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ICOM IC-756 PRO II (2) DSP HF Transceiver
(including KK5DR's PS-125 Fan Modification Notes)

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.
( 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 .

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 ( well finally..
.LED backlighting is now used in the IC-76000..see my review here ) ?

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."

"He packed it up and in a few minutes brought out a new one. We plugged this one in a let it play for a while before I took it home where it's done fine since." W4CRT


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"

"I had that problem earlier this year. I returned the transceiver to Icom for repair and it's been OK since then. The notation on Icom's Service Work Order reads WEAK DISPLAY BACKLIGHT FOUND AND REPLACED. It's been a little over two months and so far the screen has lighted up at power on, no delay. K8JQ"


"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.

N9EWO'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 FIXED 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 variable bandwidths up to 3.6 khz, but still very limited as compared to the JRC.

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 found it best. 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 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 6.1


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) ?


KK5DR's Icom PS-125 Fan Modification
(click here for details) . Adds a resistor in the fan power lead.
In our case we used a 56 OHM "wirewound" 3 WATT resistor in heat shink tubing (fan power + side).
Used one wire zip-tie to help keep it from moving around (as shown above).
Even using a
3 WATT resistor it runs near "dead cold" in my testing (even without the fan air blowing on it ) ,
so you do not have to worry about "resistor" heat issues . Be sure and PROPERLY use heat shrink tubing (no black tape here).
(N9EWO Photo)

I will NOT be held responsible for any info that is listed here.
ALL DONE AT YOUR OWN RISK !


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 :


Features on the IC-756 PRO vs IC-756 PRO II

How ICOM has reacted to the users' input ?

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.

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