Modifications for the ICOM - RogerK

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inspect your job to be sure that the battery is connected to the correct pads on the board.10. Now you can disconnect the external power and unsolder the leads from the board.11. The final step is to re-install the board in your radio and continue to use it for many more years.This modification is read 1167 times.top of page30-03-2001(IC-751) RAM Card Backup Battery Replacement InstructionsAuthor: ICOMIn the early 1980s Icom America marketed a group of transceivers and radios that utilized the latest state-of-the-art computertechnology to enhance the operation of the radios. This technology improvement allowed hams to afford a reasonably priced highperformance transceiver which until then was only available on units costing much more. Features now available to the hamsincluded: higher frequency stability, better frequency resolution, digital frequency display, almost instant recall of savedfrequencies (memory channels), quick mode signal processing and built in tones and offsets for the rapidly emerging repeateroperation.Implementation of all these features required a CPU with associated logic circuitry. In the early 80s, the most cost effective wayto implement data processing and memory functions was through a DRAM (Dynamic Random Access Memory) to control theCPU. This DRAM was a volatile memory integrated circuit which required a lithium battery to retain its instruction set. Thefollowing receivers and transceivers had such RAM units:IC-271 ; IC-471 ; IC-1271 ; IC-745 ; IC-751/A ; IC-R71AThe lithium batteries in these units typically lasted about 5 to 7 years before replacement was required. This was specificallynoted 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 accomplishthis:Procedure1. 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 thecircuit 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.Cautions1. Do not use an AC powered 3 Volt DC source, your grounded soldering iron tip could short out the battery (+) terminal. Usea 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 thebattery 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.PicturesThere are two versions of the ICOM RAM boards. Both are identical in operation, and they are interchangeable. The differencesare in the circuit board layouts only. Note that the black and red wires visible on these images are the suggested way ofconnecting the external DC backup voltage while the battery is being replaced. The wires are not a part of the RAM card, andshould be removed when the battery replacement procedure is complete. Refer to the replacement procedure outlined above.
RAM card version A images:RAM card version B images:This modification can also be found at ICOM's own homepage on the following URL: "RAM Card Backup Battery ReplacementInstructions"This modification is read 1129 times.top of page
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Modifications for the ICOMcreated 2
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(IC-271)(IC-271)(IC-271)(IC-2710)(I
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(IC-475)(IC-475)(IC-475)(IC-475)(IC
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(IC-756pro) Expand tx-freqeuncy for
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(IC-W2E)(IC-W31)(IC-W31)(IC-W31)(IC
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2. After about 0.5 second, press st
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21-10-1999(AT-500) ICOM AT-500 Tune
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4. Program the radio to the local w
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19-07-1998(IC-03) ICOM 02/03/04 & V
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This modification is read 553 times
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6. Reinstall the RAM board into the
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27-10-1998(IC-1275) Power control m
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27-10-1998(IC-1275) Modification of
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●Connect the short plug end with
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This modification is read 1316 time
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50MHz to something like 204MHz cont
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26-07-2001(IC-207) Band Expansion f
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Fig. 3: The circuit extract from IC
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19-07-1998(IC-22) Icom IC22S Packet
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More detailed:In the true spirit of
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19-07-1998(IC-229) IC-229H Fix CPU/
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In addition, if you want to put an
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By diode:●●Remove D17 diode on
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1. Remove diode D14 (if there is an
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cut... I'm guessing, but it could b
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19-07-1998(IC-24) IC-24AT enabling
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19-07-1998(IC-24) Tip to to functio
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This complete the mods done with su
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Comment:These TRX is accorded to my
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this mod of use as I have.Any comme
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other wires come in. Take the cable
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17-11-2000(IC-2700) Enabling ICOM 2
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19-07-1998(IC-271) IC-271 / 471 fue
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RAM card version B images:This modi
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12-11-2000(IC-2710) Crossband Repea
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Note:From Bill K7RIEICOM has not tr
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19-07-1998(IC-275) Improve the stab
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●●●●●●●●●●remov
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Note: a strong signal will be serio
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19-07-1998(IC-28) The long, noisy s
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not a hard mod to do,..........but
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02-04-2000(IC-2800) IC-2800H cross
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19-07-1998(IC-281) Extended Receive
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encased it in shrink-tube. The oper
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push buttonswitch ^ ^| |___________
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19-07-1998(IC-2IA) IC-2IA lousey xm
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1. Change to RECEIVER MODE (not rec
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13.0V 5.0W12.0V 5.0W11.0V 5.0W10.0V
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MODIFICATION (Refer to figure 1.)1.
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Procedure1. Remove the covers from
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19-07-1998(IC-3200) Fix for IC-3200
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4. select a frequency of 150.000Mhz
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19-07-1998(IC-3220) How to iface Ic
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Now power on and type in the freque
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One note on the above - the BNC con
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e shorted to ground and cause PLL u
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19-07-1998(IC-451) IC-451 aus 9600F
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3. If by accident you lose power to
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19-07-1998(IC-475) IC-475 Freq. ste
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Problem:This is a general transceiv
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Note: a strong signal will be serio
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Das spart einen mords Haufen Arbeit
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Dieses ist mit dieser Schaltung als
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X . X . 5.0 KHz 1 0 1 0. . . . X .
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Remove the back cover. If you place
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27-10-1998(IC-575) SSB RF GainProbl
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26-06-2001(IC-575) Pass band Tuning
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The trimpot leads will need to bent
Page 147 and 148: 19-07-1998(IC-706) Info/mods for IC
Page 149 and 150: ¦ ¦¦ ¦¦ ¦¦ ¦¦ ¦----------
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Page 154 and 155: From: gary@ke4zv.atl.ga.us (Gary Co
Page 156 and 157: Mehr Dynamik in der Modulation beko
Page 158 and 159: Operation:Be sure to read the manua
Page 160 and 161: Alternative zum modifizierten PC St
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Page 164 and 165: | IC31 uPD4094BG || |1 2 3 4 |5 6 7
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Page 178 and 179: Delete cap. CT14 at pin 6 of IC3 on
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Page 186 and 187: Also probably would apply to IC 735
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Page 190 and 191: John Schmitz NS8EAdditional informa
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Page 200 and 201: 28-01-2002(IC-751) ICOM IC-751 Dual
Page 202 and 203: Step 8: Turn the radio off and inst
Page 204 and 205: To be neater you could remove the s
Page 206 and 207: [W804] | |Remove=>[W805] | CHIP |[W
Page 208 and 209: Date: 23-02-2002 User comment From:
Page 210 and 211: less.The second way to adjust the I
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Page 218 and 219: 70% AM.My personal findings are tha
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Page 226 and 227: Add a diode on the blank position b
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Page 230 and 231: To disable the x-band repeater just
Page 232 and 233: Well this should make things verry
Page 234 and 235: Set radio in VFO mode, and select f
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28-03-1999(IC-Q7) Modifying the ICO
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●●●●●●●●Desoldering
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You should now have the RF board co
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BOOT:Attenuator protecs strong sign
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1. Use an ohmmeter to determine whi
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2. Remove battery cover and battery
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Fig. 4. Receiving AO-40 (at MA=13)O
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This modification can also be found
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The Q and not Q outputs on this IC
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Date: 30-12-2001 User comment From:
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Removing 1F unit1. Pull the 2 knobs
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16-05-1999(IC-T8) Problem with the
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800 -
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Frequencyrange after modification:5
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Offset Freq: Hold [FUNC], Press [4]
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The Icom IC W21AT handi-talkie norm
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19-07-1998(IC-W2A) IC-W2A signal le
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19-07-1998(IC-W31) IC-W31E CROSS-BA
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15-10-2000(IC-W31) Cross Band Repea
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could always try it.Set VHF and UHF
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31-07-2001(IC-W32) Icom IC-W32A pro
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IC-4GAT - Turn the radio on, hold [
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IC-M9 - Hold [HI/LO] & [DW/SCAN] bu
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IC-275H 10IC-375A 12IC-471 22IC-475
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I have tested this mod with a ic-75
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How further up the hole is the bett
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Connect the NTC, FAN and power and
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5, 31, 48, and 79.4. Does the Prior
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19-07-1998(R-7000) Modify your ICOM
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1. C231 from 1000 pf to 68 pf.2. C2
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19-07-1998(R-71) Tricking the ICOM
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There are two wires which send logi
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A. Remove the top cover of the rece
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08-11-1998(R-7100) Modify your Icom
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17-03-2002(R-7100) Icom R7100 Discr
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23-08-1998(R-8500) Operating the Ic
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Modifications for the ICOM - RogerK

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