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Yaesu FT-8900R Tx/Fx Modification



 
 
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  #1  
Old December 30th 03, 09:20 AM
Mohd Nazry Bin Mustapa
Guest
 
Posts: n/a
Default Yaesu FT-8900R Tx/Fx Modification

Anybody can help me on this type of modification cause I already reffer to
one of web site for modification and the site really show how to do it. but
unfortunately when I open my rig, the position of resistor not same as the
picture showed.

The site say there is two resistor next to the cpu, and I need to remove the
most front resistor (only one)[CPU pin No. 62]

But when I open up my rig it happen that only one resistor which sit on CPU
Pin No. 60. Do this set already open the tx frequency ie; 134 - 170Mhz.

Any idea if I removed this resistor, what will happen? This resistor got no
value written (SMD), If I remove and damage this tiny resistor I might not
able to get the substitued for it. That is why I'm a little worry for this
modification.

Any kind help much appreciated

Thank you


  #2  
Old January 6th 04, 02:07 AM
[email protected]
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Posts: n/a
Default

On Tue, 30 Dec 2003 16:20:25 +0800, "Mohd Nazry Bin Mustapa"
wrote:

Anybody can help me on this type of modification


Suggest you visit
http://groups.yahoo.com/group/FT-8900

whioch suggested:

Modifications for the Yaesu FT-8900

FT-8900R for extended TX/RX

1. Remove top cover of radio by removing all 8 screws.

2. Disconnect speaker and move top aside.

3. Locate the CPU on the radio, it has a crystal glued to the top
of it and is located in the front left corner of the radio, it's
the largest IC in the radio.

4. To the EXTREME left of the radio, you will see a row of pads,
all empty except for a diode to the front, and one to the back.
There are about 6 or 7 spots for diodes, but only 2 installed.

5. Remove the FRONT (closest to head of radio) diode with a small
soldering iron or other tool.

6. Turn the radio back on, it will AUTOMATICALLY reset.

7. You now have ext coverage eg. TX 137-174, TX 420-470, etc...




and

http://www.cqham.ru/ftp2/sch_serman_ft-8900.pdf
--
Nobody but a fool goes into a federal counterrorism operation without duct tape - Richard Preston, THE COBRA EVENT.
  #3  
Old January 6th 04, 02:07 AM
[email protected]
Guest
 
Posts: n/a
Default

On Tue, 30 Dec 2003 16:20:25 +0800, "Mohd Nazry Bin Mustapa"
wrote:

Anybody can help me on this type of modification


Suggest you visit
http://groups.yahoo.com/group/FT-8900

whioch suggested:

Modifications for the Yaesu FT-8900

FT-8900R for extended TX/RX

1. Remove top cover of radio by removing all 8 screws.

2. Disconnect speaker and move top aside.

3. Locate the CPU on the radio, it has a crystal glued to the top
of it and is located in the front left corner of the radio, it's
the largest IC in the radio.

4. To the EXTREME left of the radio, you will see a row of pads,
all empty except for a diode to the front, and one to the back.
There are about 6 or 7 spots for diodes, but only 2 installed.

5. Remove the FRONT (closest to head of radio) diode with a small
soldering iron or other tool.

6. Turn the radio back on, it will AUTOMATICALLY reset.

7. You now have ext coverage eg. TX 137-174, TX 420-470, etc...




and

http://www.cqham.ru/ftp2/sch_serman_ft-8900.pdf
--
Nobody but a fool goes into a federal counterrorism operation without duct tape - Richard Preston, THE COBRA EVENT.
  #4  
Old March 1st 11, 02:05 PM
Channel Jumper Channel Jumper is offline
Senior Member
 
First recorded activity by RadioBanter: Jan 2011
Posts: 364
Default

What happens if you remove both Diodes?
  #5  
Old April 3rd 11, 06:13 PM
Channel Jumper Channel Jumper is offline
Senior Member
 
First recorded activity by RadioBanter: Jan 2011
Posts: 364
Default

Quote:
Originally Posted by Channel Jumper View Post
What happens if you remove both Diodes?
The answer is that it opens up more bands for transmit.
The reason for this is because YAESU does not make different radios for different parts of the world and since each part of the world has it's own bands for amateur radio operation - the only way to keep people from using the radio as a all band transmit / receive is to block out certain segments of the bands by adding the diodes.

The radio will operate on most any public service band - such as fire, police, emergency - Ambulance and will even transmit on the 800 - 900 Mhz cell frequencies.

The problem with opening up those bands is that once you open them you have to be real careful - to know where you are at when you are transmitting or you might find yourself in a lot of trouble when you transmit on a band for which you are not permitted to be on.

I can hear aircraft bands on my scanner on the 155 - 156 mhz frequencies.
Not to say that it might not be a 3rd order harmonic's of the aircraft bands - just to say that I hear a lot of activity on say 155.730 mhz pertaining to aircraft.

It doesn't make much of a difference - because the local police uses CTCSS to block out any signals which are not encoded with a PL.
But if the person had the PL - it could get them into a lot of trouble.
 




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