(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

_____________________________________ D505 D507 D504 ___ ___ ___ |___| |___| |___| D506 Q506 _o_-----_o_ |___| | |___| o o | o o | | -----|<--------add diode: 1N914 or equiv.

| | | | | | | | | | | |

| -- + -| | | hole for | on/off-vol | control |__________________ | | |
Connect diode between top lead of D506 and lower right lead of Q506 as shown. Notes: D506 may be absent. If not, remove it. Reset CPU if needed.
A friend did this and his IC-2GAT can now transmit 138 to 178 MHz (no RF power output measurements were made). He did no retuning, and did not have to reset the CPU. He used a tiny axial-lead glass diode, replaced its leads with wire-wrap wire, and encased it in shrink-tube. The operation requires a super-tiny soldering iron. Observe CMOS soldering precautions: Unplug the iron and ground the tip before touching the circuit. Remember: Except for MARS and CAP, it is illegal to transmit outside the ham bands with non-type-approved equipment.
This modification is read 1076 times.
(IC-2) IC-2AT, If transmit RF indicator notwork properly
IC Micro 2AT 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. 8988-002 March 29, 1988 If transmit RF indicator is not reading properly
Procedure 1. Disassemble the radio to gain access to the RF Board. 2. Replace the following parts on the RF Board:
Reference Designator Q309 D309 R345 C349 Original Value 2SA 1162 1SS 211 New Value ICOM P/N
1SS 196 912-00965 2.2Meg 1/8W Remove this part Remove this part

3. Reassemble the radio.

This modification is read 990 times.
(IC-2) Icom IC-2GXAT open RX
>David, For the IC-2GXAT receiver opening do the following steps as listed. > >1. Turn off the radio > >2. Press and hold the " Function, Scan and Dupe keys " > >3. While holding those keys turn on the radio. > >4. WAIT until the display returns to normal then continue to hold the > keys for about 2 seconds > after the display has returned to normal before releasing the keys > >5. The receiver is now opened up and will cover 138 to 179 Mhz or so. > It WILL NOT do aircraft AM receive nor tune into that frequnecy range.

Quando si parla di destra e sinistra si intende guardare la radio con il frontale rivolto verso di noi. A questo punto le operazioni per la parte UHF sono finite, occorre recuperare la commutazione del PTT, che conviene prelevarla direttamente dal bocchettone del microfono, per fare cio' occorre smontare il frontale della radio sono solo quattro viti, e quindi armarsi di buona pazienza per cercare il punto esatto della commutazione, in quanto abbastanza arduo saldare sul bocchettone stesso, io ho saldato un filetto volante (per ragioni di spazio) e sono quindi venuto al cavo pentapolare principale. Adesso siete pronti per lavorare a 9600 bauds. Un'ultima cosa non tenete molto lungo il cavo di uscita, consiglio di attenersi alle lunghezze di quelli delle antenne, e saldare al termine di questo un bocchettone DIN pentapolare oppure un DB9, si da collegarvi poi con facilit un cavo schermato che va al TNC. Ho notato che l'IC2400 funziona perfettamente senza nessun problema Spero la modifica sia stata chiara ed esaustiva, attendo eventuali suggerimenti o richieste di chiarimento, non abbiate timore nel procedere verso i 9600 bauds non sono poi quella brutta bestia che uno pensa tutt'altro! Buon Packet de IK7RVX. Raff.
This modification is read 725 times.
(IC-2410) Expansion of receive range
The following diodes are located on the Logic Unit circuit board. The Logic Unit circuit board sits behind the front panel of the radio. To get to the board remove the top and bottom of the case. Now notice that the front section of the radio is a separate unit from the main body of the radio. Remove the 4 screws holding the sections together but do not yet separate the sections. Place the radio on a table so that it is right side up. Carefully start to separate the sections being careful of ribbon cables that connect the front section of the radio to the rear. If you look at the back of the circuit board on the front section towards the lower part of the radio, you will clearly see three glass diodes labeled D8, D9 and D10. You will know this is the right circuit board because a lithium battery will be taped to it. These are the diodes to cut to get extended receive range as follows: D8 320-399, 830-Mhz coverage requires new antenna input D9 118-135 D10 400-479
This modification is read 760 times.
(IC-2410) 800 MHz antenna input
To receive 800 Mhz you need to add a new antenna input to connector J2 on the MAIN-B unit (UHF unit) which is the large circuit board on the bottom of the radio. J2 connects to a the B-band board which is a very small daughterboard, that is connected to the MAIN-B board. The service manual offers no description of this board but it apparently is the 800 Mhz front end. Two parts are needed: One 5 3/4" grey coax jumper (this is available from ICOM but it doesn't have a part number) Either: One OPC223 pigtail with UHF connector or One OPC166 pigtail with N connector The grey coax jumper has a plug on one end that mates with J2 and bare leads on the other. The pigtail also has two bare leads on one end. This same end also has a metal flange thats designed to screw onto the back panel of the radio after removing one of the dummy caps on either side of the existing antenna pigtail. Without going into too much detail, you must: Remove the small metal cap nearest the bottom of the radio and next to the existing pigtail. Remove the metal shield at the back section of the Main-B unit. Solder the two pieces of coax together, shield to shield, center to center and screw this assembly on to the back panel. Plug the grey cable into J2 and then reassemble the radio.

This modification is read 717 times.
(IC-2410) IC-2410 TX modification
Both bands Replace the one sided D-14 on the logic board with a 1SS181 two sided diode, and short the solder tabs (position W3) which are directly below the location for D-14. Result: 136-174 Mhz tx 400-479 Mhz tx
This modification is read 764 times.
(IC-2500) Run 9k6 with an Icom IC-2500 (70cm/23cm TRX)
Yes it's possible to run 9k6 with an Icom IC-2500 (70cm/23cm TRX). I BELIEVE the 2m/70cm version (IC-2400) is similar to modify (Hopefully!) Here's my little description: RX: Pin 1 (=MDET) on the DET SW-Unit (mainboard A) Note: You receive on this Pin signals of that band, witch ist selected in the main display TX: You can take the Signal from R73, R72 or C137 Note: as written above
Comment: These TRX is accorded to my experiences relatively good qualified for 9600 Baud Packet-Radio Signals.
This modification is read 550 times.

28-03-1999

(IC-2500) Umbau des ICOM IC-2500E auf 9600 Baud
1. RX: NF an Punkt 1 (MDET) der DET SW-Unit auf Mainboard A abgreifen und z.B. auf Punkt 8 der Mikofonbuchse fuehren. Vorher LSLeitung von Punkt 8 entfernen. Es steht dann sowohl 70cm als auch 23cm vom Diskriminator zur Verfuegung. Punkt 8 der Mike-Buchse geht dann auf NFRX am TNC. (Evtl 10 Ohm Widerstand im TNC entfernen!!) 2. TX: Verbindungspunkt R73 (Hub 70cm),R72 (Hub 23cm) und C137 auf dem Mainboard A mit Punkt 4 ( NC ) der Mike-Buchse verbinden! (Leicht zugaenglich nach abschrauben und umklappen des Bedienkopfs) Punkt 4 dann mit NFTX vom TNC ueber einen 10uf-Elko verbinden. Mit einem Scope Tonrufamplitude an o.g. Verbindungspunkt messen. Dann Datensignal vom TNC auf etwa gleiche Amplitude einstellen! Das wars auch schon! Dies ist zwar eine Simpelloesung - lauft aber hier hervorragend! Fragen bitte an DL2GA @ DB0AAB! Viel Erfolg dann mit 9600!
(IC-251) Modifikcation af IC-251 for 9600 baud
Digital modulation applied to top of deviation pot at the junction of R58, R60 and R61 (just below Q13 on circuit diagram). Modulation voltage from standard G3RUH 1200 bps modem wasn't high enough but was boosted by component changes on the modem board. A higher voltage is required from the G3RUH 9600 bps modem; output level pot set to about four fifths of maximum and works well. PTT connection made inside the rig to the appropriate pins on the rear panel's accessory socket - no complications here, my TNC's PTT comes from a reed relay. No modifications done for digital output from receiver (yet). Have investigated modifying to provide up/down control but checks are incomplete. Suspect provision of this facility is possible and have identified (display) DRIVER IC2 pins 3/11 as the likely place to apply it. Once AO-21/Rudak starts with higher speeds I'll probably expedite the provision of receive output and up/down control.

i.e. for XBand Rpt on B000# D B* for XBand Rpt OFF B000# B*
Also, to enable the XBand remote from the front panel of the rig, press and hold the SET button, then immediately press and HOLD the DUP button, and then press and HOLD both of the channel buttons until the flashing L appears on both sides of the display. Regards, Paul Webster VO1HC
This modification is read 645 times.
(IC-271) PSK Transmit Audio Modification for ICOM IC275 & IC271
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.

Note: From Bill K7RIE ICOM has not tried this mod nor have we verified this problem.
This modification is read 724 times.
(IC-275) IC-275 Freq. steps mod.
This modification is read 812 times.
(IC-275) Band Expand for ICOM IC-275E/H and IC-275A/H
To expand RX range delete D 44 To expand TX range delete D 27 install D 43 Range 138-174 MHz TX not in full range PLL lockout
This modification is read 952 times.
(IC-275) IC amplifier oscillates
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. 588-001 If the IC amplifier oscillates when the noise blanker is turned on and the FL-83 CW narrow filter is installed

Bulletin #: Subject:

Procedure
1. Remove the covers to gain access to the main circuit board. 2. Remove R354 (22K) from the main circuit board and replace it with a 10K (ICOM P/N 915-01113) resistor. 3. Re-install the main circuit board and replace the covers on the radio.
This modification is read 702 times.
(IC-275) Prevent PLL unlock at high ambient temperature
1. Change the following parts on the PLL board
Original Value 12 pf 50V CH 22K 3 pf 50V New Value 6 pf 50V CH 35D 45 SN (ICOM P/N 915-04229) 15K 6 pf 50V

Part C101 R137 R133 C191

2. The thermister should be installed in series with R133. Unsolder one end of R133 and solder R137 in series with it.
(IC-275) Improve voice synthesizer and side tone audio
1. Remove C214 (.47 uf capacitor) from the main board. 2. Install a.1 mf 16V barrier layer capacitor in series with a 2.2 K 1/8W resistor from the emitter of Q58 and the base of Q59 on the foil side of the board.
This modification is read 662 times.
(IC-275) Prevention of PLL unlock at 174 MHz
1. Remove and replace the following components on the PLL Board
Original Value 120 Ohm 47 Ohm 120 Ohm 60 pf 50V 43 pf 50V New Value 270 Ohm 18 Ohm 270 Ohm 30 pf 50V 62 pf 50V
Part R130 R131 R132 C42 C47
This modification is read 701 times.
(IC-275) Improve the stability of the center meter
Replace C81 on the main board (currently 120pf 50 CH type capacitor) with a 120 pf 50V SH temperature coefficient capacitor (ICOM P/N 918-05960).

This modification is read 660 times.

(IC-275) Very fast AGC

Problem: For some modes of weak signal communication, it can be desireable to have a very fast AGC (e.g. meteor bursts with a sharp rise and a long weak "tail"). The standard fast AGC has a time constant of about 2 secs (!), which also means that a noise pulse can mute you for quite some time. Note: Never use the noise blanker when receiving high speed CW (Meteor Scatter). The noise blanker mistakes the high speed keying for noise pulses, and will seriously corrupt the signal. Solution: The solution is to move the "AGC fast" capacitor (C19) to replace the "AGC slow" capacitor (C20). You will loose the "AGC slow" option, but I find "AGC fast" adequate for most signals. Another solution is to switch out the "AGC fast" capacitor (C19) seperately, but then you will get the problem of finding an appropiate front plate switch. I already tried to use the DATA button, but it cannot be activated in CW.
Note: a strong signal will be seriously distorted in AGC OFF mode. Implementation:

(IC-275) SSB RF Gain

Cut the lead (FM8V) conneted to (pin5, J6, potmeter PCB, green) about 4 cm from the plug Connect the short plug end with R14 (on the potmeter PCB) by soldering it to the end that is connected to the plug (+8V) This will enable the FM RF GAIN in SSB/CW.

(IC-275) Tuning speed

This modification is read 679 times.

29-10-1998

(IC-275) Splitting into RX- and TX paths
This modification is read 691 times.
(IC-28) ICOM IC-28A AND IC-28H ext frq
To make the IC-28 transmit 138-174 MHz, cut D21 (no retuning required). D21 is a tiny glass diode standing on-end near the center of the upper circuit board, accessible by removing the top cover. The IC-28 is the only convertible ham rig I know that covers the 170-MHz federal government (including national park) frequencies. [source: W9MKV] Date: 16-01-2002 Subject: no cut 28-H mod The 28-H can be modified by removing a wire from a connector that connects to d21. Simply trace the circuit from d21 to the connector and pull the wire out by pressing the small metal tab on the connector and wrap it in electrical tape. The radio then can easily be "unmodified" by simple plugging the wire back into the connector. Unsure of pin# or connector number as I modified one over 10 years ago, and didn't bother to note pin or connector number.
This modification is read 1294 times.
From: Giovanni Luce, N8IWK
(IC-28) The long, noisy squelch-tail of the Icom IC-28
The long, noisy squelch-tail of the Icom IC-28 (A or H model) 2-meter transceiver can be shortened by replacing C110 (4.7 uf) with a smaller value (0.1 to 0.47 uf). (I can't remember the source of this information.) I put a 0.33 uf in my IC-28H; it's a very worthwhile modification. The capacitor is on the bottom board (the one with the lithium battery), just southeast of IC4 as you face the front of the upsidedown radio. The only difficult part is finding the right p-c pads to desolder on the back of the board. To remove the board: Remove bottom plate, unplug speaker. Unplug coaxial antenna connector (gray wire). Other connectors may remain in place. Remove 5 mounting screws, one in each corner and one near center. Tilt the board out of the radio. The button in the upper left corner is CPU reset; you may have to reprogram the memories if it is pressed. Remember that, although the radio is off, parts of the circuit are live so be sure not to short any part of the board during the modification.

This modification is read 787 times.
(IC-2SE) Extended Icom IC-2SE functions

'LIGHT+FUNC'

& SWITCH ON:
Display test Extended frequency range, 0 - 1310MHz, enters multi function mode with new PT status 'bA' for receive only, see PTT function table below for detailed operation. Tuning steps above 204MHz only 12.5KHz or 25KHz (channel number indicator changes from U to last ch. no.??) Changes PT from 'bA' to 'P' and enters multi function mode.
'LIGHT+FUNC+V/M & SWITCH ON:

'LIGHT+FUNC+C'

PTT function table
PT status Simple Mode: ~~~~~~~~~~~ P (- selects -( (TX, 144-146 'o.FF' other --pwr TX, 144-146 (*) 'o.FF' other --low beep@ TX, 144-146 'o.FF' other --pwr P PL bA
F&P - selects Multi Mode: ~~~~~~~~~~ P (- selects -( (-

TX, 144-146 --pwr

low beep, frequency low beep
high beep, 100MHz steps AM/FM toggle

F&P - selects

Notes: P stands for pushing the PTT switch, table shows in 2nd row also the result of simultaneous rotation of the tuning control, --- = no reaction. F&P stands for pushing FUNC,PTT; pwr stands for low/high toggle and for stepping by tuning control, ref. to Instruction Manual. - PT status selection via SET/PRIVATE mode, ref. to Instruction Manual. - PT status 'bA's only available for extended frequency range (after execution of 'LIGHT+FUNC+V/M' & SWITCH ON), memory contents remain unchanged (approx. working range of ext. band is 75.365MHz). - Amateur frequency range can only be recovered by 'RESET', => 'LIGHT+MON' & SWITCH ON, all memory contents will be lost! (*) THIS OPERATION IS NOT IN ACCORDANCE WITH INSTRUCTION MANUAL, P. 30 - PL SHOULD LOCK PTT (TX DISABLED) ALSO IN SILE MODE! Information was gleaned from many sources including DL8AAR, PA3FDA
(IC-2SE) Extending the Rx. coverage of the IC-2SE and IC-4SE
It is possible to extend the receiver coverage of both of the above radios without removing the covers! With the radio turned off, but beep enabled, hold down LAMP, FUNC and V/M buttons while simultaneously turning on the radio. Keep all 3 buttons pressed. The display will fill up with all sections on, then there will be a beep, a longish gap and another beep. Once the second beep is over, release the buttons. Lo and behold, you now have coverage of any freq from 0 to 1300 MHz, except, of course, that the VCO cannot cover the entire range. For example, the 4SE will cover approximately 380 to 480Mhz plus 805 to about 930MHz. Information originated from G8SEZ

(IC-3220) ICOM IC-3220A/H Frequency expansion
To extend the receiver range on VHF: 118.000mhz (AM) to 174.000mhz (FM) Cut D6 on the LOGIC board (located on the front of the radio) To extend the receiver range on UHF: 400.000mhz to 479.000mhz Cut D4 on the LOGIC board. To extend transmitter range on VHF: 136.000mhz to 174.000 Solder a bridge between the solder pads next to D9 To extend transmitter range on UHF: 400.000mhz to 479.000mhz Install 1SS190 (diode) at D9 position on the LOGIC board.
This modification is read 799 times.
(IC-3220) ICOM IC-3220A/H mini repeater function
1. Set rig to "DUAL" by using the BAND switch. 2. Set frequencies in VHF and UHF. You may set in offset on either band. You may also set it up in VFO or MEMORY. 3. Simultaneously hold BAND and SET key. The memory number will display a flashing "L". It will be in repeater mode To disable repeater mode, depress and hold "SET" key until the flashing "L" goes to a memory number or VFO mode. The repeater mode will not be disabled by turning the rig off and on.
This modification is read 897 times.
(IC-3230) ICOM IC-3230 Mods for 9k6
by IK2XYU/KF6EEZ Hi to all, here you have a step to step way to modify your IC3230 to enhance it with frequency coverage,transponder function and 9k6 Baud packet use. Is not easy make changes inside this tranceiver, so if you've not skill ask to another ham to help you !!! A good range of the frequencies are 120 - 175 MHz and 400 - 500 Mhz and 850 - 950 Mhz. Your RIG can surely handle more frequency but not with a big success on sensibility. If you make this, you'll be the responsible of your RIG. Make it just if your law permit this to you !!! 1. Take off the screws of the two covers (6+6) and remove them unplugging the speaker plug. 2. Take off the 4 screws of the front panel (2 for each side) and be careful removing it because you have a couple of flat cables. 3. Open the diodes,with a cutter, located under the front panel. They look as 1N4148 kind and you cannot make mistakes. More cuts it's meaning more new function, so you must cut all the available diodes. The diodes are located on the board called LOGIC UNIT. 4. Replace the front panel with the four screws. Connect a shield-cable (RG-58) on the small coaxial plug on the MAIN-B board and make this cable able to go outside of your RIG when you replace the two covers. To do this you can remove the small cover in the back of the RTX, the one just above the original antenna cable. This new coax-cable will be to apply the 900 MHz antenna. If you're not interested to listen to this band, you have just to replace the front panel and jump to point 5. 5. Plug in the speaker and replace the covers. If you like to make the 9k6 mod jump to point 6.

Das spart einen mords Haufen Arbeit, weil man am 475H nur sehr beschwerlich an die Buchse in der Rckwand hinkommt. Um diese Leitung umzumnzen mu man am Connector J13 den Pin 4 abklemmen, das ist eben diese Leitung zu Pin5 der Erweiterugsbuchse, und sie an PIN9/IC 6 anlten. FERTIG. Dazu braucht man nur den unteren Deckel des Gertes zu ffnen. J13 sitzt nur ca. 3 cm vom IC6 entfernt, und wenn man die Leitung an PIN 4 (schwarz isoliert) knapp am Stecker abzwickt oder aus dem Stecker herausbastelt reicht es problemlos bis zum IC hinber. Die dazugehrige Abschirmung auf Pin5 / J13 lt man natrlich dran. Das RX-Signal liegt jetzt logischerweise an PIN 5 der AQSBuchse am Gert, nicht an PIN 11, wie von DG5EM ursprnglich beschrieben. Fragen bitte an DH1SAJ @ DB0RBS, MYBBS DB0SAO ist z.Zt. ohne LINK 73 de Jochen, DH1SAJ @ DB0RBS
This modification is read 507 times.
(IC-490) Modifikation af IC-490 for 9K6
1. The back section is fixed by four screws through the side plates. Remove those screws and bend the back section as far as the wiring allows. You will see the screw heads when the top and bottom cover of IC490 have been removed. 2. 470 nF = 0.47 F The capacitance could be higher, but there are space limitations inside the rig underneath the IC490 Main Unit print. For the time being you will not need the connection with varactor D3 for any satellite, but you may need it for a 9600 baud terrestrial net. It will, however, be feasible to prepare that connection as well when the AF/FM and AF/SSB connections are being built. 3.
+12V -------+ 4.7 k X 850 k X 0.47 F +----> SSB out to 9-pin connector #3/IC3 / SSB in ->-------*cable-----+-- BC337 or similar NPN transistor 0.47 F 150 k X -
*cable from 0.47 F condenser on the Main Unit to the amplifier located at an empty spot within the rig You will need the above amplifier only when SSB signal level at #3/IC3 will not be sufficient for your TNC. I am not familar with TAPR 1200 baud psk modem. 4. As you know doppler shifts UO-14 frequency downwards only from rise to set. Often 435.077 ---> 435.058 MHz. Consequently IC490 needs down commands only. It will get such a command each time the calculated frequency drops by 1 kHz. My program calculates the current frequency, not doppler shift only. I initally tune my Rx to the frequency I know UO-14 has, when rising above horizon. I dont need to hear UO-14 at that moment. In fact I know UO-14 frequency any time without listening, just by looking at the monitor. When I tune my Rx at that frequency I know that UO-14 is there. The control system then steps the frequency down as frequency calculation tells it to do. I think you will not need the diagram for the circuitry since your tracking program apparently does not tell the above things. You would find Finnish speaking fellows at the subsidiaries of Finnish companies, like EPL-Kone Pty, in your country. That would unfortunately not solve the program problem. Pate OH2SN @ OH2RBI

+------------------------+ | | [XX] [XX] [XX] [XX] [XX] +-O Solder wire into this hole ^

* *** *

8. Solder a small wire into this hole. Be careful not to apply too much heat; use a low-wattage soldering iron. Be careful not to damage the PCB or the grey cable coming out of J8. Use a magnifying glass. 9. Run the other end of the wire you just soldered to the front of the radio and attach it to the yellow wire you just cut. 10. Re-assemble the radio.
This modification is read 3273 times.
(IC-706) IC-MHz to 200 MHz bandpass filter
From: gary@ke4zv.atl.ga.us (Gary Coffman) Ok, here's the computer simulation info I promised. I modeled the 60 MHz to 200 MHz bandpass response. To say the least, it sucked rocks. There are two poles, one at about 136 MHz and the other at about 160.5 MHz. Response is nice and flat from 60 MHz to 120 MHz with less than 4 db of ripple, but it takes a dive from there. In the 130 MHz to 170 MHz range, the loss is at least 36 db, rising back to only 30 db at 200 MHz. Image rejection at 280 MHz is only 26 db. Now the ideal fix is to change the inductors so that L49 is 27nH, L40 is 22 nH, and change C152 to 30pF. That gives a lovely passband across 60 MHz to 200 MHz, and gives strong image rejection at 280 MHz and up, with one of the nulls falling right on that frequency. The factory ought to do that. Unfortunately, examination shows these coils aren't easy to modify. So there's another way that still gives a pretty good response. If you remove C53 and C153, you'll get full response, though with a dip of 4 db in the 160 MHz to 180 MHz range, and only 26 db of image rejection at 280 MHz. But if you increase the value of C152 to 32pF by tacking the removed C153 across it, response flattens and tightens in the upper VHF range, and image rejection improves to 31 db at 280 MHz. That's about as good as we're going to get without replacing L49 and L40 and C152 with the recomended values. Here's the ARRL Radio Designer file for the filter.
************************************************** *ARRL Radio Designer v1.0 *IC-MHz to 200 MHz bandpass filter * Gary Coffman KE4ZV 1/18/96 ************************************************** Blk **Component data inductors L22:1.2uH L49:82nH L40:68nH L25:0.15uH L26:0.18uH L27:1.2uH

;ideal 27nH ;ideal 22nH

**Component data capacitors C51:.001uF C154:20pF C153:0pF C152:32pF C53:0pF C151:24pF C52:18pF C54:220pF C55:22pF C56:82pF C57:27pF **Node list IND L=L22 CAP C=C51 CAP C=C154 IND L=L49 CAP C=C153 CAP C=C152 IND L=L40 CAP C=C53 CAP C=C52 CAP C=C151 CAP C=C54 IND L=L25 CAP C=C55 CAP C=C56 IND L=L26 CAP C=C57 IND L=L27 BPF:2POR END **Frequency block FREQ

Turning this board over with the LCD now facing you there is position for 7 SMD diodes marked A or A2 on the right hand side just above the central mounting point. The easiest way of removing them without damaging the assembly is to desolder one end with desoldering braid and the while heating the contact with the soldering iron lift that end with a small pointy screw driver (0.7mm jewellers are good!). They just need to clear the board by a fraction and then they can be easily reinstalled if necessary. Reverse this procedure to reassemble and be bloody carefull!!!. Cheers ERIC. Many tnx to Eric for finding the programming diodes. In the European version (IC-Q7E) there are 3 diodes mounted. Counting from the screwhole, there are # 1,3 and 7 installed. Number 1 sets the VHF tx range to 144-146 MHz. Number 3 sets the UHF tx range to 432-438 Mhz. Number 7 enables the facilities dedicated to the E-version, 1750Hz etc. So, if You want to keep the E-version don't remove #7. Removing #1 and 3 enables tx range from 136-174 and 400-470 MHz. For expanding only rx at the celluar band on 800 MHz, it seems to be another mod. too. Take a look at ZANA's home page www.alles.or.jp/~zana/index.htm if you are keen on Japanese.
This modification is read 3070 times.

23-03-1999

(IC-Q7) Icom Q7A mods from the factory
I have received the mods for the Q7A radio from Icom. You will have to take dissasemble the radio by : 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Removeing the batteries Removeing the 2 screws in the battery compartment Remove rear cover Desolder and remove the back board Remove the last screw on right side of radio Remove the antenna and volume knob and the two nuts Desolder the speaker leads Slide main board out Hold board that faces the front of the radio towards you Remove the SMT (s) as per ic-q7a.gif image Reassemble Reprogram
I have tried this on my radio and it works just great. TX is from 140 Mhz to 170 Mhz and 400 Mhz to 470 Mhz with no degradation in the receiver or transmitter. I also placed the radio on a service monitor and specs were the same as manufacturers specs. ( except the transmitter He He He ) Be careful and have fun, Any questions about this mod please feel free to E~Mail me anytime. Ray N2ZEM

This modification is read 2905 times.

20-02-1999

(IC-W32) Crossband repeater and extended RX/TX mods
Mods for the IC-W32E tranciver by SM6VIT Rickard. 970703 The IC-W32E tranciver is a funny little radio that can do alot more than it does when it leaves the factory. On my radio i have RX on these FQs: AM 108-136MHz FM 136-200MHz 300-400MHz 400-600MHz 600-1000MHz Now these are the FQs that is shown in the display so if U got a FQ far away from ham bands that dont work that is OK. I havent tested the sensitivity on different FQs so that is for U to do. Now to the really fun part, the TX FQ can be these: FM 108-136MHz 136-196MHz 362-400MHz 400-492MHz The further away from ham FQs U use the lower the output power will be. And remember that your antenna might not be built for all these FQs. To use extended RX FQs U have to do like this. While pushing [SQL] and [BAND] turn on power. It is as easy as that at least on my radio. This can be diffrent on some radios that are sold in contrys where it is illegal to listen to other than ham FQs. WARNING! WARNING! WARNING! WARNING! Your warranty may be expired if U take your radio to pices! And most likly it is illigal to have a TX expanded radio in your contry! For the TX expantion it is a little bit more dificult. U have to solder in your radio. First U have to remove D523 (4) on the logic unit. Remove battery, remove 6 screws on the metal plate under the battery, lift up the metal plate and there is the logic unit. It shoult look someting like this.
_____________________________ |_ ic341 ic201 o ic5 flat cabel HHHHHHHHHHHH ______________________________| o | 5| |__ | | O | _| __|__ |diode| |_____| | | | O_|

WARNING!

1=D528, 2=D52, 3=D525, 4=D523, 5=D531 All diodes have 3 legs! Then push for RX expand. Crossband repeater function is possible on the IC-W32E but it dosent work on my radio. It depends on witch CPU U have. But U
could always try it. Set VHF and UHF FQs, turn tone squelch on, turn lock function on, turn off the tranciver, push [SQL], [MAIN] and [BAND] keys and turn power on. E-mail: sm6vit@hotmail.com.MODIFICATION.NET sm6vit@swipnet.se.MODIFICATION.NET packet: sm6vit@sk6yw.o.swe.eu
This modification is read 2327 times.
(IC-W32) To extend the receiver and open up 800 MHz receive (cellular blocked) for IC-W32A
Turn off the radio Press and hold the band and squelch buttons. Turn on the radio while holding these buttons, wait for 5 seconds before you release the band and squelch buttons. Now the receiver should be opened up as far as it will go.
Date: 31-12-2001 Subject: All IC-W32-A Pushbutton Mods

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