[Kenwood] TR-9000 PLL PCB ?

Wed Aug 23 15:48:33 EDT 2006

Anyone ever had a problem with the TR-9000 or TR9130 PLL board where the 
14.20055 MHz circuit locks onto the 10th harmonic instead of the 9th as 
it should?
Been playing with this one for a few months as a thought puzzle but 
don't want to replace every component trying to figure out which one is 
offending.
It is the board as a good PLL board brings the radio to life.
The 14.2 Mhz signal is injected through a cap into a resistor and a 
diode. The resistor to ground and the diode to double tuned varable L 
fixed C tuned slug transformer .
Evidently , the non linearity of the diode is supposed to spring up all 
the harmonics of the signal and double tuned network is supposed to 
resonate the 9th harmonic giving 127.805 Mhz signal used in the loop.
For some reason , this one is resonating to the 10th harmonic and so all 
signals end up off by 14.2 Mhz.
Tuning the divide by n low enough where the loop locks up gives a locked 
signal but it is off by 14.2 so all other signal processing is out of band.
Changing the divide by n moves the frequency nicely untill the loop unlocks.
Changed the tuned coils, caps, active devices...etc.
Didn't try the diode and crystal but those are next.
---
Ron