Key click and
noise blanker
improvements for
Yaesu FT1000 and
FT1000D models 

Revised 1/31/04 at 0130Z

Receiver
Improvement for FT-1000 and
FT 1000 D

The
FT-1000(D) runs an essentially unshaped CW waveform into the filters. This harsh
signal generates unnecessary key clicks. The clicks are strongest from almost 1
kHz below to 2kHz above the transmit frequency.

The
cure:

 

WARNING: The last batch of these mods will be built in the Sept 2015 in this
run. This product is obsolete.

I now have a plug-and-play 100% tested mod for the
FT1000 and 1000D. This mod just plugs in, and includes the receiver NB mod.

Neither mod requires soldering! Only a screwdriver
is required. The price for both
mods is $53 Priority
Mail in the USA. You
can contact me at
the following
address

click
this link to

View
FT-1000 and FT-1000D plug-in modification
kit

Locate
the seven-pin connector J3024 at the middle-front of the AF board. (The AF board
is the one with the audio, PTT, ALC, and key jacks as well as other connectors.)

 

This is a picture with a hand-wired mod in place. 

Download picture

Cut
the wire going to pin 2 T CNTL). This is the second terminal from the right
(front of radio viewing). This is NOT the lead with 9 volts (nine volts is on
pin 6). If you are unsure you counted the correct direction, measure the voltage!

Connect
the collector of a 2N3904 to the flying harness wire you just cut.

Connect
the emitter towards the jack on the wire you just cut. This transistor MUST be a
2N3904.

Connect
a 1.5k resistor from collector-to-base on the transistor.

Connect
a 10uF, 25-50 volt capacitor from base to ground. A non-polarized capacitor may
be better if you can find one. No one has reported problems with normal
electrolytics as long as the positive lead connects to the base of the
transistor.

For QSK operation
use a 5uF capacitor. 

The
Results:

This
modification slows the waveform rise and fall times at Q3030 and D3009. The
result is a normally sloped CW waveshape into the SSB filter.

 

This
is a nearly-perfect waveform with about 7mS fall and 4ms rise. The important
thing is there are no sharp edges that cause clicks!

Clicks beyond 1 kHz above and below the transmitting frequency
move into the
composite transmitter noise, and there is about 50 dB reduction in clicks on
some radios
above the TX frequency!

Clicks
500Hz away are reduced about 20-35dB.

There
is almost no change in “keying sound” on the transmitting frequency.
The envelope shape is near ideal, and bandwidth reduction is dramatic.

Operating

Warning: This mod is NOT compatible with QSK with
the full 10uF in circuit. For
QSK use, I suggest adding a SPST switch from the 10uF capacitor to ground. You
can place an additional 10uF capacitor across that switch, or simply add an
additional 10uF in series with the ground lead from C1 ( this gives 5uF total
value at the base of Q1) and not switch the
system. When not operating QSK, I recommend using the full 10uF of C1 for the
cleanest signal. 

The ideal wave shape occurs when the ALC  is at
the upper area of the blue ALC line
on the FT1000 meter. With full DRIVE,
adjust for desired power with the RF PWR
control. After achieving desired power, back the DRIVE
down until the ALC indication just starts to move away from full blue area
(half-scale). Anything from 1/3 to 1/2 scale is a normal waveform.

For lowest clicks, adjust DRIVE
until ALC until it just registers (perhaps 1/8 to 1/4 scale on ALC).