Superstar 3900 F, Modification confusion

[Steven D]

Hi Everyone,

I have a rig here which is a Superstar 3900 Black and was wondering if
anyone could give me some advice?

I have heard that there are simple conversions which can be done to
these to get extra frequencies by connecting and disconnecting
different points on the circuit board? I have found losts of
information on these mods but am unsure what their outcomes mean????

These are the mods which I found on internet, but what do they do or
mean?

Open Clarifier
1)Find D75 and R135 and cut one end of them.
2)On the back of the clarifier knob follow the green wire to the PC
board. Cut this wire from the PC board.
3)Now Solder this wire to a constant 8VDC source, like the collector
of TR41.
4)Take the yellow wire and cut it from the knob. Tape this wire it is
not needed.
5)This should make the radio TX/RX on the same frequency.

10 Meter Mod
1) Find IC7 near the PLL 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.

Tweak and peak
Audio Limiter - Cut R249
AM Power - VR13
SSB Power - VR12



If anyone has any advice or experience of doing this could they help?

This radio also has a small fault which the channel display keeps
flickering and shorting on and off whenever it feels like it, does
anyone know if this could be easily fixed?



Best Regards

Steven

[Richard Cranium]

Post by Steven D
Hi Everyone,
I have a rig here which is a Superstar 3900 Black and was wondering if
anyone could give me some advice?
I have heard that there are simple conversions which can be done to
these to get extra frequencies by connecting and disconnecting
different points on the circuit board? I have found losts of
information on these mods but am unsure what their outcomes mean????
These are the mods which I found on internet, but what do they do or
mean?
Open Clarifier
1)Find D75 and R135 and cut one end of them.
2)On the back of the clarifier knob follow the green wire to the PC
board. Cut this wire from the PC board.
3)Now Solder this wire to a constant 8VDC source, like the collector
of TR41.
4)Take the yellow wire and cut it from the knob. Tape this wire it is
not needed.
5)This should make the radio TX/RX on the same frequency.

Sounds correct.

Post by Steven D
10 Meter Mod
1) Find IC7 near the PLL 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.

Stay below 28 MHz!

Post by Steven D
Tweak and peak
Audio Limiter - Cut R249

Do NOT do this or you will splatter all over. If the modulation seems
weak, try a power mic.

Post by Steven D
AM Power - VR13
SSB Power - VR12

Using a watt meter tune for max, then back it off a bit. If you're
going to use an amp, set AM for about 3 watts and SSB for no more than
10 watts for a clean signal.

Post by Steven D
If anyone has any advice or experience of doing this could they help?
This radio also has a small fault which the channel display keeps
flickering and shorting on and off whenever it feels like it, does
anyone know if this could be easily fixed?

As another poster said, it's probably a cold-solder joint on the back
of the display board. If you're good at soldering PC boards, you could
touch all the solder points up with a fine-tipped iron and probably
fix it.