Modifications for the Kenwood TM-702

KENWOOD TM-702 to 9600 baud

The following description refers to the modification of RTX double band KENWOOD TM702E with the pourpose of enabling the operation at 9600 Baud with the use of modem G3RUH.
The radio functions very well and herebelow the details.
Please note that i have made the necessary connections on the main grid, souldering side, on minus of the PTT.
For the reception i have connected the audio plug for the two meters directly on the PIN 12 of IC 11, and for the 70cm directly on the PIN 12 of IC 3.
For the trasmission on 2 meters i made the contact between the resistor SMD R70 of value 0 and the trimmer VR4 while for the 70cm i made the contact between the resistor SMD R67 with value 10K and the trimmer VR3. I souldered the plug on PTT directly on the back of the microphone plug on PIN 2.
For the connections i have used earthed 5 poles cable and earthed it on the MIC AMP earth, thus on PIN 1 but earthing can be done anyhow.
Initially i have tried to keep together the connections of the two bands thus using the same conductor for the RX of the the 2 meters and the RX of the 70 cm as well for the TX.
However i have obtained etter results during transmission with separate connections. This explains the use of 5 poles cables. Eventually the afore mentioned cable was been inserted through the same hole of the power supply cable.
Of course i have removed the cut protection rubber on the hole.
For the utilization of one band or the other , i commute the connections from the radio at the inlet of the modem in the TNC. That is all.
I remain at your disposal for further clarification.
Ciao from Lino ik3ngu@i3xty of Treviso
KENWOOD TM-702E & mods. for function trsponder

I will explain the modification necessary to operate TM702E as a true transponder.

Open the radio from the lower side. Lay it on the table with the front side towards your chest. You will see six screws that sipport the circuit card. Refer to the nearest screw from the front at 2 cm on the left there is a tin place in proximity of a brown resistor mounted horizontally. Solder a piece of wirw on the tin place. The other point were to solder is another tin place which is located, tacking in consideration the previous screw, as follows: above the screw there are two rows of soldering placed vertically (they are the only ones); consider the one on the right abd starting counting from the bottom (front side) at the second pin there is the other tin place where to solder the othe tip of the wire (it is just a bridge) you cannot fail as the two tin places are the only ones free from any soldering. however pay attention to count from the bottom otherwise if you start from the top (but there is the first pin)you find another tin place similar to the others which i don't know the effect of...

Remember to remove the mike when you activate the transponder othewise the back ground noise will be transmitted.

This modification is easier ti make than to explain, The transponder is activated by F + BAND and pression again F for more than 1 second until flashing and then press low.
73 and good luck. Aldo.


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