ARLA/CLUSTER: Fwd:modification for TS2000x (1296 module) de Wayne,
Quinta-Feira, 14 de Fevereiro de 2008 - 15:29:16 WET
The problem is L132 on the TX-RX 1 UNIT (X57-605X-XX) The (HF/IF) (A/9) board...
CN27 on this board feeds the bias to the 1.2 GHz module.
The supply comes from an 8V regulator on the FINAL UNIT (HF)
X45-360X-XX (A/2) - CN9 on this board to
CN29 on the HF/IF board... The two flexible tracks marked 8A of the
harness between CN29 and CN9 have no voltage drop!
There is a 1 amp fuse on the HF/IF board before it gets to L132 -
L135 (Beware of idiots who tell you that there is a voltage drop on
tracks of this PCB...One of the original mods was to parallel these
tracks! The fuse would have been bypassed...)
What starts out as 8 volts ends up as 6.87 volts by the time it gets
to pin 3 (the bias pin) of the Mitsubishi M57762-02 1.2GHz module.
The biggest part of that voltage drop is across L132...
You have a few choices... Remove L132 and just short the two pads
where it was mounted.
Use a much smaller SMD inductor e.g. 10 nanos, which has no voltage
drop. (I did that)
Or you can just use a 0 ohm SMD resistor to replace L132...
Before this mod I was repeatedly told that I was distorted on 1296MHz
when I ran 10 watts.
If I choked the TS2000X back to 1 watt it sounded okay.
All other bands I had very good modulation reports. Typical of Kenwood...
After the mod Trevor VK4AFL and Roy VK4ZQ both gave me a clean bill of health!
The IM products are now -32 dB below a single tone on 1296 MHz or -38 dB
below the P.E.P. output.
My Icom IC-910H has the same module and it sounds very good on 1296MHz...
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