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Replacing the standard MCF (monolithic crystal filter)

1. SITITITTTTTT oh E Need help to solve some issues After removing the original filter we immediately noticed that this filter had several SMD components installed in the cavity underneath My worries grow since the replacement filter do not have any visible components But maybe these are hidden beneath the bottom cover since the bottom plate of this filter 1s lower than on the original Kenwood filter Unfortunately the service manual does not show the internal circuit the Kenwood filter The replacement 10MAD filter is specified with terminating impedance 1 kQ 10pF and I m not sure if this is the load that the filter presents or if it needs that circuit outside the filter I must admit that in this area I lack the skills to determine this Maybe someone can explain this PHP XFo32 Tus 171 0604 05 DJE D Ou 390 er Steg 333 838 Hadr DHING i00 E 2 OPTION 9 T 5 FILTER RE OUT LN oot 0 1 1 2 cn ER 100 OPTION 5 FILTER T DOS 8942 p A N 0 ctu 0 5 1 100 934 3 8k R339 100 CO34 1 O Cdu SEV 10 695MHz2 FILTER sunny 1OMAD filter pL 1 nn 2 SWITCHING T nes R47 CO50 TTE 390 0610 pa CLR T 15312 R955 72 4 _ 0935 937 100 Somme SWITCHING pgs Agape 6951 yen 5 D O Diu 1 2 EA adi Fe SWITCHING ASS ele 100 e Rogo C952
2. F DSP passband cut function The IF filter bandwidth is still 2 4 kHz with AF passband frequency 500 2500 Hz 300 Hz 2700 Hz in normal position The filter that found is a much wider 4 kHz monolithic crystal filter named LOM4D with housing package called 01 The 10M4D is a 8 pole filter with excellent characteristics a Ve This filter is available from sunny electronics corporation Minimum order is 2 units price around 100 for both including shipping Link http www sunnyna com en products pro03 htm 10MAD Filter curve plot CH1 TRN log MAG 16 dB REF 16 62 dB 4 66 447 dB E E b 2 p L1 e Pass bandwidth 6dB 4 kHz Stop bandwidth 80 dB 10 kHz Ripple 2 dB Insertion loss 4 dB Guaranteed attenuation 90 dB Terminating impedance pF 1 10 Number of poles 8 Note By installing the optional 1 8 kHz SSB filter YF 107SN you can easily switch this in to reduce strong nearby stations This optional SSB filter 1s only active in RX and not TX your TX signal will always be routed thru the 4 kHz 1OMA4D filter The TS 480 frequency drift are noticeable especially on 50 MHz band so I recommend installing the optional TCXO unit SO 3 After installing this the radio 15 dead stable after frequency calibration Modification procedure Remove the small filter unit board 78 NOIid0 2 IE y o
3. TS 480 Replacing the standard MCF monolithic crystal filter WA Vi Whew pem y ee D 2 43 Ag iS p t VEDI nl Mirac EM No ALL ae LO a E45 m N T 4 j OUT 71 m M or i x F 4 pE EM e E s gt 4 i e Ps i c bs us c di 4 i i IS c go rr 1 us 4 mos E 1 A fm ae COM 1 i i Fc ai or E m TM 1 F ee m So ls T s DAS The TS 480 has a monolithic crystal filter installed in the second IF 10 695 MHz This is a 2 4 kHz filter which is used on both RX and TX on SSB CW FSK and AM Narrow In FM mode the IF filter is bypassed The 2 4 kHz filter is named XF 932 in the service manual and is marked with a label 10 695 0604 KDC The filter is mounted on the same small removable print where you can install the two optional filters and TCXO unit Simply remove the print and turn it upside down to unsolder the filter The disadvantage with the TS 480 compared to the TS 2000 is that it lack s the possibility to transmit with bandwidth wider than 2 4 kHz There is a selection in the menu where you can choose 2 0 or 2 4 kHz transmit bandwidth but in fact this is only a A
4. i J 01 E Fife foo 5958 100 C855 i O 0Tu After modification OPTION FILTER gt E p lt a op Rm F mua i 2 How the radio worked with this filter We where not sure what to expect when we turned the radio on after installing the filter First impression where quite good the radio received with a very open and rich sound With the RX equalizer turned off we clearly had to adjust the HI side of the AF DSP filter down to 4000 or 3400 Hz to reduce some hiss in a crowded band Problems But after a while we also noticed that the IF SHIFT rotary knob curiously have no function any longer Turning this knob from one side to another had no noticeable effect I don t know why Maybe the IF filter is so wide that you can t reach the filter skirts any more Or maybe the IF shift is malfunctioning for some reason One other thing we noticed is that when you tune up or down in frequency reaching the point where you start to hear a station you first hear the station with a distorted sound like listening to a station on LSB when the station transmits on USB After turning further in frequency about 2 3 kHz further you hear the station clearly like it should be This 1 also curious maybe there is some adjustment to correct this also Maybe carrier levels or carrier points needs to be recalibrated need to do this I
5. sons can help us solve these issues and maybe make this modification work 100 Please place the corrections and notes under replies for this modification to help us June 26 Th 2006 Anonymous Warning This 1s a difficult modification Be careful If you destroy the filter board you can probably buy a complete new board from Kenwood and replace it easy but expensive
6. t eventually turned out that there is a problem on transmit as well when listening to the modified radio from a few miles away I noticed that something was wrong The audio sounded a bit hollow and strange and in LSB mode I could hear that even 5 6 kHz above the transmit frequency it was a lot of carrier signals present from the radio This must be because of some sort of incorrect carrier level or mismatch to the filter circuit maybe the terminating impedance We will try to consult the service manual to solve this problem I also wish that someone with a lot of knowledge could dive in to this matter and solve it Note that on a very crowded band the radio has a lot more problems with interfering nearby stations now than with the original filter For people who operate mostly on crowded bands at night etc I suggest you do not install this filter Apart from the issues mentioned above we found no negative effects on the radio Everything works fine The transmit audio apart from the hollow sound is also reasonably good works OK with the original hand mike and also with the MC 60A desktop microphone and mic gain at 60 I believe the transmit audio has ESSB potential 1f the problems mentioned above are solved But I must admit that because of the problems that occurred after this modification I would not recommend anyone to do this modification before the problems are solved By placing this document on the web I hope that some skilled per
7. y I said 4 T 3 12 0 een p in 1 Li 3 5 f m a Li FILTERI W 2 wu Nu J H 4 E octo mmy my MM gt x FILTER 4 a ET Sa A i a u Wo LT Soldering points on the units rear side We also installed the TCXO unit SO 3 at the same time but found that because of the copper surface on the board was oxidized we could not make the solder attach to the soldering points Use a tiny piece of fine sand paper on the end of a match or something to carefully remove the oxide Clean afterwards with alcohol Also clean the pins of the TCXO unit with alcohol before installing it in the board We used special solder without lead but with silver and copper Sn 96 5 Ag 3 Cu 0 5 This worked very nice If y ou plan to install the TC XO unit 50 3 Note that you must first clean the soldering points on the board to make the solder attach to the copper traces We ran into a problem because the solder would not attach 1 x EXT T x z i p um ual A T er d da E ra j i pe ERE 5 k Er 4 m t a p oe 5 3 isum ena J unsolder these to remove filter 1 1 ri E E n 5 mm D z aTe LU SmoUV m out FN i Pu 1 a a i y F E m

Replacing the standard MCF (monolithic crystal filter)

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