Programming volatile memory boards in older Icom Rigs and radio upgrades

[Radio Tech]

Now for the good stuff. Although tempos are climbing it is still 40 in the shop. Takes too long to get heat up. So here at the bench in the house I started playing with the modified bin file.  I really need to be doing this in the shop where all the notes are.

I have some upper limit now. Radio will receive all the way to 30.9999 then receives drops out at 31 MHz.





The limits are really set high on the top end. As you can see the display is showing well over 55 MHz.
I got tired of spinning the dial so that is where I stopped at. The "Band" button does not let you go through the upper portion so you have to use the "TS" button. Not really sure just how high the display will read.




No luck on the bottom end yet. I have to look at this more. My radio only goes down to 1.800.0.
Now this rig has a mod in it I need to remove. I have never modified a 745 to go outside the band. There is a switch in the rear that is stuck on the "ON" position.  Possible this mod is causing an issue as well.  As far as I can tell there is two wires going to it then  over to the  RF board. This looks like a transmit enable mod for out of band. .

 While in General Coverage mode it will tune all the way down to 1.6 before receive falls out. This tells me we have to do some work in the VCO area if we are going to her anything down there.  As much room that is in the radio I may build up a separate VCO section for this and switch it in with a diode matrix.  But that is for another time.  But I am sure a simple tweak of the VCO will bring the bottom end up a bit, just do not know yet what will happen on the top end on that band.

Anyway this is fun and may wait till the week end to really get into this a bit more.

[Radio Tech]

It sprinkled here today for a time, supposed to rain tonight.
Rumor has it we may get an inch or more.
/Sue is not holding her breath.

I thought it was always sunny in Kaliforny. At least the song said it was

[AF6LJ]

It sprinkled here today for a time, supposed to rain tonight.
Rumor has it we may get an inch or more.
/Sue is not holding her breath.

I thought it was always sunny in Kaliforny. At least the song said it was

Never use to be always sunny here..
Since the population explosion of the 70s and 80s, The People's Republic of Kalifornia has a large heat island along the south coast that does effect the weather...
We use to get 2 feet of rain here every year, snow in our mountains every year and the state population was somewhere south of 14 million. Now there are more people than the country of Canada. It is not such a nice place to live.
Always hot, dry the air is dirty and the cost of living out of sight.

[Radio Tech]

Was 70 here yesterday and 50 here today but temps are dropping.

I want to expand on this thread a bit more and add more modifications to the Icom radio.
The IC-745 is called a ALL MODE radio by ICOM. But they did not include AM transmit.
This week end I have started looking at the AM transmit mod listed by Paul N2FAN in 2003.
This was done on a word processor of the day and can be a bit confusing to the untrained eye.
I am working on a modern version of the mod.  Will take me a while to get this done, installed, and tested.
It really is not a lot of work to do the mod.  I am attaching the documentation here. along with the original link in case it vanishes from the internet.

http://n2fan.org/ic-745.html

Here is the original text:

14 Jan 2003 @ 20:07:31 UTC
                 Subject: ICOM IC-745 extend xmit

                 Submitted to QRZ.COM on 06-1999     7 years, better late then never!

                 73 Paul N2FAN       (n2fan@glensummit.com)

                    REVISIONS:
                 ---------------
                 ** Updates and Fixes  Submitted 05/2000 **
                    Info: Some miss labeling and updates.
                 ** Schematic Scan and Labeling  05/2000 **
                  PJH 5/2000
                 =========================================================================

----- MODIFY FORUM appended at 23:17:57 on 92/04/27 GMT (by PAULH at POKADD6) -
Subject: /********* AM TRANSMITTER ENABLE FOR THE ICOM IC-745 **********/

Intro:

After returning home from purchasing a used (but in good condition)ICOM IC-745, initial check out revealed the transmitter did not function in AM transmit mode. A look and the owners manual revealed: "AM Receive Only"  What!!!??? This is supposed to be an ALL MODE RADIO!
In reality the words used were..."ALL BAND HF RADIO"

After analyzing this perplex situation I came to the conclusion ICOM must have been doing their part in trying to save precious spectral bandwidth by not incorporating AM transmit in this particular model.
No one really utilizes AM mode these days (including myself) but this radio has every mode ever conceived and to leave AM transmit out really aggravated me!

Below is the Mod of Mods for IC-745 owners:

(All Modifications administered to the "MAIN UNIT" board located under the top cover of the radio.)(Except for R21 Removal on the logic board for the Power Mod.)

Parts list: ------------
8 pin diodes. Factory Diodes are P/N 1SS53. 1N914's are fine.
3 10k resistors 1/4 watt.
1 NPN TO-92 pkg. switching TX, 2N3904 or equivalent is fine.

                 Source Voltage Terminology and Locations:
                 -----------------------------------------
                 R8   = 8 Volt Receive Mode Source
                 AM8  = 8 Volt AM Mode Source
                 FM8  = 8 Volt FM Mode Source
                 CW8  = 8 Volt CW Mode Source
                 RY8  = 8 Volt RTTY Mode Source
                 USB8 = 8 Volt USB Mode Source
                 LSB8 = 8 Volt LSB Mode Source

                                                 ______________________
                                               |                     |
                         "J7"      Pin #1 | O O O O O O O O O O | Pin #10
                      Main Board         |_____________________|
                                                  |  |  |  |  |  |  |  |  | |
                                                  ---   ---   | |  --- ---
                                                   A     R   U L   C   F
                                                   M     Y   S S  W   M
                                                   8     8   B B   8   8
                                                              8 8

                                                       -----------
                         "J21"           Pin #1 | O O O O | Pin #4
                        Main Board               -----------
                                                          | | | |
                                                          -------
                                                             R8


                                                     /***************************** THE MOD *********************************/

1) Pull up the anode end of Diode D44. (located by TX Q39)
   Build the additional circuit below. This will enable the B+ to the
   product detector and 9 Mhz BFO oscillator.
   The 9Mhz osc will now be working for AM transmit as well as BFO Rec.

                                 C
                                   o to AM8  (Where the Anode of D44 was)
                                    \
                                     \| B       10K      1N914
                                      |------\/\/\/\/-----|<-----o to R8
                                     /|
        to R239 o----|<----/    2N3904 or Equivalent
                          D44    E

2) Remove R66.  (Located by TX Q13)
   Relocate and solder one end of R66 to the bottom of the board.
   (The end that goes to R23 and R30)

   (The schematic shows a "BREAK" in the land. By removing the
   resistor from the PC board this simulates the break.)

   Solder two 1N914's to the other end of R66. (Cathode ends of course)

   Note:  All pin assemblies will be connected on the underside of the Main
   Unit PC board.

   This is part of the Mode selection process, and turns off the
   mike shunt in AM mode. (So audio can pass to the Balanced Modulator.)

                 to R23 & R30   o-----\/\/\/--:----|<----o   Anode to CW8
                                                                |
                                                R66   :~---|<----o   Anode to RY8
                                                10K     pair 1N914's (add)

3) Solder one 1N914 diode (Cathode end) to the cathode connection of D15
   (by TX Q19) under the board. Connect the anode to AM8.
   This will enable the B+ to the Mic Amp stages and VOX ckts.

                         to R31 (10K)
                          ^
                          |
                          |
                         ___
                        break
                         ___
                          |           D15
                          |------------|<----------------o Goes to 8 Volt LSB Source
                          |------------|<----------------o Connect to AM8 Source
                          |
                          |           1N914 (add)

                         to R100 (100 Ohms)

4) Remove R31 (Located by TX Q8)Relocate and solder one end of R31 to the bottom of the board. (The end that goes to R30 and the base of Q8)
(The schematic shows a "BREAK" in the land. By removing the resistor from the PC board this simulates the break.)

Solder Three 1N914's to the other end of R31. (Cathode ends)
Tie the Anode ends to LSB8, USB8, FM8.
Function: This portion of the mod will turn Q8 off in the AM mode to unbalance the balanced Modulator (IC1) for AM full carrier operation.
                                  C
                                   o                      3 1N914's (add)
                                    \
                           (Q8)      \| B             R31     |--|<-----o to  LSB8
                         Bal/^Bal     |---------\/\/\/\/--|--|<-----o to  USB8
                         switch      /|        |   |            |--|<-----o to  FM8
                           for      /             |   |
                           IC1    o             \   \
                                 E                /   /
                                            R29 \   \ R30
                                                  /   /
                                                 |   |     R's=10K's
                                              ___  |
                                                _   o

5) Remove R24 (Located by TX Q7, "Mike Shunt Ckt")
   Solder a 1N914 Diode (Cathode end) into one of the pc holes that R24 came          out of. (The one end that connects to R65 by Xtal X1.)
   Tie the anode to AM8.
   This will enable the 9 Mhz CW xtal to generate the correct center
   frequency for AM.








                     --
                  o-||||--->|-o
                       --  |
                      X1  \
                            /
                     R64 \                         1N914 (add)
                     10K /       R65
                           |-----\/\/\/\--------------|<------o AM8
                         ___      220     |
                  C44 ___                  ---|<---o to CW8
                    47pf |
                          ---                D13
                           -

6) AM Power Level Adjust (optional)Due to the duty cycle requirements of AM, output power of 40/50 Watts RMS should be the limit. Use the Front panel RF adj to reduce the output from 100 Watts or do the following:

A) Connect a small 22 gauge (or so) wire from AM8 to the anode of
   Diode D26 by TX Q20. Add a series 10K resistor.

                     AM8 o------\/\/\/\-------------------- o-->|-----o to Q20
                                       10K                             |  D26
                    |__________________________|    o
                                       Add this                       o S1
                                                                          |

B) Set the 50/100 Watt power switch (S1) in the 100 Watt
   Position if you desire 100 watt operation of SSB,CW,RTTY.

C) Adjust R116 (in AM xmit mode) for a power output of 40 Watts RMS.

D) What were doing here is using the 50 Watt low power ckt as the AM
   power adjustment control.
   Paralleling another connection to FM8 will allow FM to be reduced in
   similar fashion (as well as AM) instead of the factory 100% duty
   cycle.

                     FM8 o---->|-------/\/\/\/----o
                                1N914    |  10K        |
                     AM8 o---->|-------              o-->|-----o to Q20
                                   1N914                 |  D26
                                                             o
                                                             o S1
                                                             |

  Note: When 10 Meters is selected port 28M (pin 47,IC3 on the logic
  unit) goes high, this turns on pin diode D27 on the main unit.
  This ultimately turns on the 50 watt (low Power) ckt allowing only
  low power operation from 28-30 Mhz?
  I don't know why Icom did this? My guess is for 10 Meter FM
  overlooking the fact SSB/CW will be running reduced also.
  You may want to remove R21 (10K) on the logic board to remedy this
  situation. After R21 is removed you can limit the duty cycle on
  AM & FM as follows:


                     FM8 o----\/\/\/\----->|----
                                    10K   |   D27    |
                                      |         |
                     AM8 o----\/\/\/\----->|-------o to Q20
                                    10K   |   D26
                                             |
                                             o
                                             o  S1
                                             |

   Low power Adjustment R116 will now adjust output power for FM as well
   as AM.

                 OPERATION/CONCLUSION
                 ---------------------

  The above AM/FM power mod is recommended. Higher power levels
  (Greater then 70/80 Watts RMS) result in severe distortion of
  the AM output signal.
  Surprisingly the audio quality is quite good on AM xmit. (40/50 Watts)
  Several on the air discerning ears concluded the fidelity was quite
  acceptable. (Even from the Johnson Viking Guys on 3.880 (+-))
  For you skeptics wondering how an AM signal can sound acceptable
  through a 3Khz wide 455Khz SSB filter....................
  A quick turn to the schematic on the IF board depicts filter F-I1.
  (Ceramic filter CFW-455IT) This filter is a 6Khz wide ceramic filter
  used for AM receive mode. After the completion of the Mod this filter
  will be used for AM xmit also, by default! >>> It's in there!! <<<
 (Wasn't that a commercial once?)
  Filter F-I2 (ceramic Filter CFT-455K14) or the optional FL-44A
 (SSB filter) is in operation for all other modes except FM.
  The optional FM board employs it's own filter arrangement.

 That's it. Your all mode radio is now all mode!

73 Paul N2FAN
 
*05/2000
I have scanned the Main Board and Logic Board to depict the electrical
changes made to the circuits. I tried to nicely re-label all the changes
using VISIO technical, but I ran into some offset problems.
The hand written changes will have to do for now until I can get Visio to
work right.
If you have any questions about this Mod feel free to ask via e-mail
only (I'm hard to get a hold of)  e-mail = n2fan@glensummit.com

This is not an easy cut the wire mod, you will need to have some good
electronic technician skills. PhD's forget it! ......
This Mod works, I still have my IC-745 after 8 years!
73 and Good Luck!

[AF6LJ]

Cool...
I have some new (to me) gear.
Look for tear down pics here in this sub form in the near future.

[Radio Tech]

Cool...
I have some new (to me) gear.
Look for tear down pics here in this sub form in the near future.

Great 
New used gear is always fun

[Radio Tech]

Well, the AM transmit mod works 

[AF6LJ]

Saw your video it was good.

[German_EE]

Nothing wrong with a bit of Ancient Modulation on Top Band.

Looking at the video most of the modifications seem to involve adding extra diodes to the connector which supplies 8V depending on mode. Rather than use individual diodes I wonder if the mod could be neater using a small PCB with all the diodes added as surface mount devices? I guess it would be about the size of a large postage stamp.

Any idea of the modulation depth or does that depend on the Microphone Gain setting?

[Radio Tech]

Saw your video it was good.

Thanks Sue, You know that modification has always looked a bit intimidating to me.  And is why I have never attempted to do it. But after spending Saturday reading over the material I thought to myself this is really nothing to it.
I will say I spent about 5 hours on this modification.  I recorded it as I went along. The was no planning ahead or reshoots.  After all said and done I had about 40 minutes of usable video.

What really tied me up the most is I cannot find my original service manual. I thought I left it at work but was not there.  The online PDF files are useless in locating the parts. Also there is no pin one location for J7 in the PDF. This forced me to search the board for each component.

Nothing wrong with a bit of Ancient Modulation on Top Band.

Looking at the video most of the modifications seem to involve adding extra diodes to the connector which supplies 8V depending on mode. Rather than use individual diodes I wonder if the mod could be neater using a small PCB with all the diodes added as surface mount devices? I guess it would be about the size of a large postage stamp.

Any idea of the modulation depth or does that depend on the Microphone Gain setting?

You got it, just moving the 8 volt lines around to do the task.
So it looks like we are thinking alike!
This was the first time I have ever attempted the AM mod on this rig. After doing it I now see more clearly as to what is going on.  Today while at work I am think like a marketing sales guy. How can I make this into a product?  Make it so anyone can do this mod?  That's when it dawned on me that it all can be done on a small pc board with surface mount. 

The board would be so thin it could be attached to the bottom of the radios main board.  Then have multi-color wires to attach to the board after the component's are removed.  I would even have D44 completely removed and add a surface mount diode for that on the mod board. I would also have to incorporate the AM power mod to keep folks from running the AM carrier up to the point of melt down.  We do not want the unmodulated carrier to be over

Now I just need to get better with circuit board programs and do it.

I have not done any hard in-depth testing on the AM modulation yet.   But looking on the scope and a nearby receiver the audio quality sounds really good, the fidelity of the signal is decent. Once I get everything sorted out I will do some further testing and see just what this rig will do on AM.

[Radio Tech]

Just an update on the AM transmit audio.
I am really impressed with the quality of it. Sounds very good. I have not yet ran the numbers on it but in all it is decent.
Will do more when I get time.  Been really busy here the past few weeks.

I need to find a easy to use circuit board design program. I do want to convert this AM mod to a single pcb mod.
So all the user has to do is remove the components and wire in the board. Should make for a nice clean install.
I will do the proto type myself then see about getting boards made from a supplier. Along with Highprecisions adapter board.

[AF6LJ]

This should be interesting...
I have also been busy and have a number of projects on hold..

[Radio Tech]

This should be interesting...
I have also been busy and have a number of projects on hold..

I can only imagine Sue. With your knowledge  I bet you get a lot of folks calling, emailing and wanting answers. Heck I have even asked you a few over the years.

 Seems the back log of projects keep on getting bigger. Seems I am doing more repair work these days than what I intended to do.  Folks are emailing me daily and I have to tell them 3 to 4 months before I can get to it.
Don't get me wrong, I love the time I spend on radio repair and picking up a few extra bucks here and there is nice. But it takes all my free time up. I never thought doing a few YouTube videos would lead to this. 

I am trying to make the Icom 745 stuff my biggest priority at the moment. As soon as I get the AM mod proto-type board done I will send you one to try out. Pauls modification posted above is really not that hard, just looks complicated. The believe  board I want to build could be installed in under 20 minutes.
I hate rushing life but retirement needs to get here sooner.

[AF6LJ]

We have to install the battery back up for our club repeaters on Thursday. I have to make sure I have all my ducks in a row on that project and also I have to modify the programming in our repeater controller. (I have to work on that tomorrow. )
After that....
There is a Yaesu FT-847 I need to look at for a ham.
Then I get to work on the club newsletter, only after that I get to return to my projects.

[Gaz]

Hi all,
Great discussion and solution to a mutual problem. I am a relatively recent addition to the ham community and have obtained an IC-271H. The previous owner wasn't able to confirm the age of the backup battery, however, the radio has been re-capped and is in excellent condition and working order so I'm looking to ensure that it remains operational for a long time to come.
I am by no means an expert in Arduino, much less programming/reading memory chips. However, my VK version of the trx (memory #06) doesn't didn't come with onboard CTCSS encoding, nor does it have the optional encoder/decoder fitted. I have managed to use an Arduino and adapt a Direct Digital Syntheses (DDS) sketch to generate the 'sub-audible' tones necessary for repeater access whilst also interfacing the existing (already functional) 6 bit encoder data bus to select different tones without the need for external modifications. The duino UNO I'm using is overkill for the task but I am also planning on utilizing it as a CW keyer and now I see the possibility of also addressing the volatile memory issue.
To that end, here is a link to a timely article in a relatively new Aussie magazine regarding using Arduino to read and program PIC uPs. It should provide some clues for those here investigating using duino to access the ICOM memory boards:

https://diyodemag.com/projects/arduino_pic_programmer

73
Gaz
VK2GTS

[Radio Tech]

Hi all,
Great discussion and solution to a mutual problem. I am a relatively recent addition to the ham community and have obtained an IC-271H. The previous owner wasn't able to confirm the age of the backup battery, however, the radio has been re-capped and is in excellent condition and working order so I'm looking to ensure that it remains operational for a long time to come.
I am by no means an expert in Arduino, much less programming/reading memory chips. However, my VK version of the trx (memory #06) doesn't didn't come with onboard CTCSS encoding, nor does it have the optional encoder/decoder fitted. I have managed to use an Arduino and adapt a Direct Digital Syntheses (DDS) sketch to generate the 'sub-audible' tones necessary for repeater access whilst also interfacing the existing (already functional) 6 bit encoder data bus to select different tones without the need for external modifications. The duino UNO I'm using is overkill for the task but I am also planning on utilizing it as a CW keyer and now I see the possibility of also addressing the volatile memory issue.
To that end, here is a link to a timely article in a relatively new Aussie magazine regarding using Arduino to read and program PIC uPs. It should provide some clues for those here investigating using duino to access the ICOM memory boards:

https://diyodemag.com/projects/arduino_pic_programmer

73
Gaz
VK2GTS

Thanks Gaz for that post.
Sorry it took so long for me to reply. Been quite busy here over the last few months.
I will take a look at that link and see what I can learn. Should be a good read as I know nothing about the Audrino let alone programming with one.  Good thing is my programmer that I bought is working quite nicely.  But would like to continue this thread further.

[Radio Tech]

Been a while since I done any updates on this thread.
I have some programmer boards being produced by JLCPCB in China.
As soon as they arrive I will be posting further testing on the 745 ram board.

Big thanks to all that have contributed to this project.

[AF6LJ]

Good Video Buddy, watched it yesterday.

[Radio Tech]

Good Video Buddy, watched it yesterday.

Thanks Sue,
The boards should be here Friday. Than I will populate them and do some testing.  Really looking at making a production run on them. Not sure how well they would sale. May do several packages, adapter board, adapter board plus programmer. Not sure yet.

On another note I am also designing a very small pcb that is in cased in epoxy.  All surface mount components. Consist of 9 resistors, one diode, and one transistor.
Mount board under main board, remove three resistors and one diode, then wire up the harness.
You now have AM transmit.  Quick and easy modification.

[AF6LJ]

Good Video Buddy, watched it yesterday.

Thanks Sue,
The boards should be here Friday. Than I will populate them and do some testing.  Really looking at making a production run on them. Not sure how well they would sale. May do several packages, adapter board, adapter board plus programmer. Not sure yet.

On another note I am also designing a very small pcb that is in cased in epoxy.  All surface mount components. Consist of 9 resistors, one diode, and one transistor.
Mount board under main board, remove three resistors and one diode, then wire up the harness.
You now have AM transmit.  Quick and easy modification.

That will be good.
looking forward to seeing the AM mod PCB.

[Radio Tech]

Great.
I have been playing around with several pcb programs for the prototype board. I really need to learn how to use them things.
This should really make the AM transmit modification a lot smoother than it is. It takes several hours to do it the way it is presented in the video.
With this mod you remove a diode and three resistors. Connect the 14 wires  and done.
I did a rough layout of the schematic and pcb layout for through hole components.  But I really need this done for surface mount. It will make the board much smaller.

[Radio Tech]

Got the boards in from JLCPCB this week end.
Not bad at all.  Bit of an interference issue with the mini pro programmer but that is ok.

[am]

Hello all,
N2CBU´s circuit just worked fine with my IC-745 and IC-271 (find some photos attached). The "essential" requirement was to find a mid-age PC working on genuine DOS, and to remark ALL drivers in config.sys and autoexec.bat, also disable all items in the BIOS menue-including hardware devices/ports/controllers. Only the LPT board was configured.
It seems like to transform this issue back to the early Nineties-but it works. I´m sure that it should be able to read/change/write the memory contents also with an Arduino etc-using today´s PCs.
73 de Armin/OE7IMI

[randman80]

Well I picked up a non working IC-751 and, in mid repair, I decided to replace the battery on the ram board....No, I didn't look on line FIRST!... you can guess the rest. Replaced the battery and killed the receiver!
I decided to "fix" the board. I found the schematic on line and a copy of the ram contents. All I needed was a programmer.
The Arduino Nano was just the ticket. I ginned up some code and built a circuit board to connect the memory board to the Nano. It is a completely passive interface. The Nano cost was about $3. the rest was a small prototyping  pcb , a couple of headers and a 30pin socket for the Nano.(The LEDs were just for testing and debug)  I just plugged the ram board onto  the new board, powered the programmer up and a couple of seconds the ram board was restored.
Happy to share if there is any interest. Oh, it worked great and the receiver is functioning....Now if I can the the transmitter to light up,

UPDATE: attached is the Arduino code. Copy and paste it into the Arduino editor (FREE ). Of course you will need to program the Nano using the Arduino IDE (FREE) ..piece of cake.
The wire list is all you need to wire it. It is a pin to pin wiring.
When you are all done, just plug in the Ram board , then connect the Arduino to a usb port and in a few seconds it will be done. The code will start over in 60 seconds so you have plenty of time to pull the USB connector then remove the Ram board.
The 512 BYTES are in the Loooooong string called codeString. You can make the changes some folks have submitted to extend the frequency range of the radio, I chose not to. It is just a few bytes. I don't have a copy of the changes in hand. They are out there.

Note that the spacing between the two connectors on the Ram board as NOT on .10 It is off by .05. I managed to bow the header pins on my breadboard and made it fit. Also note that you need long header pins. I just soldered the headers to my pcb, then went back and heated each pin on the bottom of the PCB with my soldering iron and pushed the pin till it was flush with the bottom of the PCB. That was enough, just.

Best wishes and good luck.....

Chuck  KX4SB

[TheSteve]

Nicely done!
Please do share your code/schematic - I am sure others will benefit down the road.