Instaling 4Khz Ceramic filter in FT2000 second IF 450Khz

In FT 2000 transceiver  450kHz ceramic Filter CF 1001 has been build in second IF with a BW of about 15kHz,  because  FT 2000 can be used in FM and also in AM mode.  Therefore  on SSB and CW original filter CF1001 -CFWLB450KE1Y  is too wide to reduce the  signals  that is  reaching  to DSP. DSP has less bandwith (informations content)  to process. Because I don,t work on FM and AM mode I decided to install   second Murata +/-2 kHz CFWLA450KJFA  ceramic filter successively with original CF1001 filter.  See picture 1 and  2

Picture 1   4 kHz ceramic filter Murata

Picture 2   FT 2000   IF shematics

CFWLA450KJFA  filter will  reduce bandwith on SSB and CW to 4kHz and therfore will also reduce IF wideband hissing noise and IF image. FM will be degraded, but AM  not excessively. Normal 2400  Hz SSB  and CW will not be affected. After this changes the signals will be better managed with IF-DSP filter .The  450kHz Murata ceramic filter play little role in providing the receiver selectivity. They serve only as 4kHz wide IF filter. All IF selectivity comes from the IF-DSP filter.

Picture 3  450kHz  filter layout

Preparing the new Murata  CFWLA450KJFA 4kHz filter for installation

1.     Locate the work area on PC board ( see picture 3)

2.     Unsolder SMD resistance R 1365 , 680 Ohm

3.     On this place solder two thin wires 25mm long.

4.     Stick with glue new 4kHz Murata filter On the existing original  filter CF1001

5.     With one thin  wire connect output from original filter CF1001 with  new 4Khz Murata  filter input.

6.     Solder 680 Ohm SMD resistor on a new  Murata  4kHz filter output

7.     With the second  thin  wire connect  680 Ohm SMD resistor  back with PC board .

Filter CFWLA450KJFA  can  be purchased  in Poland at: https://www.hesta.pl/pl/

Picture 4   Murata Filter specifications

Murata filter CFWLA450KJFA has 6dB attenuation, but I  detect very small diference in signal strenght  after the new filter has been built in. However we can change  IF gain for  in FT 2000 Hidden  Menu setting  B11 to B20  if  we want. But be very  carefully  this is a hidden service menu  accessible  for  maintenance  by an qualified technician.

More about the build in procedure can be seen from the pictures.

For those who mostly work on CW I suggest  for better stopband attenuation, installation two (2) serially connected 4kHz filters.  The same changes has been  wrote in my  blog  FT 950 narrow IF filter.

Picture 5  4kHz Filter final installation

Picture 6 Spectrum taken after 2nd IF -  TP1062 , together with AC0C  roofing filter build in the first IF.

After building new filter it is still possible to receive AM but  FM will be degraded. I have been testing my receiver in CQWW160 CW contest and  I  was  really  satisfied with new installation.

Oene PA3CWN upgrade March  2023:

This upgrade will bypass the new 4 kHz filter when the 6kHz or 15 kHz filter is selected because of using a relay which connects the in- and output of this new 4 kHz filter. In that case the existing 15 kHz is the only filter active and thus FM is still usable,

The article is now active on mods.dk  at  hyperlink:

https://www.mods.dk/view.php?ArticleKey=578f671d437510382c94f58af9fccaa6

Warning !!! Changing any harware inside FT2000 will void your warranty.I am not responsible for any hardware failure. You made this mods on your own risk. !This modification requires a high level of soldering skill, possibly beyond that normally possessed by the average HAM. Professional assistance is advised if you are not confident that you have  this ability.