Key Click Modification for the FT-1000MP
By Robert Peterson, W3YY
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 won’t receive
any comments. If, however, you run
high power, have big antennas, and spend long periods on a run frequency, then
you’re likely to get complaints about your signal.
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 wasn’t a pleasant thought, but cluttering up the band with noise
every time I operated was even less pleasant.
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.
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.
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.
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.
gets the impression that he offers this as a recommended alternative to both the
INRAD and W8JI modifications.
my modification, I decided to try N1EU’s suggested component values.
A .1µF ceramic capacitor was added to the RF board and a .047µF and two
470K ohm resistors in parallel (235K ohms) were added to the IF board.
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.
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 it’s 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.
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.
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.
modification you choose, however, please do it. Your signal will only be better as a result and you can’t
73, Bob - W3YY
Note: This article was submitted to and appeared in the November 2004 PVRC Newsletter, produced by Pete Smith, N4ZR.