Comparison of Yaesu FT2000 with built-in CW roofing filter with Kenwood TS890S in ARRL 2025 CW competition

Some amateurs often  buy expensive stations uncritically under the influence of the results of Close-In, IMD3, IMDR - ARRL,Peter Hard-RadCom or Rob Sherwood. None of the above - mentioned don,t test   2nd order products a IMD2 (birdies and spurs) on the receiver , which can be especially in Europe sometimes  very disturbing.They also don't test  audio receiver  quality which is very important in a pile up. Measurements on my antennas had proven that broadcasting signals between 6 and 15MHz, which cause birdies and spurs or blocking, are significantly stronger (sometimes on my antennas more than 20dB) than signals from amateur stations.   ( see table below ).

In a real test on the ham band, it turns out that even in the most demanding competitions such as CQWW, CQWPX, CQWW CW 160m or ARRL DX even some older stations with minimal changes completely satisfy in an environment with really strong signals.The strongest signal that I measured in the competition: - 30 dBm at 28MHz (S9 + 43dB)

In the ARRL DX  CW contest  1050 qso,s has been made comparing  TS890S and FT2000.

One my tip:

Before buying transceiver , make a test in contest on your antennas with  transceiver which you previously loaned from some  friend. Don't buy the bells and whistles !

Strong broadcasting signals between 6 and 15 MHz_figure below

Note: All measurements are valid for my location and are made on my antennas -3.5MHz Inverted L, 7MHz rotary dipole, 14,21 and 28MHz 3 el.Beam

                          

Amateur radio operators often spend large amounts of money on expensive transceivers, buying them almost blindly based on impressive lab test results — especially Close-In, IMDR, and NPR measurements from experts like Rob Sherwood, Adam Farson, or Peter Hart from RadCom.

But when put to the test on the air, even in demanding contests such as CQWW, CQWPX, or CQWW CW 160m, many older and less expensive rigs can still perform surprisingly well — sometimes just as well as modern high-end ones. A study written for the Bavarian Contest Club by DK4YJ came to a similar conclusion: receiver performance in real-world conditions depends much more on RMDR (phase noise sensitivity) than on IMD3 (third-order intermodulation products).

In other words, it’s often wiser to choose a mid-range transceiver with good ergonomics than to overspend on a “top performer” with record-breaking Close-In IMDR numbers. This applies mainly to HF receivers.

How to Test a Transceiver in Real Conditions

 

 Basic rule:

Never test a transceiver at a dealer’s shop, on their antennas, and especially not during the quiet mid-morning hours.

The best test is always on your own antennas, during a major contest such as CQWW, CQWPX, or CQWW 160m. Ideally, compare your rig with a reference transceiver on the same frequency, switching antennas and audio outputs in sync — as shown in the setup below.

Real-World Test Results

Transceivers tested:

• Yaesu FT-2000 with CW roofing filter installed

• Kenwood TS-890S as the reference transceiver

Test configuration:

• FT-2000: 1.4 kHz roofing filter + 300 Hz DSP filter

• TS-890S: 600 Hz roofing filter + 300 Hz DSP filter

Results summary:

• Ergonomics: FT-2000 significantly better

• Selectivity (300 Hz): Almost identical

• Phase noise / IMDR 2 kHz: TS-890S better

• Noise reduction: Roughly the same

• AF quality: TS-890S better

• Notch filter: FT-2000 better

• Fast AGC: FT-2000 better

• RF preselector: Built-in on FT-2000; not present on TS-890S

• Power supply: Built-in on FT-2000; external on TS-890S

• Panadapter: TS-890S has built-in; FT-2000 uses external via HDSDR

• Sensitivity: Depends on preamp selection — TS-890S with preamp 2 shows a few dB higher sensitivity

• Receiver noise (50 Ω termination): Nearly identical

• Strongest contest signal measured: −30 dBm at 28 MHz (S9 + 43 dB)

• Price: FT-2000 (used) ≈ €1000–1100; TS-890S (new) €4400 at Kenlab–SI or €4895 at Wimo–DE

Conclusion

In real CW contest conditions, the FT-2000 with a built-in CW roofing filter performs on par with the TS-890S — one of the top-ranked radios in the Sherwood tests. In fact, due to its better ergonomics and user-friendly layout, the FT-2000 can even be easier and more enjoyable to operate during contests.

It also offers two independent receivers, an internal power supply, and a built-in RF preselector — features that make it very convenient for everyday use.

The TS-890S is an excellent, high-performance transceiver, but it’s best suited for very experienced contest operators who can take full advantage of its capabilities.

I plan to run a similar comparison with the Yaesu FT-101D in the near future. (I haven’t done any SSB testing yet.)

The Golden Rules for Choosing a Transceiver

• Don’t buy a rig based on the brochure!
  Specs on paper rarely tell the whole story.

• Avoid newly released models.
  Let others find the bugs first — wait for real user feedback.

• Never test a transceiver at the dealer’s location.
  Their antennas and environment don’t reflect real-world conditions.

• Skip the “bells and whistles.”
  Fancy features and “shiny” interfaces often add little value.
  A good panadapter on your PC is more useful than a built-in one.
  Even a touch screen can be a problem in contest operation.
  And yes — avoid buying a radio from a smoker!

• Borrow the radio you’re interested in and test it at home on your own antennas, ideally over a weekend or during a contest.

• Prefer a radio with a built-in power supply.

• Pay attention to the communication protocol and available software support.
  The level of PC integration and software tools makes a big difference!

• If you must buy an external power supply, choose a linear one, not a switching type.

• Look for a rig with a built-in tuner, two antenna connectors, and ideally an RF preselector.

• If you buy from a dealer, check whether they also offer service and repairs.

• The best time to test a transceiver is on 7 MHz in the evening, not in the morning.

• The best “field test” for any rig is during a major contest — for example, CQWW 160m or the Marconi CW VHF contest on a real contest site.

• Your first rig can be a used one.
  Prices of used radios drop over time, much like cars.
  Once you gain experience and start contesting seriously, then consider investing in a top-tier model.

• Don’t overdo the technical specs.
  If you’re not a serious contester, a solid mid-range radio (around €1000 or $1000) will serve you perfectly well.
  Ergonomics and operating comfort are often more important than ultimate lab performance.

---

Note:
All measurements and impressions mentioned here were made at my own station, using my antennas:

• 1,8 and 3.5 MHz: Inverted-L

• 7 MHz: Rotary dipole

• 14, 21, 28 MHz: 3-element rotary beam

---

 

Some tips how to make good roofing filter for Up conversion receiver ( Slovenian language -English abstract)

Abstract 

Despite the great trend to switch to a down- conversion receiver or hybrid receiver design we have with up-conversion receiver design much better suppression of image interference.( Dr. Ulrich L.Rohde N1UL,DJ2LR-  QEX), that the importance of good second -order IMD performance can be in Europe more important than the third-order IMD product.!!! (  A typical 49m broadcast signals mix with signals near 8MHz generating ghost broadcast signals)

The down-conversion receiver may not perform on 14,10 and 7MHz as well as on other bands because of images.

The up-conversion receiver moves the image range into the VHF which a 30MHz low pass front end filter easily removes ! 

In the past in up-conversion receiver design VHF crystal filters weren,t available in the narrow widths and with the steep skirts that enabled the high dynamic range up-converting transceivers. The big change is the use of narrower roofing filter to bring the up-conversion rig to current standars for top IMD3 performing transceiver. Such narrow filter are now possible in the 50 to 75MHz range to fit the up-converting architecture

Most mid range radios have roofing filters that are to wide for serious contest. My  narrow 1,4kHz CW  and 2,4kHz SSB Roofing  50 Ohm  Filter design  can be  with minor changes used for up conversion receivers  with first  intermediate frequency (IF)  between 50 in 75 MHz  like :

          ICOM IC : 756, 765, 775,7200,7400, 7410, 7600,7700, 7850, 7851, 9100

          Kenwood  TS: 450, 480, 850, 870, 950, 2000

          Yaesu  FT :  450,847, 897, 920,950,991, 1000D, 1000MP,  2000, 9000

Some tips,how to make your own Roofing filter ( Use Google translate )

I am not responsible for any hardware failure. You made this mods on your own risk.! 

Nekaj nasvetov , kako narediti dober  roofing filter za Up conversion sprejemnike.

Down conversion sprejemniki so imeli pri produktih 3. reda IMD3 in recipročnem mešanju RMDR prednost pred up conversion sprejemniki , ker se nedavno na VHF frekvencah še ni dalo narediti ožjih filtrov od 3kHz.  Inradovi roofing filtri širine 5-6kHz  so bili za CW teknovanja preširoki , ožji NS 2,4kHz filtri, ki jih je za FT 2000 in FT 950 prodajal  Jeff AC0C pa so bili dražji od 300€.. 

Up conversion sprejemniki pa imajo zlasti v Evropi prednost , ker so bolj odporni na produkte 2. reda IMD2 ( f1+f2 , 2x f1- f2,..... na primer 7,1MHz +7,2MHz =14,3MHz  ali pa  2 x 11,95MHz - 9,7MHz = 14,2MHz ) -  črički ( birdies and spurs) zaradi broadcasting postaj , ki jih pa Rob Sherwood ne testira.

V spodnjem diagramu je jasno vidno, da so broadcasting signali,ki so vzrok motenj  bistveno močnejši od amaterskih postaj. Zato so down conversion in SDR sprejemniki na frekvencah med 7 in 15 Mhz lahko bolj občutljivi na motnje  od sprejemnikov s prvo medfrekvenco nekje med 60 in 70Mhz.

Slika 1: Jakost broadcasting postaj v dBm med 7 in 15MHz merjena na mojih antenah 

 Zato sem se odločil, da poiščem kvalitetnega  proizvajalca kristalov ,da izboljšam IMD3 ter RMDR in  sam naredim poceni  CW roofing filter 1,4 kHz,ki je primerljiv z filtrom proizvajalca  ICOM za IC 7851.  https://www.strictlyham.com.au/icom-ic-7851. 

Za izdelavo kvalitetnega roofing filtra za VHF področje  podajam nekaj nasvetov.

Poiščite kvalitetnega proizvajalca kristalov ter pri njem  naročite kristale z pribljižno sledečimi karakteristikami.;

Kristal za 3. overtonsko frekvenco npr 70 455 kHz ( primer FT 1000MP)

Kristal naj ima za SSB širino filtra 2,4kHz serijsko resonanco okrog 1000 Hz višjo Fs = 70 456 kHz

Kristal naj ima za CW širino filtra 1,4kHz serijsko resonanco okrog  1400 Hz višjo  Fs = 70 456,4kHz

kapacitvnost C0 manjša od 4pF

Upornost Rs manjša od 16 Ohm

kapacitivnost Cm= manjše od 1,5 If

toleranca manjša od +/-5 ppm

Priporočam ohišje HC 49/u

Za izdelavo roofing filtra ne potrebujete več kot 4  kose  kristalov.

Nekaj EU dobaviteljev kristalov :

www.omig.com

www.andyquarz.de

www.pupin.rs

www.krystaly.cz

Slika 2:  Primer izbire kristala za  CW filter FT 1000MP  frekvence  70.455  ( 70456,4) kHz proizvajalca Krystaly 

Program za izračun : Crystal Ladder Filter Calculator " DISHAL" by Horst  DJ6EV http://warc.org.uk/wp-content/uploads/2014/01/eDishalHelp-1.pdf

Za izračun CW filtra uporabite  tip  filtra  Butterworth za izračun SSB filtra pa  tip Chebyshev.

S spreminjajem B3dB parametra in PB ripple parametra  v programu Dishal se poskušajte čimbolj približati impedanci filtra 50 Ohm. V primeru,da konstruirate filter za drugačno impedanco ga morate

impedančno prilagoditi!

Na vhodu filtra obvezno predvidite  diplexer,ki prilagodi impedanco filtra v širokem območju na  izhod mešalnika. Uporabite diplexer calculator ( Bridged Tee) 

Kvaliteta Q na frekvencah 50 -70 MHz naj bo  1-3

https://www.changpuak.ch/electronics/calc_16a.php

V postaje vgrajeni originalni filtri so običajno prilagojeni na impedanco 50 Ohmov zato je primerno izdelati 50 Ohmski roofing filter in ga z obstoječim filtrom vezati v kaskado. Tako pridobimo tudi večje končno dušenje celotne verige filtrov.Prvemu kristalu je paralelno vezana induktivnost s katero kompenziramo Cp in s tem izboljšamo simetrijo filtra.

Zaradi dušenja filtra okrog 8dB v prepustnem pasu sem na izhodu dodal nizkošumni ojačevalnik z veliko dinamiko PGA103+, ki se mu z attenuatorjem prilagodi ojačenje tako, da celotna veriga nima večjega ojačenja od 1, sicer lahko pokvarimo IMD3 !!!

Slika 3: Primer - Shema roofing filtra za frekvenco 68,330 kHz (  FT 897D, FT 857.. )

  Slika 4: Primer PCB tiskanine

Po vgradnji boste v primeru, da lahko preklopite med različnimi roofing  filtri,kot je to npr . primer v postaji FT 2000( 15 kHz, 6 kHz, 3 kHz)  pri vključenem novem roofing filtru zaznali bistveno manjši šum,

kar je normalno !!!!

Karakteristiko filtra najlaže izmerite z VNA mostičem. Na spodnjih slikah   podajam primer izmerjenega  2,1 kHz SSB filtra. za FT 2000   izmerjeno z NanoVNA .

  Slika 5: Karakteristika 2,1kHz roofing filtra ( Logmax, SWR, Smith )

  span 15kHz 

 Slika 6:  2,1KHz  SSB filter  prenosna karakteristika na - 6 dB / 2,1kHz 

(   NanoVNA WebUSB Client - v1,4 android  10  )

Slika 7 : 2, 1kHz SSB filter prenosna karakteristika na - 65 dB / 10,5 kHz 

(  NanoVNA WebUSB Client - v1.4 android  10 ) 

Nekaj nasvetov,kako z NanoVNA merimo kristalni filter : 

https://www.youtube.com/watch?v=3uRA1p6OotA

Kako lahko sami izmerimo parametre kristalov :

https://www.youtube.com/watch?v=G9zZRNzhsEE

https://www.youtube.com/watch?v=rVIHVi-7brs

Kako simuliramo filter :

https://www.youtube.com/watch?v=Y0_H8e4QTy8

Načrt celotnega vezja je objavljen na mojem blogu :  YAESU FT 950 SSB 2,4kHz roofing filter.

Opomba:  Vgradnja v postajo na lastno odgovornost. Priporočam le izkušenim z tehniškim znanjem. Za eventuelne napake ne odgovarjam. 

YAESU FT 2000 CW 1,4kHz roofing filter ( Slovenian language - English abstract )

ABSTRACT

After  1,4kHz roofing has been successfully built_in FT950  I have decided to build the same filter in our Club S53 AJK  transceiver FT2000.  Comparing to NS ( AC0C) 2,4kHz  filter build in my FT 2000 no diference has been found. This  1,4kHz wide filter  overcomes the lack of a narrow roofing filter in an up-conversion receiver . Filter Characteristic Diagram is comparable to the IC-7851 -  1.2kHz Optimum Roofing Filter. The same Roofing  Filter can be  with minor changes used for up conversion receivers  with first  intermediate frequency (IF)  between 60 in 75 Mhz  like : 

ICOM IC : 756, 765, 775,7400, 7410, 7700,7850,7851,9100

Kenwood  TS: 450, 850, 870, 950

Yaesu  FT :  450, 847, 897, 920, 950,991, 1000D, 1000 MP, 1000MP MarkV, 9000

More in Slovenian language (use Google translate)

The photo's are self explanatory

Po  uspešni vgradnji cw roofinga v postajo FT 950 sem za klub  S53AJK vgradil CW roofing še v FT 2000.

Za razliko od Jeffa AC0C sem podobno kot že v postaji FT 950 uporabil originalni 4.polni Yaesu 3kHz filter vezan v kaskado, da sem pridobil na končnem dušenju ,kajti za filter uporabljam 3. overtonske kristale,ki nihajo  tudi na osnovni ter 5. harmonski frekvenci. Pasovno širino 1,4kHz sem izbral tako,da je moj filter še v impedančnam območju 50 Ohmov( slika).

 Filter tipa Butterworth  sem konstruiral s pomočjo odličnega programa Dishal avtorja DJ6EV. Horst DJ6EV mi je tudi dal nasvet,kako optimalno kompenzirati nesimetrijo filtra.

 Na vhodu filtra je vgrajen tudi diplexer, da optimalno prilagodim filter na prvi mešalnik. Ker ima filter v propustnem obsegu dušenje okrog 9dB sem mu na izhodu dodal nizkošumni( NF 0,55dB, Output IP3 + 37 dBm) ojačevalnik PGA-103+LNA. Ker ima ojačevalnik ojačenje na tej frekvenci okrog 26dB pa je potrebno na izhodu dodati attenuator z dušenjem okrog 14 dB. Celotna veriga ne sme imeti ojačenje večje od 1 sicer si pokvarimo IMD3 ! Shema filtra je objavljena na mojem blogu Yaesu FT 950 SSB 2,4Khz roofing filter( picture 4)  s tem, da so spremenjene vrednosti kondenzatorjev kot so označene v izračunu filtra s programom Dishal, za kompenzacijo nesimetrije pa je po nasvetu Horsta DJ6EV potrebna samo induktivnost 330 nH paralelna prvemu kristalu. Za kvaliteten filter morate dobiti čimbolj enake kristale z čimmanjšo kapacitivnostjo Co in čimmanjšo serijsko upornostjo Rs.V mojem primeru je bila kapacitivnost Co okrog 3,5pF in upornost Rs okrog 15 Ohmov.Izmerjen filter je nekoliko ožji od računalniške simulacije tako, da je širina propustnega pasu pri -3db okrog 1200Hz.

 

Vgradnja filtra je bistveno bolj preprosta ,kot je to potrebno za NS  AC0C roofing filter. Ni potrebno prav nobenega rezanja,odstranimo edino upor R 1498,ki ima vrednost 0 Ohmov. 

Enako bom vgradil še 2,4kHz filter za SSB tako, da bom  odstranil SMD upor R 1497 in povezal drugi filter v serijo z originalnim Yaesu 6 kHz filtrom.

Postopek vgradnje :

 

1.       Lociramo originalni Yaesu 3kHz filter in poleg njega  SMD upor R1498

2.       Previdno odstranimo upor R1498

3.       Filter vgradimo tako, da ga pricinimo na bližnje ohišje

4.       Vhod in izhod filtra previdno z dobrim spajkalnikom  priljučimo na mesto kjer je bil prej upor R1498

5.       Priključimo napajanje +8V na izhod regulatorja Q4046 ,ki se nahaja na modulu Local unit ( glej sliko)

6. TEST PRIKLJUČITVE

Vključi postajo FT 2000 na anteno - najbolje na 7 ali 3,5MHz, Amplifier On, CW ali SSB, DSP 3kHz.

Pri preklopih med 15, 6 in 3 Khz  filtri na S metru ne sme biti prevelike razlike.

Pri preklopih med 6 in 3kHz ( 1,4kHZ) roofing  filtrom boste zaznali pri sprejemu opazno zmanjšanje šuma.

KONČANO

7. MERITEV PROPUSTNE  KARAKTERISTIKE FILTRA 

Priključi osciloskop ali frekvenčni analizator na testno točko TP 1045,ki leži za 450kHz filtrom in eventuelno uglasi signal z rdečim trimerjem TC 1002,ki leži poleg odstranjenega SMD upora R1498 na maksimum ( običajno to ni potrebno)

 

7.       Če imaš možnost s frekvenčnim analizatorjem na testni točki TP 1045 še izmeri propustno krivuljo,ki mora biti podobna ,kot je na slikah.

 

Po vgradnji sem z dvotonskim generatorjem z razmakom 2 kHz (7050 kHz in 7052kHz)  z nivojem -28 dBm ( S 9+ 45dB) izmeril karakteristiko filtra ( spodnja slika )

Izmerjena karakteristika filtra je pri -6dB okrog 1490Hz ter pri -60dB pa 9300Hz. Končno dušenje je nekje pri -70dB. Če pogledamo karakteristiko 1,2kHz roofing filtra IC 7851 vidimo, da je moj filter celo bolj strm.

Ker imam v svoji postaji vgrajen NS roofing filter AC0C  me je zanimala še primerjava moje postaje FT2000 in postaje S53AJK z vgrajenim 1,4kHz roofingom. Pri nivoju -28dBm( S9+45dB)vhodnih frekvenc 7050kHzIn 7052kHz z razmakom 2kHz med postajami , na IMD3 produktih 7048kHz in 7054kHz ni bilo razlike večje  od +/- 1dB,  in tudi  pri merjenju  RMDR ni bilo razlike.Z Nano VNA vektorskim analizatorjem  sem posnel tudi prenosne karakteristike obeh filtrov vključno s impedanco filtra,kar je prikazano na spodnjih posnetkih.

Po rezultatih primerjalnih  meritev sem se odločil, da prodam svoj NS filter in ga zamenjam s svojim  ožjim 1,4kHz roofing filtrom.

Opozorilo: Vsi posegi v postajo so na lastno odgovornost. Če nimate izkušenj v elektroniki poiščite strokovnjaka z ustreznim znanjem. V Sloveniji priporočam ,da se za vgradnjo obrnete na Jožeta S53PJ.

YAESU FT 950 SSB 2,4Khz roofing filter

As a backup to my FT 2000 radio I am using a FT 950, which has the same 69,450MHz first IF frequency. The  first IF stage features three roofing filters (15 kHz, 6 kHz, and 3 kHz) automatically selected by mode. Each roofing filter is a four-pole, fundamental-mode monolithic crystal filter design. Unfortunately, some choices made in the first IF design of the rig left is with quite a poor performance score in one area - close-in high-strength signal handling capability. The original Yaesu 3 kHz filter measures only about 7 kHz wide at -6dB.  After Jeff AC0C wrote that  FT2K/FT950 excellent NS roofing filter in no longer in a production I have decided to make my own roofing filter. Roofing filter attenuates and reduce IMD3 products and DSP has less bandwith to process.

After I successfully installed in the second IF 450kHZ a selection of  2 (two)  Murata +/- 2kHz CFWLA450KJFA ceramic filters placed in a cascade and  therefore reduced IF noise and IF image(see picture 1) ,  I also decided  to improve the FT 950  input IMD performance with my own SSB roofing filter.  The same roofing filter can also be used for FT 2000 receiver.

Picture :1  New 450Khz  IF

A homemade SSB the 4 pole 50 Ohm Cohn crystal filters of 2,7 KHz bandwidth at  6dB has been modeled with a AADE Filter design V4,5 program and is built from discrete 3rd overtone crystals. Crystal parameters:  3rd overtone  FL 69,450 Mhz , RR = 20 oHm, C0 = 4pF, FL= 5ppm, package UM1  (see picture 2 and 3)

Picture:2 Cohn  4 pole filter  modeled with an AADE Filter design

Picture:3  Input impedance modeled with an AADE Filter design

To improve the impedance mismatch between 1st mixer and roofing filter I added a diplexer to properly terminate the roofing filter. Diplexer terminates the impedance of the roofing filter to the first  mixer in a wide frequency range. To compensate filter loss I have added ultra-low noise (0,55dB) and  high performance MMIC LNA- SPF 5189Z (or MMIC PGA 103+)with output third order intercept point typ +38.5 dBm. To lower the MMIC  gain a 4dB T attenuator has been built at the output.(see picture 4)

Picture: 4  The 69,450Mhz roofing filter circuit

Unlike Jeff AC0C, I decided to improve the ultimate attenuation and   installed my new 2,7 kHz roofing filter before the original YAESU 3kHz XF1004 filter.( see picture 5)

Picture: 5 

Before the 2,7 kHz roofing filter has been built in the Yaesu 3 kHz filter measures about 6-7 kHz wide at -6dB. The spectrum is taken from the 2nd IF TP 1056 and shows  the filter shape of the original FT filter.( see picture 6)

Picture 6 : Spectrum taken before 2,7kHz  roofing filter has been built

Preparing the 2,7 kHz roofing filter for installation

1.       Locate the working area on the PC board ( see picture 7)

Picture 7: Working area

2.       Unsolder SMD capacitor C 1583 (see picture 8)

Picture: 8

3.  Cut the PCB trace between T1026 and original Yaesu XF 1004 3kHz filter (see picture 8)

4. Solder the input coax center conductor to the center pads of T1026 (see picture 8)

5. Solder the input coax shield to the transformer T1026 casing.(see picture 8,9)

Picture: 9

6. Solder the output coax center conductor to the input pad of original XF1004   Yaesu 3 kHz filter (see pictures 7,8,9)

7. Solder the output coax shield to the ground near filter XF1004 (see pictures 7,8,9)

8. Solder back SMD the capacitor C 1583

9. Connect 9V DC to the new filter from pin 14 - J 1005 ( see pictures 10,11,12)

Picture:10

Picture: 11 

Picture:12

9. Trim T1026 and T1033 to maximum signal level

After the 2,7 kHz roofing filter has been built in ,(see picture 13)  the front end is far more selective and a new filter measures about 2,7 kHz wide at -6dB and 8kHz at -50dB. The spectrum is taken again from the 2nd IF TP 1056 and it shows a new filter shape .(see picture 14)

Picture: 13 Roofing filter  build in

Picture :14  Spectrum taken after 2,7kHz roofing filter has been built in

More about the built in procedure can be seen from the pictures above.

After this modification and  adding a selection of  2 (two)  4kHz Ceramic filter in second IF 450kHz ,   I measured IMD and RMDR dynamic range at offsets of 2kHz  and 5kHz  with   2 x -6dBm  DC4KU   HF- Zweitongenerator FA-2-HF.  Two-tone third order dynamic range (IMD DR) is the diference between MDS and the levels of two interfering signals causing IMD products 3dB over the noise floor. RMDR is Reciprocial mixing dinamic range , measured as a 3dB increase in noise floor.    See Picture 15 

Picture 15: DC4KU  Two- tone RF generator -6dBm

Results of two tone IMD testing - 1.st preamp OFF ; 500Hz Bandwith; Roofing 2,7KHz; AGC Off , Test band is 7MHz ;

MDS = - 128 dBm, 
Blocking above noise floor @ 10 kHz ,measured as 3dB increase in noise floor  107 dB
IMD2 Dinamic range second order on 14 Mhz    = 76 dB

Spacing offset:                                              IMD DR3:                    RMDR              

2  kHz                                                               86dB                       90 dB           
5 kHz                                                                88dB                       98 dB              

According to the experts’ opinion (e.g. Rob NC0B and Tom W8JI), the IMD DR3 of 85 dB is enough for CW. Thus my 2 kHz IMD DR3 86*dB results are very good.

I have been testing the new roofing in CQWW_2019 CW/LP   contest with more than 2010 QSOs  and I was really satisfied with a new installation. I used the radio on the air  several days before  CQ  WW Contest and great difference was noted  between the 6kHz filter and the new 2,7 kHz filter at dynamic range

With a little changes the same filter can be build also in FT2K

Warning !!! Changing any hardware inside FT950 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.

Note for simplified installation  10.08.2020

I found that is much easier  to  unsolder (zero) oHm  SMD resistor R 1393 to insert  roofing  filter in cascade with original Yaesu 3kHz roofing filter. See pictures  below.