Note: this modification was developed by W8JI for his FT-1000D and originally posted to the Topband reflector. There's more keyclick info on W8JI's excellent Web site. The problem: Good engineering dictates never running a square rise and fall waveform into a crystal filter. The square rise-and-fall waveform will cause filter ringing. The FT-1000(D) runs an essentially unshaped CW waveform into the filters, generating unnecessary keyclicks that are strongest from almost 1 kHz below to 2kHz above the transmit frequency. The cure: Locate the seven pin connector J3024 at the middle front of the AF board. The AF board has audio, PTT, ALC, and key jacks as well as other connectors. Cut the wire going to pin 2 (T CNTL). This is the second terminal from the right (front view). This is NOT the lead with 9 volts (nine volts is pin 6)! Connect the collector of a 2N3904 to the flying harness lead, and the emitter towards the jack. Connect a 1.5 k resistor between the base and collector, and a 10 uF 25 capacitor from base to ground. (N1EU note: I used a RS generic npn transistor) The Results: This slows the waveform rise and fall times at Q3030 and D3009. The result is a normally sloped CW waveshape hitting the SSB filter. This reduces clicks beyond 1 kHz above and below the transmitting frequency into the composite noise of the transmitter, about 50 dB reduction in clicks on my radio above my TX frequency. Clicks 500 Hz away are reduced about 35 dB. There is almost no change in "keying sound" on the transmitting frequency. Very little change in envelope shape, yet bandwidth changes are profound.N1EU's Before and After Recordings
The following edited audio clips each feature a sweep of the transmit signal before and then after the modification. A string of "dahs" is sent while a little FT-817 with a 300hz filter is swept as indicated. Please excuse the low level spurious products heard due to overdriving the FT-817 front end (S9+20dB), but they don't detract from the object of interest, the keyclicks being transmitted by the FT-1000D. Click on any of the links below and either open the .WAV file or save it to your computer: Receiver sweep from 2Khz to 1.6Khz above fundamental Receiver sweep from 1.75Khz to 1Khz below fundamental I found the mod quite straightforward to install and ran into no snafu's. I urge all FT-1000 cw operators, and definitely every cw op running QRO, to install the mod or have the mod installed by someone else.N1EU's Implementation
arrow points to transistor with leads up K1ZM's installation notes: I did as Tom said and cut the wire going to pin 2 on J3024 (this is the second pin from the RIGHT) when viewing this connector with the radio upside down with the front panel facing toward my chest. You want to follow this wire into the harness and cut it so as to leave about 1.25" of wire remaining on pin 2 of J3024. Then pull the harness side of the wire out carefully to expose a similar length of wire. I made up a little "jig" of the 2N3904, with the 1.5k 1/2 watt resistor connected between the base and the collector of the transistor - and tinned the emitter to accept a "tacked on" connection. The third component required is a 10UF electrolytic at 25v, the negative side of which must go to ground. Perhaps not the NEAREST point - but certainly the EASIEST and most accessible point at which to find chassis ground and mount the cap is at a mounting screw for the AF board in the middle of the board on the front panel side. This is about 2 inches to the LEFT of where the cut wires wind up - and it is also an open area allowing plenty of room for the cap to float above the board. I chose an axial lead cap for this project (largely because its long leads were useful to me in spanning the distance involved) and mounted it flush onto a solder lug. This I placed under the board mounting screw noted above - negative side of the cap almost directly on the lug. Then I dressed the positive axial lead with sleeving and passed it UNDER an intervening wiring harness in order to get the plus side of the cap into the general vicinity of where the two wires resulting from the cut to pin 2 at J3024 would reach. Once this has been achieved, it is a straightforward process to tack the short wire from pin 2 to the emitter of the transistor and the flying harness lead to the collector. The positive lead of the 10UF cap is most easily tacked on last and I should note that it is this lead that suspends the mod in mid air above the AF board. As an added measure to insulate the mod from all other components around it, I placed some pvc electrical tape over the top and bottom of the mod - just in case. One other point worthy of mention is that it is a good idea to bend the solder lug up at a 45 degree angle right at the screw to ensure no adjacent foil traces wind up being jumpered when you tighten the screw to hold the lug in place. I also aimed the 10UF cap into an open area on the board - where it just floats out of harms way from nearby components. It is easy to see how to do this when looking at the board - and also easy to pass the positive axial lead UNDER the harness to the right in order to make the connection to the base of the transistor where it meets one side of the 1.5K resistor.