Proper Discriminator

[jasoyeom]

I have a Realistic Pro 60 that I'm using for decoding digital transmissions etc.

Right now it's just a straight connection to the discriminator in the scanner to a headphone jack that I connect to my computer to record. When the squelch is on I'm getting some sort of audio noise that goes off and on.

I've seen specs that use a resistor etc so I'm looking for a better tap to get better audio. Does anyone have any suggestions of a good tap/slicer?

Thanks,

Jason

 

[SCPD]

Try these instructions.

Audio Recording Level Adjustment

 

[DaveH]

You really don't need to be concerned with a slicer, as recent versions of TRUNK88,
UniTrunker, etc. all run from discriminator audio to sound-card. The only case would be
running older legacy utilities like Trunker, Etrunk, Treport etc.

Dave

 

[jasoyeom]

I am using TRUNK88 without a discriminator tap but I have some other software that needs the tap. Finding information on a tap on the Pro-60 is hard to come by. I may have it connected to the wrong part of the chip.

 

[davidmc36]

I am using TRUNK88 without a discriminator tap but I have some other software that needs the tap. Finding information on a tap on the Pro-60 is hard to come by. I may have it connected to the wrong part of the chip.

This may steer you in the right direction.

 

[East_Algoma]

add a capacitor to Squelch

 

[Forts]

On the Pro-60 it looks like the discriminator output should be IC-301 pin 9 (chip could be labelled with 'TA31136FN').

 

[DaveH]

I've done three taps, all running miniature shielded cable (or small coax -- RG174/U)
from the chip to an audio jack. Identify ground pin on the chip and connect
cable shield to it, if possible, or find the nearest available ground. Careful
not to short anything, such as between IC pins. If you use single wires,
twist together over their length.

Dave

 

[jasoyeom]

Thanks for the tips. Mods.dk doesn't have the pro-60 unfortunately.

I have pin 9 connected but not sure which pin is the ground.

I've read about adding resistors and capacitors etc to improve the signal.

 

[jasoyeom]

Thanks for the tips. Mods.dk doesn't have the pro-60 unfortunately.

I have pin 9 connected but not sure which pin is the ground.

I've read about adding resistors and capacitors etc to improve the signal.

 

[DaveH]

Thanks for the tips. Mods.dk doesn't have the pro-60 unfortunately.

I have pin 9 connected but not sure which pin is the ground.

I've read about adding resistors and capacitors etc to improve the signal.

If you go to the RR Wiki, follow link to Trunked Radio Decoders, and Discriminator
Output, you can find your way to something called Scandata faq q2, which lists
the PRO-60 and chip it uses. If you search the chip name, a datasheet will show
which is the ground pin. It took me less than 10 minutes.

Dave

 

[Forts]

....or you can just use any metallic part of the chassis for ground.

 

[DaveH]

True enough, it's just that a short ground wire is better, if a chassis ground
is not close by, and can avoid possible ground-loop problems. The IC pins
are close together, so takes a steady hand to avoid shorts.

Actually, one of my taps might have been discrete wires, in which case
it's better they are twisted together over their length.

Dave

 

[jasoyeom]

Thanks. I did find the pinout for that chip and found the ground.

 

[jasoyeom]

Well unfortunately my soldering skills were not as good as I thought and pretty much ruined a couple of leads of the chip. At least it was an old scanner. Sigh....