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Forum: Radio Mods
 Topic: ICOM R-7000 Receiver Heat Sink Cooler
ICOM R-7000 Receiver Heat Sink Cooler [message #74] Sat, 09 September 2006 20:32
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The new ICOM R7000 25-2000 MHz receiver is a super radio, but the power supply tends to run hot. The two biggest heat generators are the pbasstransistor and bridge rectifier module. The stock heat sink, a flat piece of metal bolted to the inside of the cabinet rear, is inadequate. After 30 minutes of use, the back panel gets very hot, and the entire cabinet warms.

I added a small heat sink to the outside of my radio, using the screw that holds the bridge rectifer to the stock heat sink. An application of heat conductive grease between the added sink and the cabinet helps the heat transfer process. Now the rest of the cabinet gets barely warm to the touch.

Bob Parnass, AJ9S

[Updated on: Sat, 09 September 2006 20:37]

 Topic: Icom 02AT Frequency Modification
Icom 02AT Frequency Modification [message #64] Sun, 25 June 2006 16:41
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icom 02at mod 140-163 mhz

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 across the bottom right pad covering it up. the banded end ohe the diode should be facing down towards mhe 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.
 Topic: Audio Modification for Icom IC02 and IC04 Radios
Audio Modification for Icom IC02 and IC04 Radios [message #63] Sun, 25 June 2006 16:38
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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!).
 Topic: Icom IC02 PL Out of Band Modification
Icom IC02 PL Out of Band Modification [message #62] Sun, 25 June 2006 16:36
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The following method of modifying the Icom IC02. 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.

 Topic: ICOM I290 Modification
ICOM I290 Modification [message #61] Sun, 25 June 2006 16:33
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The objective of the modification is to implement a delay before scanning restarts when, in SCAN-STOP mode on BUSY frequency, the received signal disappears.

The modification will then allow a frequency to be free for a while before scanning resumes. With this modification, it will be given a chance to a signal to come back within a few seconds before the scanning restarts. Now multiple QSOs or poor signals won't be truncated any more because of a too much impatient scanning !


Very simple. On the SENSOR UNIT, just solder a jumper between: - the unused contact of switch S3 (the one corresponding to the TIMER OFF position of the circuit commanding the SEL pin of IC1) - and the EMPTY signal of connector J3 (this is the extreme pin nearest S2 on the SENSOR unit)

ATTENTION, there are some errors on the electrical scheme that I possess reference A-0488 :

* The S3 switch is represented in position TIMER OFF and not ON as written. You have to reverse labels OFF and ON.

* The signals BUSY and EMPTY on connected are reversed. EMPTY (SQ1) is on the extreme left pin of S3 and BUSY is on 2nd pin of this connector S3. In fact, the switch S2 is drawn in the BUSY position and not EMPTY.


The TIMER starts when pin SEL of IC1 goes to 0V. When the TIMER is running, the scanning is halted. The scanning also stops when the BUSY signal is low level (0V) on pin SQL of IC1. Let us suppose that a signal is received. Then BUSY goes to 0V and scanning halts. At the same time the EMPTY signal , which is the inverse of BUSY, goes to 5V and the TIMER remains off.

If the received signal disappears BUSY goes high and EMPTY low, then the TIMER is enabled and starts running. It also maintains the scanning in halt mode.

If, at the end of the TIMER delay, no signal has come back then the scanning restarts. If a signal comes back before the end of the TIMER delay then the BUSY signal returns to 0V and maintains the scanning in halt mode. In the meantime the TIMER will run until the end of its delay without any action on the process.

The TIMER delay is chosen with the R32 potentiometer on the SENSOR UNIT. The minimum value is about 4 to 5 seconds which is perfect for this working mode.

Small modification .... great effect !
============================================================ ==============
Note: Proceed at your own risk.
 Topic: Expanding Functions for the IC-V8000
Expanding Functions for the IC-V8000 [message #58] Mon, 08 May 2006 23:54
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This PDF contains content on the ICOM V-8000:

1. RX Frequency Expansion
2. TX Frequency Expansion
3. ANI Function
4. Voice Scrambler Function
5. MIC Gain Level
6. Wide and Narrow Function

Click here for the PDF document for these function mods

[Updated on: Mon, 08 May 2006 23:55]

 Topic: Icom IC-2720H Out of Band Mod
Icom IC-2720H Out of Band Mod [message #57] Fri, 28 April 2006 23:23
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 Topic: Icom 735 TX Mod
Icom 735 TX Mod [message #56] Fri, 28 April 2006 23:13
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The mod for gen/cov tx for the IC-735 involves removing D33 and D34 from the main board. You'll have to lift the PA module up to do this, locate the diodes and simply snip one end of each. Very simple, but it's amazing just how many screws need removing in the process!

Good luck,
Simon Browne G0GWA.
 Topic: Icom IC-2100H Extended Transmit Mod Sheet
Icom IC-2100H Extended Transmit Mod Sheet [message #55] Fri, 28 April 2006 23:11
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Icom IC-2100H Extended Transmit Mod Sheet

For the first time anywhere on the web, the Icom IC-2100H extended frequency transmit modification and mod instruction sheet.

The socessor to the very popular IC-2000 unit, the IC-2100H has been around for a few months now and is selling for about $200 at most hamfests. The unit uncludes PL encode/decode, and 55 watts out at high power. But up until now the modification insturctions have been unavailable!

Brought to you by:

Spectracom Communications, for all your commerical radio needs call 732-989-1091 or e-mail to

W3EAX, Amateur Radio bassociation at the U of Maryland

KB3CVD, UMBC Amateur Radio Club

And amateur stations KC2AEI and W2SJW.

Please give us credit when copying these instructions!





September 5, 1998 - KC2AEI
 Topic: Alinco DR-600 Mod Extend TX/RX
Alinco DR-600 Mod Extend TX/RX [message #54] Fri, 28 April 2006 23:05
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Hi, I just got the info on how to modify the Alinco DR-600. I have activated these mods and they seem to work fine. Here they are:

Mod 1 - Activate 108 - 142 MHz and 810 - 998 MHz Receive

Remove head unit from radio and open it up.

Inside you will see a red and blue wire.

Cut the red wire.

Open the main unit and attach a wire to CN-205. This will be your antenna for 810-998 MHz.

Close everything up.

Reset the CPU by holding down the FUNC key while you turn the radio on.

To use: The VHF key toggles between 108-142 and 2m. This toggle only works in VFO mode.

The UHF key toggles between 810-998 and 70cm. This toggle only works in VFO mode.

Mod 2 - Extened tx/rx on 2m and 70cm

Remove head unit from radio and open it. (2 screws on back)

Inside you will see a red and a blue wire.

Cut the blue wire.

Put everything back together.

Reset the CPU by holding down the FUNC key while you turn the radio on.

You can now transmit and receive on the following freqs: 130-174MHz and 400-517MHz

Be carefull!!!!! You can now transmit outside of the HAM bands. Don't do this! If you do you WILL get caught and the FCC loves those $10,000 fines.

NOTE: I take no responsibility for these modifications. If you blow up your radio it is not my fault. If you have any questions about these mods call Alinco.

Chris Levin
 Topic: BC2500XLT Cellular Mod
BC2500XLT Cellular Mod [message #53] Fri, 28 April 2006 23:02
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I have never tried this mod. I have one page which I received from Grove about this modification for cellular restoration.

The page notes that the modification may not be really necessary, because you can still hear the cellular communications in the image frequencies 21.6 MHz higher that the true cellular ranges. Thus, you will hear cellular calls in the 894.01 to 915.60 MHz range on your BC2500XLT without modification.

If you really want to do the modification, here are the step-by-step directions. Most of what follows is copied verbatim from the Grove sheet, which does not have a copyright notice on it. Therefore, I'm bassuming it's OK.

1. Remove the antenna and battery pack from the BC2500XLT. Lay it on its face on a soft cloth or towel, bottom of the radio facing you. Remove the two upper (black) and two lower (chrome) screws.

2. Carefully pry the back loose from the radio and lift it off. Similarly, grasp the visible circuit board by the edges and carefully pull it away from the radio just far enough to separate it from the white (11 pin) Molex connector. Do not stretch the remaining ribbon connector. Lay the board alongside the radio.

3. Locate microprocessor chip "UNIDEN UC-1513A", the speaker, and the battery terminals. Below the microprocessor and above the speaker and battery terminals, locate the cluster of chip resistors marked "104". Using a magnifier and fine-point soldering iron, unsolder the lower-left-most chip resistor and move it one place to the left, soldering it in place.

Cellular restoration is now complete. Rebassemble the radio by reversing steps 1 and 2, and test it by entering 879.990 MHz. Search steps in this range will be the correct 30 kHz.

As I said, I have not tried this modification, so I can't testify to whether it really works. Grove states that Grove Enterprises bassumes no responsibility for damages or other liability resulting from attempting to duplicate this procedure. It is possible (probable?) that this modification may void your warranty.

Also keep in mind that there are at least two versions of the BC2500XLT. I don't know whether these modification applies to all versions.

Finally, the obligatory note to remind you that monitoring mobile telephone conversations, including cellular, is against federal law.
 Topic: Cherokee AH-50 HT Mods
Cherokee AH-50 HT Mods [message #52] Fri, 28 April 2006 22:58
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Here is an output power mod for the popular Cherokee AH-50 6 meter handie talkie. It is the first mod I've ever seen for this radio. Regular high output is just under 5 watts. After this mod you can get about 6-7 watts output while using an external 12 volt dc input and on low power about 3 watts is typical.

1.Remove all external screws and carefully pull apart the unit. Be careful not to lose the rubber PTT and feature button pads that will become lose while doing this as well as the plastic slider that locks the battery pack and power cord in place.

2.You will notice there are two separate,sandwiched circuit boards that make up the unit, one is the CPU and LCD display, the other is the RF component section. Gently pull the display board free of the RF section. They are joined together by a multi-pin terminal.

3. With the RF section fully exposed you should see a metal grounding pad that covers the underside of the RF section as well as the rf output coaxial wire. Desolder the legs of the grounding pad, as well as the lead of the coaxial wire closest to the BNC and move the grounding pad to the side, exposing the underside of the board. Use extreme caution as there are multiple surface mount components very close to these points.

4.Find the main output transistor-2SC2078 marked "C2078". It very easy to spot. It is screwed onto the radio's heatsink. With the grounding pad moved, you can now desolder the three pins on this transistor and remove. Replace with a 2SC2166. Be sure to use heatsink compound on the back of the new transistor and the heatsink during replacement. Locate an inductor with a core behind and to the left of the output transistor. There is a small hole in the heatsink above it for tuning. Tune this and all the other spring-like coils around the output final for maximum output at 53 MHZ. Make sure the radio is set on high power for this! You should see close to 6-7 watts output now, instead of the stock 4.8 watts. Rebassemble radio in reverse order and enjoy. Don't forget the radio will put a big strain on your battery pack on high power with the higher output. It is advisable to use low power setting with battery use and high only when an external 12v source is applied.

'73 KB3HAZ
 Topic: Alinco DJ-160 Mods
Alinco DJ-160 Mods [message #51] Fri, 28 April 2006 22:55
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The new Alinco DJ-160 Radio will receive between 137-174 Mhz, and transmit in the 2Meter band only (144-148Mhz). A simple modification to the radio will enable it to transmit in the full range it receives currently. I have not tested the output power on other frequencies (Due to my one and only watt meter getting fried)however I have tried setting a weather receiver a small distance away, and I did hear the radio in the receiver. To make the mod, the following must be done: (I bassume that you have some experience with electronics and that you can tell a wire from a resistor, from a transistor)

1) Take the battery of the radio by lifting the battery release button. If you look at the bottom of the radio, there will be a metal plate that is held on with 4 small screws. Take this plate off, noting exactly how the clip was held on (like the slot for the battery release clip)

2) On the back of the radio there are two screws that hold the back of the radio on, take these screws out.

3) Now you should be able to lift the bottom part of the radio by the battery release button slightly apart. I was told that you should take the top knobs off, but I found that I didn't have to.

4) If you take the Battery Release Button and turn it about 90 degress, the button should come out easily. After you get the small piece of plastic that is the button, you should see a yellow wire behind where the clip was.

5) Take a small wire cutter and CUT this YELLOW wire. You should probably make sure that the wire doesn't have bare metal showing from a lousy cutter, because I don't think that grounding this wire to the case would be HEALTHY for your radio. Smile

6) After You cut this wire. bassemble the radio, and just before you turn on the radio, do a power reset by holding the FUNC button while turning on the radio. This will reset the radio to ALL of the factory set parameters. YOU WILL LOOSE PROGRAMMED FREQUENCIES that were programmed into the memory mode of the radio, so just write the frequencies down before proceding with the above instructions.

7) The radio should be just like new, except that the transmit will be enabled for ALL frequencies! GOOD Luck!
 Topic: Kenwood TM-2550 Mars/Cap
Kenwood TM-2550 Mars/Cap [message #46] Fri, 31 March 2006 23:49
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The TM-2500 series radios may be easily modified for use on MARS/CAP frequencies from 141-150.995mhz. Locate the control unit (X54-1860-XX) on the bottom of the radio. This is the same board that the TU-7, and or MU-1 are mounted on. Just to the left of IC3 you will find a row of diodes. Cut diodes D8, and D11. After the diodes have been cut you will have to "reset" the microprocessor. Microprocessor Reset. 1. Press and hold the [PS] key. 2. Turn ON the power switch. 3. Release the [PS] key. All of your programmed data such as memory channel data, DCL data, and Phone number data will be erased and you will have to reprogram them. If the radio is not reset, it will not recognize that you have cut the two diodes.
 Topic: Kenwood TS-940s IF-10C Serial Interface
Kenwood TS-940s IF-10C Serial Interface [message #43] Sun, 19 March 2006 23:36
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The TS-940s inside serial interface is not available now so here is a solution.

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface

Kenwood TS-940s Serial Interface
 Topic: IC-208H Extended RX-TX mod
IC-208H Extended RX-TX mod [message #42] Sun, 12 March 2006 17:33
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  • Place the radio with the front panel toward you and bottom side / speaker side UP.

  • Remove the (4) screws located in each corner.

  • CAREFUL! Go slow, you will need to disconnect the speaker cable while removing the cover.

    Look at the lower right hand corner of the main printed circuit board.

  • You should see a silver crystal with the number "D196D3C" printed on it.

  • Just above the crystal, you should see an (8x8) matrix pad (see below diagram).
    o o   o o   o o   o o
    o o   o o   o o   o o
    o o   o o   o o   o-o   <-- Remove
    o o   o o   o o   o-o   <-- Remove

    Note: there are ONLY (2) resistors in place. (Bottom right and the one directly above it).

  • REMOVE BOTH RESISTORS [Do NOT attempt this unless you know how to use a low wattage soldering iron]

  • RESET THE RADIO, hold the [SET LOCK] and [S.MW-MW] buttonsdown during power-up.

    DONE! New RX/TX Ranges

    118.0000  -  135.9875    RX-AM only
    136.0000  -  173.9875    RX & TX (15% RF power fall-off at lower freq, Full 
                             power at high freq)
    230.0000  -  399.9875    RX only
    400.0000  -  478.9875    RX & TX (Do NOT transmit below 410MHz on HI-PWR, 
                             VSWR fold-back)
    479.0000  -  549.9875    RX only
    810.0000  -  849.0000    RX only
    849.0000  -  869.0000    RX only
    894.0000  -  999.9875    RX only

    Author: KD4CWB
  •  Topic: IC-7000 Fan Mod - Cool as ice
    IC-7000 Fan Mod - Cool as ice [message #40] Tue, 07 March 2006 01:09
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    Use a baby thermometor ( the electric kind w/ the digitial readout ) and see just how hot your rig is running before preforming the mod, I know most all of my readings were over 106F then the thermometer errored out as the temp was too high.

    Tempurature Measurements were made with a baby-tempurature thermometor ( sorry its all I had at the time ).

    Heres the Proof!

    top - left front 94.6F
    top - left rear 103.8F
    top - right front N/A (below 85.5F unable to get reading)
    top - right rear 92.7F
    Right side front 90.6F
    Right side rear 91.5F
    Left side Front 95.0F
    Left side Rear 98.1F

    After cw keying for aprox 5 min continous duty the heat generated by the IC-7000 did rise enough to enable to the temp control circuit. Heres the good news!

    Once the temp control circuit kicks in, the fan goes into high-rpm mode!!! Then returns to 'normal' operation with the 2W / 100ohm resistor voltage.

    So with this mod, you get a dual speed fan without any additional modifications!!

    Forgot to mention, when you goto solder the lead to the red wire of the fan, please place a rag or something undeneath the area you will be working in ( its pretty tight ) to prevent any unwanted solder dripping down onto the main board.

    When closing everything all up, there is a little pink sticky pad ontop of the cover unit to access the mars/cap and tvro mod. Place your wire so its right on top of the sticky pad. Seemed to be the best place for it at the time.

    Options, the Red wire from the fan connecter to the main board could be snipped between the connector and the solder joint to avoid any complications with the temp circuit enabling.

    Additionally, the back left of the rig, still feels warm to the touch but its more of a luke-warm, instead of what it was previously which was excessivly hot. The back right, front left and front right all feel cool to the touch.

    Im sure there are better ways of preforming this modification, although just stealing 0.14A from the 12v+ DC on the tuner port seemed to make the most sense, since an LDG Tuner only uses 300mA when in operation.

    Although I do not know how this will affect the autotuner as I do not have one, I am unable to test this modification with an autotuner, such as the LDG Z11 or Z100.

    Your Icom 7000 Running Hot? ... Heres the FAN mod!
    ( This has been untested with an inline tuner )

    1. Tuner Lead #3 is +12v DC, tap into Tuner Lead #3 with a wire ( theres enough room to simply slip a solid copper wire into the crimp for lead #3 )

    2. Add a 100ohm Resistor at the other end of the solid copper wire ( a 100ohm pot will work if you wish to be able to vary the speed of the fan )

    3. Strip the insulation of the red wire to the fan back just enough to make a solder connection to the 100ohm resistor / 100ohm pot. We used a lighter to burn away a bit of the insulation in the middle of the wire b/t where it connects to the board and where it connects to the fan itself.

    Wrap it all up with some electrical tape to prevent grounding. and Whala! Your Done!!

    Tuner Port on back of the IC-7000
    3 +12v DC -> wire -> 100ohm resistor -> fan red wire

    A 100ohm Pot could be used instead of a resistor, values below the 100ohms will increase fan speed.

    0 resistance - sounds like an airplane.

     Topic: Yaesu FT-41 wideband receive Modification
    Yaesu FT-41 wideband receive Modification [message #36] Wed, 14 December 2005 00:22
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    Wideband receive

    1. Turn the radio off
    2. Hold down the two buttens marked MHZ and A + B ...
    3. And turn the radio on at the same time......
    4. Now you should have wideband recieve!!
    This mod covers 420 MHz -- 470 MHz FM.

    Not all laws in some countrys permit the listening of these bands so please beware when in public veiw or memoriseing channels e.t.c..

    If you dont like the mod just repeat the mod again and that will go back to normal settings..
     Topic: Extended Frequency Enhancements for the Yaesu FT-23R(2M), FT-33R(220), and FT-73R(70cm)
    Extended Frequency Enhancements for the Yaesu FT-23R(2M), FT-33R(220), and FT-73R(70cm) [message #35] Wed, 14 December 2005 00:21
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    Greetings and hello radio amateur operators.

    The topic is increasing the functional frequency coverage of what has been probably Yaesu's most popular handheld tranceivers.

    To save manufacturing costs, Yaesu engineers designed multiple personalities in the same CPU module found in the FT-23R, FT-33R,UHF FT-73R and the FT-2008/7008 tranceiver. The FT-2008/7008 tranceiver is the commercial version of the Ft-x3R series.

    Unique features of this mod include
    • the just say Mao feature (**)
      (NO FREQUENCY READOUT: Ch 1 thru Ch 9 appear on your display.
      Great when you aren';t looking and some fellow ham tries to rip off your simplex frequency)

      (opens the CPU to 50-300 Mhz or 220-550 Mhz coverage. Full (.100 Mhz to 999.9995 Mhz) adjustable freq coverage available so far only on the FT-33R;this doesn't mean you can actually transmit but the Activity light goes in TX and you get a good fake RF bargraph that indicates that you can transmit on 750 MHz.
    How to do it:
    1. Contemplate invalidating your warranty. No beginners beyond this point. If you don't know how to solder, don't learn here. Ask an elmer to bassist.

    2. If you treasure your memories, write out your contents of your radio on a piece of paper. When you make the changes, the CPU runs a small diagnostic and see that the jumpers have been changed. It will ERASE ALL PRIOR SETTINGS.

    3. Dissbassemble your tranceiver.

    4. Find the line of solder connections running down the CPU board. GENTLY move all wires aside so you won't melt them.

    5. Using solder wick and a Good low-power soldering Iron, see chart. Read special notes for the FT-33R.

    6. Rebuild radio and count your blessings.


    Removal of the solder bridge labeled number nine will activate the commercial side of the CPU module. To flip to the amateur mode, you would press F UP Arrow. To flip to the commercial mode, you would press F Down Arrow.

    +=+=+=+=+=+=+=+=+=+=+= FT-23, FT-73R Chart =+=+=+=+=+=+=+=+=+=+=+=+=
       50 to 300 Mhz spread        220 to 550 Mhz spread
       --------------------        ---------------------
       Open bridges 8,9            Open bridges 7,8,9
    +=+=+=+=+=+=+=+=+=+=+=FT-33R Chart =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
    Same chart as above, but I wanted to add my experience of the Yaesu FT-33R 220 Mhz radio.
    When I removed number 7 and then did a cold reset , the CPU cleared and showed me a L and a freq. I put .100 in.
    Press D/MR. Then a U appeared. I turned the VFo knob until 999.999 appeared. Press D/MR.

    I also had to reenter the Repeater Split to the proper value.

    On the VFO, I could QSY down to those limits (using F UP/DN) and listen to my local Channel 13 on 215.720/.660.

    Yes, 216-220 Mhz is available with this mod. Great if 216-220 is the next 220 subband.

    1 Cold Reset of the CPU Board.
    With the radio upright and your nose pointing at the CPU board, look at the Lower Right Corner of the CPU chip. You will see two parallel SMT resistors. Below them is a screw with possibly a paper washer. To the right is a SMT device (it's a cap) with a pointed end facing Left. Ground that point to the screw or to the case with a flat screwdriver. Awhile doing that, cycle on/off the radio to ensure a good reset. Remove screwdriver and then rebassemble radio.

     Topic: Modification FT-27 expanded frequency range
    Modification FT-27 expanded frequency range [message #34] Wed, 14 December 2005 00:19
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    Remove the screws holding battery track and rear cover.
    Locate the "CONTROL UNIT".
    Close jumpers 1, 3, 7, AND 8.
    Rebassemble the radio.
    Turn on the radio and program it as following:

    Press and hold D/MR, T and REV while TURNING ON if you need to reset or reprogram the radio.


    Jumper 5 is for 25 KHZ steps default value.
    Jumper 9 is for battery back-up.
    Jumper 10 is for 1750 HZ repeater tone access.

     Topic: Yaesu FT-26 Expanded Frequency
    Yaesu FT-26 Expanded Frequency [message #33] Wed, 14 December 2005 00:18
    root  is currently offline root
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    Registered: December 2004
    Senior Member
    1. Remove the battery and antenna.

    2. Remove the four screws holding the back track.

    3. Remove the two screws in the back case.

    4. Carefully seperate the front cover.

    5. Locate and remove solder on jumper pad 10. (on the control board)

    6. Apply solder to jumper pads 1,3,7 and 8.

    7. Rebassemble the radio.

    8. Turn radio on and each channel indicater will blink.

    9. Enter the following frequencies. (use the [F] and up arrow keys)

    CH.1 135.000 Press [D/MR] Lower Rx limit
    CH.2 174.000 Press [D/MR] Upper Rx limit
    CH.3 135.000 Press [D/MR] Lower Tx limit
    CH.4 174.000 Press [D/MR] Upper Tx limit

    I accept no responsibility or liability for the results of any modification.
    Performing modifications and the use of modified radios may be a violation of laws.If you have any doubts do not perform any modifications.

     Topic: Yaesu FT-10 Extended Transmit Mod for 140-174MHz use
    Yaesu FT-10 Extended Transmit Mod for 140-174MHz use [message #32] Wed, 14 December 2005 00:06
    root  is currently offline root
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    1. Remove antenna and battery.

    2. Locate the Ni-Cd battery sticker on the back of the radio chbassis. Pry up the corner of the sticker and peel it off carefully.

    3. Remove the two screws located under the sticker. These retain the keypad.

    4. Slowly lift off the keypad. Use care not to dislodge the gasket.

    5. Locate and unsolder the 0 ohm chip resistor at location "M" (see diagram below).

    6. Re-install keypad with two screws. Be sure gasket is properly seated.

    7. Replace the Ni-Cd sticker if desired. Reattach battery and antenna.

    8. Press down and hold the Top-Notch and Lamp button while turning the radio on.
       | knob |
     |  +---------------+  |
     |  |  LCD Display  |  |
     |  |               |  |
     |  +---------------+  |
     |  -----------------  |
     |  -----------------  |
     |  -----------------  |
     | (on/off) ---------  |
     |                     |
     |  +---------------+  |
     |  |    Ribbon     |  |
     |  |    Cable      |  |
     |  |    ||||||     |  |
     |  |  o         o  |  |
     |  |         ::    |  |
     |  |           #:  |  |
     |  +---------------+  |
    # = Lohoneyion "M", chip resistor to remove
    The board may actually has an "M" near the correct resistor.

    [Updated on: Wed, 14 December 2005 00:12]

     Topic: Icom 32AT Open Transmit for VHF & UHF
    Icom 32AT Open Transmit for VHF & UHF [message #21] Sun, 03 July 2005 23:51
    root  is currently offline root
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    1. Remove battery and antenna.
    2. Loosen two screws on top of unit as much as possible without removing them.
    3. Loosen 4 flat head screws on bottom of unit 1 turn.
    4. Loosen 2 screws near PTT switch 1 turn.
    5. Remove 4 black screws on back of unit.
    6. Lift bottom of front cover .25 inch, slide it down .25 inch, then lift front cover up 1 inch.
    7. Disconnect plug on 4 wires coming from the speaker.
    8. Lay front panel on table up-side down being careful of the flex circuit.
    9. All mods are done to the back of the front panel. Notice places for 5 axial diodes, which I will call 1 through 5, 1 being nearest the display. Add/remove diodes so there are diodes in positions 3 and 5. This will open up receive coverage for VHF & UHF and enable keyboard entry of the 10 MHz digit.
    10. Notice 4 surface mount resistors slightly left of center directly above the speaker, lined up in a row. Solder the anode (the side without the bar) of two diodes to the right side of the lower of the four caps. Now find the CPU. It\'s the PGA under the shield near the top of the board. Find the row of pins on the CPU nearest the speaker. Notice the the 8th pin from the right has a thicker trace coming from it. Now notice that there are small solder pads about .25 inch toward the speaker on both the fat trace and the two traces to the right of it. Solder one each of the cathodes of the 2 diodes to the solder pads on the two smaller traces. This will open up the transmit for VHF & UHF.
    11. Put unit back together in reverse order.

    This procedure worked for my unit (and many others), but I can\'t guarantee it will work for yours.

    Bill Pherigo
     Topic: Special Buttons on IC706mkII
    Special Buttons on IC706mkII [message #17] Sat, 26 February 2005 16:00
    kc2nda  is currently offline kc2nda
    Messages: 29
    Registered: December 2004
    Location: New Paltz
    Junior Member
    I have tried some special buttons on IC706mkII:

    Push TS and DISPLAY while power up and you will see a strange power on check.

    Push P.AMP/ATT and RIT/SUB while power up and you will be able to see SHIFT-ADJ on your 706mkII. Dont know what this is for, recalibrating ?

    I think that these things even works on the older version of 706, dont know.

    73 - Dennis, SM6WXO @ SM6JZZ
     Topic: More talk power on SSB from your Icom 706Mk2/Mk2G and Alinco DX70TH
    More talk power on SSB from your Icom 706Mk2/Mk2G and Alinco DX70TH [message #16] Sat, 26 February 2005 15:58
    kc2nda  is currently offline kc2nda
    Messages: 29
    Registered: December 2004
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    Junior Member
    The following adjustments are to increase the average talk power on SSB for the above radios. If your radio is still under warranty, check with your supplier to ensure warranty will not be invalidated

    For both these adjustments you will need a very small cross-point screwdriver and a steady hand! Do not proceed if you are not confident!

    Alinco DX70TH: Turn up the microphone gain as detailed in the manual. This should be set to maximum. The adjustments described here is concerned with the ALC control. ALC action is indicated by the TX light which should glow brighter when speaking into the microphone.

    Remove the top cover and locate the high power/50w switch (this switch location is detailed in the manual, it is the only switch visible under the top cover). To the left of the switch there should be a small pot which is for the ALC. Just above the pot printed on the circuit board is 100w. Set the radio to 28Mhz and while speaking into the mike turn the pot counter clockwise until the TX light just fails to glow brighter. Back off slightly to restore the increase in brigthness of the TX light while speaking into the microphone. Replace the top cover.

    This adjustment increases talk power considerably and for local contacts on SSB the compressor should be switched off.

    Icom 706Mk2/Mk2G: The Icom 706 series are notorious for low talk power on SSB. A simple tweek of the ALC can solve the problem. This procedure was published in Radcom July 1999 but is updated here to include the IC706Mk2G. As far as I can ascertain, the later model 706MK2G seems not to suffer from the problem of low talk power and this mod may not be necessary. Remove the top cover. At the front edge of the main circuit board (to the left of the crystal filter slots, with the front of the radio facing you) should be a small pot. In the 706Mk2 this is R511 and in the 706Mk2G it is R579 (the number is not actually printed on the board!). The pot may be obscured by printed ribbon. This pot needs to be turned clockwise while speaking into the microphone, with power set to high and microphone gain at 6 (compressor should be switched off). Adjust for maximum talk power.

    The article in Radcom claims that this adjustment will bring the 706Mk2 up to 100w pep without the need for the compressor. For the 706MK2G (early models), adjusting R579 can give a dramatic increase in talk power although you will find that you will still need to have the microphone gain turned up to 10 and the compressor switched on. On my own set I have noticed that some bands give more talk power than others. On 160, 80 and 2 meters I get nearly full power by speaking into the mike (gain at max and compression on). However on other bands the increased talk power is not so dramatic particulalry on 10, 20 meters).

    Another way to boost the talk power on the 706 series is to use a preamplified microphone. If you do decide on a preamplified microphone reset R511/R579 back to it\\\'s original postion or distortion may result.

     Topic: Icom V8000 MARS Mod - STRAIT FROM ICOM
    Icom V8000 MARS Mod - STRAIT FROM ICOM [message #14] Wed, 29 December 2004 01:55
    root  is currently offline root
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    Here is the Icom MARS modification that I requested from the manufacturer and had to show proof of MARS licensing. They sent me this picture in the form of a PDF. I zoomed it in a lot so you could see it. In the picture the diode is removed. You can cut the solder leads with a razor or thin knife.
     Topic: IC-746 improved AGC and weak signal volume
    IC-746 improved AGC and weak signal volume [message #13] Wed, 29 December 2004 01:47
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    In the service manual under 5-4 RECEIVER ADJUSTMENT.

    For setting the RECEIVER TOTAL GAIN.

    Part 1 follow as written.
    Part 2, set R761 for 178mV (-15dB).

    This gives a better(lower) AGC knee signal level and during weak signal reception maintains good volume level without having to manually advance the volume control. This is especially useful for Six and Two metre weak signal work.

    The noise blanker, general AGC action and S meter calibration were not adversely affected.
     Topic: IC746:Using 500Hz filters on SSB for Dig Modes
    IC746:Using 500Hz filters on SSB for Dig Modes [message #12] Wed, 29 December 2004 01:45
    root  is currently offline root
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    Hi there!

    I ran usually my old TS440S-AT with 500Hz IF filters on USB mode for the Pactor lev 1 and 2, and for PSK31 very weak signals.
    Some week ago I found in a Ham fair an FL100 CW filter for the IC746 at a bargain price, and in the last days it happened to me to have some time to devote to our hobby, and so I installed the 9 Mhz IF filter for 500Hz, FL100, on the IC746 for pactor 1 and 2 and psk31, as I am used to.

    I followed the instruction on page 78 of the ICOM user manual.
    After returning all the covers on, I went to page 60 of the instruction manual, to select the installed filter for the 9MHz-1 position.
    I selected the FL100 . Then I went on page 42 for filter program mode setting as suggested on the page 60.
    Note on the top of page 42, at the beginning of the chapter 5-11, 1st paragraph: \" Optional filters ....omissis...
    .. Filters can be independently selected for each operating mode.\"
    And so I went to program mode setting and pushed the \"filter\" button for 2 seconds and then choosed to program the CW and the SSB-Narrow for 9M on 500Hz and 455k for 2.4 k ..... but - surprise - the FL100 was not available on SSB!

    I suspiciously read carefully the manual and find nothing on selecting filters depending from mode choosen..... or relation between filter type and/or bandpbass sensing... nothing. So I went to the usual \"dirty trick way\" to gamble with the filter program mode setting: I told the IC746 that the installed filter was an SSB Narrow 1.9kHz one, the FL223 type. All OK , hi hi ....

    Then I went again on the procedure of page 42, and set the SSB-N filter mode for 9M \"1.9 kHz\" (hi!) and 455k at 2.4kHz.

    It runs OK having now bandpbass of 500Hz on SSB-N mode available for Pactor lev1 and lev 2, and PSK31. On the TS440SAT I had to correct for the IF filter frequency moving the IF bandpbass slightly clockwise to fit it for the selected tone pair (1200-1400 Hz or 1400-1600 Hz) and the same had to be done on the IC746: selecting as usual USB I had to tune the outer larger one of the twin bandpbass tuning about 90 degrees clockwise.
    This proved to be quite a god setting for operation on USB Pactor level 1 and 2 using high tones.

    I tested some lower tone pair compatible with the CW bandpbass (but take care of the CW Pitch setting!!! it should be tuned fully clockwise or you\'ll get no audio out!) and tested with 400-600Hz, 500-700Hz and 600-800 Hz , but although the PtcII controller I use is very versatile on this respect, my ears are not, and so being used to \"by ear search and pre-tuning\" and then \"spectra fine tuning\" I endly went back to the usual 1500 Hz center frequency. I got 1500 Hz as I am also using pactor level3; before it I was using 1300 Hz center.

    Here people using other controllers like KAM+ or alike have to adjust their bandpbass tuning depending on the tones frequencies they use.

    Actually I have not yet the FL52A 500Hz 455kHz filter; if I\'ll find it at bargain price I\'ll buy it and test it;
    I saw by now that having 2.4 kHz bandpbass on 455 kHz works.

    I have to say that apart from this test and related trick to get the 500Hz bandpbass for USB digital RX, I would not suggest asnecessary to buy and install such filters on the IC746 : with the PtcII controller you may work very well on pactor, psk31, rtty and other 500Hz bandpbass modes on the IC746; (do not use the DSP and or NB, NR sometimes\'s good, some others no)

    The same applies for the soundblaster software programs like Digipan or others, the normal bandpbass is more than adequate, and you may taylor it using the twin bandpbass tuning.

    I recommend the narrow filters on TS440sat and alike: more,I suggest on them to replace also the 455kHz filters with other that have better performances (IN-RAD has some good ones) and the old good TS440S will copy nicely and happily very low level digital signals.

    I hope this notes will be useful for some reader, I will appreciate any feedback on this matter.

    Thanks and 73 de I2JJR Augusto
     Topic: IC-746 Backlight Repair
    IC-746 Backlight Repair [message #11] Wed, 29 December 2004 01:44
    root  is currently offline root
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    Registered: December 2004
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    Here you go guys, here is the repair mod for the backlight.

    Remove top and bottom cover.

    Remove the 4 screws holing on the face, 2 on left and 2 on right of face holding it to chbassis. Theres 1 ribbon cable connecting the face to main unit, just pull strait out.

    Remove knobs just by pulling them off. VFO just pulls off also.

    Unplug all ribbon cables on back of face, number them with a permanent marker if you think you might mix them up.

    There is 5 screws holding the top circuit board in, take them out and lift up board, be carefull and feed 2 of the ribbon cables through the board. On the back side of this board there are 2 steel boxes on the board. Take the top off of the biggest one.
    You will see a small square transistor with the #B1201 on it. This is the problem transistor thats been giving backlight problems.

    This transistor has no way of cooling laying flat on the board.remove this at your own risk. You have to have a small tip iron and a good set of eyes and steady hands. The center leg on the transistor is cut off, this is the ground leg, and the top of the trans is soldered to the board.

    Heat the top of the transistor and lift it and it will come loose,then unsolder the legs and lift. Remember which way it came out. Take the new trans and don\'t cut the center leg off, the center leg needs to be soldered where the top of the transistor was soldered. And the other 2 where they were from the start, leaving the part standing up instead of laying flat on the board.

    Now push the transistors side against the metal box and put some heatsink compound around the transistor and between the part and box, now it can keep cool.

    Thats it, put the top back on and put the unit back together. Replacment part #s are NTE2525 or 2SA1244 or 2SB1201, good luck and take your time.

    Works well
     Topic: IC-746 modulation on AM
    IC-746 modulation on AM [message #10] Wed, 29 December 2004 01:43
    root  is currently offline root
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    If you want more crisper and louder modulation on AM, turn radio upside down and remove cover at the top right hand corner of radio you will see a varible that says (AM mod). Clockwise increases mod and counter clockwise decreases mod. You might want to use another radio on the same frequency so you can hear results. The radio that you are listening with needs no ant screwed in to it being that you are only listening.

    I have done this and mine has loud crisp modulation. Remember, no compression on AM, you will find that it will muffle you on AM.

    Do at your own risk.

     Topic: Monitor Audio Output Too Low Icom IC-746
    Monitor Audio Output Too Low Icom IC-746 [message #9] Wed, 29 December 2004 01:43
    root  is currently offline root
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    The monitor function on the IC-746 tends to have low output compared to receiver AF volume, therefore in order to listen to yourself, you have to increase the volume. When the PTT is released back to receive mode, the AF setting nearly blows your speaker or your headphones.

    If the monitor audio output is too low on your ICOM 746, you can add 4.7K resistor in parallel with R1087. This brings up the gain of IC1082 to a more reasonable level that can still be controlled by the monitor level function but with plenty more gain.

    Technical Notes:

    These SMDs are located in the Main Board. You will probably need a service manual to locate these parts on the main board. Adding modifications to these very small parts requires some skill and a good magnifier together with the appropriate tools. A 1/8 Watt resistor will be suitable for this modification, but still require some precision.
     Topic: Power mod for the ICOM IC-746
    Power mod for the ICOM IC-746 [message #8] Wed, 29 December 2004 01:42
    root  is currently offline root
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    Power mod for the ICOM IC-746
    Remove bottom cover.

    Find the voice module plug-in.Right behind it you will see 4 pots

    R993 144 mhz power adj
    R991 50 mhz power adj
    R989 HF bands power adj
    R990 AM power adj

    You can tweak these to up the power suggest on hf doing it on 40 meters. you can get close to180 watts on 40-75 meters about 125 to 150 on 20-10.

    The pots are very small be careful not to use something to big. the are all metal pots.


    [Updated on: Sun, 06 May 2007 12:50]

     Topic: Extended RX/TX for IC-746
    Extended RX/TX for IC-746 [message #7] Wed, 29 December 2004 01:41
    root  is currently offline root
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    Registered: December 2004
    Senior Member
    Open the bottom cover of the IC-746
    Place radio on surface upside down with front to your left.

    Find chip label HD6433042SFB24
    To the right of this chip (3/4 inch) are two rows of diodes.

    14 diodes in the right column and 7 diodes in the left column.

    For Icom 746 Radios with the diodes in the 1, 2, 6, 7, 9, 11 and 14 positions, remove numbers 6 and 7 leaving the other 5 in place.
    Mod complete.
     Topic: Separating the Tx and Rx lines on 2 meters in the IC746 could not be easier
    Separating the Tx and Rx lines on 2 meters in the IC746 could not be easier [message #6] Wed, 29 December 2004 01:40
    root  is currently offline root
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    Separating the Tx and Rx lines on 2 meters in the IC746 could not be easier.

    Put the rig on the bench with the front panel facing towards you, and turn upside down, with the front panel still facing towards you.

    Remove the bottom cover.

    At back-left there is a 5 inch square metal screening plate held in place by four screws - remove it.

    You will see a miniature co-ax plug and cocked, labeled VRX. Simply unplug, tuck the original plug out of the way and plug in a new plug attached to a length of miniature coax, which can neatly leave the rig through the hole on the back panel that contains an earth bolt. Now you have your separate receive input!

    You could cut off and re-use the miniature co-ax plug, but I preferred to contact my local Icom dealer and buy a new one (a couple of dollars) - the Icom description is: PLUG TMP-P01X-A1 (Min Coax) IC-125.

    David, G4YTL

    [Updated on: Wed, 29 December 2004 01:40]

     Topic: IC-746 (USA models) All Band TX Modification
    IC-746 (USA models) All Band TX Modification [message #5] Wed, 29 December 2004 01:38
    root  is currently offline root
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    Registered: December 2004
    Senior Member
    This information is to help clear the confusion about the ICOM IC-746 modification for out of amateur band transmissions. There are a couple of different mods floating around for the IC-746. For USA models, the following information is the ONLY mod for the IC-746! I verified this with my contacts at ICOM. They verified that this was the ONLY modification for the IC-746 (USA model) and that there were NO others. I then performed the modification and the radio transmits from about 100KHZ to 60MHZ and 118MHZ to 176MMZ so be careful with this mod!

    Read the following instructions all the way through before performing this mod. Perform this modification ONLY if you feel capable of soldering VERY small surface mount diodes! Do this totally at your own risk.

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

    Turn the radio upside down and position the front panel to your right. The main tuning knob will be to your lower right and the microphone connector to your upper right. This will orientate the radio in the proper direction to read the parts layout identification silk screening. (Note: the IC part numbers will be UPSIDE DOWN.)

    Remove the twelve screws from the sides and bottom securing the bottom cover.

    Locate the Circuit board with the Optional IF filters. The filters will be in the upper left hand corner of the circuit board. Look to the lower middle of the circuit board for silk screening that reads “Option UT-102”. (almost the center of the radio) Immediately to the right of the “Option UT-102” silk screening you will see two columns (14 positions in each column) of VERY small surface mount diodes in a tight configuration. I’ll call them diode positions 1-14. This column should have diodes in EVERY position 1-14. The next column to the right is diode positions 15-28. This column should have diodes in positions 15, 18, 20, 22, 23, 27 and 28 as shown below.

    [01] [15]
    [02] [ ]
    [03] [ ]
    [04] [18]
    [05] [ ]
    [06] [20]
    [07] [ ]
    [08] [22]
    [09] [23]<-- Remove this diode only!!!
    [10] [ ]
    [11] [ ]
    [12] [ ]
    [13] [27]
    [14] [28]

    Diode 23 is VERY small and has a small “Y” on top of it. Use the finest pair of tweezers you have to remove diode 23 ONLY! Make sure you remove diode 23 only and NO other diodes! Make sure you have NO solder bridges as the diode pads are VERY small!

    Use a clear piece of tape and tape the diode to one of the metal covered cans near the columns in the same orientation you removed it. This way you’ll have your diode to reinstall if you ever feel you need to and you’ll know the orientation of the diode.

    This completes the TX modification. Replace the cover and screws.

    TX should be from about 100KHZ to 60MHZ and 118MHZ to 176MMZ.

    Do this totally at your own risk. Never, transmit out of the ham bands or your privileges.


    Lyndel, N7LT
    Forum: Motorola Mods
     Topic: Motorola Maxar/Moxy 2M Conversion
    Motorola Maxar/Moxy 2M Conversion [message #1476] Sat, 01 September 2012 01:21
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    By Tom Herman, CETma N1BEC/7

    I've always wondered how easy it would be to put the Motorola Maxar/Moxy series radios onto the two meter ham band.

    My gut feeling was that it shouldn't be too hard, but any interest was strictly academic because I had multichannel synthesized equipment for 2M. I hadn't had a reason to go ahead and try a conversion until my friend John, KC7OQN, came up with an old radio that he wanted to pop onto 146.52 Simplex. Many thanks to John for the "Guinea Pig", and for ponying up the $30.00 for two crystals.

    My philosophy with radio conversions is to do the minimum amount of parts substitution that will give best practical performance. The usual approach is to replace capacitors, and not mess with coils, fragile, or hard to get to parts unless I absolutely have to. K.I.S.S!

    The victim was a "Mid Split" (150.8-162 MHz) D23TRA1300AK two channel low power unit. The first order of business was to check out the radio to see if it worked at all on its original channel. It did, and the rocks were ordered from West Crystal in British Columbia. They got here three weeks later, right on schedule.

    A quick check showed receive sensitivity was pretty good (~ .23 uV for 12 dB SINAD), but the transmit power was a tad low (4.6 watts @13.8 Volts), but I decided to go ahead with the conversion anyways.

    I inadvertently left the unit powered up while I got called away from the service bench to attend to some "honey do's". When I got back, there was the unmistakable odor of burned electronics in the air. The unit was still receiving, but had no transmit.

    Checking the circuit board showed a burned inductor (L 106). A closer check revealed this was an effect, and not a cause, and if I had installed another part, it would have burned up as well. The ultimate problem was a dead short on the other side of L 106: C 130, which turned out to be a .05 uF/25 volt tantalum capacitor.

    It's fairly common for the Tantalum caps in the Moxy/Maxars to go critical, so a good S.O.P. is to leave a potential candidate unit powered up on a current limited power supply in a well ventilated area to see if the caps will hold up or not.

    Fortunately, I have a small mountain of UHF Maxar/Moxy's, and since the exciters are practically identical to the VHF??????s, they became a valuable source of parts and quickly got the D23 going again.

    Original operating frequencies were about 158 MHz TX, and 152 MHz RX. The old crystals were removed, and the '52 rocks installed. I elected to do the transmitter conversion first. The plan was to try to just align the unit, and if that worked, to go through afterwards and mop up any circuits that needed optimizing.

    Keying up, I spotted the fundamental and triple of the oscillator, and zeroed the tripled signal on frequency.

    L 102 and L03 are tuned first, while metering M3. L 102 tuning is quite sharp, L 103 a bit broader.

    There was no L105 M5 reading, so M3 was tuned for a dip when adjusting L 105. The tuning was broad.

    L 107 and L 108 tuned broad, then the PA was adjusted. Power output screamed to 14 watts! (I assume that the lower output prior to conversion was due to a partially shorting C 130 pulling down the B+ going to the tripler stage).

    The tuning of L 105, L107, and L 108 were not optimum, the cores being bottomed out on the circuit board or close to it. (Managed to break the L 105 core, parts car to the rescue again!)

    Check out the following table for the parts that needed to be changed out:
    Inductor AffectedCapacitor ChangedHighMid"Low"
    L 105C 127434756(Note: all capacitances in pico-Farads.)
    L 107C 1316810
    L 108C 13481015

    With the new capacitors installed, all three cores tuned well towards the center of the slug form. Power was then backed down to ten watts even. Don't try going to 12 pF for C 131, 10 is ideal.

    The receiver was a most pleasant surprise! Without doing anything other than dropping the crystal in the right slot and centering it on frequency, it gave 12 dB SINAD at 1.75 microvolts! Further tuning was done, and the radio dropped to a stunning .25 microvolts 12 dB SINAD with no parts replacement. No conversion was necessary on the receiver.

    [Updated on: Sat, 01 September 2012 01:22]

     Topic: Mitrek High Split to 6M Ham Band Conversion
    Mitrek High Split to 6M Ham Band Conversion [message #1039] Sat, 15 October 2011 04:57
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    Registered: December 2004
    Senior Member

    By Tom Herman, CETma N1BEC/7

    Here are the parts that need to be changed out to make the Motorola Mitrek operate well on the Six Meter Ham Band.

    The criteria here was to make the conversion as easy as possible, and to do this by changing out capacitors only, and just as many as are actually needed for good operation.

    Possibly other parts could be changed out, but the following list will get you the best performance for the least grief!

    Do yourself a favor, and use a good, hot soldering iron. To do this conversion, a number of coil shields must be removed, and some of the parts are soldered onto fairly substantial groundplanes.

    Also, if you do not solder the cans back on well, you will wind up with annoying intermittents!

    After re-tuning, the Mitrek in question gave me the rated power of 50 watts, and good receiver sensitivity.


    Part #        Orig. Value   6M Value    Notes:
    C 701         16 pF             12 pF   Watch soldering on cans of L 701- 
    C 703         24 pF             20 pF   L 705: Very Hi Q circuits! Poor
    C 704        150 pF            120 pF   Soldering will cause erratic TX
    C 707         33 pF             24 pF   power!
    C 710         22 pF             15 pF
    C 712         22 pF             15 pF
    C 713         27 pF             20 pF
    Part # Orig. Value 6M Value Notes: C 166 100 pF 80-90 pF Rx picked up 0.05 uV sens. Tunes C 101 30 pF 15 pF much better after conversion! C 104 22 pF 15 pF C 106 22 pF 15 pF C 108 22 pF 15 pF C 110 22 pF 15 pF
    Good Luck and have fun!

     Topic: Motorola HSN1000A
    Motorola HSN1000A [message #1034] Tue, 11 October 2011 15:35
    root  is currently offline root
    Messages: 140
    Registered: December 2004
    Senior Member
    How to modify a Motorola HSN1000A amplified speaker for use with other radios, scanners, etc. Obtain a Molex # 0003061061 or 0003061062 female connector. Looking at the end of the female connector with the beveled corners to the left and the two triangular notches to the right, the pins are as follow:

    upper left: audio ground

    upper right: audio in

    middle left: +13.8 volts

    middle right: power ground & external speaker ground

    lower left: external speaker out

    lower right: internal speaker in

    Connect a 1/8' (3.5mm) mono mini phone plug across the primary winding of an audio transformer. Connect the secondary winding of the audio transformer across the audio in and audio ground pins on the Molex connector.

    Plug the mono mini phone plug into the headphone jack of your audio source. Connect power across the +13.8 volt and power ground pins on the Molex connector. Also connect the power ground pin on the Molex connector to the sleeve connection of a 1/8' (3.5mm) mono mini phone jack. Connect the external speaker out pin on the Molex connector to the tip connection of the mono mini phone jack. Connect the internal speaker in pin on the Molex connector to the normally closed connection on the mono mini phone jack. Plug an external speaker into the mono mini phone jack if you wish to use one or leave the mono mini phone jack unplugged to use the speaker inside the Motorola HSN1000A.

    If you always want to use the internal speaker of the Motorola HSN1000A, you can simply jumper the external speaker out pin to the internal speaker in pin and leave off the mono mini phone jack. If you want to use the HSN1000A with a handheld radio having its own power source (e.g., batteries) isolated from the power source for the HSN1000A, then the audio transformer is optional. Ideally, the audio transformer would have 8:8 ohm winding impedance, but I used a 600:600 ohm transformer that can easily be scavenged from an old telephone modem or bought at Radio Shack, if they still carry item # 273-1374.

    If you want to connect the HSN1000A to an audio source with a stereo output, simply use a 1/8" (3.5mm) stereo mini phone plug instead of a mono mini phone plug and connect only the tip and sleeve connections, leaving the ring connection unconnected.

     Topic: Syntor X Amateur Conversion (2M)
    Syntor X Amateur Conversion (2M) [message #309] Thu, 20 January 2011 00:38
    root  is currently offline root
    Messages: 140
    Registered: December 2004
    Senior Member
    I have found the Syntor to be a relatively inexpensive easy to convert radio for 2 Meter amateur use.

    The EEPROMS used commonly in the orange label memory module are 2816A(28C16)devices normally supplied by SEEQ and have no markings on the top of the package.

    There is a more rare version that has a white label and it uses a unique one time burned prom. Best bet if you encounter one of these would be to upgrade to the orange label module but there are a couple of devices on the personality board that are not compatible with the faster memory module Motorola document 68-80100453 explains this in depth if you have access.

    The PROMS are easily programmed using a commercial EPROM programmer that supports the 2816 device I use a Pocket Programmer from Transtronics and it seems to work fine. There is software available that allows the image to be generated and loaded to the programmer which in turn programs the memory. is an excellent source for the software.

    VCO modification may be needed in some cases for general ham use the solder jumpers on the VCO board need to be soldered together where the factory tuning cut was made as that will add the necessary capacitance to allow the VCO to lock on the new frequencies. If the unlock led located near the RF board is glowing constant when PTT is applied or in RX most likely the VCO will need modification or the software did not dump the data to the programmer correctly.

    Beware I have ran into some freeware software that may have possibly used the wrong algorithm which resulted in incorrect code plug data even when the software reads correctly.

    Good Luck with the mod.

    [Updated on: Thu, 20 January 2011 00:49]

    Forum: Radio Equipment
     Topic: FS Icom PW-1 1KW Amp & ICOM IC-756PRO III #MINT
    FS Icom PW-1 1KW Amp & ICOM IC-756PRO III #MINT [message #1509] Fri, 12 October 2012 11:05
    james2e0rum  is currently offline james2e0rum
    Messages: 3
    Registered: October 2012
    Junior Member
    Icom PW-1 1KW Amplifier
    S/N-02319, this amplifier is in excellent condition! 10/12 meter mod done.
    Includes original box, cables and manuals.
    Must be a licensed amateur, this will be verified.
    Feel free to email with any questions.
    COSTS $1800usd

    Mint ICOM IC-756PRO III in PERFECT FULL working condition and MINT cosmetics. If has been kept with cover (included) and comes with original box, cables, fuses, etc as new. I have used this radio for a while, and it puts out FULL output and absolutely everything work as it should. I can provide pictures and we can talk on 40 meters.
    Costs: $1200usd

    Contact : Mr. Jack
    Email :
    Pages (6): [ «    1  2  3  4  5  6    »]

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