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Forum: Icom Mods
 Topic: ICOM IC-735 TX Mod
ICOM IC-735 TX Mod [message #3072] Sat, 07 March 2015 22:43
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Registered: December 2004
Senior Member
The mod for general coverage TX for the IC-735 involves removing D33 and D34 from the main board. You'll have to lift the PA module up to do this, locate the diodes and simply snip one end of each. Very simple, but it's amazing just how many screws need removing in the process!
 Topic: ICOM IC-735 Transmit Mod
ICOM IC-735 Transmit Mod [message #3071] Sat, 07 March 2015 22:37
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Registered: December 2004
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I don't have either one of my 735's open and I can't seem to find the precise location or information but roughly...

There are two diodes, D30 &D31 (or maybe it's D32&D33 D34&D35 I can't remember) located toward the front center of the board containing the CPU. The diodes were end mounted with yellow insulation over the end of the leads away from the board. Cutting these diodes out of the circuit enables broadband transmit. My radios were purchased new in spring of 1989 so I don't know if they acurately reflect current production units. This is a particularly nice feature since it allows wide coverage when used with transverters. I use my 735's with my 144MHZ - 10.368 GHz transverters with the radios operating in the 20-30 MHz region. It allows 10 MHz of all-mode coverage on every vhf-uhf-uwave amateur band.
73
Glenn Elmore n6gn
From: Glenn Elmore
Date: Mon, 4 Feb 91 9:28:24 PST


>
> Do you have any documentation and/or suggestions on how to build or > design the 50 MHz through 902 MHz units ? >
> Chris

I don't have anything explicitly written but it is very much along the lines of the microwave stuff I showed.

The LOs are partly there already:

Band       LO           circuit
50M     30M             3 X 10 (2n5179 tripler from 10M) 
144     120M            I'm presently using the 100 MHz Xtal circuit
                        with a 120 M xtal but 6X20M with filtering
                        would work too.
220     200M            2X 100M  (single stage of 2n5179)
420     410/420         Just like 260M LO shown
900     620M            Like 1010M  6th harm of 100M and 20M PLL reference


Only 420 and 900 even need to use another of the PLL boards. The others just take a single stage. I have 50,144 and 220 done. 400 is sitting 90% completed. I have PA bricks for 50 and 400 waiting to be used.
As I said, 144 and 1296 have been running for years.

I build the RF decks in metal "shoeboxes". I pipe the LO and IF(with tx switching as DC on the line) to each deck which lets me remote them if I want to. The only thing I really need to add that I haven't is an ALC line coming back from each PA to control the 735 so that I keep things linear. Linearity hasn't been a problem but like any of the current commercially available transverters it is possible to overdrive things.

73
Glenn n6gn

 Topic: ICOM IC-746 mPC Chip Repair
ICOM IC-746 mPC Chip Repair [message #3070] Tue, 03 March 2015 21:58
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Messages: 192
Registered: December 2004
Senior Member
Solution for mPC chip to stop frying.

Change resistor R157 from 10 Ohm to 47 Ohm close to this chip.


 Topic: ICOM IC-746 Power Mod
ICOM IC-746 Power Mod [message #3069] Tue, 03 March 2015 21:55
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Messages: 192
Registered: December 2004
Senior Member
Remove bottom cover.

Find the voice module plug-in.Right behind it you will see 4 pots

R993 144 mhz power adj
R991 50 mhz power adj
R989 HF bands power adj
R990 AM power adj

You can tweak these to up the power suggest on hf doing it on 40 meters. you can get close to180 watts on 40-75 meters about 125 to 150 on 20-10.

The pots are very small be careful not to use something to big. the are all metal pots.

NI4L
 Topic: ICOM IC-746 TX/RX Frequency Mod
ICOM IC-746 TX/RX Frequency Mod [message #3068] Tue, 03 March 2015 21:53
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Messages: 192
Registered: December 2004
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Author: John Schmitz NS8E


Remove the twelve screws holding on the bottom cover. With the Radio laying flat on it's top remove the bottom cover. Turn the radio so that the front panel is to your left and the antenna connectors are to your right. Lohoneye the IC labeled "ICOM HD6433042SF".
About 3/4 of an inch to the right is a vertical row of diodes. The left hand column of diodes has 7 diodes (14 possible spaces). The right hand row is full with 14 diodes. Remove the diode in the 6th space from the top in the left hand column. DO NOT remove anything from the right hand column. This should get you TX from about 100KHZ to 60MHZ and 118MHZ to 176MMZ.

Do this totally at your own risk. Never, ever transmit out of the ham bands or your privileges.

John Schmitz NS8E

Additional information.

After having put a forward reading watt meter on my 746 i have found that there is NO loss of power due to this mod. It is still putting out the full 100 watts when you have a good match (5-100 on SSB and FM and 2-40 on AM).

I have also discovered that the TX was NOT opened up above 54MHz to 60MHz the top end of the 6 meter band switch on the 746.

The only effect i have noticed is that sometimes while using the built in antenna tuner in manual tune the LCD display sometimes blinks or lights up with all functions showing or sometimes disappears below the line.
Also the band edge beep function option no longer works because with wide open TX there are no more band edges. One must be careful to stay within their operator band privileges. These are the only adverse effects I have noticed with Mr. Schmitz mod.

[Updated on: Tue, 03 March 2015 21:53]

 Topic: ICOM IC-746 Out of Range TX/RX Mod
ICOM IC-746 Out of Range TX/RX Mod [message #3067] Tue, 03 March 2015 21:44
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Registered: December 2004
Senior Member
In IC746DW.JPG you can see the open bottom side from the transceiver and you will see a red marked area, too.



This marked area you can see again and bigger in the picture below.

Now something about this image.

There are some green frames. This are diodes which must be on this place. There are some red frames. Thess are diodes which you have to remove. Where no frame is, there is no diode in my transceiver.

After removing the red marked diodes you should can RX 60 khz - 60 MHz and 118 Mhz - 176 MHz TX 100 khz - 60 MHz and 118 Mhz - 176 MHz

[Updated on: Tue, 03 March 2015 21:50]

 Topic: ICOM IC-756 ACC1 Audio Output Increase Mod
ICOM IC-756 ACC1 Audio Output Increase Mod [message #3066] Tue, 03 March 2015 11:58
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Messages: 192
Registered: December 2004
Senior Member
Author: Adam MAURER, VK4CP - vk4cp@bigpond.com


Access to the Main Unit is required.

The "Line Level" audio output on pin 5 of Rear panel connector ACC1 is very low, with the manual stating 300mV. Normal Line Level is regarded as about 700mV. Although my MiniDisc Recorder had a gain control for its Analogue I/P it still couldn't make 0 VU. Here, by adding two resistors we can increase the gain of the audio appearing on pin 5 of ACC1.



1. Remove the bottom cover.
2. Remove 6 screws holding down Main Unit.
3. Remove screw on rear panel in between ALC & Send RCA sockets.
4. Remove heatsinking clip holding transistor to chassis.
5. Remove flat ribbon cable to J3 in far right corner.
6. Carefully pry PBA loose and fold over - see at left. (I actually had to remove RF Unit shield and loosen a shielded cable to allow the Main Unit PBA to fold out).
7. Locate IC-503, a NJM2058 OPAMP in an SMT SOIC14 package.
8. Remove W3 0603 SMT link.
9. Fit an 10k 0603 SMT resistor in W3's place.
10. Fit a 1/8w 5k6 through hole resistor from IC-503 pin 9 to ground.



We have effectively changed the OPAMP IC-503c from being a unity-gain follower into a non-inverting amplifier with a gain of approx 2.5.

Thanks to http://www.qsl.net/vk4cp/ for the modification.
 Topic: ICOM IC-756 Spectrum Scope Adjustments
ICOM IC-756 Spectrum Scope Adjustments [message #3065] Tue, 03 March 2015 11:51
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Messages: 192
Registered: December 2004
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Author: Adam MAURER, VK4CP - vk4cp@bigpond.com

Access to the RF Unit is required.

Remove bottom cover and then remove cover to RF Unit - see below.



To increase overall Scope gain:



Lower the value of R963 (100k as fitted).

I put a 56k 1/4w through-hole resistor across R963 - see above - making the combined resistance approx 36k. (One resistor leg was soldered to pin 2 of IC-961 and the other leg to the junction of R966 and R964)

To be neater you could remove the small 0603 SMT resistor and replace it with a 39k 0603 part.

To adjust Scope base-line:

Trimpot R966 will adjust the base-line of the Spectrum Scope.

Thanks to http://www.qsl.net/vk4cp/ for the modification.
 Topic: ICOM IC-756 General Coverage HF TX Mod (1.6 - 30.0MHz)
ICOM IC-756 General Coverage HF TX Mod (1.6 - 30.0MHz) [message #3064] Tue, 03 March 2015 11:39
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Messages: 192
Registered: December 2004
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Author: Adam MAURER, VK4CP - vk4cp@bigpond.com

VHF remains 50.0 - 54MHz TX only.

Modifihoneyion summary:

Remove the W805 jumper chip on MAIN unit by soldering iron.

Modifihoneyion Procedure:

1. Remove bottom cover of IC-756.

2. On MAIN unit board you will see I.F. filters and daughter board (DSP PBA) on the right hand side.

3. W805 jumper and IC803 chip lohoneyed under DSP PBA.

4. Remove DSP PBA (lift up carefully!)

5. Look for IC803 and line of jumpers (0603 sized SMT links).

6. Remove W805 jumper - as indihoneyed below.

7. Re-install DSP PBA

8. Re-fit bottom cover.

                    ---------------
            [W801] |               |
            [W802] |               |
            [W803] |    IC 803     |
            [W804] |               |
    Remove=>[W805] |     CHIP      |
            [W806] |               |
            [W807]  ---------------
            [W808]


Thanks to http://www.qsl.net/vk4cp/ for the modifihoneyion.

[Updated on: Tue, 03 March 2015 11:41]

 Topic: ICOM IC-756 Expand TX Frequency
ICOM IC-756 Expand TX Frequency [message #3063] Tue, 03 March 2015 11:36
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Messages: 192
Registered: December 2004
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Notice: ICOM can not guarantee specification when expand frequency. How to change full cover transmit: Remove the W805 jumper chip on MAIN unit by soldering iron. Jumpers matrix located near IC803.

What to do:
Remove bottom cover of IC-756. On MAIN unit board you will see IF filters and daughter board (DSP filter) on the right side. W805 jumper and IC803 chip located under DSP board. You have to remove DSP board (get it up careful) and look for IC803 and line of jumpers (little green bugs). When it done, unsolder W805 jumper. Install DSP board and bottom cover back.

                     ---------------
         [W801]     |               |
         [W802]     |               |
         [W803]     |    IC 803     |
         [W804]     |               |
REMOVE==>[W805]     |     CHIP      |
         [W806]     |               |
         [W807]      ---------------
         [W808]


This info are from ICOM SERVICE INFORMATION sheet.
 Topic: ICOM IC-PCR1000 Frequency Full Coverage Mod
ICOM IC-PCR1000 Frequency Full Coverage Mod [message #3062] Sun, 01 March 2015 15:22
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Messages: 192
Registered: December 2004
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You've been waiting.

You've been told it can't be done.

You don't want to pay for it.

Here's how you do it.

The PCR-1000 full coverage mod:

What you'll need:
Small philips screwdriver
Slightly larger philips screwdriver
Soldering iron with *very* fine tip
Xacto knife, or other sharp tool
2 0-ohm surface mount resistors, 0804 in size, or 30 guage wire-wrap wire
No fear of surface mount components
Ability to follow instructions

Very very very first step. Read ALL the steps before starting. Make sure you feel comfortable making a mod of this nature. It's not rocket science, but it does require a steady hand.

There are three things that can happen as a result of this mod.

You're completely successful.

You screw up a surface mount pad, but the radio still works when you're done.

You're a total hack using the wrong tools, and you send the radio back to Icom for repair.

Hopefully, you're a result 1 type person. At worst, you're a result 2. If you think your going to be a result 3 type, don't even start. Call a friend.

We've done this mod on 2 radios with complete success. We can't guarantee that in later radios this mod will still work. It works at least with serial numbers up to 1111 in the last 4 digits.

Let's get started!

Remove the 8 screws that attach the cover, and remove the top cover of the radio.

Orient the radio so that serial, power and RF connector are closest to you, and the power switch faces away from you.

On the PC board closest to you, in the upper left hand corner you should see a 80 pin surface mount chip. It has a number such as 64F3334 stamped on it. This is the processor.

Near the upper left hand corner of the chip, you should see 2 small green 0-ohm resistors. To the left of the two resistors you should see an unpopulated pair of pads. These are the 3 "R"s below, on the left. The 4th "R" is used for location reference below.


|       RRR       R
|    o          ooo
|    o     -----------------
|    o    |                 |
|    o    |                 |  D
|         |                 |  D
|    r    |                 |
|          ------------------
|
|   ---
|  |   |
|  |   |
|  |   |
|   ---
---------------------

(Picture courtesy of Alan Adamson, NE1H)

Using the soldering iron and knife, *carefully* remove the right hand resistor. You'll need to alternately heat the two ends, while apply a *light* pressure with the knife. Once it's hot enough, it will left off. It's very easy to destroy the pads the resistor is soldered to, so be *careful*.

You'll now need to short the pads of the left resistor (this is the unpopulated one). You can either try and re-use the resistor you just lifted (least good idea), short them with a short piece of wire wrap wire (OK idea), or use a real 0-ohm resistor (best idea).

For the next step you have two options. One option is easy and does not require removing the board from the radio (recommended). The other option is "more correct", but will require disconnecting all the cables, removing the 5 screws that hold the board down, etc (purist method). We'll presume you're more likely to want easy, so here are the steps for it.

Keeping the radio oriented as described above, look below the right hand resistor (the one we removed). You should see 3 vias (holes) (see picture above). Follow the left most via, and it should go to the left most pin of the processor. The second via should go to the next pin to right, and third via should go to the pin to right. At this point, you should see two pins that don't appear to be connected to anything, then a pin that connects to a small black resistor marked 201 (this is the 4th "R" in the picture).

If you've sucessfully located the 6 pins above, we want to short the pin that is the 4th from the left to ground. Above these 6 pins, you should see a small black rectangle, with 8 pins. I believe it is marked 220. On the side of this part (it's a resistor pack), there is a pin that is soldered to the ground plane.

To short the 4th pin from the left to ground, tack a wire to the pin. Be *very* careful not to short the adjacent pins to the 4th pin. It's very easy to do. It you do, use a piece of Solderwick or coax braid to remove the solder. Better yet, don't short the pins. Tack the other end of the wire to the pin on the resistor pack described above.

OK, you'd rather do it the "more correct" way. Disconnect all the cables from the board. You'll need to remove the shield from the RF section to remove the white ribbon cables. Disconnect the power and speaker cable. Remove the 5 screws that hold the PC card down. Remove the card from the radio.

Orient the board as described above. Look for the white connector above the packet connector (lower left). It's marked J12. Just above that are a pair of solder pads for a resistor. One side goes to ground, the other goes to a via. Follow the trace on the bottom side of the board. You should see that it goes to a via, but that the trace has been cut right next to the via.

Using a sharp knife and a lot of care, scratch away the solder mask to reveal bare copper on the trace. Use a piece of wire wrap wire to repair the cut trace (bridge the trace to the via). Back on the top side, short the pads for the resistor that are open (this is the lower case "R" on the left, off by itself).

Reassemble the radio. If you used the "more correct" way, make sure you get all the screws and cables back in.

Plug it in, turn it on, fire up the software. Tune a frequency you couldn't before. If you can tune it with the software, and the squelch is open, you're working!

If it's not working, review everything we described. Make sure you didn't short any pins. I can't offer you much more help if it didn't work.

Remember, you screw up your radio, it's not my fault. I don't work for Icom, I don't represent Icom. I don't endorse listening to frequencies you're not supposed to, and can't be held liable for anything that happens, anywhere in the universe, as a result of you making this mod, or even thinking about making this mod (Gawd, I hate lawyers. CYA!). This mod was done completely from our own experience and background, and did not reference any material. We don't know about these people selling the mod on the 'net, but we didn't steal it from them.

Hope this helps. If you've got any suggestions to improve how to make this mod, please send e-mail. If you made this mod, let us know how it went. Also, if you want a list of the PCR-1000 commands we know about, drop us e-mail, or use DejaNews(tm) and search the alt.radio.scanner groups for the post (look for PCR-1000 in the subject).

- Chris, KD4DTS (Thanks to Alan Adamson, NE1H for his being ready and willing to sacrifice his radio to a higher cause, and his drawing).
 Topic: ICOM IC-706 MARS/CAP Modification
ICOM IC-706 MARS/CAP Modification [message #3041] Wed, 11 June 2014 00:32
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Registered: December 2004
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Tools required:
l #0 Philips head screwdriver
l 10 - 15 watt pencil tip soldering iron
l Magnifying glass
l Tweezers
Remove the TOP cover by removing three Philips head screws on the top and one on each side. Move the speaker bracket out of the way. Locate D-59, this is a three terminal SMD diode in an SOT package, about 1 x 3 mm (with the radio front panel oriented towards you, D-59 is located in a row of SMD diodes just to the right of the ribbon cable header above the 9 MHz SSB filter FL-30. There are pads for 5 diodes with only three installed. D-59 is the second from the left).
Using tweezers and a low-wattage soldering iron (and magnifying glass, if necessary) remove D-59 by applying some heat to the single leg side of the device while lifting gently, then apply heat to the other two legs and removing the device. Be careful not to apply too much heat, not to rip or burn any traces or not to leave excess solder on the PCB. Replace the speaker bracket and top cover.
Apply power and reset the microprocessor.
TX = 1600 kHz - 54.00 MHz and 118.000 - 174.000 MHz
De James KG7FU
 Topic: ICOM IC-04 Out of Band Modification
ICOM IC-04 Out of Band Modification [message #3040] Wed, 11 June 2014 00:27
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Messages: 192
Registered: December 2004
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Out of Band Modification for the Icom IC-04

1. On the logic matrix, remove D402.
2. Add D402, D403 and D404 with the cathode at 4 o'clock and the anode at 12 o'clock. (You may use any signal diode such
as 1N914)
3. Add D405 with the cathode at 8 o'clock and the anode at 12 o'clock.
4. If you have a newer 04AT, the VCO cover will have holes in it that allow access to the tuning coils. If you have an older
04AT you will have to cut a hole in the VCO cover using a pair of small diagonals (be careful!).
5. Re-tune the VCO to cover your desired frequency spread. My 04AT goes from 441 to 473 MHz, which is pretty good.
6. Any frequency may be entered directly on the keypad (starting with the 10 MHz digit).
 Topic: Icom IC-706mkiig IF-SDR
Icom IC-706mkiig IF-SDR [message #3032] Mon, 10 March 2014 02:07
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Registered: December 2004
Senior Member
Next video will be a IC706 with TV dongle connected to the IF, it works very well.

Well here's part two for what it's worth.


It's quite easy to pick up the 69MHz intermediate frequency in an Icom 706 mk1. There are two plated holes in the track which carry the IF signal so just by inserting the inner of the coax into one of these it can be picked up by the dongle.

http://youtu.be/vY8xlmuX21s

The TV dongle accepts this signal and if it is then tuned to 69MHz you are then able to see the IF on the spectrum display and waterfall. The waterfall is not shown here . With the dongle I have here I am able 1.8MHz of spectrum but I can also zoom-in. There are lots of features in the software most impressive is the filtering.

Software used here is SDR#, another that works with the dongle is HDSDR.

So why would you do this? Well it adds a whole new dimension to an otherwise boring black box.

Try it and find out.

There is no reason, of course, why this set-up can not be applied to other rigs with an IF over 60MHz (dongle doesn't go lower).

Hope you find this of interest.

Sorry video's not up to much.

If you want more info ask me at the Club.

Next will be Powersdr-IF and CAT control of the IC706.



SDR-IF Part Three

I think that this set-up is the most likely to appeal to members.

Here I am using my IC 706 Mk1, the intermediate frequency of which is feed to a home-brewed SDR which I mostly use on Six and Four Meters, so it's ideal to receive the 69MHz IF from the 706.



The software in use here is Ham Radio Deluxe, PowerSDR-IF and Rocky.

HRD is used for the CAT control of the 706. PowerSDR-IF then connects to HRD.

http://youtu.be/0SI2rggbiFI

The waterfall display of Rocky is used to view CW, it is not connected to the 706 or the other software, using the sound card output only.

In the video I'm just tuning around the bands mostly using the mouse to click on the spectrum display/pan-adapter of PowerSDR-IF but also using both the slider and DX-spots of HRD. Of course it's also possible to use the 706 tuning knob but this seems a bit "old hat".

The pan-adapter reveals some pretty wide signals, some very clean ones, some with poor carrier suppression, sweepers, odd QRM sources and more. There is no CW filter in the 706 so the SDR output is the only way to receive CW properly.

Hope this is of interest.

If you want more info ask me at the club or post here.



I have been asked by a Club member for information on the 1st IF tap point that I used to feed the
RTL TV dongle from my IC706 Mk1.
The photos below should help.



"It's quite easy to pick up the 69MHz intermediate frequency in an Icom 706 mk1. There are two plated holes in the track which carry the IF signal so just by inserting the inner of the coax into one of these it can be picked up by the dongle."

http://www.hamradio.cc/images/forum/mods/icom_706_mkiig_if_sdr.jpg

Use the hole towards the front panel. BE CAREFUL AND TRY IT BEFORE SOLDERING.

http://www.hamradio.cc/images/forum/mods/icom_706_mkiig_if_sdr_.jpg

Daniel Fourlas - sv1jcz
 Topic: ICOM R7000 Display Issue / R7000 Sensitivity Problem
ICOM R7000 Display Issue / R7000 Sensitivity Problem [message #3004] Mon, 02 September 2013 13:29
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Registered: December 2004
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If you are having trouble with you Icom R7000 display being flaky
and then a sudden decrease in sensitivity try the following:


PROBLEM: ICOM R7000 radios that are used 24 hours a day for a long time
(2 years ) when shut off the display will become flaky and it
is also possible for a lost in overall gain (3 to 40 db).

SOLUTIONS: Officially there is ICOM ECO SB# 9288-004, attached below.

Unofficially from Tech who repairs R7000
The ECO does help the display problem, but most likely
it is not the problem. *

* note repairing your own radio my void you warranty and only
allow a qualified technician to do the job, otherwise damage
could happen to your R7000. If the VCO does not track then a
major alignment would have to be done after. Check the
ICOM IC-R7000 Service Manual for more details before starting
this repair, and to make sure I have not made any typing errors
you should get a copy of the ECO from ICOM !

1st SOLUTION:
Replace on the DC to DC Board the following capacitor.
Check the noise with an oscilloscope on both sides of
R3, if the noise is not way down on one side then
replace C2 a 33uf 16V capacitor. Noise feedback
can decrease the overall sensitivity of the R7000.

Replace on the Display Board
C19 and C20 a 10 uf 16VDC capacitor

I found that on my R7000 C19 & C20 were the cause of my
display problems. They are 10 uf electrolytic capacitors
that are lemon yellow pc mounted units, when they go bad
the base of the yellow caps change to a brown color.

I put in the following ECO first but it did not help. If
you look at the service manual you will see that the ECO
values are on the schematic but my unit had the old values.
I suggest that you check the above first, it is a lot easier
to do, C19/C20 can be done in 10-15 min while the ECO will
take about a hour.


2nd SOLUTION: The ECO


ICOM America, INc
2380-116th Ave, N.E.
Bellevue, Washington 98004
206-454-7619


SERVICE BULLETIN


UNIT MODEL R7000
SB# 9288-004
EFFECTIVE DATE 4/1/88
SERIAL # AFFECTED: ALL
PRODUCT GROUP: Amateur

BACKGROUND INFORMATION:
Display failure do to weak components

TECHNICAL INFORMATION:
Improvement in DC to DC converter and display power supply.

PARTS AFFECTED BOARD TYPE CHANGE TO NEW PART NUMBER
Q1/Q2 2SC 1214 DC to DC Board 2SC 2655 906-00385
R1/R2 3.3 KOHM DC to DC Board 5.16 K 915-01173
C3/C4 PF DC to DC Board 0.001 MF 50V 918-01500
ceramic cap
Q11/Q12 Display Board 2SC2655 906-00385
R31/R32 3.3KOHM Display 5.16k Ohm 915-01173
C13/C16 Display 0.001 MF 918-01500

DETAIL PROCEDURE:

1. Remove top and bottom cover.
2. Remove front panel sub-assembly from main chassis of radio
3. Remove the DC to DC board and replace components as listed
4. Reinstall DC to DC board.
5. Replace front panel sub-assembly onto main chassis of radio
6. Replace top and bottom covers.

ESTIMATE TIME TO COMPLETE IS 1 hour

 Topic: ICOM IC-R7000 Repair - Capacitors
ICOM IC-R7000 Repair - Capacitors [message #2999] Wed, 10 July 2013 11:01
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Registered: December 2004
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** There is no retuning of the IC-R7000 radio required as the capacitors being changed are power supply related, or audio coupling/decoupling.

** Installation Time is approximately 4-6 hours from start to finish for an experienced technician. For all others, take you time and enjoy its a great project!

The kit is comprised of the following capacitors (118 in all):


.47uf 50V - Qty 14

.47uf 50V BP - Qty 2

1uf 50V - Qty 5

2.2uf 6.3V 7mm - Qty1

2.2uf 50V - Qty 1

3.3uf 50V - Qty 4

4.7uf 50V - Qty 5

4.7uf 25V 7mm - Qty 1

10uf 16V 7mm - Qty 3

10uf 16V - Qty 35

22uf 10V - Qty 5

22uf 25V - Qty 1

33uf 16V - Qty 3

47uf 16V - Qty 12

47uf 6.3/10V 7mm - Qty 2

100uf 16V - Qty 7

100uf 25V - Qty 4

220uf 10V - Qty 4

470uf 16V - Qty 7

4700uf 35V - Qty 2

[Updated on: Wed, 10 July 2013 11:02]

 Topic: ICOM IC-R1 Keypad Problems
ICOM IC-R1 Keypad Problems [message #2998] Tue, 09 July 2013 00:24
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Registered: December 2004
Senior Member
If your keypad goes south on the IC-R1, open the unit,take out the 6 screws on the board with the speaker de-solder the speaker and both boards come out together.where the 8 solder joints join the daughter board to the backboard look at those joints under mag.what you will notice first is one set of#s 1479 etc. when you loose a contact between these boards you will loose a row of buttons.......use a small gun,,don't need to de-solder these just add more .....take care not to solder all legs together as this would be bad!!! also turn board over and do the other side...don't forget when your backing out to re-solder the speaker leads.......been there done that ....take your time don't be watching the kids close door and go for it......partspig
 Topic: IC-476 and PRO LCD backlight repair mod
IC-476 and PRO LCD backlight repair mod [message #1484] Thu, 06 September 2012 02:07
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Messages: 192
Registered: December 2004
Senior Member
IC-746 Backlight Repair / IC-746PRO Backlight Repair

Here is how I mounted a TO-220 type transistor in place of the original backlight driver transistor, Q302. An ECG/NTE 378 in the TO-220 case style will substitute for the surface mount 2SB1201 that came with the IC-746.
You will need to unsolder and remove the shield, drill a hole in the case and mount the new transistor.

This provides a larger heatsink and a transistor with more thermal dissipation ability. You will need to isolate the transistor from the shield using the insulating kit that comes with the transistor. Be sure and use thermal heatsink silicone grease.

After mounting the transistor, solder the shield back into place.

You will need to run small jumper leads soldered to the NTE-378 and run over to the pads on the PC board where Q302 was lohoneyed. Looking down from the top where Q302 was lohoneyed, the lead configuration is Base Collector Emitter from left to right. The Base pad is close to the shield, and the Emitter pad connects to L301. Collector goes to the center pad.

index.php?t=getfile&id=59&private=0

E. Kirk Ellis, KI4RK

[Updated on: Thu, 06 September 2012 02:07]

 Topic: IC-746 PRO Repair - Low TX Power on all Bands
IC-746 PRO Repair - Low TX Power on all Bands [message #1236] Tue, 17 January 2012 00:23
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Messages: 192
Registered: December 2004
Senior Member
On Checking an IC-746PRO with low output power, it was found that the pre-predriver transistor tr Q1 (2SK2973)had overheated because of insufficient heatsinking (this has been covered many times before). The transistor was replaced only to find no improvement. Further investigation proved that the small choke L2 100uh had gone open circuit.

I replaced the choke and all has been well with 100w output on all bands. Check the standing current of this transistor as the specs per the w/manual is incorrect. The standing current of 500ma as per another published article has proved perfect.

The IC746-PRO is again functioning perfect - better than before!

Author: zS2ACP
 Topic: Icom R71 Synchronous detector
Icom R71 Synchronous detector [message #1083] Tue, 15 November 2011 01:44
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Messages: 192
Registered: December 2004
Senior Member
Author: Dayle Edwards

The Icom R71 in all its flavours is one of the best performing receivers of all time, and its AM reception can be improved enormously with the inclusion of a synchronous detector. As it happens, this is very easy to do, as much of the necessary circuitry is already present, in the form of a balanced SSB detector and carrier insertion oscillators, used in the existing SSB modes.

Looking at the SD circuit, it comprises nothing more than a dual opamp. The Icom SSB product detector output, when close to zero beat with the wanted AM signal will contain the difference frequencies, either a audio heterodyne, or when locked, a DC voltage. The DC voltage is a function of any phase difference between the two inputs to the mixer, the carrier insertion oscillator, and the IF ouput. This voltage is heavily filtered to remove as much audio as possible , amplified by opamp A, and the resultant is fed to the varicap diode frequency shift of the 30.2 MHz master oscillator on the Icom PLL board, thereby correcting any phase error to the received signal. Any mistuning will result in a hetero-dyne from the mixer output, this is amplified by opamp B, rectified and switches the display "tune" segment via TR1/TR2. Diode D3 allows the Synch board to coexist with the FM option if fitted... this also uses the "TUNE" segment.. The "TUNE" display segment will activate within 20 cycles or so from the center frequency, giving a lock indihoneyion when correctly tuned.

The Synch detector will lock well on signals below the noise, and can exhibit a dramatic improvement on many marginal signals. With stronger signals, the audio quality can be very much improved, selective sideband fading or cancellation can be almost eliminated, and any noise is held to the level of the wanted signal. The Synch detector uses selectable sideband, simply by selecting either USB, or LSB, all installed filters able to be used with this design, as too the Pass Band Tuning and notch filter. It is important to note, the capture range of the design is limited to around 20 Hz, it is only required to lock the phase, not the frequency, so correct initial tuning is critical, the lock range being approximately 80 Hz. The limited bandwidth also allows normal SSB/CW modes to be used with no interaction from the synch detector which is permanently active. Normal AM remains selectable from the front panel.

The board will mount on the two pillars used when installing the FM option, or if this is already installed, it will piggy back above using longer screws and spacers. The unit is wired as follows.

REMOVE POWER FROM THE RADIO.

The signal input is got from R157, rear right of main circuit board.
The minus 10 volts is got from R197, rear center between the crystal and FM option connector.
The 8 volt plus is found at jumper W46, center on the circuit board opposite the regulator chip.
The tuning voltage will connect to R105 extreme right lead on the PLL board, rear right hand side.
The indihoneyor voltage connects to the RED wire in the two pin connector for the FM option The circuit boards need not be removed for these connections to be made, it is sufficient to carefully solder the wires to the exposed resistor leads. All added wires are at DC only, so no additional birdies, spurs or noises are created.

Initial setup:

Connect a voltmeter to IC1 pin 1, and with the radio tuned off a station at around 25MHz, slowly adjust VR1 to obtain a reading of near 3.5 volts. The unit is now ready for use. Tune in a weak AM station in SSB mode, slowly tune for a zero beat. At some point, the carrier will lock, the audio will become clear and natural sounding, and the "TUNE" segment should light. Unless the ICOM high stability VXO option is fitted, its likely each station will need to be manually tuned slightly up or down from the set frequency indihoneyed. Remember, the R71 tunes in 10 Hz steps, these are not recorded on the frequency display.

http://www.hamradio.cc/images/forum/mods/ICOM-R71_1.jpg

http://www.hamradio.cc/images/forum/mods/ICOM-ic-r71_synch.gif

[Updated on: Tue, 15 November 2011 01:45]

 Topic: ICOM IC-751 Mod Unlock Transmitter
ICOM IC-751 Mod Unlock Transmitter [message #1043] Sat, 15 October 2011 17:15
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Messages: 192
Registered: December 2004
Senior Member
ICOM IC-751 Mod

Locate the RF board on the side of the radio and cut the black wire going to pin 1 of jack 2. Your transmitter is now unlocked. (This mod also described in "73 Magazine", July 1985 p. 12.)
 Topic: ICOM IC-745 Mod Unlock Transmitter
ICOM IC-745 Mod Unlock Transmitter [message #1042] Sat, 15 October 2011 17:12
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Messages: 192
Registered: December 2004
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ICOM IC-745 Mod

Locate the RF board on the side of the radio and cut the light brown wire at jack 7., which is going to pin 1. Your transmitter is now unlocked.
 Topic: ICOM IC-720 Mod Transmitter Unlock
ICOM IC-720 Mod Transmitter Unlock [message #1041] Sat, 15 October 2011 17:11
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Messages: 192
Registered: December 2004
Senior Member
ICOM IC-720 Mod

Transmitter is unlocked by snipping the light blue wire that's at the very end of the top hatch cover to the left middle side of the
transceiver.
 Topic: ICOM IC-735 Mod - Unlock Transmitter
ICOM IC-735 Mod - Unlock Transmitter [message #1040] Sat, 15 October 2011 17:10
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Messages: 192
Registered: December 2004
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ICOM IC-735 Transmitter Mod

To unlock the transmitter: cut diodes D33 and D34 that are standing on end near the microprocessor section toward the rear top of the radio.
 Topic: Icom IC-25 expanded RF (keyboard mod)
Icom IC-25 expanded RF (keyboard mod) [message #785] Wed, 17 August 2011 23:36
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Messages: 192
Registered: December 2004
Senior Member
1. Set offset to 0.0

2. Select VFO (A).

3. Press and hold [SIMP/DUP] and [NOR/REV].

4. Dial in desired frequency.

5. Release [SIMP/DUP] button.

6. Select the other VFO (B).

7. Repeat steps 3, 4, and 5

if VFO (B) can not be set, transfer VFO (A) VFO (B) using the [WRITE] button as described on page 7, item 6, of the owners manual.

Note: [SIMP/DUP] must be out when the VFO is changed.

If the tuning knob is turned again, the radio will revert back within the normal band range.
 Topic: IC-R7000 Audio Modifications
IC-R7000 Audio Modifications [message #385] Thu, 26 May 2011 23:08
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Messages: 192
Registered: December 2004
Senior Member
The following modifications provide the following facilities.

- base band audio output, to utilizing digital transmissions such as AIS etc.
- a CTCSS filter insertion point, to eliminate annoying hum from the speaker Both these mods are best tackled at the same time.

1. Undo the screws holding the IF unit in position. Disconnect interconnecting cables.

2. As as indicated by the circuit diagram & board layout the baseband signal is taken from the discriminator output via a 10K resistor. Solder the 10K resistor to R97 on the solder side of the board and solder the other side to the inner braid of some thin audio coax cable. Connect the other end to the spare connector on the rear panel. Use some 3mm heat-shrink tube to cover the 10K resistor & hold in position with some hot glue. Connect the earth braid to a convenient earthing point with some insulated wire.

3. Remove C86 & connect some thin stereo coaxial cable (red = filter input & yellow=filter output) to each now empty pad. Connect the earth braid to a convenient earthing point with some insulated wire. The coaxial cable should be long enough to reach where the filter is installed. In my case I put this at the bottom where the IR receiver & Speech unit can be mounted.

4. Re-install the IF unit by screwing it in position & restoring the interconnecting cables.

5. An essential requirement is that both the input & output of the filter are capacitively coupled. For the filter unit, I used a recovered a CTCSS board from a Motorola SYNTRX FM radio. It contains the essential HP filter required to filter out the CTCSS tones, but in addition it contains a LP filter, which I will use to feed a CTCSS detector/display ( for info purposes). I used a hacksaw to cut off only the circuitry that I wanted. Alternatively a filter could be home brewed.

6. A switch could be provided to to enable straight through audio should this be required.

http://www.hamradio.cc//images/forum/mods/IC-R7000_baseband_CTCSS_modifications-1.jpg
Illustration 1: IF Unit modifications

http://www.hamradio.cc//images/forum/mods/IC-R7000_baseband_CTCSS_modifications-2.jpg
Illustration 2: IF unit modification locations

http://www.hamradio.cc//images/forum/mods/IC-R7000_baseband_CTCSS_modifications-3.jpg
Illustration 3: Typical CTCSS filterboard
 Topic: Icom IC-9100 Mod - Partial TX
Icom IC-9100 Mod - Partial TX [message #340] Tue, 05 April 2011 00:21
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Registered: December 2004
Senior Member
There are several ranges that can be selected by arranging diodes. First you can choose to only open up some areas and leave other frequencies (non amateur bands) locked.

40m amateur bands expansion (7.00MHz - 7.300MHz) : remove diode D1517
60m band expansion (5.255MHz - 5.405MHz) : remove diode D1515

index.php?t=getfile&id=42&private=0

Assemble radio.

Reset radio (full reset) by holding [F-INP ENT] and [M-CLR] and turn power ON.

[Updated on: Tue, 05 April 2011 00:26]

 Topic: Icom IC-9100 Mod - RX Expansion
Icom IC-9100 Mod - RX Expansion [message #339] Tue, 05 April 2011 00:13
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Messages: 192
Registered: December 2004
Senior Member
RX-range: 30kHz - 60MHz, 180MHz - 174MHz, 420MHz - 480MHz, 1240MHz - 1320MHz

Locate diodes behind front panel.

Remove diodes D1504 and D1505 for full RX.

Assemble radio.

Reset radio (full reset) by holding [F-INP ENT] and [M-CLR] and turn power ON.

index.php?t=getfile&id=41&private=0

 Topic: AM transmitter enable for the Icom IC-745
AM transmitter enable for the Icom IC-745 [message #310] Sun, 23 January 2011 01:23
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Messages: 192
Registered: December 2004
Senior Member
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:
1.

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 
                                             | 

2.

Set the 50/100 Watt power switch (S1) in the 100 Watt Position if you desire 100 watt operation of SSB,CW,RTTY.
3.

Adjust R116 (in AM xmit mode) for a power output of 40 Watts RMS.
4.

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!
 Topic: ICOM IC-756 Expand Transmit Frequency Mod
ICOM IC-756 Expand Transmit Frequency Mod [message #307] Sun, 16 January 2011 23:58
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Messages: 192
Registered: December 2004
Senior Member
Notice: ICOM does not guarantee this to expand the frequency.

How to change full coverage transmit:
Remove the W805 jumper chip on MAIN board with a soldering iron.
Locate the jumper matrix located near the IC803.

What to do:
Remove bottom cover of ICOM IC-756. On the MAIN board you will see IF filters and a daughter board (DSP filter) on the right side. The W805 jumper and IC803 chip is lohoneyed under the DSP board. You have to remove the DSP board (carefully) and look for the part labeled IC803 and the line of jumpers (little green parts). When done, unsolder the W805 jumper. Install the DSP board and put the bottom cover back.
                     ---------------
         [W801]     |               |
         [W802]     |               |
         [W803]     |    IC 803     |
         [W804]     |               |
REMOVE==>[W805]     |     CHIP      |
         [W806]     |               |
         [W807]      ---------------
         [W808]

This info is from the ICOM SERVICE INFORMATION sheet.
http://www.hamradio.cc/images/forum/mods/ICOM-ic-756tx-mod.jpg

[Updated on: Mon, 17 January 2011 00:02]

 Topic: Icom IC-77 Mars Mod - tx expansion
Icom IC-77 Mars Mod - tx expansion [message #306] Wed, 12 January 2011 04:03
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Messages: 192
Registered: December 2004
Senior Member
For Ham Mod remove the lower RIGHT diode (d14) from the pcb behind the lock button. it looks like this:

[d12] [d13]
[d11] [d14]

For TX expansion you have to leave (d11) intact and take the diode (d14) that you removed and install it at (d13).

http://www.hamradio.cc/images/forum/mods/icom_ic-77_Ham-TX-exp-1.jpg

If the diodes are all gone and no original diodes can be obtained normal 1N4007 diodes or similar can be used.

http://www.hamradio.cc/images/forum/mods/icom_ic-77_Ham-TX-exp-2.jpg

http://www.hamradio.cc/images/forum/mods/icom_ic-77_Ham-TX-exp-3.jpg

Author: V51JP

[Updated on: Wed, 12 January 2011 04:06]

 Topic: Icom IC-A20 Mod Extend Frequency
Icom IC-A20 Mod Extend Frequency [message #305] Tue, 11 January 2011 01:20
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Messages: 192
Registered: December 2004
Senior Member
To extend frequency range (high end)from 135.975 to 136.975 MHz on the Icom IC-A20, proceed as follows:

1. Remove 4 screws holding back panel,
2. Remove 4 screws holding battery clip,
3. Remove battery clip and separate front and rear halves of radio
4. Remove 4 screws holding VOR unit mounted on the front panel so as to reveal Logic Unit.
5. Looking at the component side of the Logic Unit(opposite side to buttons and display), locate D711,
6. Directly above D711 You will see 3 empty pads in a triangle (SO-23 outline, this is where You need to fit a diode. The original diode used is 1SS187, but any SMD diode will do, or even a standard small wire ended diode. Solder anode to UPPER pad, and cathode to LOWER LEFT pad.
7. Reassemble the radio and reset CPU by holding Function and Clear buttons while powering up the radio.
8. Test the extended frequency range to see if mod was successful (mine was)118.000 to 136.975 MHz.

Den
 Topic: ICOM IC-V8000 Power Mod - Transistor Replacement
ICOM IC-V8000 Power Mod - Transistor Replacement [message #218] Sat, 26 December 2009 09:27
root  is currently offline root
Messages: 192
Registered: December 2004
Senior Member
After the power transistor 2SC1971 blow up Adnan Al-ZADJALI replaced it with another 2SK3075. This transistor was more available and easier to get, and at the same time it also added a little more power, from 68 to 71 watt.


[Updated on: Sat, 26 December 2009 09:30]

 Topic: Unblock Cellular on IC-2820H
Unblock Cellular on IC-2820H [message #198] Tue, 02 June 2009 20:32
micwin31  is currently offline micwin31
Messages: 1
Registered: June 2009
Junior Member
WOULD LIKE INFO ON HOW TO UNBLOCK CELLULAR ON MY IC-2820H.

[Updated on: Fri, 20 March 2015 18:20] by Moderator

 Topic: IC-7700 Mod - Expand 40M
IC-7700 Mod - Expand 40M [message #195] Sun, 29 March 2009 00:38
root  is currently offline root
Messages: 192
Registered: December 2004
Senior Member
To Expand the 40m band on the IC-7700, add diodes D52 and D56 to the LOGIC UNIT as shown in the image.

***Do this at your own risk.***

[Updated on: Sun, 29 March 2009 00:40]

 Topic: Icom IC2200H FM Discriminator Location
Icom IC2200H FM Discriminator Location [message #188] Wed, 19 November 2008 23:12
fungkh  is currently offline fungkh
Messages: 2
Registered: September 2008
Location: Keningau
Junior Member

Anyone could help me where is the location of FM discriminator for link it to repeater COR. I need to get a SQL signal to the repeater COR, pls help me, if possible with photo, thanks....

[Updated on: Fri, 20 March 2015 18:22] by Moderator

 Topic: Icom IC2200H FM Discriminator Lohoneyion
Icom IC2200H FM Discriminator Lohoneyion [message #187] Wed, 19 November 2008 22:43
fungkh  is currently offline fungkh
Messages: 2
Registered: September 2008
Location: Keningau
Junior Member

Hello all, someone could help me the lohoneyion of Icom IC2200H FM discriminator/SQL location on board? Thank you

[Updated on: Tue, 30 December 2008 23:41]

 Topic: IC-7200 Band Voltage Modification
IC-7200 Band Voltage Modification [message #179] Fri, 29 August 2008 21:40
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Messages: 192
Registered: December 2004
Senior Member
IC-7200 Band Voltage Modification
If you want to connect an external unit which can be controlled by the band voltatge from [ACC] connector, the modifihoneyion is necessary as in pdf attached.
The band voltage appears from pin 5 of [ACC] connector after modifihoneyion (1) is completed, or the regulated 8 V appears from pin 1 of [ACC] connector after modifihoneyion (2) is completed.

Performing this mod is the customer's responsibility. Icom does not guarantee this modifihoneyion's result.

[Updated on: Fri, 29 August 2008 21:46]

 Topic: ICOM V-8000 Aircraft Mod ?
ICOM V-8000 Aircraft Mod ? [message #175] Sun, 22 June 2008 22:50
shredddincali  is currently offline shredddincali
Messages: 1
Registered: June 2008
Location: Up North, USA
Junior Member
Okay, so I already saw the mod for the V8000 to expand the TX from 136-174, however, I heard there is a mod to expand the RX to recieve aircraft frequencies, is this true, if so does anybody know how to do it? ICOM V-8000 (US ver).

[Updated on: Mon, 04 April 2011 11:19] by Moderator

 Topic: Icom SM-20 desktop microphone wiring
Icom SM-20 desktop microphone wiring [message #174] Fri, 16 May 2008 22:02
root  is currently offline root
Messages: 192
Registered: December 2004
Senior Member
Icom SM-20 desktop microphone wiring

1. microphone output (white)
2. +8 VDC input (red)
3. frequency up/down (blue)
4. no connection
5. PTT (yellow)
6. GND (PTT ground) (black)
7. GND (mic ground) (shield)
8. No connection

ICOM SM-20 Microphone pinout
View from cable side of plug

[Updated on: Fri, 20 March 2015 18:21]

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