Topband: FT-1000(D) click mod

[Tom Rauch]

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 


--
FAQ on WWW:               http://www.contesting.com/FAQ/topband
Submissions:              topband@contesting.com
Administrative requests:  topband-REQUEST@contesting.com
Problems:                 owner-topband@contesting.com