Modifications for the ICOM - RogerK

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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 asurprise.Howard, G6LVBThis modification is read 3324 times.top of page30-03-2001(IC-R71) 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:
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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
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19-07-1998(IC-706) Info/mods for IC
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¦ ¦¦ ¦¦ ¦¦ ¦¦ ¦----------
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●●●●●●●●●●●
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From: gary@ke4zv.atl.ga.us (Gary Co
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Mehr Dynamik in der Modulation beko
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Operation:Be sure to read the manua
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Alternative zum modifizierten PC St
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●●●●●(Another receiver wi
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| IC31 uPD4094BG || |1 2 3 4 |5 6 7
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D116 and D118 are responsible for o
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Transmit power output after modific
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This information and photos was sup
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22-02-2002(IC-706MKII) IC-706MKIIG
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Delete cap. CT14 at pin 6 of IC3 on
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18-06-2000(IC-729) Using two Icom r
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19-07-1998(IC-735) IC-735 Remote Wo
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19-07-1998(IC-736) Icom IC-736 DDS/
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Also probably would apply to IC 735
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RAM card version B images:This modi
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John Schmitz NS8EAdditional informa
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13-01-2002(IC-746) Monitor Audio Ou
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19-07-1998(IC-751) IC-751 Bad Cap P
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inspect your job to be sure that th
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28-01-2002(IC-751) ICOM IC-751 Dual
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Step 8: Turn the radio off and inst
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To be neater you could remove the s
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[W804] | |Remove=>[W805] | CHIP |[W
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Date: 23-02-2002 User comment From:
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less.The second way to adjust the I
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23-11-2001(IC-756pro2) IC-756PRO2 T
Page 214 and 215: 19-07-1998(IC-765) Icom IC-765 Pass
Page 216 and 217: 19-07-1998(IC-775) New product info
Page 218 and 219: 70% AM.My personal findings are tha
Page 220 and 221: 11. Re-install board and all cables
Page 222 and 223: The Yaesu FT726R first appeared ten
Page 224 and 225: There seemed to be no way of changi
Page 226 and 227: Add a diode on the blank position b
Page 228 and 229: ---- gar keine Diode ----Breitband
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
Page 236 and 237: 27-05-2001(IC-910) Expanded functio
Page 238 and 239: ●●●350-470 MHz RX/TX800-950 M
Page 240 and 241: This modification is read 242 times
Page 244 and 245: 1. You're completely successful.2.
Page 246 and 247: ●●●●●●●●●Für Han
Page 248: 28-03-1999(IC-Q7) Modifying the ICO
Page 252 and 253: ●●●●●●●●Desoldering
Page 254 and 255: You should now have the RF board co
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Page 258 and 259: BOOT:Attenuator protecs strong sign
Page 260 and 261: 1. Use an ohmmeter to determine whi
Page 262 and 263: 2. Remove battery cover and battery
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Page 268 and 269: The Q and not Q outputs on this IC
Page 270 and 271: Date: 30-12-2001 User comment From:
Page 272 and 273: This modification is read 3462 time
Page 274 and 275: Removing 1F unit1. Pull the 2 knobs
Page 276 and 277: 16-05-1999(IC-T8) Problem with the
Page 278 and 279: 800 -
Page 280 and 281: Frequencyrange after modification:5
Page 282 and 283: Offset Freq: Hold [FUNC], Press [4]
Page 286 and 287: The Icom IC W21AT handi-talkie norm
Page 288 and 289: 19-07-1998(IC-W2A) IC-W2A signal le
Page 290 and 291: 19-07-1998(IC-W31) IC-W31E CROSS-BA
Page 292 and 293: 15-10-2000(IC-W31) Cross Band Repea
Page 294 and 295: could always try it.Set VHF and UHF
Page 296 and 297: 31-07-2001(IC-W32) Icom IC-W32A pro
Page 302 and 303: IC-4GAT - Turn the radio on, hold [
Page 304 and 305: IC-M9 - Hold [HI/LO] & [DW/SCAN] bu
Page 306 and 307: IC-275H 10IC-375A 12IC-471 22IC-475
Page 308 and 309: I have tested this mod with a ic-75
Page 310 and 311: How further up the hole is the bett
Page 312 and 313: 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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