To Icom IC-290H Mobile

To T8V on J5, pin 5 or J3, pin 6 Chassis Ground To NC (R15 (10K)
**Optional Use (see 55-64 Instruction Sheet)
REDi BLACK 2 YELLOW 3 ORANGE 4
Optional Use (see SS-64 Instruction Sheet)

GREY 5

If YOU want the reverse burst function, follow the directions on the SS-64 instruction sheet to install into your radios push-to-talk. The Orange wire must be grounded to encode tone if jumper JP-1 is out
m426 WEST TAFT AVENUE ORANGE, CA 92865-4296 14) 998-3021 FAX (714) 974-3420 tire U.S.A. (800) 854-0547 FAX (800) 850-0547
COMMUNICATIONS SPECiALiSTS, INC.
http://www. corn-spec. corn

(IC-271) (IC-271) (IC-271) (IC-2710) (IC-2710) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-275) (IC-28) (IC-28) (IC-2800) (IC-2800) (IC-2800) (IC-2800) (IC-2800) (IC-2800) (IC-2800) (IC-2800) (IC-2800) (IC-2800) (IC-281) (IC-281) (IC-281) (IC-2AT) (IC-2AT) (IC-2GAT) (IC-2GAT) (IC-2GAT) (IC-2GAT) (IC-2GXAT) (IC-2GXAT) (IC-2IA) (IC-2IA) (IC-2IA)
IC-271 / 471 fuer 9k6 German language IC-271 sounds raspy in SSB/CW English language RAM Card Backup Battery Replacement Instructions English language Some modification for IC-2710 English language Crossband Repeater Operation for the IC-2710 English language PSK Transmit Audio Modification for ICOM IC275 & IC271 English language IC-275 Freq. steps mod. English language Band Expand for ICOM IC-275E/H and IC-275A/H English language IC amplifier oscillates English language Prevent PLL unlock at high ambient temperature English language Improve voice synthesizer and side tone audio English language Prevention of PLL unlock at 174 MHz English language Improve the stability of the center meter English language Noise coming from speaker during transmit with audio turned up English language Eliminate possible spurious emission when thermal switch has turned on during TX English language Frequency range & CTCSS tones English language Power control modification English language Restoration of pass band tuning English language Modification of cw pass band (BFO) English language Disabling of SBB squelch English language Very fast AGC English language SSB RF Gain English language Tuning speed English language Splitting into RX- and TX paths English language ICOM IC-28A AND IC-28H ext frq English language The long, noisy squelch-tail of the Icom IC-28 English language Icom IC-2800h Extended RX Mod English language Icom IC-2800 Extended RX/TX Mod English language Icom IC-2800 Extended RX/TX Mod, Australian model English language IC-2800/HM98 tx-audio mod English language sensitivity ICOM IC-2800H English language IC-2800H cross band mode operation English language DTMF options card English language Screen saver Turn OFF option for IC-2800 English language Cross Band Repeat for IC-2800 English language Enable crossband function for IC-2800 English language Crossband repeat English language Extended Receive for IC-281 English language Extended Transmit for IC-281 English language Coverage IC-2AT 140-150 MHz English language Operation and L3 ADJUSTMENT English language Out-of-band transmit mod for IC-2GAT handheld 2M transceiver English language Step mods for IC-2GAT English language IC-2GAT to packet English language ICOM IC-A20 alkaline headset-adapter lost-in-the-soup English language The ICOM 2GXAT HARDWARE MOD English language Software mod, to open IC-2GXAT English language IC-2Ia mic mods English language IC-2IA lousey xmit audio fix English language IC-2IA mod. English language

(FM) (AM) (FM) (FM) (FM) (FM) (FM)
Frequency ranges are appoximately and not garantied. Receiver sensitivity garantied only in HAM-Band (144 - 146 MHz). In RECEIVER Mode equipment running exclusively as a Receiver, cannot transmit at all. Achtung: nur fu:r den Fachha:ndler zum Zwecke des Service bestimmt. Es mu:ssen die Bestimmungen des Fernmelde-Anlagengesetz heachtet werden.
This modification is read 1063 times.
(IC-2SAT) IC-2SA/E Frequency range expantion
Remove any diode position on D6 Install diode DA (code No. 1750000160) position D6
After this modification frequency lock range will be expand typicaly :
RX (MHz) TX (MHz) : : 108 - 140 (AM) , 138-169 (FM) , 310-370 (FM) , 139 - 163 (FM) ,
------------------------------------------------| | | | | | | | | R R | | | | | | o | | R R R ### <--- | | 4 ### | | 3 o o R | | 6 | | ___________ 1 | | / | | / | | | SP1 | | | | | | | | | | | / | | \___________/ | | | -------------------------------------------------
Yeah, the above is crude, just meant to give the relative locations of the mysterious diode, SP1, R38, R39, R41, R42, R43, and R61. The 3-terminal box with an arrow drawn to it (the arrow is in the original image) looks like the below. A diode is connected from the lower left tab to the upper tab.
___ | | -------------------| / | | --| | /_ | | ____| | | / | | | |
-------------------| | | | -----
diode matrix programming To simplify/fool-proof this, if the schematic has: (X) --->|--- (Y) I'll say "from X to Y". From the "IC-2SAT IC-2SET SCHEMATIC DIAGRAM":
Japan Version Europe Version Italy Version D6: D5: D6: D5: D6: D4: D9: D5: D6: D4: DA115 DA115 DA115 DAN202U DA114 DA115 ISS254 DA114 DA115 DA115 from from from from from from from from from from from KEYI2 KEYI0 KEYI2 KEYI1 KEYI0 KEYI0 KEYI2 KEYI1 KEYI1 KEYI2 KEYI2 to to to to to to to to to to to KEYS2 KEYS3 KEYS2 KEYS3 and KEYS3 KEYS2 KEYS3 KEYS2 KEYS3 KEYS2 KEYS3
U.S.A. Version Australia Version Asia Version
Now, can anyone use this to figure out the Icom-Europe memo??? Bob KC9RG cromwell@ecn.purdue.edu top of page
(IC-2SAT) Icom IC-2SAT unpublished Specificatons
I have access to some test equipment at work and did some studies on this little marvel of a transceiver. Here are some of my studies I have found so far: 12 dB SINAD Receiver Sensitivity:
Frequency: 80.00 MHz 90.00 MHz 100.0 MHz 110.0 MHz 140.0 MHz 150.0 MHz 160.0 MHz 170.0 MHz 180.0 MHz 190.0 MHz 191.61MHz V dBm 217 ----101.185 -122.16 -123.3 -117.9 ---74 --- vfo goes unlocked ---
210.0 MHz 590 -50 220.0 MHz 590 -50 230.0 MHz 2000 -40 250.0 MHz 173 -62 260.0 MHz 340 -56 270.0 MHz 27 -78 280.0 MHz 4 -94 290.0 MHz.7 -110 300.0 MHz.38 -115 310.0 MHz.5 -113 320.0 MHz.275 -118 330.0 MHz.23 -120 340.0 MHz.23 -120 350.0 MHz.32 -117 360.0 MHz.4 -115 365.0 MHz.72 -110 -------------------------------vfo goes unlocked-------------------

Confused??? I thought so.How about an example.
Mission: receive normal coverage plus from 150Mhz to 152Mhz. Steps: 1. go into VFO A mode. 2. change the off-set to 10Mhz in the minus mode. 3. select a tuning step of 15Khz
4. select a frequency of 150.000Mhz 5. press function. 6. press and hold, very important not to let go, MR button. 7. simultaneously turn channel selector knob one notch to the right. 8. let go of MR button and press VFO select button TWICE. 9. observe that frequency in VFO A is now 150.015Mhz. 10. repeat from step 5 until frequency in VFO A is 152.000Mhz. 11. store this frequency in channel 1 by pressing MR button. Notes: Be careful, the radio will transmit out of band.
This modification is read 825 times.

17-02-2001

(IC-3200) Frequency Extention RX / TX for ICOM 3200 E
Author: Thomas Zimmat - do6ftz@tntweb.de.MODIFICATION.NET
1. Remove power + antenna 2. Open radio 3. Locate diode matrix (located behind display unit) 4. Install or remove Diodes (Tables below ) 5. Reassemble radio 6. Reset TRX
VHF D 15 --- D 16 --- D 17 --RANGE ======================================== open open open 144 - 154 set open open 144 - 146 open set open 140 - 148 set set open 140 - 150 open open set 144 - 156 set open set 140 - 154 open set set 140 - 150 D 19 --- D 20 --- D 18 ---- RANGE ======================================== open open open 430 - 440 set open open 432 - 437 open set open 430 - 440 set set open 430 - 440 open open set 440 - 450
All the Modifications worked out pretty good. But I haven't found out what happens when you set all 3 Diodes in VHF and UHF. If somebody finds out,let us know. Remember it is not allowed to transmit outside of hambands !! VY 73 de DO6FTZ
This modification is read 805 times.
(IC-3210) IC-3210 prevent signals on TX when the PA modul
IC-3210 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. 28Oct86-027 October 26, 1986 To prevent spurious signals on TX when the PA module was changed form a Toshiba part to a Mitsubishi part

Procedure:

1. Replace the following parts on the main board: Current Part 470K 560K 4.2K 47K Component Identifier R40 R41 R42 R44 New Part 680K 1Meg 4.7K RH0521CS3J04A 100K RH0651C15J1UA
This modification is read 612 times.
(IC-3210) 9K6 with IC-3210 A/E
From: SM4OTI@SM4TYA.W.SWE.EU Just like to inform that I've tried to modify an ICOM IC-3210 for 9k6 use, and it seems to work ok. 1. Inject TX-Audio to junction C90/C91 on the main board (for UHF 9k6). Don't try to disamble the UHF shileded box. Connect outside at the above discribed junction. 2. Inject TX-Audio to junction C89/R2 on the main board (for VHF 9k6). Don't try to disamble the VHF shileded box. Connect outside at the above discribed junction. 3. Pick up RX-Audio at junction of C145/R112 (seems to be a good place, some filtering already taken place at this junction). Note! I had to adjust the TX-Delay a little high probably due to som chirping or slow RX/TX shifting, but otherwise it works great. 73 de Stefan (SM4OTI / AA8PH @ SM4TYA.W.SWE.EU)

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
1. 2. 3. 4. 5. Remove top and bottom covers from rig. Remove cover for RF unit (left side). Locate J2 near center of RF board (multi-pin connector). Clip brown wire (pin 1). Maybe the wire is black Rig will now transmit in Gen. Cov. mode above 1600 khz.

PA3HGT@ON1CED.WVL.BEL.EU

Here is two pictures from astra.
Here is anothe two photo from kb1vi

Date: 23-02-2002

From: Greg/K6QPV San Diego, CA. USA
Subject: Making 756P continuous Xmit 1.6 - 29.999 MHz Mods desired to use 756P as Xverter on 24 MHz which is out of its stock Tx range. I followed the suggested steps for making 756P continuous Xmit from 1.6 - 29.999. Bottom cover removed by 10 screws (6 on bottom and 4 on sides), no need to remove feet. CPU box is connected to mother board via two multi-conductor connectors. Easy to gently "rock" it back and forth, pops right off. Diodes on my Ver #2 were instantly identifiable. Heated one end, used very small blade knife to lift desoldered end. Left diodes connected and "hanging" by other end. Total time required approx 10 minutes. Piece of cake. No observable reduction in operation upon firing it up.
This modification is read 3371 times.

10-02-2002

(IC-756PRO) ICOM IC-756PRO CW Filter Shape Selection
Author: Greg Ordy - ordy@seed-solutions.com.MODIFICATION.NET

by Greg Ordy

Introduction The Undocumented BPF Indicator Two Ways to Specify the Filter Width Do It Yourself The Difference

Introduction

The ICOM 756PRO documentation is silent when it comes to describing the CW filter shape factor, and how it can be selected. ICOM tried to improve the situation with a brief mention of this topic in its Advanced Operation Guide for the 756PRO, but it does not clearly describe how to select the filter shape. I will try to do a little better on this page. I would like to thank Rob Peebles, W8LX, for bringing these capabilities of the radio to my attention. The 756PRO receive audio, coming out of a digital signal processing (DSP) intermediate frequency (IF) stage, is much different in character than other purely analog receivers. I have captured some of my impressions on another page. On CW, the filter response created by the DSP is extremely sharp. That is, signals outside of the passband are substantially attenuated. In the analog domain, sharp filters can lead to ringing, and other artifacts. Digital filters can have similar problems. In addition, it has been claimed that the 756PRO receiver highlights flaws (key clicks) in the transmitted signal. In other words, it hears the clicks better than other receivers. These various factors lead to CW receiver performance which some operators do not like. One suggestion to improve performance has been to alter the CW filter shape. Perhaps if the filter was not as sharp, the artifacts would not be as pronounced. Apparently a special DSP ROM (software) is available in Japan, but information on this modification has been difficult to obtain, and in any case, changing the DSP software is claimed to be a major project, in terms of taking apart the radio to access the relevant parts. It turns out that for filter widths of 500 Hz and less, it is possible to select one of two filter shape factors. One is the sharp CW filter, and the other appears to be the SSB shape factor, which is not as sharp. Calling one the CW shape factor and the other the SSB shape factor is my own terminology. Rob Peebles, W8LX, estimated the sharp CW shape factor to be 1.5, and the SSB shape factor to be 2.0. This page describes how to select the two different shape factors (in the CW mode, it cannot be selected in SSB mode).

(IC-900) IC-900 Memory Expansion Modification (Preliminary Rev II)
This modification, done to the controller head, will double the amout of available memories to two banks of ten memories per band. Remove the screw from the back of the control head, and carefully open the unit. Remove the five screws holding the "Display B" unit buard to the rear cover, and unplug the white three pin connector that goes to the "beeper". Locate IC2, the 24 pin RAM chip on the back of the board. Carefully cut the small etch between pins 19 and 20. Solder a #30 wire about 6 inches long to pin 19, (address bit 10). Solder a 22K 1/4 resistor to the cathode of D5, (1N4002). This is a good "pullup" voltage. Locate this resistor next to D5, on the top side of the board. Connect the wire from pin 19 of IC2, and another 3 inch long #30 wire to the other end of the 22K resistor. (Trim the wires as needed). The "DIM" switch is connected to two fine etches that go between diode D5 (1N4002)and the rectangular cutout on the board. Carefully cut these two etches, removing at least a 1/16 inch section of each etch. Carefully scrape about 1/16 inch of the green varnish on the "upstream" side of these two etches (one of them is connected directly to the cathode of D5. Bridge these two etches together. (The display will now be only "bright", but this is no real loss, since the display isn't all that bright anyway). On the bottom side of the board, there are three pads for the "DIM" switch, with two of them connected together. There will be a glass zener diode (D2) across this switch. Remove this diode. Solder a short piece of wire from these two pads to a convenient ground point on the board. Solder the 3 inch piece of wire from the 22 K resistor to the third pad of the DIM switch. When the DIM switch is in the "bright" position (down) the memory will contain the original data. If the switch is in the "dim" position (up), then the second bank of memories can be loaded and used. Combined with the RX and TX expansion mods, this is a good way to have the first bank loaded with ham band freqs, and the second bank filled with police/fire/whatever channels. The new bank of memories will read 999.9995 MHz when first called up, and will have to be loaded with the desired frequencies, offsets and PL tones. (This is not a way to open up the RX to receive the 800 - 950 MHz band, unfortunately). Ed Brown KB1MZ
This modification is read 486 times.
(IC-901) IC-901A Frequency Ranges
Here are the frequency coverage ranges for the various band modules and the modifications to the control head diodes to get these extended ranges:
Band 10m 6m 2m 1200 Range (MHz) 28-40 40-54 138-174 216-236 400-479 1240-1300 RX diode no no 25 no out out change change out change TX diode 23 no in in in in in change

This modification is read 491 times.
(IC-DELTA1) Band expansion modification for IC-Delta1A
Remove diode D14 Replace diode D13 with a MA132HK (icom part#1790000830) Replace diode D15 with a MA132WK (icom part#1790000850) Reset Radio

After mod, you get:

118-136 MHz AM RX 136-174 MHz RX/TX
350-470 MHz RX/TX 800-950 MHz RX 1240-1300 MHz RX/TX
IC-Delta1A Logic Unit: /---------| | \___________________________ | D D D D D | <-Matrix D14 D13 D15 Q21 Q22 | D D D R | D11 D12 D10 R78 R79 | | | | | | \_____________________________________/ ____ Replacement of D13 =| | MA132HK | /|=k a=|/_| Replacement of D15 ____ a=| | | >|=k a=|/_| MA132WK
1N916 or 1N914 can be used too. Reset The Radio When Finished
Cool radio, too bad its so big and doesn't tx on 800mhz.
This modification is read 575 times.

14-05-2000

(IC-DELTA1) IC-Delta 1E repeater mode
Author: Walter, DH0KAR You can change the delta 1 E to -repeater mode- while two of three modules are switched on and squelch is on. You have to press and hold -func, moni and ent- keys, then two blinking -Ls- will show up on the bottom off the display. When one of the two modules receives a signal strong enough to open the squelch this signal is immediately transmitted on the other module and vice versa. You stop the mode by pressing the buttons in the same manner as above and see the blinking -Ls- going away. 73 Walter, DH0KAR
This modification is read 540 times.

09-12-2001

(IC-F3/4) Icom F3/4 extended RX & TX
Author: Jonathan Davis - jd865@uplink.net.MODIFICATION.NET
While holding down the [C] + [Monitor] button turn on radio. Dealer will appear on LCD. Imput 159357. You can ch up or down and you will see the freq corresponding with each ch. Radio will promp to enter RX. Do so and push [#] to enter or again to del.
Push the [left arrow] button to enter TX freq. I have not been able to get ctcss entered this way yet, I'll keep trying. This will only work if Dealer set mode is enabled in the common screen in software. I think enable is by defalt anyhow. Jon.
This modification is read 1362 times.

30-01-2002

(IC-M100) Icom IC-M56, M58, M59, M100 - M125 Additional frq. range
Author: Honico - honico@hotmail.com.MODIFICATION.NET
Power off radio. Unplug. Inside, under the cover, all have a switch labeled PRV. Centrally located in the small radios; and on circuitry -inside the face, bottom-end - Toggle it to enable *to be released* channels.
Coding matches other ICOMs, including handhelds --but not other brands--. See ICOM IC-M11 for freq. chart.
This modification is read 190 times.
(IC-M11) Icom IC-M11 Additional frequencies and range
Author: honico - honico@hotmail.com.MODIFICATION.NET

After you have assembled radio, insert battery and radio will automatticly turn on, and the display should say "CLEAR". The proccess is now complete. FREQUENCY RANGES: RX:30-1310MHZ,cellular blocked TX:136-174VHF,400-470UHF 73,from KB8WNA ELYRIA,OHIO 44035
This modification is read 2946 times.
(IC-Q7) Expand transmit from 136-174 and 400-470 for IC-Q7E. (Australian version)
Hi once again, well I have carried out the mod to expand my IC-Q7E ICOM HANDHELD and it was not as bad as I thought it was going to be. The most important thing about this mod is to do it slowly and carefully, do not use force and if you are unsure stop and study it for a while and then proceed. You must have a good quality Soldering Station such as HAKKO, WELLER, etc with a 0.5mm conical tip, a very small jewelers screwdriver and some good quality de-soldering braid, If you do not have the above tools then I suggest that you leave the screws in the radio. Remove the batteries and the two screws under them, remove the antenna and dial knob, remove the slotted retaining nuts below the knob and antenna, the back half of the case can now be removed which will expose the top board and next stage. There are three solder points and one screw to be removed on the AUSTRALIAN E MODEL at the top board shielding, two at the top, one next to the blue channel switch and on the other side next to the antenna connector, the third is above the speaker to the left with the speaker closest to you, the screw is at the right bottom corner of the big shield, very slowly lift this board until it clears the multi pin white connector in the centre of both boards and with pressure applied to the end of the antenna connector with the thumb cautiously remove the top board. The rest is pretty easy, remove the two screws from the bottom main board, one close to the speaker at the bottom of the small tin shield and the other between the PPT and FUNCTION switch, DO NOT TOUCH THE TWO AT THE TOP OF THE BOARD, desolder the two speaker wires at the speaker and being very careful of the rubber seals lift the board out and turn over and carry out the mod as per my jpeg pictures. Re-assemble in the opposite manner USING EXTREME CARE my radio will now transmit from, 136 - 174 and 400 - 470. I have not checked to see if there is any drop off in performance specs now, the mod works and seems to work well so I guess that is the most important thing.
This information was supplied by, David Spicer, VK7ZDJ, 5a Helen Street, ULVERSTONE, 7315. Tasmania, Australia. vk7zdj@southcom.com.au.MODIFICATION.NET Packet vk7zdj@vk7ax.
This modification is read 2260 times.
(IC-Q7) IC-Q7 Programming utility 1.05 ( Goran Vlaski ), Wide RX 0-30MHz, Adjustment mode

Fig. 4. Receiving AO-40 (at MA=13) One last problem is that the VCO is rather sensitive to temperature, which with a unit like this at this frequency is hardly a surprise. Howard, G6LVB
This modification is read 3324 times.
(IC-R71) RAM Card Backup Battery Replacement Instructions
This modification is read 737 times.

18-11-2001

(IC-R71) RAM board programming interface & R71A modification
11 December 1999 by Andrew Gerald, N2CBU eMail-1: Lorand@QwestInternet.net eMail-2: N2CBU@ARRL.NET A word of caution before you begin: It's possible that due to a wiring error, parallel port error or software incompatibility you might erase the contents of your RAM module. If your RAM module is from an R71A you can restore its contents from the enclosed "ORIG-R71.BIN" file. I do not have any other "recovery" files and until some become available I urge caution. Perhaps it would be wise to test your interface on a RAM module from a R71A first before reading RAM modules from other radios. I will add "recovery" files for the other radios to this archive if they are sent to me. *** Note-1: If the "WP" Write-Protect pin (see J2 on the interface schematic) is tied to ground instead of to +5v the critical lower RAM locations in the module are write protected. A simple modification to the interface board would be to add a write protect switch. *** Note-2: If the "/WR" Write pin (see J2 on the interface schematic) is left unconnected when testing the interface then the entire RAM will be write protected. Thus you can test without much chance of erasing the contents of the RAM module. Icom RAM board programming interface & R71A modification notes You will need a CD4040 IC, a 78L05 voltage regulator, an 8-pin strip of 1" tall 0.1" spaced header pins, a 12-pin strip of 1" tall 0.1" spaced header pins, a DB25M, a length of ribbon or other type cable, and a piece of perf board. For the prototype I used a Radio Shack part number 276-149 prototyping board. It should be noted that my prototype does not have an on-board voltage regulator. I included the regulator on a subsequent board I built in 1991 which I gave away. All parts may be obtained from Digikey (www.digikey.com) and certainly from other sources. A suitable header pin strip is Digikey part number "S1081-36" but any similar header pin material will work. Circuit layout is simple, just take a look at the ram module in the R71 and imagine how the header material will have to be positioned. What you want to do is make a "socket" on the programming adapter which looks just like the "socket" in the R71A. Build up the circuit on a small piece of perf board with the 4040 in the center. The long side of the header pins will have to be bent slightly outwards for the ram module to fit. The ribbon cable from the PC will attach near the smaller header strip.

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

+-+ | | +-+ +-+ | | +-+

<---- Installing diodes in either of these seems to do nothing.
+-+ +-+ | | | | <---- IN: +-+ +-+ OUT: ^ | +------------ IN: OUT:
US Version 144-148 TX 440-450 TX Extended 136-174 TX 380-470 TX (Lose auto-repeater and tone encode) US European 144-148 TX 440-450 TX 144-148 TX 430-440 TX

"D15"-->

+-+ | | <---- IN: US Version Stock +-+ OUT: Extended TX 136-174 380-470 (keeps auto-repeater and tone encode)
A word of warning about messing with the four diode pads: If you detach either one of the installed diodes, the CPU will reset and you'll lose ALL of your memories. (found that out the hard way.) D15 doesn't seem to affect the memories at all. Since the 800MHz band is not available in US versions, my guess is that there's a keyboard mod to unlock it instead of a diode. The diodes only seem to control the country versions. If anyone has any more keyboard mods, please post them. Bruce KD6ALI Thanks to Edmund F Leavitt for this photo.
This modification is read 697 times.

04-12-2001

(IC-Z1A) IC-Z1A 800-900 MHz Receive
800MHz receive. Install two transistors. Part #UN9110 can be ordered from ICOM Service Department. This mod is not for the non-technical person. The radio pretty much has to be completely disassembled to get to the pads. 1. Remove the control head and battery. 2. Remove the 4 back screws and 4 battery compartment screws. 3. Separate the case. 4. Locate the circuit board with the two channel select/squelch knobs. This is the board we're looking for. Unfortunately, it's an the back. 5. CAREFULLY remove the wide ribbon cable that connects the upper and lower circuit boards. 6. LOOSEN the three screws an the LOWER circuit board. 7. Remove the two screws an the back of the radio, an the top of the battery compartment. 8. Remove the three screws an the battery contacts. 9. Slide the RF assembly up and it should separate from the rest of the radio. 10. Remove the knobs and carefully remove the ring nuts from the case. 11. Remove the metal bracket that is between the case and the pots. 12. CAREFULLY Desolder the grounding tob an the left side of the circuit board. 13. Remove the two screws holding the board down. 14. The board should now be free. Carefully wiggle and pull and pry until the board is released. You may have to partially or fully remove the battery spring mechanism. 15. Flip the board over. There is a large multi-pin jack an the back, slightly high and centered. Look for two empty, 3 pin pads right next to it. 16. Carefully solder the two transistors onto the pads. 17. Check your connections. You do NOT want to have to disassemble this twice. 18. Check them again. 19. Reassemble the radio in reverse order. Remember to resolder the grounding tab. 20. Turn it on. Select UHF, key in an 800MHz frequency and listen. There is no need to reset the VFO or memories. Diagram: This is a close up view of the area to looking for. (sorry, no picture yet.)

(R-7000) Intermittent display
Author: Burt I. Weiner - biwa@pacificnet.net.MODIFICATION.NET
I have an ICOM R-7000 that has had an intermittent display from the time I purchased it. It has been back several times for repair at an authorized service center. The problem would re-appear after a few weeks. I got tired of sending it back and decided to live with the problem. After a while it became so bad I became too annoyed to live with the problem and decided to track it down for myself. I did discover the actual cause of the problem and after making repair the display has been 100 percent reliable. The problem turned out to be the flat ribbon type cable that runs between the display and the display board. Checking the conductors of the ribbon cable with a meter was misleading because of the intermittent nature of the problem. The repair was a lot simpler than I had imagined. I did not replace or remove the ribbon cable but instead connected parallel conductors across it. The process is simple if you have experience with delicate stuff. It's necessary to remove the display board and the display. First and most important - UNPLUG THE RADIO! Remove the top and bottom cover of the radio. Remove the screws on the left and right side of the front panel brackets that attach it to the main chassis. The front panel will hinge down to about a 45 degree angle. Support it in that position. Remove the 2 screws from the back of the display board. Carefully remove the display board and the metal shield on the back of the board. Carefully swing the board back revealing the component side. Unplug the "dimmer" control plug on the right side of the display board. I found it necessary to cut the tie wraps on the wires connecting to the display board. Be very careful not to cut any of the conductors. Once you've done that you can swing the display board back even farther. Next, remove the two flat head screws on the top of the front panel. This releases the bracket that holds the display against the front panel. Again, be very careful in handling the display. You will notice a foil shield along the bottom of the display ribbon cable. Carefully peel it away exposing the ribbon cable and both ends. I rotated and positioned the board and display so that the pins on both were facing up with the soldered side of the ribbon cable towards me. I used stranded wire from a ribbon cable out of a computer for the jumper wires. DO NOT USE SOLID WIRE! Make the jumpers one at a time. I stripped about 1/16th of an inch of wire, tinned it and then soldered it to one end. Before cutting the other end I dressed it to length following the ribbon cable's "curve" and then cut the other end. Do not make it to tight or leave too much slack. Then I stripped 1/16th of an inch of wire, tinned and soldered it to the other side. Be careful not to bridge any of the connections together. You will note that four of the points, two on each end are connected together. I used only a single conductor for these. Take your time doing this. Check each jumper as you put it in by following the trace in the ribbon cable, which is quite visible, to be sure you are not cross connecting somewhere. JUMPER ALL OF THE CONDUCTORS! If one is intermittent, then the others are or soon will be. When you are finished and just before you start to re-assemble things, carefully clean the display and the inside of the display window with Windex. I used a clean piece of old t-shirt. Rotate the board and display back into position for re-assembly. Re-position the foil shield under the (new) conductors and ribbon cable. I did not replace the tie wraps previously cut but carefully positioned the leads so they do not become pinched under brackets during re-assembly. When installing the display make sure that the fingers at the bottom of the display bracket go under the display easily. Reverse the procedure described above for re-assembly of the rest of the radio. Don't forget to replace the "dimmer" control plug on the right side of the display board once the board is mounted. Since making this repair the display has worked without failure. The sensitivity of the receiver is as good or better than before indicating that the noise output from the display is still well contained. If you have been suffering from the annoying intermittent display as long as I had been this will be well worth the effort. Burt, K6OQK - biwa@pacificnet.net Burt I. Weiner Associates Broadcast Technical Services Glendale, California - U.S.A. biwa@pacificnet.net.MODIFICATION.NET K6OQK