Icom 706 extended tx

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M0JSW
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Icom 706 extended tx

Postby M0JSW » 24 Dec 2010, 15:01

Ive got an Icom IC-706 mk1 that I would like to wideband but all the mod pages on the net show a row of diodes,one of which has to be removed,but my radio has the same row of diodes but mine are in a different configuration.All the mod pages show a row of diodes,2 diodes 2 spaces and another diode.You have to remove the second diode to extend the tx.But my row of diodes goes 1 space 2 diodes 1 space and another diode.Has anyone done this mod before or knows why might be different?Any suggestion gratefully recieved. :?
M0JSW

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Re: Icom 706 extended tx

Postby mattyboy » 29 Dec 2010, 17:45

ive had this done to my 706 mk1 and the mod done as well in the radio i think its something to do with what year it was made get your seral number off the radio and do a serch that might give u a insite m8 some one else ad the same probblem and they did that and they got it sorted by doing it that way .

hope that helps .
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Re: Icom 706 extended tx

Postby M0JSW » 31 Dec 2010, 13:37

I`ll give that a go.Thanks for that!
M0JSW

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Re: Icom 706 extended tx

Postby Ashtec » 01 Jan 2011, 20:57

ICOM-706 MODIFICATIONS

SUMMARY
-------

MODIFICATION 1: Enables extended transmit from 1.6 to 54 MHz inclusive.
MODIFICATION 2: Enables extended receive from .05 to about 165 MHz inclusive.

CAUTION
-------

Improperly performed modifications can severely damage your radio.
Use extreme caution. Proceed at your own risk.

Transmitting on frequencies other than those assigned to the amateur
radio service may be illegal.

TOOLS RECOMMENDED
-----------------

1) Small philips-head screwdriver
2) Magnifying glass
3) Small wattage (15 watt) soldering iron with a small tip
4) Long-nosed pliers
5) Paper clip
6) Tweezers


MODIFICATION 1
--------------

Result of modification: The IC-706 transmits only on the ham bands.
This modification allows for transmit on any frequency from 1.6 to
54 MHz. The radio will also continue to transmit on 2 meters (144
to 148 MHz in the United States) at 10 watts output. This modification
will NOT allow for transmit on the AM or FM broadcast bands. The radio
will appear to transmit on most frequencies above 54 MHz, but the power
output will be a milliwatt or less. The highest power output will be
100 watts from 1.6 to 54 MHz (SSB, FM, CW; 40 watts AM) and 10 watts
on 2 meters. (SSB, FM, CW; 4 watts AM) Note: This modification
requires that you reset the CPU. All memory information will be
erased.

1) Disconnect the power cable. Open the TOP cover of the radio.
You will need to remove only 5 screws: three on the top of the
radio and one screw on each side. Pull up the speaker carefully and
set it aside. Look at the radio from the front; the speaker area
should be in front.

2) Locate the rectangular, silver 9 MHz SSB filter. This is clearly
marked on the top of it. Now look to the right. Note the "D 108"
marking. Below this marking, there are three tiny black diodes.
There are two diodes, followed by two blank sockets, followed
by another diode.

3) The second diode from the left (the middle diode) is diode D-59.
This diode needs to be removed. There are many ways to remove this
diode. The easiest way is to crush it with long-nosed pliers. Another
way is to use a low-wattage soldering iron and tweezers and carefully
heat the diode, then pull with the tweezers. Be extremely careful not
to apply too much heat.

4) Re-assemble the radio. Press and hold the UP and DOWN buttons on the
right side of the front panel, and while holding them down, turn on the
power. This resets the CPU.


MODIFICATION 2
--------------

Result of modification: The bandpass filters on the IC-706 are
improperly wired. As a result, the radio does not receive any
stations above 129 MHz, except in the 2-meter band. This modification
allows for reception up to about 165 MHz.

(Note: If your radio receives the FM broadcast band (88-108 MHz), the aircraft band
(108-136 MHz), 2 meters, and stations above 148 MHz, it is possible that the modification
has already been performed by Icom; you may have a later model.)

1) Open the TOP cover of the radio. You will need to remove only
5 screws: three on the back of the radio and one screw on each side.
Pull up the speaker carefully and set it aside. Look at the radio
from the front; the speaker area should be in front.

2) Locate the rectangular, silver 9 MHz SSB filter. This is clearly
marked on the top of it. Now move your eyes toward the back of the
radio until you notice a long white connector with several colored
wires on it.

3) The 4th wire from the left, a yellow wire, needs to be removed
from the connector. You can cut this wire carefully if you wish.
Or, another alternaive is to remove it from the connector. Stick a paper clip or
perhaps a pin into the side of the connector under the yellow wire.
Pull the wire with tweezers and remove it. There are two yellow wires;
be sure to remove the 4th wire from the left, not the other one.

4) Open the BOTTOM of the radio, removing similar screws as you did
when you removed the TOP.

5) Look at the PC board just behind the MENU button. You will notice
a jack marked "J8" with a grey cable coming out of it.

6) To the left of jack J8, you will see five tiny transistors.
Look at the middle transistor. Follow the light green circuit board
trace from the middle transistor to a tiny hole just to the left of J9.

7) The yellow wire from the top of the radio needs to be connected
to this transistor. The easiest way is to solder a small insulated
wire to the yellow wire you just removed, run this new wire underneath
the radio to the hole you found in #6 above, put the wire into the hole, and
solder the wire into the hole with a low-wattage soldering iron.
Use caution not to damage the grey cable or to apply too much heat.
This could damage the PCB and seriously affect the radio.

If you perform only steps 1 through 3, you will be able to hear stations
above 148 MHz, but you will not be able to hear FM broadcast stations
on the 88-108 MHz band.

RECEPTION SUGGESTIONS
---------------------

1) You need to use wide FM to receive FM broadcast signals on the
88-108 MHz band, or TV sound signals between 59 and 87 MHz. To
receive wide FM, press the MODE button until "FM" or "FM-T" appears
on the display, then press and hold the MODE button for two seconds.
"WFM" should now appear on the display, and you should be able to
hear the FM broadcast stations. Reception quality is quite good
if you use a decent external speaker.

2) Aircraft (118-136 MHz) uses AM. You will need to set the radio
to AM to receive aircraft.

3) The sensitivity of the radio diminishes rapidly after about 165 MHz.
NOAA weather stations (162.40 to 162.55) are clearly audible, however.

4) If you find the FM broadcast signals overload the aircraft portion
of the bands, disable the preampifier by pressing PREAMP (the green
light should go out.)

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Re: Icom 706 extended tx

Postby M0JSW » 02 Jan 2011, 13:53

PAUL27UK wrote:2) Locate the rectangular, silver 9 MHz SSB filter. This is clearly
marked on the top of it. Now look to the right. Note the "D 108"
marking. Below this marking, there are three tiny black diodes.
There are two diodes, followed by two blank sockets, followed
by another diode.

3) The second diode from the left (the middle diode) is diode D-59.
This diode needs to be removed.


This is the mod I have found on the net,however,my row of diodes is different.I have a blank,2 diodes,a blank and then another diode.
M0JSW

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Re: Icom 706 extended tx

Postby Ashtec » 02 Jan 2011, 14:40

MODS FOR THE ICOM 706

Icom IC-706 mods

MODIFICATIONS
WARNING: Improperly performed modifications can severely damage your radio.
I have performed these modifications successfully, but I offer no guarantee
or warranty for them. Proceed at your own risk.

TOOLS NEEDED:

1) Small philips-head screwdriver 2) Tweezers 3) Magnifying glass
4) Low-wattage (15 watt) soldering iron 5) Long-nosed pliers

MODIFICATION 1:
Enables out-of-band transmit for 1.6 MHz to 54 MHz.This does not enable
extended VHF transmit This does not enable AM or FM broadcast band transmit.
Your memories will be cleared after this modification, since you need to reset
the CPU.
1) Open the top of the radio by removing the 3 top screws and 2 side screws.
Look at the radio from the with the front panel facing you.screws.
2) Gently pull up the speaker and set is aside without damaging the speaker
or the wires that attach it to the rig.
3) Note the silver rectangular box near the middle of the PCB marked something
like "9 MHz SSB Filter".
4) Move your eyes up from this filter toward the back of the radio. Just
before you get to the "D 108" marking, you will see two tiny
diodes, two blank spaces, and one additional diode. They look something like
this:

D108
[XX] [XX] [ ] [ ] [XX]
Remove this diode ^^^^

5) The second diode from the left needs to be removed. I did this by crushing
it with long-nosed pliers. You can also heat it with a
low-wattage soldering iron and pull it up with tweezers. Be sure not to
damage the other diodes or the PCB. Be sure that you don't
apply too much heat, since the heat can damage the PCB and the other diodes.
6) Re-assemble the radio. Reset the CPU by pressing and holding down the UP
and DOWN buttons on the front panel and pressing POWER.

Improved VHF recieve mod:

154-200 MHz RANGE
To open up the 154-200 range,cut the yellow wire on the plug labled "j-4" on
the right side of the radio on the bottom,the book points to this connector.
I did this and it opened up the rx between 154-200 mhz. (It was printed in CQ VHF a couple of months ago.)
For those who like to scan VHF Hi-band, there is a mod that restores
sensitivity, but at the cost of reduced sensitivity below 120 MHz.
This allows the filter to switch at the corner frequency (apparently around
129 MHz) as you tune.

PROCEED AT YOUR OWN RISK
There are no guarantees you won't trash your radio.

Remove the radio top and bottom covers according to the manual.Remove the
speaker. Now with the radio facing you and right side up, you'll see a single
connector with discrete wires at the rear of the control board. The fourth
wire from your left should be a yellow wire (caution, the 5th and 6th wires
on the other end of the connector are yellow too, don't get confused).
Disconnect this wire from the connector. This will enable the 2 meter
band-pass filter to work outside the 2 meter band, and will restore
sensitivity between about 130 MHz and about 165 MHz (above and below that
range, sensitivity still stinks, especially above 165 MHz). Before this mod,
a low pass filter with a corner frequency around 129 MHz was in the circuit
all the time except when you were actually tuning inside the 2 meter band,
and that killed high band sensitivity completely. Before removing the yellow
wire, sensitivity at 155 MHz was 30 uV for an S1 indication,after the yellow
wire is removed, sensitivity increases so that only 0.5 uV is required for a
S1 reading. At 165 MHz after the mod,sensitivity is 3 uV for an S1 reading,
before the mod, a very large signal was required for an indication.
Disconnecting the yellow wire has the unfortunate side effect of reducing
sensitivity between 60 and 129 MHz since the radio never switches from the
2m bandpass filter to the low pass filter. Signals below 60 MHz don't go
through either filter and are unaffected by the mod.

Now here's how to get the low pass filter back when tuning below 129 MHz.
On the bottom board, right behind the MENU button,
there are 5 SMD transistors. These transistors apparently switch the VCOs
for the various band segments. The one in the middle of the 5 apparently
switches the 60-129 MHz VCO. The single pin (one side of the SMD transistor
has 2 pins the other only 1) switches to 5 volts when this VCO is active,
and is low otherwise. This is exactly what we need to feed the yellow wire.
There's a board trace coming from this pin over to a feedthru hole near J8.
Connect the yellow wire you disconnected earlier here.

The filter should now toggle between low pass and 2m bandpass as you tune
below and above 129 MHz, and you should have good sensitivity both above and
below this frequency (at least up through 165 MHz).

Remember, CAUTION WARNING This is tiny SMD stuff. If you trash your radio,
you're on your own.

I have an Icom IC-706 and did the mod. I did this mod and it works great!!!!

As far as FM Broadcast intermod in the Aircraft band, I noticed the IF is a
little overdriven into compression, so I turn the preamp off(greeen to no
light---preamp switch), and noticed no difference in sensitivity, intermod
in aircraft band disappeared.Running the preamp in the Aircraft 118-129 does
not really help sensitivity, even though the S-meter shows higher signal
levels (jumps around alot due to saturating IF when signals are not there!!)
the noise floor actually, degrades, thus I leave the switch (no preamp-black
instead of green). Leaving it on green is just driving the IF into saturation,
with worst dynamic range.
Now connecting it to the VCO switch bank, the radio performs to my
satifaction, hearing the weather at 162, forestry at 171, TV audio
near 200Mhz and remembering to turn the preamp off in 118-129 aircraft
region, no 2 meter images any more in 82-83Mhz area from 2 meters.I can
listen to FM broadcast in the 88-108Mhz area.

Q:Does this mod affect HF or 6m?

A:The mod affects only frequencies above 60 MHz. If you just cut or remove
the yellow wire, the 2m bandpass filter is used all the time.

After the mod you can listen to the airport on 134 MHz but 128.4 is still
drowned in intermod from the FM BC band.

Proceed at your own risk

The receiver sensitivity above 120MHz (except the band between 144-148MHz)
is very poor and also the transmitted FM deviation for NARROW FM is too
small; therefore I did some tests and came to the following two modifications.

To carry out these modifications it is necessary to use the IC706 service
manual, which can be bought at any ICOM dealer.

1. When choosing NARROW at FM, then during transmitting the max. deviation
is reduced from 4.8kHz to 2.4kHz. It is still desirable to choose NARROW at
FM because the receive performance is better then.
After changing resistor R272 from 1K to 8K2. (at the bottom side of the MAIN
UNIT), then the max. deviation during transmitting goes from 4.8kHz to 4.3kHz
when choosing NARROW at FM.
The modulation at AM is also changed now, but this can be corrected with
potmeter R271.

2. To improve the receiver sensitivity between 120 - 144MHz and between
148 - 200MHz the following modifications can be carried out.
At the PA UNIT, change the 60 - 200MHz bandpass:
1) Remove C53(20p), C152(20p), C153(12p) and C154(20p).
2) Short-circuit L49(82nH) by soldering an interconnection at the place of
the removed C153.
3) The inductance of L16, L17, L18 and L19 must be reduced somewhat.
This can be done by separating the windings somewhat with a small screwdriver.


Now the sensitivity is good up to about 175MHz. Also the sensitivity in the
airband is much better now.

For receiving above 175MHz the low-pass filters at the ANT2 input have to be
changed (components around L16, L17, L18, L19. I would not recommend that,
because the spurious suppression during 2M transmitting becomes worse then!


To expand the band on the VHF portion.

(I have not tried this mod.I received this infomation via e-mail)
Caution: This is quite involved. If you are not too good you might be advised
to get someone who has the experience to handle this mod!

1. Remove the main board from the unit. Keep the cutout hole away from you.
This I consider the top of the board.

2. Remove the shield from the top of the board. There are 30-40 solder
points from the shield to the board.

3. Under the board on the top of the board, remove R-353 and Q-38. They are
located to the left of the IC-36 chip on the top of the board under the
shield.

4. On the underside of the board, Locate IC-32. There are two IC chips.
IC-32 will be just down and to the right of the shield.

5. Using a pointer, point at the left upper pin, and go toward the top of the
board. You will find a trace that stops. It comes out from under IC-31, and
stops. It should be the sixth trace up from the top of the Chip.

6. Using a Xacto knife, (or something similar) Cut the trace the bend
halfway between IC-31 and the solder point.

7. Make a jumper wire, and jump the connection, from Pin 11 of IC-32 to the
newly isolated trace.

8. Reassemble the radio.

Transmit from 200 Hz to 200 MHZ continuous!!!

ICOM does not warranty these mods.

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Re: Icom 706 extended tx

Postby M0JSW » 02 Jan 2011, 15:56

Hi Paul.Thanks for looking.Thats the same mod as I have already found,but as I say,the configuration of diodes in my icom is not the same.Both the posted mods show diode,diode,blank,blank,diode whereas my config is blank,diode,diode,blank,diode.
The mod says to remove the second diode in the second space,but my second diode is in the third space.
M0JSW

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Re: Icom 706 extended tx

Postby Ashtec » 02 Jan 2011, 16:21

warlock wrote:Hi Paul.Thanks for looking.Thats the same mod as I have already found,but as I say,the configuration of diodes in my icom is not the same.Both the posted mods show diode,diode,blank,blank,diode whereas my config is blank,diode,diode,blank,diode.
The mod says to remove the second diode in the second space,but my second diode is in the third space.



Funny that sorry i couldnt help you there mate..................

There most be some one on here that knows the mod for you.............

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Re: Icom 706 extended tx

Postby DaJetzi » 01 Apr 2011, 15:56

Do you have already success with extended tx?

73´s
Sigi

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Re: Icom 706 extended tx

Postby Graza82SCO » 26 Apr 2013, 14:10

How did you guys get on with this?

I have one coming tomorrow and would consider these mods...

Lemme know.

Thanks.
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Re: Icom 706 extended tx

Postby bigpimp347 » 26 Apr 2013, 16:33

the original diodes also depends on where the radio came from, if it's a UK set then it'll be set for UK, a US set will have different diodes..

i did a 7400 and was nothing like the mods on the net as it was a UK radio but the mods most are for US radios..
i also did a 706mkG recently which was a US radio but i was trying to do a UK mod..!!
so again different diodes in different places to suit the country of origin..
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Re: Icom 706 extended tx

Postby astradyne » 26 Apr 2013, 21:45

Thankfully my 706 MK1 had been modded prior to me getting it (apparently it used to belong to Mr weetabix). It sounds very much like a job I would not want to do..........
Never, ever, ever....bloody anything ever!

Far too many radio's to list here. But I do own a legal one...

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Re: Icom 706 extended tx

Postby tenrohle » 13 Sep 2017, 23:12

Anyone ever done this mod to a 706? Not the mk2.
I've just done it by crushing the middle diode and I still can't TX on 27mhz.
Radio still works fine on other bands like it did before.

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Re: Icom 706 extended tx

Postby MrWeetabix » 14 Sep 2017, 10:22

astradyne wrote:Thankfully my 706 MK1 had been modded prior to me getting it (apparently it used to belong to Mr weetabix). It sounds very much like a job I would not want to do..........


For the record, if this were mine, I did not do the mod. I'm not brave enough to do these mods! :geek:
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Re: Icom 706 extended tx

Postby astradyne » 14 Sep 2017, 14:57

MrWeetabix wrote:
astradyne wrote:Thankfully my 706 MK1 had been modded prior to me getting it (apparently it used to belong to Mr weetabix). It sounds very much like a job I would not want to do..........


For the record, if this were mine, I did not do the mod. I'm not brave enough to do these mods! :geek:


Definitely was yours Mr. W. I bought it off the disabled guy who bought it off you. I seem to remember him saying you bought his President George off him during your visit.

Bloody good radio that 706. Wish I'd kept it...
Never, ever, ever....bloody anything ever!

Far too many radio's to list here. But I do own a legal one...


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