CTCSS encoder upgrade on a Kenwood TS711E / TS811E

Modification of Control Unit (X53-1410-XX);
to accomodate TU-5 board

 

Remove the Tone Unit X52-1290-60 (1750 Hz)
Disconnect alle the connectors of the Control Unit
Remove the 2 screws on the side which locks the coolingplate to the chassis
Remove all screws which holds the Control Unit
Open up the 6 solderholes and place a 6 pen header with sufficient  pinlength
Solder and cut header to correct length.
Remove R55 22 kOhm (near J9)
Place jumper W2 (near J9, across one side of the removed R55 connecting  J9-1 and TU-5 pen TH)
Place C56 470 pF axiaal ceramic capacitor (near J9, between J9-1 and  ground)
On TS-711:
Remove D30, D33 and D34 (near J1)
On TS-811:
Diodes 30, D31 and D34 in, connect pin 3 (TH) with pin 4 (5C) on TU-5 unit
On TS-711/TS-811:
Remove D16 (near TU-5 unit)

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Modification of Switch Unit

 

Remove on/off switch
make a cut in the circuittrace of S9 (on the rightside of the text 'S9')
Place a jumper wire from the middle switch S8 left-under to the right switch S9 right upper side as done with the green wire.

By wiring the TONE switch to the absent middle switch access to the CTCSS menu is obtained.

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Activate the changes in the diode matrix

 

Keep knob A=B pressed while switching on the TS711, release knob A=B.
The RX-range is now 144-153 MHz, the TX range remains 144-146 MHz
When the OFFSET button is pressed pin 3 (TH) of the TU-5 gets active   (5Volt) and an CTCSS tone is generated.

Different tones are selected by pressing the TONE switch and rotating the VFO knob.

Adjustment of CTCSS modulation

Adjust for a deviation between 500 and 750 Hz

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Part list

1 x condensator 470 pF keramisch axiaal
1 x header 6 pen
1 x tu-5 unit, either original from kenwood or tu-5px from www.piexx.com

Please read the full story on a bigger screen.

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