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ICOM    MODLARI

(ICOM) TA1DX de OE9XPI>r 107

ICOM @EU de:OH3FP 19.09.91 15:20 0 3115 Bytes

IC2410E RX COVER. MOD.

*** Bulletin-ID: 11806_OH3RBC ***

Read: 2

Path: OE9XPI!DB0CZ!DB0SAO!DB0GV!DB0SIF!DB0EAM!DB0BQ!DB0AHA!PI8DAZ!PI8AIR

Path: !SM2EKM!SK2DR!SK2AU!SK2AT!OH6RBG!OH6RDW!OH6RBC!OH6RBV!OH6RBT!OH1RBF

Path: !OH1AK!OH1AU!OH2RBI!OH3RBC

Sent: 910914/1832Z @OH3RBC.FIN.EU #11806 [Lahti - FBB5.12b]

 

Riihimaki 14.09-1991

 

 

New ICOM IC-2410E Receiver coverage modification

 

ICOM introducing a new dual band mobile tranceiver this year 1991 summer

and i thing that this is maybe good buy and i buy it.

First think when i get this rig and put it in power on ,i see this

incredibly bad display. When sun is very good shining this display is

very bad, you not see allmost nothing this type display.

But when darkness is coming there is very much better visibility...

 

So i want also that receiver coverage have to be very large so that is

ICOM IC-3220 and etc. I looking this radio logig unit so that i can see

there is somelike initial matrix and i looking also technical infos

what say that RX have to go "normal" ICOM coverage 138-174 and 400-479 MHz

so i opened this rig face side where logig unit is located.

Holy cow there is so much surface mounting parts so i decide forget this

soldering any components becouse i not have circuit board pictures.

So i decide try is there any combine of pushing some buttons same time when

push power on.

 

I found that like combining:

 

PUSH SAME TIME V/MHz + SET + MICROPHONE DN BUTTONS AND THEN PUSH POWER ON

 

After this anything happens BUT VHF side frequency coverage is :

118 - 174 , 320 - 479 MHz

UHF side frequency coverage is:

138 - 174 , 320 - 479 and 820 - 970 ? MHz but this 820-970 MHz rig doesn't

hear anything.

 

have nice modification and sorry my bad english.

 

73 de Markku OH3FP@OH3RBC

 

ICOM IC2400a MOD INFO

**************************

ICOM 2400A MINI REPEATER FUNCTION

1. CUT D9 (MAY NOT BE REQUIRED NOT IN ALL RADIOS)

2. TURN OFF POWER

3. PUSH AND HOLD MONI, MHZ, SET BUTTONS & MIC DOWN BUTTON

4. TURN ON POWER

5. RELEASE ALL BUTTONS

ICOM 2400A REPEATER FUNCTION CANCELL

1. PUSH AND HOLD SET BUTTON

2. THEN DEPRESS MHZ

 

NOTES:

IF YOUR RIG HAS D9, THE DIODE ABOVE IT WILL EXPAND THE 440

BAND RECIVE IF IT IS CUT ALSO.

TO FIND D9, LOOK AT THE BACK OF THE FACE PLATE INSIDE RADIO

ON LEFT HAND SIDE, YOU SHOULD SEE A VERTICAL LINE OF 7

DIODES, D9 FOR REPEATER IS 2ND FROM THE BOTTOM AND 440

EXPANDED RECIEVE IS THE 3RD ONE FROM THE BOTTOM. THIS IS

KINDA HARD TO EXPLAIN, AS OF THIS WRITING THERE ARE NO

SERVICE MANUALS AVAILABLE, BUT ICOM WILL SEND YOU THE MOD

WITH A PHOTOCOPY OF THE MOD IF REQUESTED.

CALL GARY FIBER KF7XV, ICOM TECH. CUSTOMER SERVICE REP. AT

PHONE # 206-454-7619, OR FAX AT 206-454-1509.

********************************************************************

HM-56 New Autodialer Mic with 32 memories for 2400/2500A

MIC GAIN adj for 2400A is R13 (70%dev adj +/- 3.5 KHZ.)

********************************************************************

IC 2400A CROSS BAND REPEATER OPERATION

1) put both bands in "VFO" mode

2) set up one band with repeater offset and tone (if needed)

3) set other band for simplex

4) turn off radio

5) get a Octopus to help you, with the power off, push and

hold following buttons: MONI, MHZ, SET, & DOWN button on

microphone, while holding all above, turn on power.

Note- for Icom 2500A substitute CALL button for SET in

step 5.

TO GET OUT OF REPEATER OPERATION:

With power on, push SET button and hit MHZ button

Note- Some rigs will have to have D9 diode cut on Logic

board, however, later rigs do not have this diode.

Anybody have out of band RX/TX mods for this rig? Please

send to Bill N2EZG @ KC2AZ PBBS in Elmira N.Y.

**NOTE** If above does not work, reset the CPU as per Operation Manual before

tearing in and looking for diode, I had to reset mine, and my 2400A serial#

02402 did not have the diode. Info obtained from "Gary" at Icom Bellevue

Service Dept.



 

8506r 8506

Date: 03 Sep 90 16:31

Message-ID: <22513@VE4KV>

From: VE4KV@VE4KV

To: ALL@ALLONT

Subject: Mod for IC-24AT

Path: VE3EUK!VE3INF!VE3FJB!VE3KYT!VE4KV

 

 

 

OUT OF BAND MODIFICATION OF THE ICOM IC-24AT

 

The Icom IC-24AT is truly a remarkable unit. Having it's

genesis in the IC-R1, Icom's extremely wide band Hand Held

Receiver, it is capable of receiving a wide range of frequencies,

as well as being able to transmit on short excursions, outside of

the amateur two meter and 440 MHZ. bands.

The more current models can be modified to receive out of

band, by a simple software (not necessary to physically open the

transceiver) procedure as follows;

o Turn the power switch off. While simultaneously holding the

"light" button, the "B" button, and the "#" button, turn the

radio on. All elements of the display will light up.

Continue holding the buttons until the display goes out. It

may be helpful to have a buddy give you an extra hand during

this procedure....Your unit will now receive out of band.

The older models of this transceiver, require the removal of

diode D13, before performing the above procedure. D13 is on the

main logic board and is a discreet diode near the center of

the board. It is the diode on the left of the two on the board

when the radio is open and held with the controls away from you.

The "stock" transceiver, was also not designed, to provide

full direct keyboard entry of the operating frequency. This can

also be modified by one or both of the two procedures below;

o To directly key in the 10Mhz. frequency, simultaneously hold

the "light" button and the "2" button, while turning the

radio on.

o To directly key in the 100Mhz. frequency, simultaneously

hold the "light" button and the "3" button, while turning

the radio on.

The modification of the unit to enable it to transmit out of

the amateur bands is a fairly simple procedure. It is however,

complicated by the fact that the construction technique used in

this transceiver is "Surface Mounted Technology." If you have no

experience dealing with this technology, you may well be better

advised to defer this procedure to someone who has. It is

extremely small and delicate, and is best done with specialized

equipment. Also, because the unit may not be FCC type accepted

for all the frequencies on which it can then transmit, it may not

be legal for you to use it, despite the fact you may be licensed

to transmit on those frequencies. This information is provided

only for those who are licensed for and want to use the unit on

MARS and CAP frequencies, where there are no type acceptance

restrictions. The procedure is as follows;

o Order a couple of DA204u diodes from Icom or your Icom

dealer. These are a special three terminal device with two

diode in one package. They are very very small, about half

the size of one of the key buttons on the touch tone pad.

o Locate and remove the diode device in position D8

o Locate the vacant position of diode D7 and attach one of the

DA204u diodes at that location.

o Locate the vacant position of diode D12 and attach the other

DA204u diode at that position.

o If diode D13 (procedure above) has not been removed, remove

it.

The unit will now transmit out of the amateur bands.

The IC-24AT can also function as a Mini Repeater transmitting on

the UHF band while simultaneously receiving on the VHF band, or

vice versa. This procedure requires both a small hardware as well

as a software modification, and is performed as follows;

o Locate diode D14. It is located adjacent to the location for

diode D13 (see above procedure). Clip or remove it.

o To enable Mini Repeater operation

1. Push and hold the "Function" key and then the "C"

key.

2. Push and hold the "Function" key and then the "5"

key and the "D" key.

o To cancel the Mini Repeater operation, push and hold the

"Function" key and then push the "D" key.

The above modifications provided the following capabilities with

my particular unit.

FREQUENCY COVERAGE

(VHF)

RECEIVE TRANSMIT

74.9 Mhz. - 127.9 Mhz. OFF

138.0 Mhz. - 168.0 MHz. 138.0 Mhz. - 159.0 Mhz.

174.1 Mhz. - 189.69 Mhz. OFF

200.0 Mhz. - 287.22 Mhz. OFF

310.0 Mhz. - 349.0 Mhz. OFF

(UHF)

355.0 Mhz. - 409.98 Mhz. OFF

412.37 Mhz. - 498.0 Mhz. 410.5 Mhz. - 470.0 Mhz.

792.85 Mhz. - 966.66 Mhz. OFF

Receive sensitivity throughout both of the Ham bands was better

than .5 of a microvolt. Sensitivity in the 200 Mhz. range was a

disappointing 1 millivolt and in the 800 Mhz. band a good .7 of a

microvolt. Remember, while the unit will receive on those

frequencies, it is illegal to monitor cellular telephone

communications.

Good luck with your unit.

"73"

Joe Taylor, W9JO

 

 

r 2381r 2381

Date: 28 Apr 90 00:04

Message-ID: <5490@N5WX>

From: N5WX@N5WX

To: MODS@ALLONT

Subject: IC24AT New Info

Path: NT8V!VE3WZL!VE3JEZ!KI4BT!WB9TYT!KC9BK!WA9KEC!N9BYS!N9GTM!AF9M!WA9UXP!NQ9Q!KD9LP!KD9QB!WJ9U!KK9G!WD4PPF!K4BFT!WB4GHL!N5WX

There is a later version of IC24AT that does not require

D13 as in a previous bulletin.

All programming of extended frequency coverage is available

from the keyboard.

To Enable extended freq coverage - 75 to 195, 200 to over 900 Mhz.

Hold down Light, and B and turn on, wait for display to stop.

To enable 10 and 100 Mhz digit entry direct from keyboard:

Hold down light and 2 key and turn on, then turn off.

Hold down light and 3 key and urn on.

Gud luck @ 73 Ron, N5WX

VE3PZR de VE3GYQ: at 0221z on 900508 B,C,D,H,?,I,J,K,L,M,N,P,R,S,T,U,V,W >

bb

AX25 session 1 closed: Normal

Hit enter to continue

 

 

ICOM IC22S MODS & INFO

Packet Modification

The Icom IC22S is a ten watt diode matrix PLL synthesized

2 meter rig manufactured in the early 1970's. In it's stock

condition it tunes 146-148 MHz in 15 KHz steps. Since I am

sure there are a few of these sitting on shelves collecting

dust due to the limited tuning range, why not modify them

for the perfect packet rig.

First replace the 7.68 MHz Oscillator/Divider crystal (X1)

with a 5.12 MHz crystal. This will move the band to 145.00-

146.94 MHz in 10 KHz increments. The repeater offset will

now be 400 KHz which should not pose a problem in simplex

packet operation. I will give the diode matrix settings for

the most commonly used packet frequencies. You can formulate

others as needed using the formula N=100*(f-145)+61 and the

manual. The diode positions indicated ARE WHERE DIODES ARE

PRESENT. The other positions are left empty.

145.01= D5,D4,D3,D2,D1

145.03= D6

145.05= D6,D1

145.07= D6,D2

145.09= D6,D2,D1

************************************************

I have prepared information to modify the IC22S sythesizer to allow it to

have 5 KHZ steps in lieu of the original 15 KHZ steps. This will allow the

rig to go onto 145.01 MHZ for packet radio operation.

In short, the modification requires changing a crystal, making some copper

path cuts, adding some jumpers, and installing a new divide by N counter

which consists of three CMOS digital integrated circuits.

If you put it on a frequency as low as 145.01 you will also need to re-tune

the front end and you may need to re-tune the VCO free running frequency. I have

made the mod to my radio and am using it to up-load this file. I re-tuned the

front end to increase sensitivity back to the normal although it did work

without re-tuning. I did not have to adjust the VCO.

If you would like to receive the information which consists of a schematic

of new counter, old and new block diagrams and instructions to

incorporate and test the modifications, send an SASE (standard business

envelope, 22 cents postage) to:

 

***************************************************************************

ICOM IC-22S MODIFICATIONS:

Here are some technical details and modifications for the IC-22S. If you know

some other things about this rig, your messages are welcome.

Before doing any other modification, pins 13 and 16 of IC1 (programmable

divider, TC-5080P, PLL board) should be connected together. This allows the

PLL to accept all the binary codes and then cover all the frequency range

possible with the 22S. This modification is currently done and could be

already done on your rig.

**********************************

STEP MODIFICATION (PACKET RADIO OPERATION):

The normal STEP between "channels" is 15 KHz. For example, you can tune

146.610, 146.625, 146.640 MHz, but not 146.620, 146.630, etc...

The step is settled by the crystal X1 (on the PLL board), located near the

VCO (big metal box). The normal frequency of this crystal is 7.680 MHz. This

crystal also sets the offset (normal: 600 KHz) when using duplex mode, since

the offset is made by a logic circuit that adds 40 to the binary code applied

to the programmable divider (PLL). Think about it: 40 x 15 KHz = 600 KHz!!!

The step produced by a given crystal is calculated this way:

STEP = Xtal freq.(Hz) / 512

Example: Xtal 7.680 MHz: STEP = 7 680 000 Hz / 512 = 15 000 Hz = 15 KHz.

The offset is calculated this way:

OFFSET = STEP x 40

or: OFFSET = Xtal freq. / 12.8

Example: 15 KHz x 40 = 600 KHz

7.680 MHz / 12.8 = 600 KHz

If you want to have a 10 KHz STEP, you need to change the crystal X1 for a

5.120 MHz crystal:

STEP = 5.120 MHz / 512 = 10 KHz

Doing so will make the rig operate from 144.390 to 146.950 MHz, in 10 KHz

segments. However, the OFFSET will be 400 KHz instead of 600 KHz. Repeater

operation is therefore impossible, but

this modification is best for PACKET RADIO operation!

Suggestion: You can use a 10.240 MHz Crystal (which is common in CB rigs and

electronic stores) and divide its frequency by 2 with a divider. You can use

the unused pins of IC6 (uPD4013C) as a divider. To do this connect pins 9 and

12 together, enter your 10.240 MHz signal on pin 11 and you get a 5.12 MHz

square wave on pin 13.

If you want a 5 KHz step, You need a 2.560 MHz crystal.

IC22S.3

BAND SEGMENT MODIFICATION:

The normal frequency coverage of the IC-22S (with X1=7.680 MHz) is 144.390 to

148.215 MHz, a range of 3.825 MHz (Fmax - Fmin), by 15 KHz steps. The

frequency segment covered by the IC-22S is settled by Crystal X2 (near X1 on

PLL board). Its normal frequency is: 44.563 333 MHz. The lowest frequency

(Binary code 00) and the highest frequency (binary code 255) covered by the

radio with a given crystal (X2) is calculated this way:

Fmin. = (Xtal freq. x 3) + 10.7 MHz

Fmax. = (Xtal freq. x 3) + 10.7 MHz + (RANGE)

RANGE = (X1 / 2) - (X1 / 512)

Example:

Fmin=(44.563 333 MHz x3) + 10.7 MHz=144.390 MHz

Fmax=(44.563 333 MHz x3) + 10.7 MHz +((7.68 MHz/2)-(7.68 MHz/512))=148.215 MHz

 

As I said before, the normal coverage of the IC-22S is 144.390 to 148.215 MHz

(With X1=7.680 MHz). The 215 KHz Higher than 148.000 are useless and limits

coverage in the low portion of the 2 meter band. Changing X2 by a 44.488 333

MHz crystal will make the IC-22S covering from 144.165 to 147.990 MHz (15 KHz

steps).

Fmin = (44.488 333 x 3) + 10.7 = 144.165 MHz

Fmax = (44.488 333 x 3) + 10.7 + ((7.68/2)-(7.68/512)) = 147.990 MHz

An interesting modification is to change X1 for a 5.120 MHz crystal, allowing

a 10 KHz step, and change X2 for two appropriate crystal, each one allowing

2 MHz coverage.

With X1=5.120 MHz, replacing X2 by a 44.923 333 MHz crystal will give the

following coverage:

Fmin = (44.923 333 x 3) + 10.7 = 145.470 MHz

Fmax = (44.923 333 x 3) + 10.7 + ((5.12/2)-(5.12/512)) = 148.020 MHz

With X1=5.120 MHz, replacing X2 by a 44.250 000 MHz crystal will give the

following coverage:

Fmin = (44.250 000 x 3) + 10.7 = 143.450 MHz

Fmax = (44.250 000 x 3) + 10.7 + ((5.12/2)-(5.12/512)) = 146.000 MHz

These two crystals could be installed with a switching device, to use one at a

time. This allows fuull coverage of the 2 meter amateur band (144-148 MHz),

in 10 KHz segments. Local oscillator can be slightly detuned to allow

operation on 5 khz steps (146.745 MHz, example). I have not worked on it yet.

If you do it successfully, let me know!

IC22S.4

OTHER INTERESTING MODIFICATIONS:

Would you like to convert your IC-22S to receive SSB and CW signals? If you

own a shortwave receiver, or a general-coverage HF rig, you can do it easily,

for less than a dollar!

All you need to do is to take a sample of the 455 KHz IF amplifier signal in

your IC-22S and apply it to your shortwave receiver, tuned on 455 KHz in USB,

LSB or CW.

Connect a 68 K ohms resistor on the collector of Q6 (455 KHz IF amplifier).

It's a 455 KHz IF amplifier, NPN 2SC945; collector is the center pin. Connect

the free end of this resistor on the inner conductor of a coaxial cable.

Connect the shield of this coaxial cable on the ground (-) of the IC-22S.

The other end of this coax is connected on the antenna connector of your

shortwave receiver, with the appropriate connector. This coax could be RG-58U

or shielded speaker wire; the length is according to your convenience. The

resistor is used to limit loading of the IF amplifier.

The frequency you want to listen is selected on the IC-22S. Your SW receiver

must be tuned on 455 KHz. The mode you want to use (USB, LSB, CW) is selected

on your SW receiver. This modification can NOT be done in transmission,

because too many modifications of the IC-22S are involved. You would need to

change the RF amplifier because it's in class C, which doesn't work in

AM and SSB.

*****************************

R149 pot: adjusts low power. Reducing R148 increases maximum low power (less

than 10 Watts...) possible with R149 pot.

R73 pot (30K): adjusts TX meter readout. When this pot is connected on D10

instead of D11, the meter indicates SWR. R73 could therefore be used to

calibrate FORWARD reading.

R89 pot (100K): Adjusts SWR feedback, and therefore SWR protection level.

R132 pot: adjusts Mic. Gain.

R124 & R112 pots: Adjusts Maximun deviation.

R124 pot: Adjusts symmetry of clipping of mic. amplifier.



 

ICOM IC228 MOD INFO

I have the mod info from ICOM. It is best to have the diagram in

front of you when performing the mod, but for the bold ones, here goes:

There are three PC boards in the rig. The TX and RX boards are on the

top and bottom of the rig. The logic board is behind the front panel, and

the LCD display and front panel switches are mounted on it. It is the

logic board which will be the object of your surgery.

1. Remove D-19

2. Install D-7 - (Type 1SS193)

D 7 should have three terminals, but only one is used.

It looks something like this:

| C

-----------

| / | There is no connection to the terminal on the

| / | lower right. The Cathode of a 1N914 diode

----------- Can be connected to the upper terminal, and

A| | the Anode to the lower left. (as indicated by

the C and A.

 

In locating the positions of D-19 and D-7, reference the lithium battery.

D-19 is at the 1 O'clock position near the edge of the board, and

D-7 is at 2 O'Clock and adjacent to the battery.

 

*****************************************

Model: IC-228

Division: Amateur

Note: This service bulletin is meant for technical per-

sonnel with experience working on solid state com-

munications equipment. Damage caused by im-

properly installing this modification may cause

ICOM to charge for subsequent repairs to the

product. ICOM does not warrant this modification.

Bulletin #: 13889-002

Date: May 1, 1989

Subject: "Dampened" S-meter response at low ambient tem-

peratures.

Procedure

1. Replace the following components on the Main Board.

Original New ICOM

Part Value Value P/N

R33 15K 8.2K 915-01112

C8 120pf 50V 39pf 50V 918-01643

Bulletin #: 13888-001

Date: May 17, 1988

Subject: Some radios may not maintain programmed memory

data

Information: There is a solder bridge that is missing to com-

plete the lithium battery circuit to maintain

memories.

Procedure

Write to ICOM's customer service department for a copy of

this service bulletin.



 

ICOM IC04AT MOD INFO

********************************************

OUT OF BAND MODIFICATION FOR ICOM IC-04

1. On the logic matrix, remove D402.

2. Add D402, D403 and D404 with the cathode at 4 o'clock and the anode at 12

o'clock. (You may use any signal diode such as 1N914)

3. Add D405 with the cathode at 8 o'clock and the anode at 12 o'clock.

4. If you have a newer 04AT, the VCO cover will have holes in it that

allow access to the tuning coils. If you have an older 04AT you will

have to cut a hole in the VCO cover using a pair of small diagonals (be

careful!).

5. Retune the VCO to cover your desired frequency spread. My 04AT goes from

441 to 473 MHz, which is pretty good.

6. Any frequency may be entered directly on the keypad (starting with the 10

MHz digit).

 

*************************************

Subject : ICOM AUDIO MOD

===== AUDIO MODIFICATION FOR ICOM IC02 AND IC04 RADIOS =====

This audio mod works on the 02 and 04AT. It increases the level of audio, as

well as rolling off some of the lows. Sounds real nice. It involves the

circuit around Q105.

1. Replace C119 with a .01 uF cap (disc ceramic is fine).

2. Parallel R131 with a 1 uF cap (use a tantalum cap).

3. Parallel R132 with a .01 uF cap (disc ceramic is fine).

This is not the same mod as the one International Radio is advertising, which

involves changing C117.

I tried an AB-1 Audio Blaster from Engineering Consulting, and was very

unhappy with the results. I am very pleased with the audio given by this mod

(much cheaper too!).

***********************************************

Subject: ICOM 02/03/04 & Vox Unit

The ICOM Family of Hand-Held Radios (02/03/04 AT) are well suited

for packet radio given the many available power supply options.

The big problem is getting the PTT to operate " CLEANLY " while

not compromising the audio level from the TNC when using the resistor

or resistor/capacitor interfaces suggested in some manuals.

I am using the ICOM HS10-SA Vox unit to interface the ICOM 02/04 AT

here.It has worked somewhat well for some time but I was always plagued with

a MINIMUM 200 msec transmit "hang " delay until I tore it apart for

examination and correction.

The small " delay " pot on the front of the unit is in series with a

2.2 Megohm resistor (R-19 on the board). The adjustable pot is also

about 2 megohms as well. This combination allows a MINIMUM VOX "hang" transmit

delay of 200 msec.

By identifiying the solder connections for R-19 on the back of the PC board

and placing a low value resistor ( or jumper ) in parallel....I was able to

achieve a ZERO "hang" transmit delay time with the delay pot in the FULL

COUNTER-CLOCKWISE position. The minimum 200 msec delay has been defeated.



 

OUT OF BAND MODIFICATION FOR ICOM IC-04

------------------------------------------------------------------------------

1. On the logic matrix, remove D402.

2. Add D402, D403 and D404 with the cathode at 4 o'clock and the anode at 12

o'clock. (You may use any signal diode such as 1N914)

3. Add D405 with the cathode at 8 o'clock and the anode at 12 o'clock.

4. If you have a newer 04AT, the VCO cover will have holes in it that

allow access to the tuning coils. If you have an older 04AT you will

have to cut a hole in the VCO cover using a pair of small diagonals (be

careful!).

5. Retune the VCO to cover your desired frequency spread. My 04AT goes from

441 to 473 MHz, which is pretty good.

6. Any frequency may be entered directly on the keypad (starting with the 10

MHz digit).

-----------------------------

***->Be careful not to transmit out-of-band, or accidentally operate on

any non-amateur, unless you are authorized to do so.

DO NOT JEOPARDIZE YOUR LICENSE!

 

===== AUDIO MODIFICATION FOR ICOM IC02 AND IC04 RADIOS =====

------------------------------------------------------------------------------

This audio mod works on the 02 and 04AT. It increases the level of audio, as

well as rolling off some of the lows. Sounds real nice. It involves the

circuit around Q105.

1. Replace C119 with a .01 uF cap (disc ceramic is fine).

2. Parallel R131 with a 1 uF cap (use a tantalum cap).

3. Parallel R132 with a .01 uF cap (disc ceramic is fine).

This is not the same mod as the one International Radio is advertising, which

involves changing C117.

I tried an AB-1 Audiolaster from Engineering Consulting, and was very

unhappy with the results. I am very pleased with the audio given by this mod

(much cheaper too!).

 

[EOF]

 

ICOM IC03AT

ICOM 02/03/04 & Vox Unit MOD INFO

The ICOM Family of Hand-Held Radios (02/03/04 AT) are well suited

for packet radio given the many available power supply options.

The big problem is getting the PTT to operate " CLEANLY " while

not compromising the audio level from the TNC when using the resistor

or resistor/capacitor interfaces suggested in some manuals.

I am using the ICOM HS10-SA Vox unit to interface the ICOM 02/04 AT

here.It has worked somewhat well for some time but I was always plagued with

a MINIMUM 200 msec transmit "hang " delay until I tore it apart for

examination and correction.

The small " delay " pot on the front of the unit is in series with a

2.2 Megohm resistor (R-19 on the board). The adjustable pot is also

about 2 megohms as well. This combination allows a MINIMUM VOX "hang" transmit

delay of 200 msec.

By identifiying the solder connections for R-19 on the back of the PC board

and placing a low value resistor ( or jumper ) in parallel....I was able to

achieve a ZERO "hang" transmit delay time with the delay pot in the FULL

COUNTER-CLOCKWISE position. The minimum 200 msec delay has been defeated.

**********************************************************

If you own one of the IC2A, 3A, or O2AT series Hand-helds, you may be

interested in reading on. I know my hearing is pretty good, but have you ever

tried to listen to the audio coming out of your speaker mike on the above

ICOM's? For the most part, it's pretty low. I may be the last guy to figure

out a cure for this, but here it is anyway. On the O2AT,etc., there is a

groove on the back near the top of the rig that is just the right size to

accept the HM9 speaker mike turned 90 degrees so that the mike plug fits in

that groove in the rear of the rig. Thus allowing all the audio to be heard

from the internal speaker of the rig, usually much better than the speaker

mike. Now, in the case of the 2A series, etc., the fix is more complex.

These rigs don't have that handy groove built in, so I decided a groove had to

be made to accept this configuration. I thought long and hard about a minute,

before getting the "Dremel" out and making my own slot or groove. It works

well on both hand-helds I have. In fact,you can hook up an external speaker

for even more loudness in the auto. So, give it a try or see me for a demo.



 

ICOM IC02AT

AUDIO MODIFICATION FOR ICOM IC02 AND IC04 RADIOS

This audio mod works on the 02 and 04AT. It increases the level of audio, as

well as rolling off some of the lows. Sounds real nice. It involves the

circuit around Q105.

1. Replace C119 with a .01 uF cap (disc ceramic is fine).

2. Parallel R131 with a 1 uF cap (use a tantalum cap).

3. Parallel R132 with a .01 uF cap (disc ceramic is fine).

This is not the same mod as the one International Radio is advertising, which

involves changing C117.

I tried an AB-1 Audio Blaster from Engineering Consulting, and was very

unhappy with the results. I am very pleased with the audio given by this mod

(much cheaper too!).

If you own one of the IC2A, 3A, or O2AT series Hand-helds, you may be

interested in reading on. I know my hearing is pretty good, but have you ever

tried to listen to the audio coming out of your speaker mike on the above

ICOM's? For the most part, it's pretty low. I may be the last guy to figure

out a cure for this, but here it is anyway. On the O2AT,etc., there is a

groove on the back near the top of the rig that is just the right size to

accept the HM9 speaker mike turned 90 degrees so that the mike plug fits in

that groove in the rear of the rig. Thus allowing all the audio to be heard

from the internal speaker of the rig, usually much better than the speaker

mike. Now, in the case of the 2A series, etc., the fix is more complex.

These rigs don't have that handy groove built in, so I decided a groove had to

be made to accept this configuration. I thought long and hard about a minute,

before getting the "Dremel" out and making my own slot or groove. It works

well on both hand-helds I have. In fact,you can hook up an external speaker

for even more loudness in the auto. So, give it a try or see me for a demo.

**************************************************

ICOM IC02AT

BAND EXPANSION MODIFICATION FOR IC-02AT FOR SERIAL NUMBERS ABOVE 34000

1. Remove back from radio (5 screws) and bottom plate (4 screws).

2. Carefully remove radio chassis from front case by pulling out top of

radio and lifting slightly (to remove battery contacts from bottom

case). Be extremely careful of ribbon cable and heat sink compound

on power amplifier module.

3. Remove diode D2 from matrix board.

4. Add diode D4 (any small diode 1N4148; 1SS211).

5. The following is a schematic of the matrix board:

ADD D4 REMOVE D2

I--+ --+-- --+-- +

V D4 ID3 I ID2 I D1

I I I I I

+ + +---+ +---+ + +

6. Install radio chassis back into front cover. Leave back off temporarily.

7. Carefully apply power to radio and enter the lowest desired frequency.

8. Adjust slug through bottom hole on VCO cover for .5 VDC at VCO test

point (just below VCO shield) at lowest desired operating frequency.

9. This completes the modification. A few words of caution: 1. The

radio is not type accepted for use in the commercial band. 2. Make

sure you reinstall the battery latch correctly on bottom of radio or

battery will become permanently locked onto radio. 3. Tighten screws

on bottom of radio snuggly. If they loosen while battery is connected

you cannot remove the battery. (This has happened to many units and

it would be prudent to periodically check these screws to assure their

tightness.)

 

*******************************************************

Another Icom IC02 Modification

The following method of modifying the Icom IC02 is an alternate

to the IC02.MOD file. This one should give you PL out of band without

jumpering 5 VDC to the tone chip. Use 1N914 or equivelent when adding

diodes.

1. On the logic matrix, remove D402 and D403.

2. Add D402, D403 and D404 with the cathode at 4 o'clock and the anode at 12

o'clock.

3. Retune the VCO to cover your desired frequency spread. My 02AT did not

want to go beyond 163 MHz. I have a friend who was able to get his to the low

170s.

4. To jump from 140 to 150 or from 150 to 160 (or vice versa) you must "tune

across" the boundry, in the same way that you do for an unmodified 02AT. For

example, key in 149.995 and then move up until you are in the 150s. You can

then enter any 150 MHz frequency (starting with the MHz).

 

**********************************************8

Subject: ICOM 02/03/04 & Vox Unit

The ICOM Family of Hand-Held Radios (02/03/04 AT) are well suited

for packet radio given the many available power supply options.

The big problem is getting the PTT to operate " CLEANLY " while

not compromising the audio level from the TNC when using the resistor

or resistor/capacitor interfaces suggested in some manuals.

I am using the ICOM HS10-SA Vox unit to interface the ICOM 02/04 AT

here.It has worked somewhat well for some time but I was always plagued with

a MINIMUM 200 msec transmit "hang " delay until I tore it apart for

examination and correction.

The small " delay " pot on the front of the unit is in series with a

2.2 Megohm resistor (R-19 on the board). The adjustable pot is also

about 2 megohms as well. This combination allows a MINIMUM VOX "hang" transmit

delay of 200 msec.

By identifiying the solder connections for R-19 on the back of the PC board

and placing a low value resistor ( or jumper ) in parallel....I was able to

achieve a ZERO "hang" transmit delay time with the delay pot in the FULL

COUNTER-CLOCKWISE position. The minimum 200 msec delay has been defeated.

 

********************************************************************

ICOM HS-10SA VOX MODIFICATION

The ICOM headset VOX model HS-10SA for the IC-O2AT can be a

handy unit for mobile use but it has a serious limitation as

it comes from the box. There is no way to turn it off other

than unplugging it! This means any conversation with a

passenger, cough or sneeze goes out over the air.

Fortunately there is any easy remedy. Remove the 3 screws

holding on the rear cover and the single screw holding the

circuit board. Carefully lift out the board and locate R23.

It is a 4.7K 1/8 W resistor located near the lower edge of

the board.

One end of it connects to the white lead of the cable to the

HT. The other end connects to the collector of Q7. This is

the keying circuit. In normal operation, Q7 is saturated

when the VOX is active. Since the emitter of Q7 is grounded,

R23 is effectively connected from the white lead to ground,

keying the HT. Carefully unsolder the end of R23 which goes

to Q7 and lift this lead out.

Drill a 1/4 inch hole in the center of the end of the case

and mount a SPDT switch. The switch the author used was a C

& K 7207 which is a 3 position, center off, SPDT, with one

side spring return momentary and the other side latching.

This allows the momentary side to be used to key the HT

manually, the latching side for the VOX operation, and the

center OFF.

Now connect the center pole of the switch to the end of R23

which used to go to Q7. Connect the latching side of the

switch to the hole in the board where R23 was (Q7) and the

momentary side of the switch to ground (shield of cable to

HT). Now reassemble the unit and test.

 

 

 

***********************************************************

TRANSCEIVER TRANSMIT UNLOCK (FINAL PART)

(IC-O2AT, IC-O4AT, IC-751, IC-720

Of course, in an emergency, anyone may use any type of

frequency to attract attention. The emergency must be life-

threatening or pertain to "immediate protection of property"

before one would resort to using frequencies outside of the

ham band. For mariners, the United States Coast Guard works

closely with the high seas marine radio telephone service

that is easily accessed via a geral coverage ham set modified

to transmit on general coverage marine telephone channels at

4, 6, 12, 16, and 22 MHz. However, using ham radio equipment

on telephone channels for routine phone calls is not allowed.

Even though you may have a ship radio telephone license that

allows you the use of marine telephone channels the license

only allows Part 81 and Part 83 type-accepted equipment to be

used for transmitting purposes - and again, Amaeur Radios

don't meet this type acceptance. Let me put it bluntly - if

you get caught using ham radio equipment on frequencies that

you're not authorized to use, you could lose your license and

might also face stiff fine or imprisonment. Before even

contemplating making any modification to your equipment,

weigh carefully the consequences of operating on frequencies

outside of your license category.

The ICOM 02-AT 2 meter handheld will go into the 150 MHz

range with some modification.

On the ICOM 02-AT, as well as on the ICOM -4-AT for VHF

and/or UHF work, both units require semi-major diode surgery

for frequency expansion. For VHF, two diodes are removed and

three are added for the ICOM 02-AT to extend all the way up

to 165 MHz. For UHF work, two diodes are added to extend the

range of the ICOM 04-AT. The modification is tricky, and a

bit complicated.

On the brand new ICOM 735, to unlock the transmitter, you

simply cut diodes D33 and D34 that are standing on end near

the microprocessor section toward the rear top of the radio.

On the IC-745, locate the RF board on the side of the radio

and cut the light brown wire at jack 7, which is going to pin

1. Your transmitter is now unlocked.

On the IC-751, locate the RF board on the side of the radio

and cut the black wire going to pin 1 of jack 2. Your

transmitter is now unlocked.

The ICOM thumbwheel VHF handheld IC-2AT, can also be modified

for 150 MHz transceive, but once you make the mod, you lose

all of your 2-meter frequencies. You would be better to

simply go out and buy a type-accepted VHF transceiver as

opposed to ruining your present 2-meter ICOM IC-2AT!

The older high frequency radios with VFO tuning (as opposed

to PLL tuning) do not easily allow any type of modification

for expanded transmit or receive coverage. It would require

so much modification that you would be ill-advised to try and

step up any Yaesu FT 101 series, 980, Kenwood 120, Kenwood

520, 820 or any of the older ICOMs.

For the old ICOM 720, the transmitter is unlocked by snipping

the blue wire that's at the very end of the top hatch cover

to the left middle side of the transceiver.

Again, using your ham radio outside of normal ham radio band

limits is illegal except in an emergency or where

specifically authorized. Keep this in mind before opening up

your set and attempting any modification. This article is

presented purely for the safety sake of mariners, aviators,

and backpackers who lay their lives on that one piece of

radio equipment that will come to the rescue when an

emergency should arise.

 

*************************************************

A simple procedure for resetting the CPU that doesn't require opening the

rig.

1)Turn there radio off

2)Press the FUNCTION button on the side of the radio and hold it on.

3)Turn the radio on.

That's it. The CPU is reset to the rig defaults to (144 Mhz).

 

***********************************************************

IC02AT INTERFACE TO MFJ 1270B TNC 2 PACKET RADIO

SPEAKER JACK

1. CONNECT THE SHIELD (PIN 2 - GROUND, AUDIO AND PTT COMMON) TO THE

LONG OR OUTSIDE POST OF THE SPEAKER JACK.

2. CONNECT THE BLACK WIRE (PIN 4 - RECEIVE AUDIO) TO THE SHORT OR

CENTER POST OF THE SPEAKER JACK.

 

MICROPHONE JACK

1. CONNECT THE YELLOW WIRE (PIN 1 - MICROPHONE AUDIO) TO ONE SIDE

OF A .05 MICROFARAD DISK CAPACITOR (RADIO SHACK CAT. NO. 272-134)

AND THE OTHER SIDE OF THE CAPACITOR TO THE SHORT OR CENTER POST

OF THE MICROPHONE JACK.

2. CONNECT THE WHITE WIRE (PIN 3 - PUSH-TO-TALK) TO ONE SIDE OF A

1/4 WATT, 2200 OHM RESISTOR (RADIO SHACK CAT. NO. 271-1325) AND

THE OTHER END OF THE RESISTOR TO THE SHORT OR CENTER POST OF THE

MICROPHONE JACK.

3. CONNECT THE SHIELD (PIN 2 - GROUND, AUDIO AND PTT COMMON) TO THE

LONG OR OUTSIDE POST OF THE MICROPHONE JACK.

4. ISOLATE THE RED WIRE (PIN 5 - SQUELCH) WITH BLACK TAPE AS IT IS

NOT USED.

 

*******************************************************************

Modifications for IC02AT

1/ Purpose: for increased receive audio and improved response.

Solution: Remove C117. C117 is a .22 uf capacitor. It can be located by first

finding the 8 pin IC that is neart the middle of the "Main Unit". Looking

immediately above it (above pin 4) untill you see 2 round polarized capacitors.

The one on the left is C117. It can be successfully removed by just bending it

back and forth untill the leads break. Be carefull to get the right one!

2/ Purpose: To increase the memory scan and search scan speed.

Solution: Install a 100k ohm resistor across R413. To locate R413 Remove the

DTMF Board that is attatched to the inside front of the radio by removeing the

two small screws. You will now have the logic unit exposed. IC401 (which is the

postage stamp sized IC near the middle of the board) is easily visible. Locate

the bottom right corner of this device and continue down until you come to the

first micro chip resistor. This is R413. Carefully install a 1/8 Watt or smaller

100K ohm resist or across it.

This dramatically increases the scan speed but also raises the "BEEP" tone

frequency.

 

*********************************************

ICOM IC2AT MODS & INFO

If you own one of the IC2A, 3A, or O2AT series Hand-helds, you may be

interested in reading on. I know my hearing is pretty good, but have you ever

tried to listen to the audio coming out of your speaker mike on the above

ICOM's? For the most part, it's pretty low. I may be the last guy to figure

out a cure for this, but here it is anyway. On the O2AT,etc., there is a

groove on the back near the top of the rig that is just the right size to

accept the HM9 speaker mike turned 90 degrees so that the mike plug fits in

that groove in the rear of the rig. Thus allowing all the audio to be heard

from the internal speaker of the rig, usually much better than the speaker

mike. Now, in the case of the 2A series, etc., the fix is more complex.

These rigs don't have that handy groove built in, so I decided a groove had to

be made to accept this configuration. I thought long and hard about a minute,

before getting the "Dremel" out and making my own slot or groove. It works

well on both hand-helds I have. In fact,you can hook up an external speaker

for even more loudness in the auto. So, give it a try or see me for a demo.

************************************************************

Icom 02at mod 140-163 mhz

a. locate a copy of the june 1986 issue of 73 mag.

a. locate a copy of the june 1986 issue of 73 mag.

b. the article on pg. 60 is for models with id numbers

lower than 35,000. if yours is one of the newer

models like mine..... then follow these changes:

1. read the entire article b-4 doing anything!!!

2. follow steps 1 to 3 on pg. 61 "modify ur 02at"

then s t o p ! refer to fig.2 on pg. 60 and remember

the diodes on urs are in different locations than in

the pix.

3. using a very small flat blade iron and some solder wick

remove the the three leg diode d2 notice that the

numbering for d1,d2,d3,d4 are off to the left of the

actual location of the diodes on the board.

4. resolder d2 down in position d5 try to use the solder

on the pads.. only add solder to the pads if absolutely

necessary, b-4 you put the diode in place to avoid

bridging.

5. solder a store bought 1n914 or 1n4148 diode from the top

pad to the bottom left pad of d4. you will need to bend

and cut the leads of the diode and pre-tin with solder.

bend the leads of the diode so that the body of the

diode lays across the bottom right pad covering it up.

the banded end of the the diode should be facing down

towards the bottom right pad.

now you are ready to follow steps 7 to 13 and the rest of the

instructions in the article. the only difference you will find

is that a letter "u" will flash to indicate unlocked instead

of the entire display flashing. gud luck and enjoy the fruits

of you labor. if you are unable to locate the article pls

send sase to: ka1ghf

po box 1397

leominster, mass 01453

****************************************************************

ICOM IC-2AT INTERNAL ANTENNA CONNECTION PROBLEM.

I ROUTINELY USE A HALF WAVE ANT. ON MY IC-2AT HANDHELD. WHEN COLLAPSED, THE

ANTENNA HAS THE SAME GAIN ( LOSS ) AS A RUBBER DUCK ANTENNA WHILE GIVING ME

GREATER RANGE WHEN FULLY EXTENDED.

THERE IS A CERTAIN AMOUNT OF MOVEMENT OF THE CENTER PIN OF THE BNC CONNECTOR

WITH THE HALF WAVE ANTENNA ON THE HANDHELD.

THIS MOVEMENT CAUSES FATIGUE FRACTURING OF THE WIRE CONNECTING THE PRINTED

CIRCUIT BOARD TO THE BNC CONNECTOR.

AFTER NUMEROUS FAILURES, I USED THE BRAID OF RG-174 COAX TO MAKE THE

CONNECTION.

FIRST REMOVE THE BNC FROM THE RADIO AND BRAKE OFF THE NON-USED GROUND LUG.

THE PIN OF THE BNC SHOULD BEPLACED INTO THE END OF THE BRAID.

A THIN PICE OF WIRE IS THEN WRAPPED AROUND THE BRAID 3-4 TIMES, AND THEN

SECURED, THEN SOLDERED. REINSTAL THE BNC AND DRESS THE BRAID TO THE SOLDER PAD

ON THE PRINTED CIRCUIT BOARD AND SOLDER. DO NOT HEAT THE BRAID TO LOG

WHILE SOLDERING, AS SOLDER WILL BE DRAWN UP, MAKING IT STIFF AND SUBJECT IT TO

FATIGUE FRACTURING.

 

**********************************************************

Connecting Icom 2AT to packet. Jim Gerritz WA4FMA

The Icom 2at HT is an excellent little rig to operate packet. It features usual

fast electronic switching between transmit and recieve as well as a reciever

that comes back imediatly after a transmission without delay. A slow recovering

reciever can be a real hinderince to packet operation. The best feature is that

the Icom 2at is one of the most ecmonimical fully synthesized of the HT on the

market today. Like many of us, it is my only full coverage 2mtr rig. Following

it with the Heath 15 watt amp gives it the power of many larger radios. A must

for packet.

The only problem is that it has no seperate PTT line. Any time the resitance of

the center pin of the outboard mike jack is lowered, the transmitter keys. This

is the difficulty with packet. What follows is a simple schematic showing how

to connect the 2at to the TNC ustilizing a simple inexpensive audio output

transformer.

 

 

. --------) (---------- (To Center pin of

. ) ( Icom mike jack)

. 600 ohm ) ( 8 ohm

. To TNC out ) ( To Icom 2at mike jack

. ) (

. --------) (--------- (To PTT line of TNC)

 

If there is a center tap on the transformer, this may be clipped off as it is

not used in this application. The speaker jack of the Icom 2at is connected as

per instructions provided with the TNC.

For best results, I have found that if the volume control of the HT is between

the 9 and 11 O'clock positions, good copy should result. I am using the MFJ

1270 TNC.



 

Date: Wednesday, 5 June 1985

From: Russ Schroeder

Subject: IC-02A mod

Re: Modified PLL rigs

The modification to the IC-02A to increase the receiver is fairly

straight forward although a little delicate. The programming diodes

are located on the board directly behind the front panel, and are

located in the corner of the board. They are little rectangular black

three leaded devices.

The proceedure to modify the radio is as follows:

1) Remove diode D2 - use a very small iron and solder wick to remove

most of the solder, then lift the diode GENTLY while heating the

single tab side. After getting the first tab free, proceed to the

other two tabs, lifting them one at a time. Do NOT use a large iron or

too much heat.

2) Take the diode and locate in the position labled D5. Carefully

solder the diode in place.

3) Reassemble the radio except for the back.

4) Program the radio to the local weather channel (162.400 or 162.550)

in the following manner: 6 2 4 0 0 or 6 2 5 5 0

NOTE: the programming proceedure now requires that you enter the

ten's of Mhz when entering a frequency.

5) Look at the back of the radio. In approximately the center of the

exposed board is a metal can with two adjustments. The top adjustment

is a metal screw (actually a trimmer capacitor) while the bottom

adjustment is a black slug with a small rectangular adjusting slot

6) With the squelch open, adjust the lower black core counterclockwise

approximately 1 1/4 turns until you receive the weather station. As

soon as you receive the weather, STOP turning the adjustment.

7) Replace the back on the radio and you are in business.

With this modification, the radio will tune from 140.000 Mhz to

something over 162.550 without difficulty. Just remember that you

must enter the ten's of Mhz when entering a frequency. This

modification does not affect the transmitter which still covers

140.000 to 151.995 Mhz.

Please note: This mod does not retune any of the RF stages of the

receiver so the sensitivity is down some at the weather frequency,

however, I have no difficulty receiving it at thirty to forty miles.

I do have the ICOM service manual on the IC-02A. I purchased it from

Delaware Amateur Supply at a local hamfest several weeks ago.

According to the manual, the VCO on the PLL should cover 25 Mhz.

minimum.

Good luck. If you hear of any other mods to the IC-02A please let me

know.

Russ W2DYY

[email protected]



 

===== AUDIO MODIFICATION FOR ICOM IC02 AND IC04 RADIOS =====

------------------------------------------------------------------------------

This audio mod works on the 02 and 04AT. It increases the level of audio, as

well as rolling off some of the lows. Sounds real nice. It involves the

circuit around Q105.

1. Replace C119 with a .01 uF cap (disc ceramic is fine).

2. Parallel R131 with a 1 uF cap (use a tantalum cap).

3. Parallel R132 with a .01 uF cap (disc ceramic is fine).

This is not the same mod as the one International Radio is advertising, which

involves changing C117.

I tried an AB-1 Audiolaster from Engineering Consulting, and was very

unhappy with the results. I am very pleased with the audio given by this mod

(much cheaper too!).

----------------------------------

 

[EOF]

 

Another Icom IC02 Modification

===============================================================================

The following method of modifying the Icom IC02 is an alternate

to the IC02.MOD file. This one should give you PL out of band without

jumpering 5 VDC to the tone chip. Use 1N914 or equivelent when adding

diodes.

1. On the logic matrix, remove D402 and D403.

2. Add D402, D403 and D404 with the cathode at 4 o'clock and the anode at 12

o'clock.

3. Retune the VCO to cover your desired frequency spread. My 02AT did not

want to go beyond 163 MHz. I have a friend whowas able to get his to the low

170s.

4. To jump from 140 to 150 or from 150 to 160 (or vice versa) you must "tune

across" the boundry, in the same way that you do for an unmodified 02AT. For

example, key in 149.995 and then move up until you are in the 150s. You can

then enter any 150 MHz frequency (starting with the MHz).

-----------------------------

***->Be careful not to transmit out-of-band, or accidentally operate on

any non-amateur, unless you are authorized to do so.

DO NOT JEOPARDIZE YOUR LICENSE!

 

[EOF]

 

BAND EXPANSION MODIFICATION FOR IC-02AT

FOR SERIAL NUMBERS ABOVE 34000

BY LTC STEVE PETERS, CAP

------------------------------------------------------------------------

1. Remove back from radio (5 screws) and bottom plate (4 screws).

2. Carefully remove radio chassis from front case by pulling out top of

radio and lifting slightly (to remove battery contacts from bottom

case). Be extremely careful of ribbon cable and heat sink compound

on power amplifier module.

3. Remove diode D2 from matrix board.

4. Add diode D4 (any small diode 1N4148; 1SS211

 

5. The following is a schematic of the matrix board:

ADD D4 REMOVE D2

I--+ --+-- --+-- +

V D4 ID3 I ID2 I D1

I I I I I

+ + +---+ +---+ + +

6. Install radio chassis back into front cover. Leave back off temporarily.

7. Carefully apply power to radio and enter the lowest desired frequency.

8. Adjust slug through bottom hole on VCO corr for .5 VDC at VCO test

point (just below VCO shield) at lowest desired operating frequency.

9. This completes the modification. A few words of caution: 1. The

radio is not type accepted for use in the commercial band. 2. Make

sure you reinstall the battery latch correctly on bottom of radio or

battery will become permanently locked onto radio. 3. Tighten screws

on bottom of radio snuggly. If they loosen while battery is connected

you cannot remove the battery. (This has happened to any units and

it would be prudent to periodically check these screws to assure their

tightness.)

------------------------------------

***->Be careful not to transmit out-of-band, or accidentally operate on

any non-amateur, unless you are authorized to do so.

DO NOT JEOPARDIZE YOUR LICENSE!

 

[EOF]

 

Newsgroups: rec.radio.amateur.misc

From: [email protected] (David E. Meer)

Subject: ICOM P2AT keyboard mods

Message-ID: <[email protected]>

Originator: dmeer@scgraph

Keywords: ICOM, P2AT, HT

Sender: [email protected]

Nntp-Posting-Host: scgraph.afit.af.mil

Organization: Air Force Institute of Technology

Distribution: usa

Date: Thu, 10 Sep 1992 12:45:54 GMT

Lines: 45

 

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

 

 

 

 

 

 

===== BAND EXPANSION MODIFICATION FOR ICOM MICRO2 =====

1. Remove battery.

2. Remove 4 screws securing battery. Slide from front panel.

3. Remove small black screw below PTT switch.

4. Carefully separate the front speaker from the body by pulling front

and rear down toward battery. Flip it over.

5. Next remove steel chassis assembly by gently prying up the sides,

lift up, fold it down.

6. Solder in new diode next to Q131 and Diode D113. Looking at Diode

Matrix with top of radio to the top, add diode to the empty pad to

the left of diode D119. There are 3 points of connection on the

diode pad. Two on the left and one centered vertically on the right.

The diode should be installed between the lower left and the right

centered connection. (Arrow on diode points to right centered connection.)

7. Reset CPU by following instruction manual page 23.

----------------------------------

***->Be careful not to transmit out-of-band, or accidentally operate on

any non-amateur, unless you are authorized to do so.

DO NOT JEOPARDIZE YOUR LICENSE!

 

[EOF]

 

Date: 17 May 90 15:54:21 GMT

From: [email protected] (Ken Wyatt)

Subject: IC-24AT Receive Mods

At the request of several interested hams, I am posting the modification

instructions for the Icom IC-24AT. This set of instructions originated

from Icom America and was downloaded from the Icom Library of HamNet

(Compuserve).

Ken WA6TTY ([email protected])

-----------------------------------------------------------------------

IC-24AT Undocumented Features - (from ICOM)

 

The IC-24AT dual band handheld had three additional features that

are not described in the owners manual. These have been left out

of the owners manual because some countries restrict the use of

the radio in these modes.

 

AM AIRCRAFT RECEIVE PLUS 740 to 960 MHz RECEIVE

Remove D13 from the main logic board (this diode may already be

removed by ICOM in some units). This diode may already be

removed in some radios. D13 is on the main logic board and is a

discreet diode (one of the two in the radio) near the center of

the board. It is the left discreet diode of the two on the board

when the radio is open and held with the controls away from you.

Simultaneously hold "Light", "B", and "#" keys depressed and turn

power on.

It is important to note that the radio will not meet specifica-

tion on the out of band receive frequencies that are enabled with

this modification.

 

DIRECT KEYBOARD ENTRY of 100 MHz FREQUENCY

Simultaneously hold "Light" and "3" keys depressed and turn power

on.

 

CROSS BAND REPEAT (simplex)

Remove D14 from the main logic board (this diode may already be

removed by ICOM in some units). The diode is a discreet diode to

the right of D13 (from above) and directly beside it.

Simultaneously hold "Funct" depressed and push "C".

To turn on cross band repeat:

Hold "Funct" depressed then push "5" and then push "D".

To turn off cross band repeat simultaneously hold "Funct" and "D"

depressed.

 

2-14-90

------------------------------

 

 

 

at-500 automatic antenna tuner modification

i have been using the icom at-500 automatic antenna tuner for six months, and

it is a great piece of gear. however, there is a very minor modification i

performed to the tuner to better suit my needs.

the tuner automatiacally selects one of four antenna s0-239 connectors on the

back depending upon which band you are operating. many of us utilize one feed

line for an 80 and 40 meter dipole or inverted vee. the at-500 (and at-100)

has two seperate antenna terminals for these bands. if you desire to use one

feed line for both of these lower band antennas, you either have to install a

coax switch and manually switch the tuner in line, or unscrew the pl-259

connector from one antenna terminal and install it on the other. all of this

is inconvenient and defeats athe purpose of an automatic tuner. the mod i

performed is extremely simple. i moved the wire going to antenna terminal #3

and moved it to terminal #2. this directs the 80 meter rf to the same terminal

as the rf for 40 meters and allows one to use the same antenna terminal for

both bands and one feed line. to perform the change, remove the top cover of

the tuner, locate the two correct terminals using page 6 of the manula,

unsolder the one to be move, and s9lder it to the correct terminal. the

terminals are easy to reach. just be sure all connections are good.

by ku5j. RELAYED BY N0KGX...GENE

 

From : M1AHG

To : EMC@WW

Type/status : B$

Date/time : 09-Feb 19:56

BID (MID) : 6E0337M1AHG

Message # : 330907

Title : 706 noise /m

Path: !W0XK!KB0NCE!WD0DAN!KB0TDF!WB0TAX!WU3V!PP5BLU!9A0YRB!OK0POK!OK0PRG!

!OK0PPR!OK0PKL!DB0MAK!DB0ERF!DB0HSK!PI8DRS!PI8DAZ!PI8GCB!PI8WFL!PI8VNW!

!GB7PMB!GB7MAX!GB7COV!GB7COV!GB7WAR!GB7AVM!GB7SRC!GB7DEO!GB7UWS!GB7HSN!

!GB7DAA!GB7TUT!

 

 

From: M1AHG@GB7TUT.#32.GBR.EU

To : EMC@WWW

 

Hello, here is a quick run down of what I have.

Ford Escort-electric ignition.

706 mk2 Brand New With non ICOM external speaker

Twin Comet quality hatch mounts.

Caravan Battery NOT trickel charged from car

%emote head option.

The radio and battery are in the boot.

Gnd terminal on radio connected to EMC filter only.

Battery is not bonded to the body work. The only connection to the body

work is via the twin hatch mounts.

Should I connect the back of the radio to the car body? Do the same with

the battery?

Any other comments?

How should I best to any of the above??

---------------------------------------------------------------------------

 

Also, whilst using the radio static mobile (not used radio for a few

weeks) I heard a clicking noise.

When I tuned or moved any other control, I got a buzzing sound. Move the

controls slowly, and I get a rapid click that changes with the speed of

the tuning.

Also, has the bar graph changed, this also produced a "ticking" sound!

It sounds a bit like "synthisiser(?)" sound. A sort a harsh buzzing

screech.

No DSP OR NB switched on.

Damp?

Ground prob?

Duff radio???!:-(

It stopped after I got out a couple of times and checked connections. It

came back after a closed the door briefly! However, after another check it

was fine. HF lovely and clear:-)

By the way, turning the RF gain down help to reduce the "ticking sound",

but of course, whilst turning it, I got a buzzing sound!

Help!

[email protected]

http://members.xoom.com/jamesridout

A member of the Sutton & Cheam R S

73 - James, M1AHG (M0BOV) @ GB7TUT

Message timed: 18:33.43.2 on 08 Feb 99

Message sent using WinPack V6.42 on Win2kPro Beta

 

 

--- End of messsage #330907 to EMC from M1AHG ---

(2) TA2EM BBS (H for help) >

From : M1AHG

To : ICOM@WW

Type/status : B$

Date/time : 08-Feb 14:31

BID (MID) : 170334M1AHG

Message # : 330813

Title : Grounding 706 /m?

Path: !I6BNW!IK6PYS!IK6RUY!I4UKI!IK5CKL!IK0XUM!IK0VTC!IW0QMN!WB0TAX!N7NEI!

!WB7AWL!VE4UA!ON6AR!PI8HWB!PI8ZAA!PI8GCB!PI8WFL!PI8VNW!GB7PMB!GB7MAX!

!GB7COV!GB7COV!GB7WAR!GB7AVM!GB7SRC!GB7HSN!GB7DAA!GB7TUT!

 

From: M1AHG@GB7TUT.#32.GBR.EU

To : ICOM@WWW

 

Hello, here is a quick run down of what I have.

Ford Escort-electric ignition.

706 mk2 Brand New With non ICOM external speaker

twin Comet quality hatch mounts.

Caravan Battery NOT trickel charged from car

remote head option.

The radio and battery are in the boot.

Gnd terminal on radio connected to EMC filter only.

Battery is not bonded to the body work. The only connection to the body

work is via the twin hatch mounts.

Should I connect the back of the radio to the car body? Do the same with

the battery?

Any other comments?

How should I best to any of the above??

---------------------------------------------------------------------------

 

Also, whilst using the radio static mobile (not used radio for a few

weeks) I heard a clicking noise.

When I tuned or moved any other control, I got a buzzing sound. Move the

controls slowly, and I get a rapid click that changes with the speed of

the tuning.

Also, has the bar graph changed, this also produced a "ticking" sound!

It sounds a bit like "synthisiser(?)" sound.

Damp?

Ground prob?

Duff radio???!:-(

It stopped after I got out a couple of times and checked connections. It

came back after a closed the door briefly! However, after another check it

was fine. HF lovely and clear:-)

By the way, turning the RF gain down help to reduce the "ticking sound",

but of course, whilst turning it, I got a buzzing sound!

Help!

[email protected]

http://members.xoom.com/jamesridout

A member of the Sutton & Cheam R S

73 - James, M1AHG (M0BOV) @ GB7TUT

Message timed: 21:23.43.2 on 06 Feb 99

Message sent using WinPack V6.42 on Win2kPro Beta

 

 

 

--- End of messsage #330813 to ICOM from M1AHG ---

 

From : M1AHG

To : ICOM@WW

Type/status : B$

Date/time : 10-Jan 10:29

BID (MID) : D60264M1AHG

Message # : 325920

Title : 706+car electrics

Path: !I6BNW!IK6PYS!IK6RUY!IW0QMN!PP5BLU!9A0YRB!OK0POK!OK0PPL!OK0PKL!DB0ZWI!

!DB0HOT!DB0LPZ!DB0ERF!DB0HSK!PI8DRS!PI8DAZ!PI8GCB!PI8WFL!PI8MBQ!PI8VNW!

!GB7PMB!GB7MAX!GB7COV!GB7COV!GB7WAR!GB7AVM!GB7SRC!GB7HSN!GB7TUT!

From: M1AHG@GB7TUT.#32.GBR.EU

To : ICOM@WWW

 

Anyone had any probs with using the 706 mk2 with car electronic systems??

E-Mail [email protected]

http://members.xoom.com/jamesridout

73 - James, M1AHG (M0BOV) @ GB7TUT

Message timed: 21:34 on 08 Jan 99

Message sent using WinPack V6.42 with Win98

--- End of messsage #325920 to ICOM from M1AHG ---