(IC-2) Modification For IC-2AT
If you have studied the schematic diagram for this radio, you will notice that pins 15 and 16 are not indicated on the programmable divider chip IC1 (TC9122). By simply connecting pin 15 thru a switch to pin 1, you will be able to move the radio up in frequency by 10 MHZ. Some of these radios were sold without covering 140-150 MHZ. The modification for this extended coverage is described below: 1. Open up the radio and locate the FLEXIBLE BOARD, this connects the thumbwheel switches to the MAIN BOARD. 2. At the MAIN BOARD end of the FLEXIBLE BOARD, add a jumper at location C4. There should already be a jumper at location C2. 3. At the thumbwheel switch end of the FLEXIBLE BOARD, remove the jumper which connects C3 and COM. 4. Reassemble the radio. Coverage is now 140-150 MHZ.(MARS/CAP) Now, if you activate the switch described above, the radio will now operate in the 150-160 MHZ range, after L3 adjustment, described below. OPERATION and L3 ADJUSTMENT: 1. Activate switch and dial up a known active frequency. 2. Adjust L3 until PLL locks up and radio begins receiving. (you need an active frequency to tell when this happens) 3. To return to 140-150 MHZ, repeat above steps with switch off. NOTES and DISCLAIMER 1. 2. 3. 4. Drill a hole in the case of the radio so that L3 can be adjusted from outside of the radio. The above information is presented for educational purposes only, and is not an endorsement of any particular practice. This MOD has been in operation for 6 years with no ill effects on the radio This MOD courtesy N2MOD.
This modification is read 1316 times.
(IC-2) Low audio speaker mike on IC2A, 3A, 4A OR 02AT
This modification is read 1012 times.
(IC-2) ICOM IC-2AT internal antenna connection problem
I routinely use a half wave ant. On my IC-2AT handheld. When collapsed, the antenna has the same gain ( loss ) as a rubber duck antenna while giving me greater range when fully extended. There is a certain amount of movement of the center pin of the bnc connector with the half wave antenna on the handheld. This movement causes fatigue fracturing of the wire connecting the printed circuit board to the bnc connector. After numerous failures, i used the braid of RG-174 coax to make the connection. First remove the bnc from the radio and brake off the non-used ground lug. The pin of the bnc should beplaced into the end of the braid. A thin pice of wire is then wrapped around the braid 3-4 times, and then secured, then soldered. Reinstal the bnc and dress the braid to the solder pad on the printed circuit board and solder. Do not heat the braid to log while soldering, as solder will be drawn up, making it stiff and subject it to fatigue fracturing.
This modification is read 1016 times.

This modification is read 726 times.
(IC-22) Modifying the IC22A for 9600 baud operation
Author: Mike Curtis by Mike Curtis, wd6ehr and Dave Shalita, w6mik This is one of the more difficult rigs to modify - most are even simpler! This mod will make your IC22A into a dedicated 9600 baud packet radio. Components with * are added to the crystal board. Remove the trimmer capacitor for the transmit crystal socket you'll be using for 9600 baud. Replace with the above circuit. The 420 pF trimcap should be a good quality ceramic or other low-drift trimmer. (Sorry - Radio Shack doesn't have anything suitable.) Connect 2 10K resistors to C-53 (both sides) and tie the other ends together. This junction is where you'll pick off your RXA. Turn R-67 (dev control next to P-1 and P-2) completely counterclockwise. This kills signals that may get into the phase modulator. Using a service monitor, or oscilloscope connected to the detector of a receiver, adjust the varactor bias for the best eye pattern. Alternate bias adjustment: Use the k9ng's 4800 Hz "idle" tone to adjust your modulator for best linearity. Using a service monitor, or a receiver with a fairly wide passband, adjust varactor bias for the "best" sine wave. Thanks to Brian Kantor wb6cyt for this tip.
This modification is read 685 times.

(IC-228) IC-228 mods

I have the mod info from ICOM. It is best to have the diagram in front of you when performing the mod, but for the bold ones, here goes: There are three PC boards in the rig. The TX and RX boards are on the top and bottom of the rig. The logic board is behind the front panel, and the LCD display and front panel switches are mounted on it. It is the logic board which will be the object of your surgery. 1. Remove D-19 2. Install D-7 - (Type 1SS193) D 7 should have three terminals, but only one is used. It looks something like this:
| C ----------| / | | / | ----------A| |
There is no connection to the terminal on the lower right. The Cathode of a 1N914 diode Can be connected to the upper terminal, and the Anode to the lower left. (as indicated by the C and A. In locating the positions of D-19 and D-7, reference the lithium battery. D-19 is at the 1 O'clock position near the edge of the board, and D-7 is at 2 O'Clock and adjacent to the battery. Date: 25-08-1999 Subject: What did this modification.? Please mail me if you know what this modification do.? Best regards Erik Hansen - OZ2AEP webmaster www.mods.dk

q q q q

The unit will now transmit out of the amateur bands. The above modifications provided the following capabilities with my particular unit. FREQUENCY COVERAGE
(VHF) RECEIVE 74.9 Mhz. - 127.9 Mhz. 138.0 Mhz. - 168.0 MHz. 174.1 Mhz. - 189.69 Mhz. 200.0 Mhz. - 287.22 Mhz. 310.0 Mhz. - 349.0 Mhz. (UHF) 355.0 Mhz. - 409.98 Mhz. OFF TRANSMIT OFF 138.0 Mhz. - 159.0 Mhz. OFF OFF OFF
412.37 Mhz. - 498.0 Mhz. 792.85 Mhz. - 966.66 Mhz.
410.5 Mhz. - 470.0 Mhz. OFF
Receive sensitivity throughout both of the Ham bands was better than.5 of a microvolt. Sensitivity in the 200 Mhz. range was a disappointing 1 millivolt and in the 800 Mhz. band a good.7 of a microvolt. Remember, while the unit will receive on those frequencies, it is illegal to monitor cellular telephone communications.
This modification is read 1011 times.
(IC-24) IC-24AT ext frquency
I received the following mods for 24AT out-of-band from a very reliable source (although they don't specify RX only or RX/TX), for 75-195 MHz, 200-490 MHz, and 740-960 MHz. Rumor has it (unconfirmed) that the unit even switches to AM in the air band! 1. 2. 3. 4. 5. Remove diode D8 [see figure below] Attach diode D7 [I believe this is already equipped] Attach diode D12 Remove diode D13 Simultaneously hold "LIGHT", "B", and "#" keys and turn the power on. Release all keys after the display goes out (checks all LCD segments). [This is supposed to enable the out-of-band frequencies above] 6. Simultaneously hold "LIGHT" and "2" keys and turn the power on. This enables the 10 MHz frequency digit entry. 7. Simultaneously hold "LIGHT" and "3" keys and turn the power on. This enables the 100 MHz frequency digit entry.
__________________ | | | | | | | CPU | | | | | | | |________________| o [D7] o o o o [D8] o o o [D12] o D7 lower left pin is anode of one diode, lower right is cathode of the other. Top pin is common D12 upper pins are cathodes of diodes, lower is common anode. See text
__I_ | | |__| |/| | | |__| I
__I_ | | | | D? | | | | |__| I
WARNING: I have NOT tried the hardware mods and cannot vouch for them, so proceed at your own risk! I am told that the newer 24AT's (believed not to have made it to the US yet) will have the hardware mods in place, so only steps 5-7 will be necessary. So, try this first. Steps 5-7 don't seem to have any effect on a 24AT without the correct hardware mods. BTW, this has been attempted on 2 units with serial numbers around 1000 and mid-1100's, neither of which worked. :-( Like I said, the ones with the mods aren't here yet. There are 5 screws to remove the case (5th is on the strap hook). Keep the top panel controls with the front of the radio, and be VERY careful pulling the back off because there are fine ribbon cables connecting the front & back. I don't think they'll take much flexing. Additionally, diodes D7, D8, and D12 are surface mount components. They contain 2 diodes connected to 3 pins. Diodes D7 and D12 are different configurations. I believe D8 and D12 are different, so I wouldn't put the removed D8 in the spot for D12. Since they are surface mount, removal of D8 may not be all that difficult for those with steady hands and a fine low power soldering iron, but adding D12 would be a bear. I know of no reason that small discrete diodes couldn't be used in for D12. D13 is a small but standard axial diode, and can be easily cut. It is for this reason I have not attempted the hardware mods. Now, if the referenced posting is correct, and only D13 needs to be

May 1, 1989 Procedure 1. Remove top and bottom covers. 2. Remove PA section from radio. 3. Remove shield from power amplifier. 4. Replace R7 (originally 10K 1/4W) resistor with a 1K 1/4 watt resistor (ICOM part number 915-01165). 5. Replace R8 (originally 10K 1/4W) resistor with a 1K 1/4 watt resistor (ICOM part number 915-01165). 6. Replace the shield on the PA section. 7. Replace the PA section in the radio. 8. Replace the top and bottom covers.
This modification is read 671 times.
(IC-275) Frequency range & CTCSS tones
This modification is read 742 times.
(IC-275) Power control modification
This modification is read 757 times.
(IC-275) Restoration of pass band tuning
This modification is read 707 times.
(IC-275) Modification of cw pass band (BFO)
Note: The BFO coils are switched in successively to give the required offset from the LSB frequency. Therefore adjusting CW-T also changes USB/CW-R.
Re-adjusting all of the BFO frequencies is a good idea in any case to compensate for crystal aging. If the passbands sound different in LSB and USB it is a sure sign of mis-alignment due to crystal drift - they should be more or less the same. Disabling of SBB squelch Problem: Squelching is nice to have in FM mode, but it doesn't really work for SSB, where you will be looking for weak signals. Therefore you have to adjust the squelch level every time you change mode. Furthermore I enjoy using FM as a monitoring mode on the SSB calling frequency, so changing the mode happens quite often. Solution: The solution is quite simple. Just cut the connection to the SSB input of the squelch circuit in some way. Implementation: The easiest way to break the connection is to connect the base of Q7 to ground. The base is the lead facing into the centre of the PCB.
This modification is read 667 times.
(IC-275) Disabling of SBB squelch
Problem: Squelching is nice to have in FM mode, but it doesn't really work for SSB, where you will be looking for weak signals. Therefore you have to adjust the squelch level every time you change mode. Furthermore I enjoy using FM as a monitoring mode on the SSB calling frequency, so changing the mode happens quite often. Solution: The solution is quite simple. Just cut the connection to the SSB input of the squelch circuit in some way. Implementation: The easiest way to break the connection is to connect the base of Q7 to ground. The base is the lead facing into the centre of the PCB.
This modification is read 660 times.

1. Open the radio by following the manuals instructions. 2. On the half with the display and tone keys find the big chip (logic chip) 3. To the right of it there are some small parts that look like this:
|--------| | Logic | XX XX | Chip | x | |D14----> x XX | | x x |--------| XX XX XX<-D13
4. Remove both d13 (rx) and d14 (tx) and close the radio back up!
5. Reset the CPU and you're done! 6. If you mess up your radio I take NO RESPONSIBILITY. You do this at your own risk. If anything you'll break the back light as most people do. But to help not do this the transistor d14 DOES NOT LOOK LIKE d13!!!

06-03-2002

(IC-2GXAT) Software mod, to open IC-2GXAT
Author: - Happy_Hamer2001@yahoo.com.MODIFICATION.NET
This is a software mod to open up the receiver for the IC-2GXAT. (YOU DO NOT NEED TO EVEN TAKE THE RADIO APART!) 1. Turn off the radio. 2. Press and hold the, F KEY, Scan and Dup keys. 3. While holding all 3 keys turn on the radio, continue to hold the keys for about 3 seconds WAITING until the display returns to normal before releasing the keys. I did this to my HT and it receives from 50Mhz 204Mhz.
This modification is read 188 times.

(IC-2IA) IC-2Ia mic mods

Hello folks.I bought an ic-2Ia last week for use by my xyl kb8czl. I chose this particular ht for its simplicity of operation (after initial setup). However, it didn't take long before we began receiving poor xmit audio reports. It was described as "muffled and constricted like talking thru a garden hose". As it turns out the design engineers at icom left no provision to get the melodious tones of your voice to the microphone except to go thru the plastic case. After i noticed this problem, i returned the radio to my dealer and tried several others. They all sounded the same. Then the salesman called icom service-they admitted they knew of the problem and recommended a hole be drilled in front of the mic. Heres how to do it - proceed carefully1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Shut off radio Remove battery pack Remove 4 phillips head screws from rear of case Carefully pull off front of case Gently remove mic element from rubber holder Unscrew 4 phillips head screws retaining speaker Support case on soft surface Drill hole thru center of mic rubber from inside - i used 5/64 inch (2mm) drill Reassemble in reverse order Marvel at fb audio Thats it, folks.Hope you like your new ht as much as we do.73, ART-K8CIT.
This modification is read 584 times.
(IC-2IA) IC-2IA lousey xmit audio fix
From: K8CIT@N8NNN.#SEMI.MI.USA.NA Hello folks.i bought an IC-2IA last week for use by my xyl KB8CZL. I chose this particular ht for its simplicity of operation (after initial setup). However, it didn't take long before we began receiving poor xmit audio reports. It was described as "muffled and constricted - like talking thru a garden hose" As it turns out the design engineers at icom left no provision to get the melodious tones of your voice to the microphone except to go thru the plastic case. After i noticed this problem, i returned the radio to my dealer and tried several others. They all sounded the same. Then the salesman called icom service-they admitted they knew of the problem and recommended a hole be drilled in front of the mic. Heres how to do it - proceed carefully1. Shut off radio 2. Remove battery pack 3. Remove 4 phillips head screws from rear of case 4. Carefully pull off front of case 5. Gently remove mic element from rubber holder 6. Unscrew 4 phillips head screws retaining speaker 7. Support case on soft surface 8. Drill hole thru center of mic rubber from inside - i used 5/64 inch (2mm) drill 9. Reassemble in reverse order 10. Marvel at FB audio

This modification is read 919 times.

From: Geoffrey Dann

(IC-32) Cross-band repeater (Icom)
Icom Service Bulletin #13889-005 The IC-32AT has the capability of being used as a cross-band repeater. This function is not enabled as the unit is shipped from the factory. To enable this function perform the following steps: 1. 2. 3. 4. 5. 6. Cut D912 on LOGIC UNIT. (see above figure) Push and hold the (FUNCTION) switch. Push the (C) key. Push the (6) key. Push the (D) key. Release the (FUNCTION) switch.
To cancel "MINI REPEATER" perform the following steps: 1. 2. 3. 4. Push and hold the (FUNCTION) switch. Push the (D) key. Push the (C) key. Release the (FUNCTION) switch.
This modification is read 837 times.
(IC-32) Receive coverage for VHF & UHF and enable keyboard entry
Remove battery and antenna. Loosen two screws on top of unit as much as possible without removing them. Loosen 4 flat head screws on bottom of unit 1 turn. Loosen 2 screws near PTT switch 1 turn. Remove 4 black screws on back of unit. Lift bottom of front cover.25 inch, slide it down.25 inch, then lift front cover up 1 inch. Disconnect plug on 4 wires coming from the speaker. Lay front panel on table up-side down being careful of the flex circuit. All mods are done to the back of the front panel. Notice places for 5 axial diodes, which I will call 1 through 5, 1 being nearest the display. Add/remove diodes so there are diodes in positions 3 and 5. This will open up receive coverage for VHF & UHF and enable keyboard entry of the 10 MHz digit. 10. Notice 4 surface mount resistors slightly left of center directly above the speaker, lined up in a row. Solder the anode (the side without the bar) of two diodes to the right side of the lower of the four caps. Now find the CPU. It's the PGA under the shield near the top of the board. Find the row of pins on the CPU nearest the speaker. Notice the the 8th pin from the right has a thicker trace coming from it. Now notice that there are small solder pads about.25 inch toward the speaker on both the fat trace and the two traces to the right of it. Solder one each of the cathodes of the 2 diodes to the solder pads on the two smaller traces. This will open up the transmit for VHF & UHF. 11. Put unit back together in reverse order. This procedure worked for my unit (and many others), but I can't guarantee it will work for yours. Bill Pherigo WR0Y

This modification is read 582 times.
(IC-471) RAM Card Backup Battery Replacement Instructions
Author: ICOM In the early 1980s Icom America marketed a group of transceivers and radios that utilized the latest state-of-the-art computer technology to enhance the operation of the radios. This technology improvement allowed hams to afford a reasonably priced high performance transceiver which until then was only available on units costing much more. Features now available to the hams included: higher frequency stability, better frequency resolution, digital frequency display, almost instant recall of saved frequencies (memory channels), quick mode signal processing and built in tones and offsets for the rapidly emerging repeater operation. Implementation of all these features required a CPU with associated logic circuitry. In the early 80s, the most cost effective way to implement data processing and memory functions was through a DRAM (Dynamic Random Access Memory) to control the CPU. This DRAM was a volatile memory integrated circuit which required a lithium battery to retain its instruction set. The following receivers and transceivers had such RAM units: IC-271 ; IC-471 ; IC-1271 ; IC-745 ; IC-751/A ; IC-R71A The lithium batteries in these units typically lasted about 5 to 7 years before replacement was required. This was specifically noted in each of the Owners Manuals for the products. This lithium battery can be replaced by the radio owner if care is used. The following is a recommended procedure to accomplish this: Procedure 1. Disconnect the power cable from the radio, and take the cover off. 2. Unplug the RAM board and remove it from the radio. 3. Temporarily solder a 3 Volt DC battery source across the existing battery terminals (see suggested connection points on the circuit board pictures). 4. Unsolder the old lithium battery and replace it with a new one. (BR2325 1HC, ICOM stock number 945 03112) 5. Unsolder your temporary 3 Volt DC source. 6. Reinstall the RAM board into the radio. Cautions 1. Do not use an AC powered 3 Volt DC source, your grounded soldering iron tip could short out the battery (+) terminal. Use a 3 Volt battery DC source only (2 alkaline cells for example). 2. Do not solder the external DC wires directly to the lithium battery tab pads. If you do so, you will not be able unsolder the battery without having the wires drop off.
3. If by accident you lose power to the RAM unit it must be sent to Icom America for reprogramming. 4. Be careful not to damage or bend the connector pins on the radio side while removing or reinstalling the RAM card. Pictures There are two versions of the ICOM RAM boards. Both are identical in operation, and they are interchangeable. The differences are in the circuit board layouts only. Note that the black and red wires visible on these images are the suggested way of connecting the external DC backup voltage while the battery is being replaced. The wires are not a part of the RAM card, and should be removed when the battery replacement procedure is complete. Refer to the replacement procedure outlined above. RAM card version A images:

16-04-2000

(IC-706) IC-706, MKII, MKIIG xmit mods - tip
Author: Emory - KD3DQ Ref Xmit Mods for 706s shown above The xmit expand mod for the IC-706, MKII, MKIIG require removing very small diodes, these diodes are about the size of a flea, and require the use of very small tools. I have done mods before but these are difficult. After lots of thought I did my mod with an x-acto knife. I needed a magnifing glass and a new blade for the x-acto knife. I cut just the solder on one side of the tiny diode, making sure that is all I cut, then pushed up on the diode, the other side breaks loose from the board. I cut both diodes this way and it was easy and worked fine. I could not find a soldering iron small enough to fit into tiny space available. Good luck. Emory KD3DQ
This modification is read 4862 times.

20-08-2000

(IC-706) IC-watt tune modification/An Icom IC706 Tune Trigger
Author: Larry Lefczik, WA2EHZ - wa2ehz@netzero.net.MODIFICATION.NET (Some assembly required) The ICOM IC-706 has a nifty feature built in to help the operator tune the HF antenna SWR. By pushing the TUNE button on the front panel, the radio switches to CW mode and transmits a 10 Watt carrier. This state last for approximately 10 seconds or the operator can terminate sooner by pushing the button again. This was designed to work with the Icom automatic antenna tuners. There have been a few circuits developed to fool the 706 into thinking there is a Icom tuner attached and produce the same tuning signal which can be used with a manual antenna tuner or many automatic tuners, some get quite complex. Well, being the cheap guy I am, and being one to tinker, I felt there had to be a simple way to do this. I began reading the various postings on the Internet. I went back to an e-mail exchange I had with Ed, W1AAZ in early April 1999 on Vartel's ICOM 706 Discussion Group. Ed explained the functions of the TKEY and TSTR pins on the "AH-3" connector on the 706. The outcome was a simple RC circuit which I have built right on a Molex connector which plugs into the AH-3 jack on the back of the IC706. Construction: The (+) side of C is connected to the 13.8VDC pin. The (-) side connected to TSTR and TKEY which are connected together. Resistor R is in parallel with C. Below is a diagram of the AH4 connector on the back of the IC706 where the < indicates the pointy end of the connector (Pin 1 = TKEY). You can buy the Molex connector at Radio Shack (#274-0224).

21-08-1999

(IC-706mkii) TX range expansion for IC-706MKIIG
Author: Karel OK1DNH - kebert@ext.epe.cz.MODIFICATION.NET
TX range expansion on HF, VHF and UHF is very simple. When modified the radio will also transmit AM mode in the aircraft band with approximately 1 watt at 118 MHz to about 17 watts am carrier at 136 MHz. On MAIN BOARD under speaker near Xtal you can see two rows of solder dots for SMD components. Only on position 10 (from left) is diode (D2030), which is necessary to remove. Thats all. After connecting power radio will be reseted and TX range is expanded.
More pictures from Ken Bessler KG0WX.
Transmit power output after modification Power output in watts as measured from an uncalibrated Diawa CN-620 wattmeter with vhf,uhf dummy load. Power output on radio set to highest level.

FM PWR AM CARR FREQ

0.0 0.0 0.0 0.7 1.0 3.5 15.0 17.0 18.0 18.0 18.0 18.0 10.0 1.5 0.0 1.0 2.0 3.5 5.0 14.0 20.0 25.0 28.0 32.0 32.0 20.0 13.0 6.0 1.5 0.5 0.1 0.467 470

FM PWR

7.0 9.0 10.0 12.0 15.0 18.0 20.0 20.0 19.0 18.0 15.0 8.0 0.8 0.15 0.00

105 MHz 1.0

400 MHz 2.0
This modification is read 8202 times.

22-08-1999

(IC-706mkii) Expand only mod for the IC-706MkII
Author: David Spicer,VK7ZDJ - vk7zdj@southcom.com.au.MODIFICATION.NET HI ALL, as an owner of a IC-706MkII, I have noticed that there is no detailed photos of how to go about the mods on any of the mod sites, so I pulled my radio out of the car and I have taken some photos of the only mod that I was interested in doing to my radio,.EXPAND RX /TX. I hope that the photos will help all new owners and or old ones that have not been game enough to tackle the mod, its quite a simple mod to do as long as you have good quality desoldering equipment, if not then do not attempt it, take it to someone that has the gear. If you follow the text file on this page by "Len SantaMaria, KC2ADV" headed,.Icom 706 MkII Extended Transmit Mod and use my photos as a reference then I do not think you can go wrong, my radio works like magic. PLEASE NOTE THAT THESE MODS WERE DONE TO AN AUSTRALIAN IC-706MkII RADIO,.AS FAR AS I CAN TELL THERE IS NO DIFFERENCE BETWEEN MY RADIO AND THE AMERICAN MODEL, IF ANYONE FINDS THIS NOT TO BE CORRECT THEN I AM SORRY BECAUSE I CANNOT HELP YOU.

Remove the bottom cover. Remove 6 screws holding down Main Unit. Remove screw on rear panel inbetween ALC & Send RCA sockets. Remove heatsinking clip holding transistor to chassis. Remove flat ribbon cable to J3 in far right corner. 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). Locate IC-503, a NJM2058 OPAMP in an SMT SOIC14 package. Remove WSMT link. Fit an 10k 0603 SMT resistor in W3's place.
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.
This modification is read 1531 times.
(IC-756) General Coverage H.F. TX Mod (1.6 - 30.0MHz)
VHF remains 50.0 - 54MHz TX only. Modification summary: Remove the W805 jumper chip on MAIN unit by soldering iron. Modification 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 located 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 indicated below. 7. Re-install DSP PBA 8. Re-fit bottom cover.
--------------| | IC 803 |
[W801] | [W802] | [W803] |
[W804] | | Remove=>[W805] | CHIP | [W806] | | [W807] --------------[W808]
Thanks to http://www.qsl.net/vk4cp/ for the modification.
This modification is read 1807 times.

13-02-2002

(IC-756) IC-756 wide band modulation
Author: - pa1zz@home.nl.MODIFICATION.NET
In order to improve the transmitted audio from a IC-756 most off these radios have a tiny switch next to the 455kc wideband xtal filter. Open de bottom side off the radio and turn it so you can read the text on de 455kc standard wide ssb filter. Next to te right down side off the filter you will find a tiny smd switch with W-N printed on de pcb. Change the switch position to wide. Make sure you use a good mike! A bad one will sound even wourse! And be carefull not overload the ALC. Otherwise you might splatter!!! BTW Early numbers (below 01900) do not have this secret option!
This modification is read 490 times.

06-03-2000

(IC-756pro) Expand tx-freqeuncy for the IC756-PRO

27-05-2001

(IC-910) Expanded functions for the IC-910H (All versions)
Author: SM4RNA Anders Janis - sm4rna@telia.com.MODIFICATION.NET
Backside of the Displayborad looks something like below:
+------------------------------------------------------------------------------+ | +----+ | | | r d | | | | r d | | | | r d | | | | r d | | | +----+ | | +---------+ +--+ | | VFO | | | | ENC| +---+ | | ODER | | | | | +---+ | +---------+ | | | | | +---------------------------------------------------------------------------+
Top left is vertikal row with resistors be seen. Beside the resistors to the right a vertical row with diodes is located. From top is the diodes called D1, D2, D3, HD4, D5, D6, D7, HD8.
To enable RX 136-174MHz Remove D5. To enable RX 420-480MHz Remove D6. To enable RX 1240-1320MHz Remove D7. To enable narrow FM on 1,2GHz band install a 1SS355 diode at HD8. TO enable crossbandrepeater install HD4
To use crossbandrepeater: 1. Activate [LOCK] 2. Switch off the radio. 3. Puch and hold M/S while switch on the radio. To exit push [LOCK] (Crossbandrepeat will not be canceled if power is switched off.)
This modification is read 2473 times.

22-07-2001

(IC-910) IC-910H mods

Author: Unknow

To modify your rig for:
TX-144 remove R188 (1k) on the display board. 136-174 MHz TX-430 remove R187 (1k) on the display board. 420-480 MHz TX-1200 remove R186 (1k) on the display board. 1240-1320 MHz
Narrow FM mode for 1200MHz install HD8 1SS355 on the display board. You do not have to reset the CPU.
This modification is read 2323 times.
(IC-970) IC-970 with 9600 Baud
To use the ICOM IC-970 on the UOSAT's (9600 baud), I made the following modifications: Transmit Solder a shielded wire (I used RG174) to the anode of D16 (1SV50E). This is at the junction of R52 (470K) and C44 (.0047). Make sure to solder the shield to the adjacent PC board ground plane. Receive Solder a shielded wire to pin 9 of IC11 (MC3357P), again make sure to solder the shield to the PC board ground plane. Both transmit and receive are on the main unit circuit board. Make sure that you use IC11 as this is the sub band receiver. If you plan to use the IC-970 for terrestrial packet (ie. simplex on either 145 or 440) you will need to add another shielded wire to IC5, which is the main receiver discriminator. I then brought the shielded wires out the rear of the radio. I did this by removing the plate which covers the two holes located below ACC(1). In order to disconnect the wires from the modem, I installed two phono jacks in the center of the holes on the metal plate. I have used this setup with the G3RUH modem, PacComm NB96, and the MFJ-9600. I found that it was not necessary to add the 10K series resistor to the transmit audio/deviation line. On all three, with the center of the 10K pot range as 12 o'clock, I found that about 1 o'clock to work best on for me. Note: Make sure that the DC power source for the TNC and 9600 baud modem are on a clean supply (no ripple). Several users have found this to be the reason they could not get their modems to work. Also make sure that the TNC modem switch is set to 9600 baud as this provides the 153.6kHz to the modem. The modem documentation is not very clear in this area. I run the terminal speed at 19,200. If you have any questions, I can be reached at: Dale Hagert NM0H 3881 Serpentine Circle Eagan, MN 55122 612-452-1030

This modification is read 3421 times.

From: realist946

05-09-1999
(IC-T81) IC-T81 Frequency Expansion
Remove the Diode D53 and D61.
Frequencyrange after modification: 50.000 - 53.995 MHz RX/TX 118.000 - 173.995 MHz RX 136.000 - 173.995 MHz TX 400.000 - 469.995 MHz RX/TX 1240.00 - 1300.00 MHz RX/TX FM Broadcast (WFM): 76.000 - 109.995 MHz RX
This modification is read 3959 times.

30-07-2000

(IC-T81) ICOM IC-T81A Cellular Mod
The IC-T81A may be blocked from direct entry of cellular frequencies, but you can still receive analog cellular frequencies on it quite nicely. All you need is a little arithmetic. If you've performed the mods listed on this site to open up the receive range to 999.95MHz, cellular is no problem. All you have to do is dial in the image frequency for cellular. That is, dial in a freq that is the cellular freq minus 2 times the IF frequency for the T81A, which is 69.4 MHz. The cellular band (for analog phones only) from handheld to cell site is 824-849 MHz. Transmit back from cell site to handheld is 869-894 MHz. (There are a few control and data channels interspersed in those ranges too.) That corresponds to 685.1 to 755.1 MHz display on the T81A. So, for example, to receive transmissions from a cellular phone at 826 MHz, just set the T81A to 826 - 138.9 = 687.1 MHz. Towers Output (display on T81A 730.1 to 755.1 MHz) to RX 869-894 MHz Cellular Input (display on T81A 685.1 to 710.1 MHz)to RX 824-849 MHz
This modification is read 3528 times.
(IC-U16) How to program the ICOM-U16
Here's how to program the ICOM-U16 - if the U16 has been made programmable by moving a jumper: Try holding FUNCT down and entering 159357. It's now in prog mode. Exit with FUNCT-CLR. Function + 159357 (Enter program mode)
Function + 1 Encoder tones (1-37) 1=67.0,2=71.9,3=74.4,4=77.0,5=79.7, 6=82.5,7=85.4,8=88.5,9=91.5,10=94.8, 11=100.0,12=103.5,13=107.2,14=110.9, 15=114.8,16=118.8,17=123.0,18=127.3, 19=131.6,20=136.5,21=141.3,22=146.2, 23=151.4,24=156.7,25=162.2,26=167.9, 27=173.8,28=179.9,29=186.2,30=192.8?, 31=203.5,32=210.7,33=218.1,34=225.7, 35=233.6,36=241.8,37=250.3 Decoder tones (1-37) ? Delta + / Delta - offset, 5 digits Frequency, 5 digits (400MHz +) ? Sch. Ch. numbers. Allows alias ch numbers. Transmit timeout enable. TI, Transmit Inhibit
+ 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9
+ SCAN Priority Scan/Ch Scan + S.CH Channel Masking + CLEAR End progamming mode
--------------------------------------------------------------------------Channel select: Standard method (up/down Frequency: Hold [FUNC], Press [5], enter [FUNC] Rx CTCSS: Hold [FUNC], Press [2], enter [FUNC] Tx CTCSS: Hold [FUNC], Press [1], enter [FUNC] arrows or CH# + [ENTER]) 6 dig freq, [ENTER], release 2 dig code, [ENTER], release 2 dig code, [ENTER], release

(R-71) Here is the R-71 version of the Drake R7/R8 type passband tuning system
Add a jumper wire between the cathodes of diodes D42 and D45 on the main unit circuit board. The cathode end of the diode is marked by a band. The diodes are located near Filter Switch 1 (the switch you set when you add the optional narrow filter). Turn Filter Switch 1 on. That's it. Usage: select LSB mode and narrow filter position, and tune to zero-beat. Rotate the pass-band tuning control to select between LSB and USB, or anywhere in-between. Select normal or wide filter position and you get the original ICOM PBT. The mod for the R70 should be just as easy, but you'll have to find the diodes on your schematic. Just jumper the cathode of the diode that selects the optional narrow 2nd IF filter to the cathode of the diode that selects the "through" postion in the 2nd IF. This modification will bypass any narrow filter you may have installed. It forces the narrow filter selection to bypass the 2nd IF
filters, while still selecting the narrow filter in the 3rd IF. The standard ICOM pass-band tuning shifts the 3rd IF passband against the 2nd IF passband:
No PBT shift __|__ 2nd IF / | / | ___/ | \___ __|__ 3rd IF / ___/ result / | | \___ / _/ LSB shifted __|__ / | / | ___/ | \___ ____| / | | | __| / | / | | | ^ ^ \_____ USB shifted __|__ / | / | ___/ | \___ |____ /| / | _____/ /| / | \_____ _____/ ^ | | ^ \___ | |__ \_

| __|__ / | / | | | ^ ^

full b/w

narrowed b/w

This mod bypasses the 2nd IF filter, so you have just the 3rd IF filter, which the PBT control can move around relative to the center frequency:
No PBT shift __|__ 3rd IF / ___/ ^ / | | | | ^ \___ / _/ ^ LSB shifted ____| / | | | | ^ \_____ USB shifted |____ /| / | _____/ ^ | | ^ \_

shifted b/w

I haven't performed this mod on my R71 (I have to install PBT tuning first - I got one of the ones without PBT), so you're on your own with this one. I expect that the close-in dynamic range will be worse when using this flavor of PBT on the R71, since the 2nd IF filter is bypassed
(R-71) R-71A Memory Notes
I have heard that a new company named Willco is going to sell no fail memory for the Icom radios. Two models, one with 64 channels for around $70 and a 1000 memory channels for around $149 will replace the small battery backup unit. The Willco board will use standard AA batteries. When the batteries die in the Willco unit, the radio won't fail and need servicing as is now the case. (However, the memories would need to be re-programmed.) Using the lock button and memory switch, one steps through the banks of 32 channels each. One channel in each bank can be used to store the channel number for display to identify the bank number according to the maker. Willco's address is P.O. box 788 NewLenox Il. 60451 If someone orders one, let me know what you think of it. I am not sure which radios other than the R-71A in which it will work.