noch Platz fr ein RX-NF Kabel. Fr die NF-Signale mssen vernnftig geschirmte Leitungen geringer Kapazitt verwendet werden. Fragen bitte an DH1SAJ @ DB0RBS. MYBBS DB0SAO ist zur Zeit ohne Link. 73 de Jochen, DH1SAJ @ DB0RBS
This modification is read 429 times.
(IC-27) IC-27 mic-connector mods
For those interested in an alternate method here is what has been done by wb4fow on several other radios: Since about 1985 most icom radios have pin 8 of the microphone connector wired to the speaker. This is convenient for the wiring of a tnc and is usually easy to modify so that receive audio is taken from the high side of the volume control. On the ic-27/37/47 radios, on the bottom side of the radio, since about 1985 most icom radios have pin 8 of the microphone connector wired to the speaker. This is convenient for the wiring of a tnc and is usually easy to modify so that receive audio is taken from the high side of the volume control. On the IC-27/37/47 Radios, on the bottom side of the radio, just under the area of the speaker, is a two pin connector with a green and red wire attached. The green wire is speaker audio and the red wire is +8 volts. By cutting these wires and attaching the green wire to the high side of the volume control and atted wire to switched 12 volts. A TNC can be wired to just the microphone connector and makes a clean installation provided the radio is dedicated to packet. To get back to the subject of the alternate modification for the ic-3200a you can rewire pin 8 of the microphone connector to the high side of the volume control and avoid the muting circuit but if you plan to leave the tnc wired permenantly to the radio and also,to use the radio on voice you will need to change a resistor in the tnc so as not to load down the audio at the volume control. The value of this resistor will have to be determined experimentaly. If anyone requires more information or assistance with this matter feel free to call clark, wb4fow, at 305-594-4313 monday through friday 10am to 6pm or leave a message in the wb2wpa or n4ldg pbbs's. Good luck!
This modification is read 751 times.
(IC-27) ICOM IC-27H 2M transceiver for use with the 9k6
Here are the mods I made to my radio for use with 9600 baud modem. I hope they make sence to you. How to modify the ICOM IC-27H 2M transceiver for use with the 9600 baud modem (for use with uosat-3)
+---------------------------------------+ MAIN UNIT SIDE +-------------------- +----------+ VCO UNIT x--------------- +----------+ PLL UNIT +---------------------------------------+
"x"= D4 1SV50. Connect wire direct to cathode side of diode.
Front of the icom ic27h. viewed from bottom. Bring a thin single core shield audio cable through the hole on the rear of the set where the power cable comes out, there was quite enough space on my radio. Feed this cable up the side of the radio to the front panel and along to the PLL UNIT where the

Jack - the notes about mods to the FT736R were specific to that machine, and won't be relevant to the IC735. 1. What you need to do is work out a way to belt the varactor directly. Then inject a square wave (1200 hz will do) and measure the deviation that results. 2. You can do this measurement with either a proper deviation instrument or more likely with a monitor RX, by looking at the output from it's discriminator. 3. You can calibrate the monitor RX quite easily, Tune in a steady unmodulated carrier and note the discriminator DC output voltage Change the RX frequency by 1 Khz (knob on the RX front) and note the change in DC voltage. That gives you the monitor RX sensitivity in volts per Khz. 4. Now return to the TX, and adjust that driving square wave to give you approx +/- 3 kHz, you want to see about 6x volts peak to peak square wave on the monitor. (Somewhere between 4x and 6x will do, no more.) 5. Now return to the modem and juggle about with the TXAudio output components to achieve this level of drive signal, and look at the monitor RX too. 6. When you have done this, which should take you all of 30 minutes, you should be in business. If you can't get square waves TX to produce squarish waves out of the monitor RX, then the varactor dept. must be suspect, and so on. All is fairly logical. Hope useful. Let me know the results. 73 de James G3RUH @ GB7SPV 1990 Mar 28 Since I am not going to be able to try the mods until I return from a vacation I won't be able to give you an answer as to whether they work or not. But it is my opinion they will. What is happening is that between the mic connector and the varactor the digital signal is being badly distorted and the bird does not respond to the digital signal. This would not make much difference on voice but on a digital signal it makes all the difference in the world. Please feel free to contact me further if I can be of any further help. Best regards Jack W9FMW Note: From Bill K7RIE ICOM has not tried this mod nor have we verified this problem.
This modification is read 731 times.
(IC-271) VOX of an IC-271,471,1271 usable for FM

This modification is read 834 times.
(IC-2GAT) IC-2GAT to packet
For those of you who are trying to interface something to a rig which has a single two-conductor plug for both microphone input and push-to-talk connections, such as many of the handheld rigs including the Icom IC-2AT and IC-02AT, here are three circuits that may be useful to you: ::: Electret condenser microphone to radio: Radio Shack #270-092 mic element?
MIC--------------+--------------------O------------> Mic/PTT on radio | | | | | | <-- Shield +------///----+ | | (20-30K) / <-- PTT | | / switch | +--------------------+ +-----------+------------> Ground on radio ::: Dynamic microphone to radio: MIC +-----------------------O----------> Mic/PTT on radio COIL C | C | C / | <-- Shield | / | +-----------+ +-------+----------> Ground on radio ::: High-level input (such as from tape recorder, RTTY AFSK generator, or Packet TNC output) to radio: HIGH LEVEL OUTPUT: RADIO INPUT: (0.47 uf) Audio to transmitter -------||-------+----O------> Mic/PTT on radio (25K) | | Push-to-talk -------///------------+ | <-- Shield
| Ground -----------------------------------+------> Ground on radio
I made a big mistake in the previously-posted schematic of the connection between an Icom IC-2A, 2AT, or 02AT and a packet radio TNC, RTTY afsk unit, or another microphone. The resistor and capacitor were backwards. The correct schematic follows:
Audio from TNC* PTT | | --/ (C1) --(R1) | / | | Icom HT | | mic input------+-------------+
Ground | | | | | | | | ground--------------------------------+
C1 - 0.47 uf capacitor R1 - 25K resistor
* TNC or RTTY afsk or another microphone or whatever you are interfacing to your Icom HT.
This modification is read 780 times.
(IC-2GAT) ICOM IC-A20 alkaline headset-adapter lost-in-the-soup
dralle@roxanne.tmc.edu (Sir Matthew G. Dralle)
> > > > > > > > > >
>.I paid $449 + sales tax for a new IC-A20, $26 for the ICOM >alkaline battery pack, and $50 (arrgghhh) for the headset adapter >(Sigtronics, with a yoke mounted PTT switch). If you can find >the aviation-standard connectors, it would be easy to fabricate >a headset adaptor and save a few dollars. Be careful - There is a LOT more to the ICOM PTT switch than meets the eye. There is no easy way to match up an external mic and the ICOM with out the PTT unit from ICOM. A couple of jacks and a switch or two isn't gonna do it. Icom uses a wierd wiring scheem in the mic jack so that if you were to plug a mic into the Icom directly, you would have to use the PTT *ON* the radio. I..[ stuff deleted some where in here ] can't remember the exact wiring now, but without extensive modification and an additional relay *ADDED* to the PTT cicuit from Icom, you won't be able to use your standard PTT that you got with your headphones. I hate to be a downer, but those are the facts.

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

FIGURE 2

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

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

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

Information:

Procedure 1. 2. 3. 4. 5. Remove the covers from the radio and locate the main board. Locate C-749 and replace it with a 2.2 uf 16 V tantalum chip capacitor. Reassemble the radio, power up and allow the unit to enter the power save mode. Check to see that the pulse type noise has been eliminated. Replace the covers and return the radio to service.
This modification is read 769 times.

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

Bedienungsanleitung fr die "Halbautomatik": Die TUNER-Taste hat die gleiche Funktion wie mit Automatik-Tuner, nur Abstimmen muss man manuell. Falls die Antenne vor Ablauf der 20 Sekunden angepasst ist, schaltet ein Druck auf die TUNER-Taste den Transceiver auf QSO Betrieb um.
Haftungsausschluss: Der Autor bernimmt keine Haftung fr eventuelle Schden an Gerten, Leib und Leben der Nachbauer.
Literaturhinweis: [1] ICOM @DL de:DJ9XB 24.08.99 18:1555 Bytes tune control' fuer IC706, aber Handbetrieb HI *** Bulletin-ID: O89DB0ZDF02H ***
Stckliste R1 = 1M Widerstand R2 = 10k Widerstand R3 = 8k2 Widerstand R4 = 100k Widerstand R5 = 1k Widerstand R6 = 5k6 Widerstand R7 = 15 Widerstand C1 = 22Tantal-Elko 16V C2 = 10n Sibatit C3 = 100n Sibatit C4 = 100n Sibatit C5 = 22Tantal-Elko 16 V T1 = BC548 NPN-Transistor T2 = BC559 PNP-Transistor T3 = BC548 NPN-Transistor D1 = ZPD 5V1 Z-Diode IC1 = NE 555 Lochrasterplatine ca. 46mm x 25mm Schrumpfschlauch St1 = siehe Text
Alternative zum modifizierten PC Stecker: Steckergehuse Molex 03-09-2041, Best.Nr. 143-207, ca. DM 0,40 Chrimp-Kontakte 02-09-2118, 143-219, ca. DM 12,- (gibt es nur in Beutel = 100 St.) Fa. Farnell, Grnwalder Weg Deisenhofen. oder Original ICOM Kabel fr AH-3 oder AH-4 zum Preis von ca. DM 80,00

Bild 1 Stromlaufplan

Ausschneiden Bild 2 PC-Stecker
Bild 3 Layout ( vergrssert )

Bild 4 Lochrasterplatine

Bild 5 Lochrasterplatine Ltseite
This modification is read 3018 times.

(IC-706) FM Transmit Fix

(This article appeared in "Six News" Issue 59 and "Radio & Communications" April 1999)
Is your 706 not transmitting on FM properly? This maybe why Having taken my Icom IC-706 back for service twice before for the same fault, I was not prepared to be inconvenienced a third time! As it turns out IC-706s all over the World have been exhibiting the same fault. Ive had e-mail from other unhappy IC-706 owners as far away as the U.S.A. and the U.K. Upon checking the previous Fault Reports I noticed that the FM VCO had been tweaked. Hmmm There is a 9MHz VCO active during FM mode only which is modulated from the mic amp. Fault condition symptoms are;
Very low Output power (enough to be heard on a nearby receiver on the shack bench but that's about it). Carrier frequency is NOT what the dial indicates, typically 5 - 30kHz on the low side. Carrier tends to wander and sounds spurious.

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

all diodes :

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

: : : : : : : :

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

This modification is read 270 times.
(IC-P2AT) ICOM P2AT keyboard mods
There was a recent posting requesting mods to the ICOM P2AT. I received the following info from ICOM Customer Service and they work fine on my P2AT: To enable wideband receive and direct keyboard entry of the entire frequency: with the HT off, hold down "Light" "B" and "#" keys and turn the HT on Get into the set mode and you will have a new option labeled "PL". Turn the upper right knob to change this to a value of 100. (The rep at ICOM said "PL" stands for "decimal placement") Get out of set mode You should now be able to enter VFO mode and just press seven digit keys to enter any freq directly. I don't have mine with me now, but I think you can enter any freq from 0 to 1GHz (within PLL Lock range). Dave Meer, N6KEF
This modification is read 499 times.

02-11-1999

(IC-P2ET) Sensitivity for the Icom IC-P2ET
UHF 410 MHz 415 MHz 420 MHz 425 MHz 430 MHz 435 MHz 440 MHz 450,10 MHz 465,10 MHz 470,10 MHz 475,10 MHz VHF 112,4 MHz 118,45 MHz 131,125 MHz 137,5 MHz 145,5 MHz 155,5 MHz 160,5 MHz 165,5 MHz 170,5 MHz 175,5 MHz AM AM AM FM FM FM FM FM FM FM unlock 6V 1,6V 0,3V 0,2V 0,2V 0,2V 0,6V 12V 17V 30V 1V 0,6V 0,5V 0,5V 0,15V 0,15V 0,15V 0,2V 0,3V 2,5V

30-12-2000

(IC-P3AT) RX and TX modifications for ICOM P3AT
RX Modification. To open up the receiver from 215.00 to 230.00 and allow direct keyboard entry of the entire frequency: With the HT off, hold down "Light" "B" and "#" keys and turn the HT on. Get into the set mode and you will have a new option labeled "PL". Turn the upper right knob to change this to a value of 100. (The "PL" stands for "decimal placement") Get out of set mode, your radio should go from 215 to 230 MHz and allow you to key in the frequency on the key pad. This mod was courtesy of Icom America.
Wide band TX mod for ICOM P3-AT. This will open up the transmitter from 215 to 230 MHz. Open the radio as shown on page 66 in the manual. Look at the back of the CPU board and locate the CPU. Look to the left of it and you will see a surface mount diode (D18 on the diagram) mounted parallel to the CPU. This will be between 3 solder pads that look like they will fit a surface mount transistor. If for some reason you cannot find it just drop me a note and I will provide you with a copy of the board layout from the service manual. Remove this part and reset the radio. The radio will now tx over the whole frequency range. I discovered this mod my self after performing the modification for the p2/4at and discovering that it does not work. 73's, Bryan Fields, KB9MCI

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
Hello.on the mod to expand the receiving capabilities, (powering up while holding the multi and squelch keys), If the xcvr was previously programmed via Icom software and cable via PC, and the mod was enabled, you cannot re-program the radio via PC. The software reports an error that the version doesn't match..the only way to access the xcvr via PC again is to do a CPU reset (power up while holding the squelch, vfo, and, mr).. Solution. You can reprogram the radio if it was previously programmed. You just have to rerun the CS-T81 setup option that's in the start menu with the radio turned on. It will retrieve the programming info from the radio. I've done it myself several times. I use my opened T81 with my software and program my buddy's newer t81s that the receive trick does not work on just fine with this little tip. Date: 09-12-2001 Subject: Does not work on all! This Modification DOES NOT WORK ON ALL RADIOS. Please do not e-mail me for more info. I just thought I would point out that it is not valid for all of these radios. Additionally, on some, you must enter VFO Mode then turn the radio off to get the "All Segments Display". This has been confirmed by ICOM as well. So if you plan to purchase this radio in the hopes of using this mod, be careful. It is not valid. Date: 13-01-2002 Subject: Serial numbers After asking around, it appears that the "new" production IC-T81A had the majority of the extended RX tables taken out of the microprocessor due to FCC part 15 rules. The IC-T81A has a 1st IF in the 70 MHz range. The image response was poor, and so you could tune in the cell stuff via the image (140 MHz away, using this IF freq as an example). The FCC and the ECPA now require a minimum of -38 dB of image rejection for cell freqs on comm radios, scanners and yes, HTs. I cannot test my IC-T81A because it won't go into that band. But I hazard a guess that the radio didn't cut it in that department, so the microprocessor was "updated" to reflect the new reality. To my understanding, there have been at least three, steadily increasing levels of "big brother" wrt to the ECPA and how it affects what your radio toys can do/can't do in the 800 MHz region. Maybe this also explains why the ICOM "vaporradio" IC-T82A never made it to market. FYI-my IC-T81A is serial 04553 and it won't do anything above 470.000. This pissed me off as I use my radio to listen to US TV channel 17, where I work (493.75 MHz audio). Oh well, the IC-T8A I got today does just fine, and the loss of 1200 MHz doesn't affect me one bit as there is zip activity where I am located.

This modification is read 3421 times.

From: realist946

05-09-1999
(IC-T81) IC-T81 Frequency Expansion
Remove the Diode D53 and D61.
Frequencyrange after modification: 50.000 - 53.995 MHz RX/TX 118.000 - 173.995 MHz RX 136.000 - 173.995 MHz TX 400.000 - 469.995 MHz RX/TX 1240.00 - 1300.00 MHz RX/TX FM Broadcast (WFM): 76.000 - 109.995 MHz RX
This modification is read 3959 times.

30-07-2000

(IC-T81) ICOM IC-T81A Cellular Mod
The IC-T81A 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 minus 2 times the IF frequency for the T81A, which is 69.4 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 685.1 to 755.1 MHz display on the T81A. So, for example, to receive transmissions from a cellular phone at 826 MHz, just set the T81A to 826 - 138.9 = 687.1 MHz. Towers Output (display on T81A 730.1 to 755.1 MHz) to RX 869-894 MHz Cellular Input (display on T81A 685.1 to 710.1 MHz)to RX 824-849 MHz
This modification is read 3528 times.
(IC-U16) How to program the ICOM-U16
Here's how to program the ICOM-U16 - if the U16 has been made programmable by moving a jumper: Try holding FUNCT down and entering 159357. It's now in prog mode. Exit with FUNCT-CLR. Function + 159357 (Enter program mode)
Function + 1 Encoder tones (1-37) 1=67.0,2=71.9,3=74.4,4=77.0,5=79.7, 6=82.5,7=85.4,8=88.5,9=91.5,10=94.8, 11=100.0,12=103.5,13=107.2,14=110.9, 15=114.8,16=118.8,17=123.0,18=127.3, 19=131.6,20=136.5,21=141.3,22=146.2, 23=151.4,24=156.7,25=162.2,26=167.9, 27=173.8,28=179.9,29=186.2,30=192.8?, 31=203.5,32=210.7,33=218.1,34=225.7, 35=233.6,36=241.8,37=250.3 Decoder tones (1-37) ? Delta + / Delta - offset, 5 digits Frequency, 5 digits (400MHz +) ? Sch. Ch. numbers. Allows alias ch numbers. Transmit timeout enable. TI, Transmit Inhibit
+ 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9
+ SCAN Priority Scan/Ch Scan + S.CH Channel Masking + CLEAR End progamming mode

remove the battery pack. remove 4 screws that hold the sliding guide that the battery pack mounts on. This is the piece of metal that frames the PL tone switches. remove the sliding guide. Be careful that you don't lose the battery release button. there's a screw on the left side of the HT just below the light switch. Remove it. CAREFULLY pry the front panel up. There's speaker wires AND a flexable lead that goes to the front panel.
There's a shielded PCB that these leads run to. Carefully pry this up. It will then fold down. There's several flexable leads at the bottom. You should see the CPU now. With the manual, locate where D113, D119, Q131 are. Where the new|diode goes is not marked in the diagram of the CPU PCB. Locate the anodes of D119. This land connects to pin 27 of the CPU chip ic101. Locate the cathode of D113. This land connects to pin 20 of the CPU chip. These diodes are SMDs, and do not look like what you'd expect diodes to look like. In the area between Q131, D119, D113, and the CPU chip, you should see a set of 3 solder pads that form a trianglular pattern that would accept a 3 legged SMD, like the neighboring diodes and transistors. one of these pads connects to the anodes of D119. The new diode's anode goes to this pad. Another pad connects to the cathode of D113. The cathode of the new diode goes here. This means that the new diode athode will connect to pin 20 of the CPU, and that the anode will connect to pin 27 of the CPU. Carefully prepare the diode leads to line up with the proper pads, and take care that when you solder it on, you don't short to something. Also, take anti-static precautions. I used a bit of double-sticky-foam tape to hold the diode in place when I soldered it. And I left the tape to help keep it in place after I was done. Be sure that you will be able to replace the PCB you pried up, without it touching the diode. Reassemble the rig. Do a CPU reset. That is: Turn the power on while holding the light switch down. You should be able to xmit between 139 to about 160 Mhz. You could tweak the PLL to extend it further, but I didn't do this. The xmit power will be lower on the higher freqs.
Disclaimers: Be sure to have the proper permits for out of band operations. And, do this mod at your own risk!

on. on. Partial reset: on. Partial reset: on. Partial reset:

on. Partial reset:

hold [SPCH] button and turn the radio on. IC-2710H - Hold both [S.MW] buttons and turn the radio on. IC-2800H - Full reset: hold 3rd buttons from the top on both sides of the LCD display and turn the radio on. Partial reset: hold 2nd buttons from the top on both sides of the LCD display and turn the radio on. IC-3200A - Hold [F] button and turn the radio on. IC-3210A - Hold [SQUELCH/MONITOR] & [LOCK] buttons and turn the radio on. IC-3220A/H - Hold [SET] & [MW] buttons and turn the radio on. V H F / U H F B A S E: IC-271A/H - Reprogram the RAM card. IC-275A/H - Hold [M-CL] button and turn the radio on. IC-375A - Hold [M-CL] button and turn the radio on. IC-471A/H - Reprogram the RAM card. IC-475A/H - Hold [M-CL] button and turn the radio on. IC-575H - Hold [M-CL] button and turn the radio on. IC-820H - Hold [MW] button and turn the radio on. IC-821H - Hold [MW] button and turn the radio on. IC-970A/H - Hold [MW] button and turn the radio on. IC-1271 - Reprogram the RAM card. IC-1275A - Hold [M-CL] button and turn the radio on. H F B A S E: IC-77 - Clone with a computer. IC-706 - Hold [UP] & [DOWN] buttons and turn the radio on. IC-706MKII - Hold [UP] & [DOWN] buttons and turn the radio on. IC-706MKIIG - Hold [UP] & [DOWN] buttons and turn the radio on. IC-707 - Hold [MW] & [LOCK] buttons and turn the radio on. IC-718 - Hold [UP] & [DOWN] buttons and turn the radio on. IC-725 - Hold [FUNCTION] & [MW] buttons and turn the radio on. IC-726 - Hold [FUNCTION] & [MW] buttons and turn the radio on. IC-728 - Hold [FUNCTION] & [MW] buttons and turn the radio on. IC-729 - Hold [FUNCTION] & [MW] buttons and turn the radio on. IC-735 - No CPU reset available. IC-736 - Hold [CLR] & [ENT] buttons and turn the radio on. IC-737 - Hold [CLR] & [ENT] buttons and turn the radio on. IC-737A - Hold [CLR] & [ENT] buttons and turn the radio on. IC-738 - Hold [CLR] & [ENT] buttons and turn the radio on. IC-746 - Hold [F-INP] & [M-CL] buttons and turn the radio on. IC-751 - No CPU reset available. IC-751A - No CPU reset available. IC-756 - Hold [F-INP] & [M-CL] buttons and turn the radio on. IC-756PRO - Hold [F-INP] & [M-CL] buttons and turn the radio on. IC-761 - Hold [M-CLEAR] button and turn the radio on. IC-765 - Hold [M-WRITE] button and turn the radio on. IC-775 - Hold [CLEAR] button and turn the radio on. IC-775DSP - Hold [CLEAR] button and turn the radio on. IC-781 - Hold [M-CLEAR] button and turn the radio on. R E P E A T E R S: IC-RP1220 - Turn the power off for a few minutes. Push S1 on the logic circuit board. IC-RP1520 - Turn the power off for a few minutes. Push S1 on the logic circuit board. IC-RP4020 - Turn the power off for a few minutes. Push S1 on the logic circuit board. Receivers: H A N D H E L D S: IC-R1 - Hold [F] and [CL] buttons and turn the radio on. IC-R2 - Hold [FUNC] & [BAND] & [V/M] buttons and turn the radio on. IC-R10 - Full reset: hold [CLR] button and turn the receiver on. Rotate the main dial to select YES, then push [ENT] button. Partial reset: hold [MODE] button and turn the radio on. B A S E / M O B I L E: IC-R71A - Reprogram the RAM card. IC-R72 - Hold [MW] button and turn the radio on. IC-R75 - Hold [UP] & [DN] buttons and turn the receiver on. IC-R100 - Hold [FUNC] & [ENT] buttons and turn the radio on. IC-R7100 - Hold [MW] button and turn the power on. IC-R8500 - Hold [MW] button and turn the receiver on. IC-R9000 - Hold [M-WRITE] button and turn the radio on. Marine: H A N D H E L D S: IC-M1 - Push and hold [ALL CLEAR] button IC-M1V - Clone with a computer. IC-M5 - Push the button on the main circuit board next to the lithium battery. IC-M7 - Turn the radio on, hold [HI-LOW] & [LOCK] buttons, turn the power off and on again. Push [CH16/D] button to select dial mode. IC-M8 - Hold [LIGHT] button and turn the radio on.

IC-706MKIIG 58

IC-756PROII 64
This modification is read 929 times.
(MISC) QRP mod for ICOM transceivers
/ 9-volt - o-------/ ------/////--------alkaline S1 R1 battery + o-| | _____ variable R2--> --| | > shielded cable > <------------------> ALC < ------------------> JACK > | | | | ground | ON |__| | RADIO | | _____ _____ ----<
With this circuit connected to the radio, the power output is adjustable between 0 ---> 100W. For best results. leave the RF power control at maximum and adjust for desired power using R2. S1 is used to turn off circuit when radio is not in use or QRP operation is not desired.
Radio Model: IC-761, 765 IC-720(A), 735, 740, 745, 751(A), 275A/H IC-725, 726, 728, 729, 736, 737(A) R1 value 47K 2M 220K R2 value 20K 1M 100K
06/01/94 CJR For the IC-820H use the values for the IC-761, 765. The IC-781, IC-765 and the IC-820H all have the same ALC characteristics:
Control voltage Input impedance : -4 to 0 volts : More than 10 K ohms
This modification is read 898 times.

16-04-2001

(PS85) ICOM PS85 fan modification
Author: Mark - pe3hmp@hotmail.com.MODIFICATION.NET When I bought the icom PS85 power supply one thing inmediatly catched my attention, THE NOISY FAN. You would expect if You pay $450 usdollar (in the Netherlands) that this would be a great power supply and not a noisy one ! Well after 2 day I decided that it was time to do someting about it, after contacting icom I heard that there was no mod. for it so I had to do it myselve. This mod is using a NTC to sense the temp and control the speed of the fan so the temp wil not exeed 50 degrees celcius. Potentiometer P is used to adjust the lowest speed of the fan (I set P so that the fan gets at least 6,5V at 20 degrees celcius)
I have tested this mod with a ic-756 and it works great, the noise has gone down with about 50% and the PS85 works as good as before the mod. How to proceed (after building the above)
Remove upper and lower covers.
You must find a place to drill a hole for the NTC close to the diodes
Begin with drilling a hole of 3.5mm (just look on the inside so You wont drill thru a component).
How further up the hole is the better, now You have to tap M4 in the hole (be sure to use a drop of oil).

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9/13/2006 Page 1 / 1 Your Price

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