I haven't looked at an MP yet, but here are the
results on a 1000(D)...
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 to the base, and a 10
uF 25 capacitor to ground.
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.
73, Tom W8JI
W8JI@contesting.com
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