The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

Radio Make and Model:
Superstar 158EDX
Test gear available:
Basic meters
Symptoms:
Drifts on TX an RX
What is working:
Everything else
What has been tried:
Checked power supply stability
Did it suddenly happen ?:
Since it was new.
Anything else that may be of help?
I have considered reducing the supply voltage to the coarse clarifier to reduce the frequency varience. Or to make tuning easier making the fine clarifier two way as well.

These things always drift like crazy - they certainly needed the factory fitted slider

They can be made better (not fixed completely) by adding a PTC heater to the main reference crystal.

Crystal heaters can be had from: http://www.minikits.com.au/kits3.html#eme177

They also sell the component alone (pictured below) if you want to make something up yourself.

Fit it here:

You'll need two, one for each crystal, if you want to cut the drift down on both 27Mhz and on the 10M ham band.
Otherwise, just fit one to the crystal that controls the band that you use.

Here's what they look like:

Connect the - to ground and the + to the DC power socket positive terminal (not the switched voltage)

This will only make it better, not fix it completely (it will cut it down from 1000Hz+ to about 200-250Hz).

The only way to cure it completely is to replace the synthesiser circuit with an addon type, this will see it stable to within 25Hz or so (basically inaudible), but that would cost about the same as what you paid for the radio new, and would have to be professionally fitted (doing this is NOT a beginners project!).

Hope this helps