This is original the 9600 baud mod for the IC-475H. Yann - F1NGP f1ngp@wanadoo.fr.MODIFICATION.NET has reported this to me. I've tried the MODS for 9600bds for my ICOM IC-475H. Working OK. I've tried to build the same mod on my 23cm ALL-MODE ICOM IC-1275E as the MAIN UNIT is the same as the 475. ALL WORKING OK ! Thanks to Yann. The original ICOM IC-475H 9600 baud modification. Warning: I'm writing this message to help out owners of Icoms 475 H to modify their transceivers for use with a G3RUH modem. I will not take any responsability if you destroy your transceiver while doing this modification. This modification requires that you have a minimum experience in soldering and electronics. If you feel that you cannot undertake this modification, don't even try it and leave it up to someone else!
Reception of FSK signal: The reception has to be taken directly off the demodulator chip. This is the chip referenced as IC6 (MC3357P) on the electronics diagram. Demodulator output is on pin 9 of this chip. You will have to run a SHIELDED wire from this pin to the outside of your transceiver. I've done this by connecting it to pin 11 of J4 (AQS socket on the back). This pin is originally unused. But this is not as easy as it sounds; you will have to unscrew both sides of the transceiver and undo a lot of parts to finally solder on a very small plug! Be careful here. Transmission of FSK signal: The FSK signal is simply injected on pin 2 of the AQS socket. BUT, as you will see on the electronic diagram, this signal goes through a variable resistor (R152) and a capacity (C142). So you might encounter two problems: not enough and/or distorted modulation. In my case, I used a MFJ 9600 Bauds card and I had to put the level almost to the maximum on this board, while also putting the variable resistor to the minimum! The capacity on the other hand is very very bad for the modulation of the FSK signal as the transceiver should respond to DC! My solution: simply short circuit the capacity (C142). This is most easily done directly on the components side of the circuit board, since it's very difficult to take it out of the transceiver. Other signals: You will be able to put the PTT line to pin 6 and the ground to pin 1 of the AQS socket. You will also notice that on pin 13, you have 13.8 V available. This can be used to power the TNC for example. I have now a much more stable 9k6 signal than before, when I still had the C142 in the line. Although, this was reportedly been working for other people, it simply didn't for me! Maybe you can avoid short circuiting the capacity, so try it first (although I doubt it!). I hope this will help somebody and if you have any more questions, don't hesitate to contact me at my homeBBS: HB9VBC @ HB9IAP.SROM.CHE.EU

Otherwise, things are done as the review says. The CQ review gave a good report of its AM aviation band performance. I would agree with that, and suspect that at least some of the complaints were due to the original signal -- there's a ton of background noise in a private plane. However, airliners should sound quite clear. Sensitivity, even that far away from the ham band, seems good. Airliners at altitude up to 50-100 miles away can be heard, even with just a J-pole antenna near ground level. (assuming you're not at the bottom of a steep valley, of course!) Sensitivity in other non-ham bands seems good as well, it has no trouble picking up sheriff's dispatchers maybe 45 miles away. Too much sensitivity and too much bandwidth may cause big problems with intermodulation, if you're in an RF-rich environment. I have no idea how it would perform in, say, downtown Chicago, but I suspect you'd hear all sorts of intermod and images. There were a couple of odd images I noticed, but nothing distractingly bad. The built-in attenuator might help. My father is now using one, with a J-pole at 53' and an 11-element beam at 48', from relatively high ground in a rural, hilly area. It seems to do very well for such an application, as it gives you three radios (ham, aviation, public-service scanner) in one box. 45-50W output means you can hit what you can hear, and it's sensitive enough to hear quite a bit (some some repeaters out to 100 miles are useful). At least two NOAA weather broadcasters around 162 MHz are audible. Oh yeah, when you rotate the knob in "VFO" mode to tune up from 174 MHz, it skips to the range 340-380, and then to 870890, before wrapping around to 118 again. Don't get excited, it doesn't receive in 340-380 or 870-890, as the VCO won't lock up there. It does AM demod 118-134 and FM 134-174 MHz. On to the excerpts. For the following, only the pad pair marked as "D5" had a diode in my dad's:
> > > > > > > > > > > > > > > > > > > > > > > > > >
From: jpd@pc.usl.edu (Dugal James P.) Date: Tue, 10 Dec 91 13:12:42 -0600 To: cromwell@rvl2.ecn.purdue.edu Subject: Re: IC-229A/H AM aviation band mod Newsgroups: rec.radio.amateur.misc Organization: Univ. of Southwestern La., Lafayette I retrieved this from my "archive" --James N5KNX -- hope it helps!

cut. I'm guessing, but it could be that the rest of the diode changes are for the 10 MHz & 100 MHz digit entry (which I'd like but could live without) or out-of-band TX, or the like. If anyone has tried only cutting D13 and resetting? Did it work? What is your serial number? Please post to the net! Mike Pflueger Packet: WD8KPZ @ W1FJI Transmit range doesn't appear to be affected unfortunately. I was at least hoping for 420-450 coverage. BTW, I tried each amateur band from 6m to 23cm. The PLL doesn't lock up at either end. Another negative is the frequency step on 220 doesn't allow one to hit each possible repeater slot. 73 de Gene WA1UXA
This modification is read 871 times.
(IC-24) IC-24AT Keyboard command summary
This is an attempt to document all of the known key sequences for the ICO IC24AT (144/440MHz dual band hand held). Some key sequences may be common with the IC[2,3,4]SAT, therefore a fewkey seqences fr thoseradios re also on this list. Some ke sequenes requre optins (such as the PL encode/decode board). This is not designed to replace the owners manual, but to summarize the information in one place. Note: Many controls vary depending on the current mode, i.e.: Scan up/down will search frequencies when in VFO mode, and will scan meory channels when in Memory mode. Consult the owners guide for complete iformation.
KEY/COMBINATION = Result, action ---------------- ------------------------------------------------------------0-9,A,B,C,D,#,* 0-9 A B C D * # MONI H/L/DTMF FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC FUNC + + + + + + + + + + + + + + + + + A B C D * # 5 + D = = = = = = = = = = = = = = = = = = = = = = = = = = = note: when transmitting these will generate DTMF tones Enter frequency (can also use the VFO knob) VFO mode / clear incomplete entry Memory mode VHF / UHF change Call channel Step frequency down/scan down Step frequency up/scan up Open squelch and change to input frequency (if not simplex) while button is depressed Select High/Low power, or (while transmitting) send preprogrammed DTMF codes Dial set PL enable (when option is installed) Code squelch [NOT for the IC24AT, IC[2,3,4]SAT option only] Skip memory Duplexoperatin Code [NOT for the IC24AT, IC[2,3,4]SAT option only] Mask freuency Priority mode on/off (operation dependent on current mode) Set mode (several different functions, press A to exit) Real time clock and timer functions (press PTT to exit) Memory to VFO transfer Memory Write Split operation (cross band full duplex) Lock mode / Cross Band Repeat disable Scan programmed limits (down) Scan programmed limits (up) Cross Band Repeat enable (split mode must be on!) Diode D14 (right diode on CPU board) must be removed to enable the use of this function) RX/TX light enable / disable Select DTMF Autodialer memory Change frequency/memory channel (according to dial set, see FUNC+0) Lock light on (don't time out)

Jack - the notes about mods to the FT736R were specific to that machine, and won't be relevant to the IC735. 1. What you need to do is work out a way to belt the varactor directly. Then inject a square wave (1200 hz will do) and measure the deviation that results. 2. You can do this measurement with either a proper deviation instrument or more likely with a monitor RX, by looking at the output from it's discriminator. 3. You can calibrate the monitor RX quite easily, Tune in a steady unmodulated carrier and note the discriminator DC output voltage Change the RX frequency by 1 Khz (knob on the RX front) and note the change in DC voltage. That gives you the monitor RX sensitivity in volts per Khz. 4. Now return to the TX, and adjust that driving square wave to give you approx +/- 3 kHz, you want to see about 6x volts peak to peak square wave on the monitor. (Somewhere between 4x and 6x will do, no more.) 5. Now return to the modem and juggle about with the TXAudio output components to achieve this level of drive signal, and look at the monitor RX too. 6. When you have done this, which should take you all of 30 minutes, you should be in business. If you can't get square waves TX to produce squarish waves out of the monitor RX, then the varactor dept. must be suspect, and so on. All is fairly logical. Hope useful. Let me know the results. 73 de James G3RUH @ GB7SPV 1990 Mar 28 Since I am not going to be able to try the mods until I return from a vacation I won't be able to give you an answer as to whether they work or not. But it is my opinion they will. What is happening is that between the mic connector and the varactor the digital signal is being badly distorted and the bird does not respond to the digital signal. This would not make much difference on voice but on a digital signal it makes all the difference in the world. Please feel free to contact me further if I can be of any further help. Best regards Jack W9FMW Note: From Bill K7RIE ICOM has not tried this mod nor have we verified this problem.
This modification is read 731 times.
(IC-271) VOX of an IC-271,471,1271 usable for FM
How to make the VOX of an IC-271,471,1271 usable for FM : 1'st type of 'main-board' : The only thing to be done is to add a diode such as 1n4148 or bax13 on the MAIN board on the position D74 When D74 is inserted. the vox works in FM also. The diode is on the shematic diagram of the Main board but is not mounted on the pcb in the factory. 73's de stefaan ON4BY @ ON4HU 16/03/1990 18.31 h 2'nd type : (On this board a D74 is present (near PA- and RF-YGR- Unit)) (It might be not present in the plans !) Disconnect the cathode of D69 from it's old postition. It's new position is the cathode of D50 or D51
position on main board near 'CW-DELAY'. near 'RF-YGR-Unit' near 'RF-YGR-Unit'
(old) function 'FM -VOX-OFF' 'USB-VOX-ON' 'LSB-VOX-ON'

(IC-271) 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:

ENTER REMOTE MODE "REMO": X-BAND ON: X-BAND OFF: EXIT REMOTE MODE: B+XXX (password)+#
B+XXX(password)+#+DB* B+XXX(password)+#+B* B*
This modification is read 1061 times.
(IC-275) PSK Transmit Audio Modification for ICOM IC275 & IC271
From AMSAT-Australia Newsletter #59 (Graham Ratcliff, VK5AGR) After reading a FUJI-OSCAR-20-PRBBS message from James, G3RUH, regarding the modifications he made to his Yaesu FT736 to improve the PSK transmit audio, I decided to investigate the situation on my ICOM IC275H to see if the same problem existed. I was certainly less than satisfied with the results I was getting in the first few days with FO-20 Mode JD. I was feeding the TX audio in at the front microphone socket and results on the uplink were quite poor but my downlink copy was 100%. The first change I made was to move the Tx audio to the rear connector, ACC1. Results improved but I was still not satisfied. Some scoping around the Varicap diode, D40, revealed considerable distortion of the PSK audio. To prove if this was the cause of my problem I studied the IC275 circuit to see how I could feed the TX audio in as close to the Varicap modulator diode, D40, as possible. In the IC275H there are several Audio feeds to D40, including 3 via Q33, and in my unit one of these, the feed from the Tone Squelch is unused. P46 normally plugs into the Tone Sq card but as this option is not installed it is left unterminated inside the rug. I also found that Pin 1 on ACC1 was unused so a shielded wire from P46, pins TSTN and GND to ACC1, Pins 1 and 2 would give easy access from outside the rig to D40 and NOT alter any of the existing functions of the IC275H. The installation of the wiring is not as easy as it sounds however: (1) You have to find a way to connect P46. I stripped a small amount of insulation from the wires just behind the plug housing and soldered the extension wire there. (2) To gain access to ACC1 you must remove the PLL PCB that it is mounted on. With the board removed I soldered the extension wire to the underside of the board taking care not to short out any surrounding tracks. The whole exercise took about 30 minutes. You will probably need more audio level from you PSK modem (see changes recommended by G3RUH in his FT-736 discussion). You can then use the pot, F151, in the IC275H to set the TX modulation level. Results from making this change have been outstanding with many less retries on the uplink than previously. The waveform being applied to the Varicap diode is now identical to the output from the modem. Performance via LUSAT and PACSAT digipeaters have been equally pleasing. EXTRA hint: Use DWAIT=0 RESPTIME=0 and start TXDELAY=100 ms and reduce to as low as possible for your radio - I use 30 ms. A similar change could be performed on the ICOM IC271 by wiring to J12 on the Main Board. J12 is normally unused in Australian IC271's. Since the above article referred to G3RUH's FT-736 discussion, I sent a message to James Miller G3RUH on FO20 and asked him to repost it on the bird. I had lost the copy I downloaded since I did not anticipate any need for it. Jack - the notes about mods to the FT736R were specific to that machine, and won't be relevant to the IC735. 1. What you need to do is work out a way to belt the varactor directly. Then inject a square wave (1200 hz will do) and measure the deviation that results. 2. You can do this measurement with either a proper deviation instrument or more likely with a monitor RX, by looking at the output from it's discriminator. 3. You can calibrate the monitor RX quite easily, Tune in a steady unmodulated carrier and note the discriminator DC output voltage Change the RX frequency by 1 Khz (knob on the RX front) and note the change in DC voltage. That gives you the monitor RX sensitivity in volts per Khz. 4. Now return to the TX, and adjust that driving square wave to give you approx +/- 3 kHz, you want to see about 6x volts peak to peak square wave on the monitor. (Somewhere between 4x and 6x will do, no more.) 5. Now return to the modem and juggle about with the TXAudio output components to achieve this level of drive signal, and look at the monitor RX too. 6. When you have done this, which should take you all of 30 minutes, you should be in business. If you can't get square waves TX to produce squarish waves out of the monitor RX, then the varactor dept. must be suspect, and so on. All is fairly logical. Hope useful. Let me know the results. 73 de James G3RUH @ GB7SPV 1990 Mar 28 Since I am not going to be able to try the mods until I return from a vacation I won't be able to give you an answer as to whether they work or not. But it is my opinion they will. What is happening is that between the mic connector and the varactor the digital signal is being badly distorted and the bird does not respond to the digital signal. This would not make much difference on voice but on a digital signal it makes all the difference in the world. Please feel free to contact me further if I can be of any further help. Best regards Jack W9FMW

.-------------------------------------------------------------------l.------------DIODE-Da--------. l l D915 +-+ ['] D909 : l l.------------DIODE-Db--------+ l l D916 [ ] ['] D910 : l l. : l l D917 +-+ +-+ D911 : l l.----------------------------------------. : l l l.-----------. l : l l l.' '; l : l l l.' '; l : l l l : BACK OF : l : l l l : SPEAKER : l +--+ +-:+ l l l '.' l : : : ': l l l '.' l +--+ +--+ l l l ------------l l l l l +--+ +--+ l l l Removing this diode results in -----> l : --REMOVE-- : l l l expanded UHF coverage from l +--+ +--+ l '--------' 400 - 479 MHZ. l l l +--+ +--+ l l : : : : l l +--+ +--+ l l l l l l +--+ +--+ l Removing this diode results in -----> l : --REMOVE-- : l enabling the unit as a crossl +--+ +--+ l band repeater. l l l +--+ +--+ l l : --DIODE--- : l l +--+ +--+ l l l ------------------'

FIGURE 2

.------------------------------------. l.----------. l l : : l l : : l l : PA CHIP : l l : : l l : : l l '----------' l l.----. Attach V.O.M.----. l l : : meter lead --> O : : l l : () : : () : l l : : : : l l : : : : l l '----' '----' l l VHF VCO UHF VCO l '------------------------------------' Bottom
This modification is read 987 times.

(IC-32) IC-32E auf 9k6

Hallo, habe mein IC 32E erfolgreich umgebaut auf 9600BD. NF Ausgang vom IC 32E zum TNC an MAIN UNIT an IC707 TK1042M Pin 11. NF Eingang vom TNC zum IC 32E andie Leitung R779 nach R781 Signale UMOD VMOD. PTT an Stecker J710 Signal PTT. Fragen ueber Box DB0IZ oder Digi DB0END in 1200BD oder 0202/521349. Sowie ueber DB0IZ-9 in 9600BD Joerg aus Wuppertal DD8JM. PS: UMOD VMOD sind auch auf MAIN UNIT.
This modification is read 786 times.
(IC-32) IC-32AT Elimination of possible faint pulse noise
IC-32AT Amateur This service bulletin is meant for technical personnel with experience working on solid state communications equipment. Damage caused by improperly installing this modification may cause ICOM to charge for subsequent repairs to the product. ICOM does not warrant this modification. 13889-004 May 1, 1989 Elimination of possible faint pulse noise from speaker when radio is in power save mode The power save mode employs a circuit which creates a high level square wave signal used in the power save function. This modification alters the square wave characteristic to eliminate the noise.

This modification is read 1332 times.
(IC-751) IC-751 Bad Cap Problems
This info may be helpful to ICOM-751 owners with units approaching five years of many operating hours; two UNRELATED problems occurred, both due to a similar 10uf electrolytic opening up. The first was the input cap. to the 5-volt regulater chip which supplies PLL board. Proper by-passing is required, probably to prevent internal oscillations in the chip. Replaced it with a tantulum. (Also arbitrarily replaced electrolytic on the output side of the 5-volt reg. chip). The symptoms were 3 or 4 minutes delay before unit would function. Also the screw holding the reg-chip to its heat-sink was a little loose.probably due to COLD-FLOW characteristics of aluminum. This can also occur in pheof aluminum. This can also occur in phenolic P-C boards where the groundfoil is supposed to be bolted tightly to the chassis. It would probably be a good idea to use small splitring lock-washers (along with flat-washers) in these cases to maintain tension over time. The second malfunction was failure of the display digits etc to appear until a warm-up time of perhaps 10 minutes or more (after which you must power-down up to generate a new reset-pulse). It also turned out to be an open 10uf electrolytic on the -5volt line which supplies IC-1 IC-2 on the Display Unit Board. This board attaches to the front assembly near the display digits.parallel to the floor. The front assembly DOES unscrew with 4 screws and move forward an inch or two, but this is actually not necessary. The board has a 3-position connector attaching, but only the two outside ones have wires.red is 13.8v outside ones have wires.red is 13.8v dc input, and purple is -5v output. The purple (-5v) wire, but rather is on the opposite side of the inductor (L1) which does connect to the purple wire. A -5v zenerto-ground appears here, and the culprit 10uf is directly in parallel across the zener. I didn't have a 10uf tantulum handy but a 39uf did the job. I also arbitrarily shunted C-17 (easily visible) with a 33uf tantulum, and C-25 which is another 10uf (easily visible) was shunted with a 2.2uf tantulum. (Tack-soldered on foil-side). I didn't have a 10uf tantulum handy but a 39uf did the job. I also arbitrarily shunted C-17 (easily visible) with a 33uf tantulum, and C-25 which is another 10uf (easily visible) was shunted with a 2.2uf tantulum. (Tack-soldered on foil-side). With such a trend developing.it would appear that if you are experiencing other kinds of malfunctions, open electrolytics might be under suspicion. it should not be necessary to remove them in most cases.just tack-solder a tantulum in parallel on the foil-side.
This modification is read 1246 times.
(IC-751) General coverage mod for the ICOM IC-751A

/----I I I D D D D D D D D I

all diodes :

--/ ----I I
D22 D25 D23 D26 D24 D27 D30 D28

: : : : : : : :

When soldered, Europe version, activate the 1750 When not soldered, RX on VHF from 136 to 174 MHz When soldered, USA version, activate the Sub-tone on TX When not soldered, RX on UHF from 420 to 460 MHz ? who knows ?, not soldered When not soldered, TX on VHF from 136 to 174 MHz When soldered, activate the transponder When not soldered, TX on UHF from 420 to 460 MHz
The initial matrix on a US-820 (from D22 to D28) OFF ON ON ON OFF ON OFF ON on a European 820 ON ON OFF ON OFF ON OFF ON
4. to activate the 1750, remove the diode on D23 and put it on D30. You don't need to either reset the 820 or remove the battery. You have now a quiet 1750Hz when you push the TONE button, and a standard Europe bandwith on VHF and UHF (144-146, 430-440 MHz) 5. Now we need to boost the modulated 1750Hz, to do so, you have to short two resistors : R80 100k, located near J16,J1 which is between R79 and R29. Also R17 1k, located near IC11, IC8. 6. Now the level is near to correct. If you whish, you could trim with R64. It's an adjustable resistor marked STBN located on the large printed circuit board on the bottom of the 820. Remember that you lose the capability of sub-tone on TX (CTCSS), but not on RX, if you have the optional module installed. What to say more ? It's works fine on my old-US-820 !!! Please leave me a message on my BBS, if you need more informations ! 73 de Francois HB9IBI @ HB9IAP.SROM.CHE.EU (old HB9RTE)
This modification is read 741 times.
(IC-820) ICOM IC-820H extended receive/transmit modification
This modification is to open the IC-820H for extended receive (and transmit) operation. This is a two (four) step modification which will open the IC-820H to the following frequencies:
VHF Band UHF Band 136 - 174 MHz 420 - 460 MHz
These frequencies are not guaranteed for accuracy or sensitivity. 1. Remove Diode D25 on logic board for VHF RX Expansion. 2. Remove Diode D26 on logic board for UHF RX Expansion. 3. Remove Diode D27 on logic board for VHF TX Expansion. * 4. Remove Diode D28 on logic board for UHF TX Expansion. * * RX modification must be done before the TX modification will work. *

(IC-M700) ICOM M-700 Marine Transceiver
Despite that the literature says, no lock-out is employed. For ham frequencies on 40, 80 or 160 meters, set the mode switch to the hard left position of "A3," to enable the lower sideband filter (all marine HF uses upper sideband).
This modification is read 616 times.

05-11-2001

(IC-M710) Cloning program for IC-M710
Cloning program for IC-M710 MF/HF Transceiver.
This modification is read 538 times.
(IC-MU2) IC-MU2 Ext Band mods
1. 2. 3. 4. 5. 6. Remove battery. Remove 4 screws securing battery. Slide from front panel. Remove small black screw below PTT switch. Carefully separate the front speaker from the body by pulling front and rear down toward battery. Flip it over. Next remove steel chassis assembly by gently prying up the sides, lift up, fold it down. Solder in new diode next to Q131 and Diode D113. Looking at Diode Matrix with top of radio to the top, add diode to the empty pad to the left of diode D119. There are 3 points of connection on the diode pad. Two on the left and one centered vertically on the right. The diode should be installed between the lower left and the right centered connection. (Arrow on diode points to right centered connection.) 7. Reset CPU by following instruction manual page 23.
This modification is read 270 times.
(IC-P2AT) ICOM P2AT keyboard mods
There was a recent posting requesting mods to the ICOM P2AT. I received the following info from ICOM Customer Service and they work fine on my P2AT: To enable wideband receive and direct keyboard entry of the entire frequency: with the HT off, hold down "Light" "B" and "#" keys and turn the HT on Get into the set mode and you will have a new option labeled "PL". Turn the upper right knob to change this to a value of 100. (The rep at ICOM said "PL" stands for "decimal placement") Get out of set mode You should now be able to enter VFO mode and just press seven digit keys to enter any freq directly. I don't have mine with me now, but I think you can enter any freq from 0 to 1GHz (within PLL Lock range). Dave Meer, N6KEF

As of this time ICOM has shown no willingness to redesign the batter retaining tab, nor have they given any indication that they are going to change the type of plastic used in the manufacturing process. They have yet to acknowledge that there may be a problem with the T-8 batteries. As of this time ICOM is replacing batteries that fail while under warranty. If you have a broken battery contact ICOM America via e-mail or phone 425-454-8155 or FAX 425-454-1509 for a replacement.
This modification is read 1215 times.
(IC-T8) TX Mod for the IC-T8a
Important note: Transmitting on the 220 MHz band, will blow the TX module!!
After the modification: 136-174 174-229 300-399 400-599 MHz MHz MHz MHz VHF FM VHF FM only FM only UHF FM top of page
This modification is read 1583 times.

27-02-2000

(IC-T8) Sensitivity for the IC-T8E after freq modification
Author: Martin Swif - martin.swift@virgin.net.MODIFICATION.NET
Ref Chris KC8DHN's freq expansion mod, I checked the mute opening sensitivity on my IC-T8E across the bands.and below are the results.
MHz - uVPd ---------80 - - 0.- <0.- <0.- <0.- - - <0.- <0.- <0.- <0.- 0.- 1.- 1.- No Rx 550 - No Rx 580 - No Rx 600 - - - 0.- <0.4
<0.4 <0.4 0.6 1.2 1.2
This modification is read 1251 times.

26-03-2000

(IC-T8) Cellular mod
This Tip comes from Robin (WA4TEM): The IC-T8A 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 plus 2 times the IF frequency for the T8A, which is 41.85 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 907.7 to 977.7 MHz display on the T8A. So, for example, to receive transmissions from a cellular phone at 826 MHz, just set the T8A to 826 + 83.7 = 909.7 MHz.
This modification is read 9266 times.

03-07-1999

(IC-T81) IC-T81 AM/FM/Wfm function
Just got an Icom T81A quad bander. There is a simple mod to expand the RX capability. To perform the mod hold the "Multi" key and the SQL keys while turning on the power. The display will light all segments. RX is now enabled for the following frequencies: 50.000 - 75.995 Mhz 76.000 - 107.995 Mhz 108.000 - 135.995 Mhz 136.000 - 174.000 Mhz 174.000 - 229.995 Mhz 300.000 - 229.995 Mhz 400.000 - 470.000 Mhz 470.000 - 599.995 Mhz 600.000 - 800.000 Mhz 800.000 - 824.000 Mhz 849.000 - 869.000 Mhz 894.000 - 999.000 Mhz 1240.000 - 1300.000 Mhz Date: 23-10-2000 Subject: Software error User comment From: Steve AI6Q

# = 3 pin part, diode/transistor || = 2 pin SMD diode/resistor (*) = 3 pin surface mounted transistor. (*) (*) || || # #
|| || || || +-------------------------------+ | MULTI-PIN JACK | +-------------------------------+ == == || ||
(kinda hard to draw in ascii. This diagram needs a non-proportional font to look right.)
This modification is read 598 times.

08-12-2001

(IC-Z1A) Pictures for the two modification above
This modification is read 580 times.
(MISC) ICxx71 ram adaptor for use with eprom programmer
ow to read/programm the ICOM-battery-RAM by EPROMER:
Adapter ICOM-RAM <==> 2764-Programmer socket 12.dez.89.. R 5V 20.------ 28 +5V the factory programs Q4-7 16-19 -+. A CS 19.---(*) the lower 255 Nibbels. 0V 14 ----+-- 1 E M AD 9 18.------ 24 A 9.2 AD 8 17.------ 25 A 8 you find the frequency+5V 28 --o.o- 3 WP U AD 7 16.------ 3 A 7 range reading the 'hexdump' Q-------.4 D3 N AD 6 15.------ 4 A 6 backwards. Q-------.5 D2 I AD 5 14.------ 5 A 5 Q-------.6 D1 T AD 4 13.------ 6 A 4 my tnx to dl8scu @ db0aaa, Q-------.7 D0 AD 3 12.------ 7 A 3 df8wu @ db0lj , Prog 27 -------.8 WR' AD 2 11.------ 8 A 2 dc4fe & testet with:. AD 1 10.------ 9 IC-751 , 271h,. upside AD 0 9.------ 10 471e,1271a.. CE--20-inv.-OE--22nand--(*) nand-PGM-27A 1 A 0 dl8zaw @ db0sif
use a 4011 for the nand's and the inverter. dont forget to set the unused 4011 inputs high.
if your eprommer cancels operation with a 'no eprom inside'-error contact each eprommer-pin to a normal 2764 but dont connect the pins 11,12,13,15,27 of the normal eprom, dont connect the pins 16-19 to 0V as shown above, program the 2764 to all bytes = low before. 73's de Karl (dg8fz @ db0sao.deu.eu) 12.Dez.89, 21.Okt.91
This modification is read 1269 times.
(MISC) BNC connectors for ICOM HTs replacement
The BEST replacement BNC connector that I have seen (and have used to repair the jacks on 3 different Icom radios) is made by Amphenol for Tektronix. They are not in any catalog I can find, and are not in the salesmans literature. I was told (after the salesman called the factory) that they are not available to the public unless you want to buy 500 of them. I've purchased them on a business trip to Portland (from the Tek Company Store - open to the public) and from the local Tek repair shop. They are very "tight" connectors - the antenna does not slop around, and the center contact has 4 gold fingers to grip the antenna center pin. They are not cheap - $45 each comes to mind - but the oldest one that I fixed is stil going strong after 3 years of _daily_ use. The hole in the metal chassis and the plastic case both have to be enlarged slightly, and the pc board will have to be releived a little. When you install the new connector throw away the solid wire that Icom uses to connect the PC board to the BNC center pin. Replace it with a piece of braid. I used a short length of the narrowest solder -wick I could find, but another friend used a small piece of RG-174 braid. It is 'way too wide, but it worked. You're after a flex connection between the board and the connector pin. It's a little tricky to make a connection with the solder-wick without filling up the braid with solder, but it can be done. Yes, the whole job is tedious, and you'll be swearing at the engineers when you are done, but the couple of hours the entire job will take is worth it. You'll need, besides common hand tools: The new connector - the one that I have left has "28JR200-1" stamped on it. When I picked it up from the local Tek fixer I asked for a replacement BNC connector for a Tek scope. He didn't need a number or anything. Some white heat sink goop. There is no way that you will _not_ get some on your hands. ANd you'll want to put some back on the radio heat sink anyway - the three radios I've done the mod on have all been short on it. And the less there is the more the final will overheat 'cuz the heat can't be carried away. The small tube I picked up at Radio Shlock 3 years ago is still 1/3 full. A small piece of solder-wick type braid - the narrowest you can find. Buy a small roll - you'll need some to clean up the PC board where the old center contact is soldered and wired down. Small needle-point soldering iron - I use a Weller solder station with a 700-degree PTA tip. I should be using the next narrower

Amateur: H A N D H E L D S: IC-Delta1 - Hold [FUNCTION] & [A] & [CLR] buttons and turn the radio on. IC-2GAT - Turn the radio on, hold [LIGHT] & [FUNCTION], turn the radio off, then turn back on. Release the buttons after the display returns to normal. IC-2GXAT - Hold [FUNC] & [VMC] & [DUP] & [HI/LO] buttons and turn the radio on. IC-02AT - Serial numbers below 34000: push the button on the main circuit board next to the lithium battery. Serial numbers above 34000: hold [FUNC] button and turn the radio on. IC-2iA - Hold [LIGHT] & [MONITOR] buttons and turn the radio on. IC-2SA - Hold [LIGHT] & [MONITOR] buttons and turn the radio on. IC-2SAT - Hold [FUNCTION] & [A] buttons and turn the radio on. IC-2SRA - Hold [FUNCTION] & [A] & [CLR] buttons and turn the radio on. IC-P2AT - Hold [FUNCTION] & [A] buttons and turn the radio on. IC-2AT - Hold [LIGHT] button and turn the radio on. IC-03AT - Serial numbers below 34000: push the button on the main circuit board next to the lithium battery. Serial numbers above 34000: hold [FUNC] button and turn the radio on. IC-3SA - Hold [LIGHT] & [MONITOR] buttons and turn the radio on. IC-3SAT - Hold [FUNCTION] & [A] buttons and turn the radio on. IC-4iA - Hold [LIGHT] & [MONITOR] buttons and turn the radio on.
IC-4GAT - Turn the radio on, hold [LIGHT] & [FUNCTION], turn the radio off, then turn back on. Release the buttons after the display returns to normal. IC-4GXAT - Hold [FUNC] & [VMC] & [DUP] & [HI/LO] buttons and turn the radio on. IC-04AT - Serial numbers below 34000: push the button on the main circuit board next to the lithium battery. Serial numbers above 34000: hold [FUNC] button and turn the radio on. IC-4SA - Hold [LIGHT] & [MONITOR] buttons and turn the radio on. IC-4SAT - Hold [FUNCTION] & [A] buttons and turn the radio on. IC-4SRA - Hold [FUNCTION] & [A] & [CLR] buttons and turn the radio on. IC-P4AT - Hold [FUNCTION] & [A] buttons and turn the radio on. IC-4AT - Hold [LIGHT] button and turn the radio on. IC-12AT - Hold [FUNC] button and turn the radio on. IC-12GAT - Turn the radio on, hold [LIGHT] & [FUNCTION] buttons, turn the radio off, then turn back on. Release the buttons after the display returns to normal. IC-24AT - Hold [FUNCTION] & [A] buttons and turn the radio on. IC-32AT - Hold [FUNCTION] & [A] & [LIGHT] buttons and turn the radio on. IC-Q7A - Hold [FUNC] & [BAND] & [V/M] buttons and turn the radio on. IC-T2A - Hold [A] & [C] buttons and turn the radio on. IC-T2H - Hold [aV] & [cT] buttons and turn the radio on. IC-T21A - Full reset: hold [A] & [*] & [FUNC] buttons and turn the radio on. Partial reset: hold [A] button and turn the radio on. IC-T22A - Full reset: hold [A] & [*] & [FUNC] buttons and turn the radio on. Partial reset: hold [A] button and turn the radio on. IC-T41A - Full reset: hold [A] & [*] & [FUNC] buttons and turn the radio on. Partial reset: hold [A] button and turn the radio on. IC-T42A - Full reset: hold [A] & [*] & [FUNC] buttons and turn the radio on. Partial reset: hold [A] button and turn the radio on. IC-T7A - Hold [MR] & [VFO] & [BAND] buttons and turn the radio on. IC-T8A - Hold [MR] & [VFO] & [BAND] buttons and turn the radio on. IC-T81A - Hold [SQL] & [VFO] & [MR] buttons and turn the radio on. IC-V21AT - Hold [F] & [A] & [*] buttons and turn the radio on. IC-W2A - Hold [FUNCTION] & [A] & [CLR] buttons and turn the radio on. IC-W21A - Hold [HI/LO] button and turn the radio on. IC-W21AT - Hold [F] & [A] & [*] buttons and turn the radio on. IC-W31A - Full reset: hold [A] & [*] & [MONI] buttons and turn the radio on. Partial reset: hold [A] button and turn the radio on. IC-W32A - Full reset: hold [SQL] & [VFO] & [MR] buttons and turn the radio on. Partial reset: hold [VFO] button and turn the radio on. IC-Z1A - Full reset: hold [A] & [*] & [MONI] buttons and turn the radio on. Partial reset: hold [A] button and turn the radio on. M O B I L E S: IC-27A/H - Push the reset button under the top access cover. IC-28A/H - Push the reset button in the aft left corner under the bottom cover. IC-37A - Push the reset button under the top access cover. IC-38A - Push the reset button in the aft left corner under the bottom cover. IC-47A - Push the reset button under the top access cover. IC-48A - Push the reset button in the aft left corner under the bottom cover. IC-Delta100 - Full reset: hold [SET] & [SPCH] buttons and turn the radio on. Partial reset: hold [SPCH] button and turn the radio on. IC-207H - Full reset: hold [SET] & [S.MW] buttons and turn the radio on. Partial reset: hold [V/MHz] button and turn the radio on. IC-228A/H - Hold [SQUELCH/MONITOR] & [LOCK] buttons and turn the radio on. IC-229A/H - Hold [SET] & [MW] buttons and turn the radio on. IC-281H - Full reset: Hold [SET] & [SPCH] buttons and turn the radio on. Partial reset: hold [SPCH] button and turn the radio on. IC-448A - Hold [SQUELCH/MONITOR] & [LOCK] buttons and turn the radio on. IC-449A - Hold [SET] & [MW] buttons and turn the radio on. IC-481H - Full reset: Hold [SET] & [SPCH] buttons and turn the radio on. Partial reset: hold [SPCH] button and turn the radio on. IC-706 - Hold [UP] & [DOWN] buttons and turn the radio on. IC-706MKII - Hold [UP] & [DOWN] buttons and turn the radio on. IC-706MKIIG - Hold [UP] & [DOWN] buttons and turn the radio on. IC-900 - Hold [MR] button, turn the power off and then on again. IC-901A - Hold [CHECK] & [MW] buttons and turn the radio on. IC-1200A - Hold down the tuning control and turn the power on. IC-1201A - Hold [SQUELCH/MONITOR] & [LOCK] buttons and turn the radio IC-2000H - Hold [SET] & [PGR/CS/MW] buttons and turn the radio on. IC-2100H - Full reset: hold [SET] & [S.MW] buttons and turn the radio hold [V/MHz] button and turn the radio on. IC-2340H - Full reset: hold [SET] & [SPCH] buttons and turn the radio hold [SPCH] button and turn the radio on. IC-2350H - Full reset: hold [SET] & [S.MW] buttons and turn the radio hold [DUP] & [LOW] and turn the radio on. IC-2400A - Hold [SUB VOL] & [MW] buttons and turn the power on. IC-2410A/H - Hold [SET] & [MW] buttons and turn the radio on. IC-2500A - Hold [SUB VOL] & [MW] buttons and turn the power on. IC-2700H - Full reset: hold [SET] & [SPCH] buttons and turn the radio