Key Click Modification for the FT-1000MP

By Robert Peterson, W3YY

I think most are aware that the FT-1000MP series of transceivers have a reputation for generating key-clicks.  If you have one of these rigs and are a casual operator, you probably wont receive any comments.  If, however, you run high power, have big antennas, and spend long periods on a run frequency, then youre likely to get complaints about your signal.

After receiving a few unsolicited comments about key-clicks on my signal, I decided I better look into doing something about it.  The thought of tearing my FT-1000MP apart and working on the high-density PC boards wasnt a pleasant thought, but cluttering up the band with noise every time I operated was even less pleasant.

There is lots of information on the Internet regarding key-click modifications for FT-1000MP and MP Mark V.  I found three suggested modifications, all of which involved adding some components to the RF and IF boards to slow the rise and fall times of the CW envelope.

Probably the best-known modifications are those presented by W8JI on his web site at http://www.w8ji.com.  Although the rigs and associated modifications are similar, W8JI devotes different sections of his web site to the MP and MP Mark V.  Modifications involving both fixed component values and experimentally determined values are presented.   The modifications appear to be very effective.  In the example presented for a FT-1000MP, W8JI experienced a 30dB reduction in noise at 1 kHz from the transmit frequency.

Another well-known modification is available from INRAD.  A good article and information is available at http://www.qth.com/inrad/about-key-clicks.pdf.  This modification adds just one component to the RF board, two to the IF board, and no experimentation with component values is required.  In the particular example presented (an already pretty clean FT-1000MP) INRAD shows a further 10 to 11dB reduction in noise at 1kHz from the transmit frequency.  This degree of improvement is enough to make any FT-1000MP quieter than most stock rigs.

Finally N1EU presents a solution that is essentially the INRAD mod with a change in one of the component values.  N1EU does not present any spectrum analysis to provide quantitative results, but does provide an interesting set of audio recordings that illustrate the effectiveness of the modification.  See http://n1eu.tripod.com/Yaesu/MPclicks.htm. 

One gets the impression that he offers this as a recommended alternative to both the INRAD and W8JI modifications.

For my modification, I decided to try N1EUs suggested component values.  A .1F ceramic capacitor was added to the RF board and a .047F and two 470K ohm resistors in parallel (235K ohms) were added to the IF board.

The result of the modification was quite gratifying.  The sideband noise 1 kHz from my transmit frequency was around 46 dB prior to the mod (about 4 dB worse than the FT-1000MP illustrated on the W8JI web site) and improved to about 60dB after the modification was installed.  See before and after spectrum pictures below.

 

      

 

             Unmodified FT-1000MP                                 Modified FT-1000MP

 

I found the actual modification to be difficult, but not as difficult as I feared.  The FT-1000MP disassembles quite easily.  Definitely plan on removing the RF board entirely.  It might be possible to do the mod with the board still partially connected, but its not worth the hassle.  The black clips that hold the ribbon cables in place require some experience to remove.  To remove them, first lift them slightly and then use a bent paper clip underneath the side tab to pull and release it.  Then ribbon cable will pull out with zero force.  Also, there is very little space for the additional components under the IF board.  I put a couple layers of tape on the chassis at that point to prevent any accidental contact with the new components.  Finally, be careful not to accidentally disturb the settings of the many alignment potentiometers that seem to be everywhere.

 In summary, I believe this is a worthwhile modification that can be done in an afternoon by most hams that are reasonably proficient with mechanical assembly and soldering techniques.

 Please note that this article is not intended as an endorsement of any particular key-click modification.  I chose one approach and am happy with the results.  Would I have done better with another approach?  Perhaps.  Please study the information on the different modifications before making your choice.  Also, it should be noted that there is information to indicate that every stock FT-1000MP or MP Mark V may not be identical in key-click performance.  Consequently, unless you compare the different modifications on the same rig, you may be comparing apples and oranges.

Whatever modification you choose, however, please do it.  Your signal will only be better as a result and you cant beat that.

73, Bob - W3YY

 

Note:  This article was submitted to and appeared in the November 2004 PVRC Newsletter, produced by Pete Smith, N4ZR.