Noise Floor on SS3900

[HomerBB]

I picked up a SuperStar 3900 Plus and find it to have about the noisiest receive of any radio I've owned. The white noise is terrible. I managed to bring the noise level down on my 959 while improving the receive by simple adjustments within the radio. The question here is whether anyone knows where or what I can do on this EPT360010 board to accomplish an improvement. I have found a mod that enhances receive, however, it is said to make it sensitive to the point of potentially causing harm to the receive of the unit should a loud audio signal nearby be keyed into it.

Any hope for quieting the white noise down without losing receive?

Thanks,
Homer

Looks like this:

 

[tecnicoloco]

I picked up a SuperStar 3900 Plus and find it to have about the noisiest receive of any radio I've owned. The white noise is terrible. I managed to bring the noise level down on my 959 while improving the receive by simple adjustments within the radio. The question here is whether anyone knows where or what I can do on this EPT360010 board to accomplish an improvement. I have found a mod that enhances receive, however, it is said to make it sensitive to the point of potentially causing harm to the receive of the unit should a loud audio signal nearby be keyed into it.

Any hope for quieting the white noise down without losing receive?

Thanks,
Homer

Looks like this:

Hello:

I have the same radio and I did this mods to mine,works pretty good

RX Sensitivity
Change R44 100K to 39K
Change R46 39K to 100K
***Just swap both resistors***

D20 to Schottky
D21 to Schottky

Change R81/100 Ohms to 180 Ohms (DONE)
***Improves Noise Floor,Lessens Stage Gain***

Try this mods at your own risk


73 de Tecnicoloco

 

[HomerBB]

Hello:

I have the same radio and I did this mods to mine,works pretty good

RX Sensitivity
Change R44 100K to 39K
Change R46 39K to 100K
***Just swap both resistors***

D20 to Schottky
D21 to Schottky

Change R81/100 Ohms to 180 Ohms (DONE)
***Improves Noise Floor,Lessens Stage Gain***

Try this mods at your own risk


73 de Tecnicoloco

Thnx!
What might the risks be? Any in particular, or just the general warning issued with all mods?

 

[sp5it]

Which schematic fits to this radio?
Mike

 

[HomerBB]

Which schematic fits to this radio?
Mike

The only info I've found on it is here:



EPT690010Z Main Board Modifications

(Galaxy DX2517, Ranger RG66, RG99, Cobra 148F GTL DX+, Texas Ranger, TR6900, TR6900 Jumbo, TR6900F and others)

I believe my board is the EPT360010C

I just located this one, too: CHASSIS EPT690010Z/CHASSIS EPT069610Z

 

[9C1Driver]

I would have a good shop do a proper alignment on it first and see if that helps. Since it's a 10m Export it was probably just converted, the receive needs to be aligned for 11m use.

 

[tecnicoloco]

Thnx!
What might the risks be? Any in particular, or just the general warning issued with all mods?

Just the general warning issue,I did this mods to my Superstar 3900GHP/EPT360010C.

Is very similar to the Galaxy48T

Hope this helps
Tecnicoloco

 

[HomerBB]

Thanks everyone. I have a reasonable bit of info now because of you guys.