If your set has been stamped with a “1” or higher in a circle located near the serial number then these modifications have been done at the factory.  The modifications improve speech amplifier, VOX and balanced modulator performance.  Interaction between the audio level control and VOX sensitivity is eliminated with this modification.

1-Remove the lead from the mic connector and add R208 (39K 1/2W) between the center contact and unused lug of the terminal strip located between TB101 and J103 (key jack).  Reconnect the hot lead which formerly went to the mic connector to the terminal end of R208.

2-Remove C101 (100 mfd) connected between pin 11 of V101 and ground and connect it between the terminal at R208 (above) and ground.

3-Remove C216 (.22 mfd) connected between

4-Change R102 ( located on pin 11 of V101-6C10) from 100K to 1 meg

5-Change R103 (located on pin 3 of V101-6C10) from 3.9K to 1K

6-Disconnect the tube socket end of the lead from the AF level control R106 (connected to pin 9 of V101-6C10) .  Completely remove C103 from the terminal strip (connected to the hot side of the AF level control) and pin 2 of the 6C10.  Add R209, 470K between pin 9 of V101-6C10 and both pin 6 of V101 and ground.  Connect a .005 mfd disc ceramic (now becomes C103) between pin 2 of V101 and pin 9 of V101.

7-Remove C218 (5 mfd 6V, located between pin 1 of V106 and ground).  Remove R140 (1.5K located between pin 1 of V106 and ground).

8-Change R107 from 3.9K to 1.5K by using the resistor removed in step #7 above.  R107 is located between pin 4 of V101 and ground.

9-Remove C106 (.22 mfd, between two terminal strips near V101 and V106)

10-Remove R108 (47K, wired on terminal strip under V101)

11-Change R101 from 220K to 120K and connect between pin 10 of V101 and the B+ lug of the terminal strip (near V101-has red wire attached to it)

12-Remove R207 (47K 1/2W) if it was installed in a previous modification or at the factory.

13-Wire C110 between pin 10 of V101 and the lug of the terminal strip to which the hot side of the AF level pot is connected (white wire with red tracer).  It may be necessary to add wire to one lead.

14-Replace R113 (47K 1/2W) with capacitor C234 (.002 mfd disc between ground and the center tap of T102).

15-Add matching transformer T101 in holes located between the terminal strip and chassis as shown in the diagram below, red and blue leads facing toward the terminal strip.  Blue lead connects to ground. Red lead connects to the empty lug of the terminal strip.  Yellow connects to ground.  Green connects to the center tap of T102 secondary.

16-Re-dress the shielded lead (white-blue tracer connected to arm of AF level control) to facilitate connection of the center conductor to the same lug of the terminal strip as the red lead of transformer T101.  Ground the shield to the ground lug of the terminal strip.

17-Remove R204 (100K 1/2W) and CR109 (zener diode) from the lug of the terminal strip (see attached pictorial diagram).  Connect a yellow lead 9.5” long between this lug and the junction of R199 and R200 (this point is on a terminal strip between V109 and C175, extreme right lug closest to rear of chassis-see pictorial diagram).  Remove completely both of the above noted components. (NOTE: These two parts are not shown on the original schematic in the manual but are shown on the unmodified diagram  for this modification which is not available).

18-Connect a red wire 4.9” long from pin #1 of V106  to S101B (function switch-wafer nearest the front panel-red wire which is connected to R203, 100K 1/2W on operation switch S104 rear.  This resistor R203 is not shown on the original schematic diagram.)

19-Connect C235, a .22 mfd 400V capacitor from pin #1 of V106 to ground (use the capacitor C106 previously removed in step 9)

20-Add a 470K 1/2W resistor across R153 (910K 1/2W to make R153 equal to 330K. (R153 is located on the terminal strip between V109 and C175, lugs 3 and 6 counting left to right).

21-Remove the orange-white tracer lead from the rear pot R149A of the VOX/CW Delay control and connect it to the wiper arm of R149B, wiper arm of the front pot.  Remove the jumper between R149A and R149B and replace with R210, 470K 1/2W.

22-Change R148 (1 meg 1/2W) to 470K (R148 is located between pin 8 of V106 and terminal strip adjacent to V107).

23-Disconnect the short shielded lead from pin #11 of V101 and re-dress it to reach the lug of the terminal strip which is connected to the junction of C110 and the hot side of the AF level control (white-red tracer shielded lead).  It may be necessary to add a short piece of wire to this lead.

24-Add a .0005 mfd capacitor between ground and the lug to which C104 is terminated.

25-Inspect the power transformer secondary winding connections.  If the red-yellow tracer wire is connected to choke L112 and the red-black tracer wire is connected to the 680 ohm resistor these wires should be reversed so that the red-yellow tracer wire is connected to the resistor and the red-black to the choke.

After modifications have been completed the balanced modulator must be readjusted.