> From: firstname.lastname@example.org
> Date: Thu, 1 Aug 96 6:44:27 MSZ
> To: <email@example.com>
> Subject: FT-900 mods (noise blanker) needed!
> Hi Dave !
> I mean that if you power on the rig while pressing the four buttons
> simultanously and shorten the 2 testpins, it will display 02 and off (if no
> general TX is possible). Maybe there are another settings on the place 01 or
> 03 do modify other unknown factory defaults, maybe to increase the maximum
> shift up to 7.6 Mhz to use it with a transverter on the 70 cm relais band -
> who knows ? But I have no information on how to improve performance of the
> noise blanker. Please, can you mail me the service bulletin if you have it in
> a digital form or can you fax it, if it's not much paper ? The number is +43
> 316 1707 788.
> Thanks in advance.
> 73 de OE6RJD
> josef roell
OK; this mod is simple enough that if you have access to the factory
service manual, you can do it. Yaesu states in bulletin # TB-9448-A,
dated 18 October 1994 that FT-900's with "Insufficient Noise
Blanking" can have improved Noise Blanking by changing R2335.
It's present value is 3.3K ohm, and to test-select a value between 6.8K
ohm and 10K ohm. As you approach 10K, some receive audio distortion
will be noticed.
I believe I ended up using 9.1K ohm in mine with some distortion on
signals with a high peak to average ratio.
I believe this was a fitting trade
This is a chip component on the bottom of the receiver board, so it
does require removing this board and popping off the chip. There is
room for a 1/8W. leaded component.
It really made the blanker work though. It now takes the tops off
lightning crashes on 75Mtrs.
So get out the bright light and glasses and have fun!