GTX Squelch Detect ??

Big BOB · Post by **Big BOB** » Sun Jan 04, 2004 12:14 pm

How do you get the squelch detect to work on the GTX mobile? The pinouts seem similar to the Maxtrac, but on pin 12 all I get is a constant voltage.

Nand · Post by **Nand** » Sun Jan 04, 2004 2:03 pm

There is no COR or anything like it available on the rear connector for the GTX radio. But it does have buffered RSSI (RX signal strength indicator) on pin 15. This isn’t really very useful for COR though.

The IF IC typically has the squelch circuit in it. But in the GTX model this is not used. Instead the squelch is contained in the ASFIC U0201. The easiest available output is pin H1 called SQDET. It is a CMOS output that is high when a carrier is detected.

If you don’t have a circuit board layout, I can take a photo of the area where you can find this IC and the pin you need to connect with.

Nand.

Big BOB · Post by **Big BOB** » Sun Jan 04, 2004 4:17 pm

Nand,

I do NOT have a board layout for the GTX. If it is not to much trouble a photo would be very helpful. You can stick it in my PM box.

Thanks,

Big BOB

Nand · Post by **Nand** » Sun Jan 04, 2004 8:07 pm

The above manual would have been fine if it showed the page that you need. It seems to be partially missing.

I hope the image below will help you.

Nand.

Nand.

Nand · Post by **Nand** » Mon Jan 05, 2004 2:12 pm

Because the previous drawing is for the bottom side of the board, here is the top view of the board were you can pick up the squelch indicator.

Nand.

Nand.

Big BOB · Post by **Big BOB** » Mon Jan 05, 2004 9:07 pm

Thanks Nand! That did the trick.

Big BOB

n_zero_ndp · Post by **n_zero_ndp** » Wed Jan 07, 2004 12:37 pm

A big thank you to all of the above... From the rest of us who wanted to know the same thing!

d119 · Post by **d119** » Fri Jan 09, 2004 7:34 pm

Now if we could just figure out where the PL/DPL Detect line is... Or do I have to use a freakin TS-32P with this thing... Oh god where is my reverse burst...... *pop pshhhhhhhhhhhhht*

stupid ts32s

Nand · Post by **Nand** » Fri Jan 09, 2004 9:35 pm

d119 wrote:Now if we could just figure out where the PL/DPL Detect line is... Or do I have to use a freakin TS-32P with this thing... Oh god where is my reverse burst...... *pop pshhhhhhhhhhhhht*

stupid ts32s

From looking at the diagram, there is no signal that will only indicate the presence of correct PL. You could AND the “audio _PA_enable” signal with the SQDET signal. This would produce an indication of carrier with correct PL and not give an indication when any of the warning beeps enable the audio PA. If the beeps are not going to be a problem, you could just use this signal all by it self as a COR+PL indication.

One problem is that this “audio_PA _enable” signal is a bit difficult to get at and doing this also needs some additional logic to implement if you need to AND it with SQDET.

Nand.

d119 · Post by **d119** » Sat Jan 10, 2004 12:04 am

They certainly don't make this easy, do they.

I wish I could find some pre-modded MaxTrac 902 mobiles ready to go. I know W1Ksomething had some, but he won't return my e-mails.

Oh well. For ease of installation, TS-32P it is! I've got a box with a couple of them in it. Oh boy! Anyone have any great ideas on where to get good audio to feed the TS-32P with? It'll generate a PL Indicate line just fine... *pop pshhhhhhhht* F*%$#( lack of reverse burst.....

GTX Squelch Detect ??

GTX Squelch Detect ??

Thank you all