In some early model of TM-3530 transceiver transmit noise may be generated as the unit warms up. The following procedure will reduce the noise.

1. Disconnect the power cord and antenna.
   
   
2. Remove the top and bottom covers.
   
   
3. Replace L3 on the Compound unit (part number L15-0308-06). Before soldering the coil to the board, place a drop of contact or silicon glus under the coil to prevent mechanical vibration.
   
   
4. On the Compound unit, solder two springs (part number G02-0550-04) to the heat sink as shown in figure 1. The springs must be mounted high enough to make firm contact with the top cover when installed.
   
   
5. On the PLL unit, solder a spring (part number F10-1206-04) to the TX VCO shield (See figure 2). The spring must make firm contact with the bottom cover when installed.

Caution: The next step requires complete disassembly of the front panel and Display unit. This step may be reserved for problem units.

6. On the Display unit, replace jumper JP3 with a diode (part number 1S1555) as shown in figure 3.
   
   
7. Reassemble the transceiver and test the modulation for correct adjustment:
   
   
   1. Apply a 1 KHz, 50mV signal to pin 1of the mic jack.
   2. Turn VR7 on the Compound unit fully CCW.
   3. Use a service monitor, linear detector, or deviation meter to measure the TX deviation at the antenna jack.
   4. Adjust VR5 on the Compound unit for +/- 4.5 KHz.
   5. Reduce the mic signal to 5 mV. Adjust VR7 for +/- 3.0 KHz.

Figure 1.

Figure 2.

Figure 3.

Time required for this modification is 1 hour or less.