Detector Audio and Pin 11? Difference?

[adamj812]

What's the difference between Detector Audio (audio from the interboard connector J6 pin 3) and pin 11 on the 16 pin accessory connector on Maxtracs? I'd like to use pin 3 audio on a masked 5 pin board, but it seems like the level is much lower on it than pin 11 on a 16 pin. Is there an amp or something I can use to raise the level? I have the pin 11 audio on one radio in the line-in jack of the PC at 1/2 gain and it's perfect. The Detector audio pin 3 requires me to plug it into a mic jack and use the mic boost and still barely registers.

I have several of the 5 pin masked boards and would like to use them so if someone has a schematic or an idea on how to increase the level I'd be very interested.

-Adam

[adamj812]

Can I use one of the Radioshack audio output transformers (210-3254) to increase the signal or would that distort the signal too much making it useless for packet data?

[jackhackett]

A few tips:

1) Try not to start multiple threads about the same subject.

2) We don't all have access to manuals to look things up on the weekend, so have a little patience.

Now, if nobody else gets you an answer first I'll look it up when I get a chance and see if I can find a better point to connect to.

[Will]

Try connecting to the top of the volume control... Use a capacitor to block any DC.

[adamj812]

I didn't mean to start multiple topics about the same thing. I just realized my posts have to approved before they show up in the board, thought maybe I didn't do something right and it didn't post.

As far as connecting it to the volume control, will that affect the data? I need non-deemphasized audio, and from what I read the audio at the volume control is the just the opposite. Would combining the 2 cause any problems?

[jackhackett]

Okay, look for a 3 pin header with a jumper on it around the middle of the board, JU601. Position B (the pin towards the front) will give you amplified detector audio after a 3KHz low pass filter, Position A (the pin towards the rear) is amplified detector audio after a 3KHz low pass and a 300Hz high pass filter. The jumper connects one of these to the center pin which goes to the High Speed Data circuit. Try connecting to one of those pins through a DC blocking capacitor.

Hope that helps, welcome to the board

[adamj812]

Thanks a bunch. I got it all soldered up and there's plenty of signal there! Also for the DC Blocking capacitor. I'm using a 4.7uF 16V electrolytic cap with the positive on pin B. Just want to make sure that's the correct polarity.

Thanks again,
Adam

[jackhackett]

That should be right, there should be around 4.5V DC on those pins. The audio level there is supposed to be around 750 mV, J6 pin 3 is only around 22 mV.