Superstar Radio Frequency Modifications:

Superstar 121:

Export Conversion:

1. Remove the top cover from the unit and locate the PLL chip (MC145106P). Unsolder the short jumper wire running from the +8.2vdc source to pin 9 of the PLL chip. 2.
2. Resolder the three pins of the PLL chip, Pins 10, 11, and 12, being carefull not to short them together

+10KHz Jump Switch

  1. Get a SPST switch and mount it in the radio
  2. Find IC 6 and 7 by the PLL Chip.  You will see J25 and J27
  3. Solder a wire from one side of the switch to J27
  4. Remove the jumper that is J25
  5. Install a 4.7KOhm resistor in its place
  6. Solder a wire from the other side of the switch th J25 (see pic above)
  7. That's it.  Flip the switch to jump up one channel.

Channel Expansion:

  1. You will need 3 SPST switches and mount them in the radio
  2. Find the MC145106 PLL
  3. Locate pin #10 and cut the trace going to this
  4. Switch #3 will be soldered to the cut traces on pin #10
  5. Solder wires to the other 2 switches as shown in pic above
  6. That's it.

ALL switches down give normal FCC 40

Radio in "HIGH" band, switch 1 UP, 2 and 3 DOWN:
Channels 10-19 yield 27.845-27.995

Radio in "MID" band, switch 1 and 2 UP, 3 DOWN:
Channels 1-12 yield 27.925-28.065

Radio in "HIGH" band, switch 1 and 2 UP, 3 DOWN:
Channels 27-38 yield 28.045-28.155

Radio in "HIGH" band, switch 1 and 2 DOWN, 3 UP:
Channels 1-40 yield 26.135-26.575

Superstar 140:


1. Use the diagram above to boost the power range and eliminate the HI-LO power switch if desired. The AMC is boosted by removing C53 or adjusting RV-2.
2. Frequency modifications are shown in Diagram A and B. The diodes must be replaced with 2.2K Ohm resistors if you wish to make these modifications. A SPST center off switch is used to cover various combinations of frequencies shown in diagram B and the frequency chart. Choose the bands you desire and wire the switch accordingly. A simple variation can also be made by using the HI-LO power switch on the unit.
3. Talk back can be added to the unit by soldering a 68 Ohm resistor from pin 3 of the Mic. socket to ground (Pin 2 of Mic. socket). The HI-LO power switch can also be used to switch in and out the talk back if desired.

Super Star 140 Microphone wiring is the same as all Midland Radios.

Superstar 3900:
Export Frequency Conversion,
Frequency Expansion,
10 Meter Expansion,
Unlock Clarifier Mod:

Export Frequency Conversion

  1. Remove the top cover from the unit and locate the row of 15 pins across the front of the unit. Unsolder the short jumper wire from the 7th. pin to pins 11 and 12 (connected together).

  2. Unsolder the shorting solder bridge of pins 11 and 12 so that they are independent pins having no connection between them.

 

+10 KHz modification:

  1. Get a SPST switch and mount it in the radio.
  2. Find IC6 and 7 by the PCC chip.  You will see J68 and J69.
  3. Solder a wire from one side of the switch to J68
  4. Solder a wire from the other side of the switch to J69.
  5. That's it.  Flip the switch to jump up one channel.

Unlock Clarifier:

  1. Find D75 and R135 and cut one end of them.
  2. On the back of the clarifier know follow the green wire to the PC board.  Cut this sire from the PC board.
  3. Solder the green wire (end you just cut) to a constand 8VDC source, like the collector of TR41.
  4. Take the yellow wire and cut it from the know.  Tape this wire, it is not needed.
  5. This should make the clarifier track tx/rx on the same freq.

10 Meter Mod

  1. Find IC7 by the PCC chip.
  2. Get a SPST switch and mount it in the radio.
  3. Solder a wire from one side of the switch to Pin #13.
  4. Solder a wire from the other side of the switch to Pin #12.
  5. That's it.  Put the radio on 'Band D' then flip the switch to jump up to 28.300 to 28.500

Peak and Tweak:

  1. Audio Limiter: cut R249
  2. AM Power: VR13
  3. SSB Power: VR12

 

Superstar 4900 B:

Export Frequency Modification
(23.815-30.555 MHz!!!)

Remove the top cover from the unit.  There are a total of 14 screws and 4 different types that have to be removed.  (3 flat head screws on top, 1 round head on the back, 4 round heads on the sides, 2 chrome screws from the handle (don't lose the 2 brass inserts) and 4 small screws from the rubber feet)

Locate the 4 position jumper block located next to the K3170 IC chip.  Move the two jumper blocks to the pins shown in the diagram.  Note: see diagram for  different conversion positions.

Export frequencies will be selected by the way you choose to place the jumper blocks.  If you choose the position shown in the diagram above (3 & 4) the display will indicate the frequency and band selection with the + or - A B C D E symbols.  The so called "A" channels (or "RC" channels) are designated with a small "A" symbol after the frequency indication.  If you choose to remove all jumpers, the unit will cover all frequencies with continuous coverage.  The desired frequency can be entered directly on the keypad.  The ANL button will function normally in this position and the step button will select all three segments of the frequency display.  This may be a little confusing for some users so choose your method carefully.

The "STEP" button can be used to select +1, +10, +100 KHz depending on the jumper placement.  Jumper blocks on 2 & 3 or 3 & 4 will only select 1KHz mode.  Removing all jumpers selects all modes.

AMC:
To open the AMC limiter circuit, locate the small surface mount transistor approximately on inch from the 5 and 6 pin connectors at the front left side.  Carefully unsolder and lift the center pin up from the circuit board,  or remove the part entirely.

Clarifier Control:
The clarifier tracks transmit and receive on SSB operation only.  The control will move several KHz with No modification necessary.  Use "STEP" button for Frequency Offset Operation.