digital modes, such as PSK31. |
| No one touch clear of RIT. | User customizable. |
| The monitor level is not enough. | Raised the level. |
| The wake-up/sleep timer is not easy to use. | Improved the user interface. |