CTCSS Preventing PTT

I have modified a generic cm108 sound fob

If i set the ctcss to no in the simpleusb config
i can receive input in to my node but there is no ptt.
even if you force the node to transmit still nothing.

If you set the ctcss to usb the node will transmit but it now receives nothing.

Where should I look firts?

Thanks in advance
Isaac
VK4NEU

That sounds like it might be a wiring problem. Setting the CTCSS should only affect Rx, not the Tx in any way.

Sorry for a late reply,
Spend some time at a friends with some test equipment and checked out all the wiring all ok,

It seams more software as when you use the simple usb setup software audio is received and you can toggle the ptt.

but in normal mode if the setting in ctcss is set to no ptt seams to be inhibited.
but can still toggle it in the setup mode?

CTCSS must be disabled or satisfied by a proper signal from your radio in order to receive. If you want to transmit and receive at the same time you must set duplex=2 in rpt.conf

Thank you for you help so far,
I had to put the project down for a bit.

I am unsure how to put this.
Ok from a fresh install of asl debian stretch,
setup the node for the account,
the node transmits fine but if you try to send any dtmf tones to it
it does not register them.
that’s ok as the ctcssfrom in usbinvert.
adjust the simple usb config to turn ctcssfrom to no
this now allows the node to receive dtmf input but inhibits transmission.
but we know the node can transmit as when it was before the config change.

Would a video help explain?

A video might help. Let’s take a look.

Here is a link to the video.
Hope it helps.

Is it possible to get a look at the modified cm108 fob and the connection to the radio?

It appears that you may be sending unsquelched discriminator audio to your sound fob. If this is the case you will need to use the usbradio channel driver so that the software can do the squelching. Otherwise find a different radio receiver output that is squelched audio. You also need to verify what signal is coming out of the radio for COS, is it active Low or active high. Once you get these questions figured out you should be able to get things working right.

73

Marshall

···

Sent from my iPhone

On Nov 27, 2019, at 11:14 PM, Isaac via AllStarLink Discussion Groups noreply@community.allstarlink.org wrote:


kidzaac

    November 28

Here is a link to the video.
Hope it helps.

drive.google.com

VID20191128151031.mp4 (video)

Google Drive file.


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Previous Replies


wd6awp
ASL Admin

    November 27

A video might help. Let’s take a look.


kidzaac

    November 27

Thank you for you help so far,
I had to put the project down for a bit.

I am unsure how to put this.
Ok from a fresh install of asl debian stretch,
setup the node for the account,
the node transmits fine but if you try to send any dtmf tones to it
it does not register them.
that’s ok as the ctcssfrom in usbinvert.
adjust the simple usb config to turn ctcssfrom to no
this now allows the node to receive dtmf input but inhibits transmission.
but we know the node can transmit as when it was before the config change.

Would a video help explain?


wd6awp
ASL Admin

    October 20

CTCSS must be disabled or satisfied by a proper signal from your radio in order to receive. If you want to transmit and receive at the same time you must set duplex=2 in rpt.conf


kidzaac

    October 20

Sorry for a late reply,
Spend some time at a friends with some test equipment and checked out all the wiring all ok,

It seams more software as when you use the simple usb setup software audio is received and you can toggle the ptt.

but in normal mode if the setting in ctcss is set to no ptt seams to be inhibited.
but can still toggle it in the setup mode?


wd6awp
ASL Admin

    October 19

That sounds like it might be a wiring problem. Setting the CTCSS should only affect Rx, not the Tx in any way.


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This is the third one have had the same issues with the first two.


picture of the plugs on the back of the radio.


the model of the radio

have used the usb radio before to no success setting it up (will try again),
using the line in and out from the radio there is also a data in and out,
using a option board on this radio with a 9 pin socket.
will try data port again to see if it’s a better path.
am looking in to schematics but hard to find for this option board in these radio’s.
had to modify to get a cos output, the cos is active low when in receive mode.
Have tried on two of the same model taits (t2030) am sourcing another type for testing.
Have used these radios successfully with aprs

Double-check that transistor. I believe the cm108 connects through a resistor to the base on the transistor. I think I used a 4401 on mine and the base was the center pin. It could be different if you’re using a different transistor.

You’re only sending one signal back to the fob, so you can’t have ctcss independent of cos. When using ctcss on the radio (not in software) I’ve been connecting ctcss back to that single cos input.

Follow up… how are you getting ptt, cos, and audio in and out of that radio? I’m pretty sure the data port on that radio is actually data, as in rs-232. There was an option board that had an hd-15 connector that had some or all of those connections. I use a couple of T-2010’s and I ended up finding my own tap points on the logic pcb and installing a db9 without any option boards. I can share the details if you need them. I was planning on doing a write-up on the process eventually.

The transistor that is being use is a BC639 NPN the data sheet shows base on the right hand side leg of transistor when flat side is facing you. It appeared strange to me when searching up the transistor.
Have thought about also tacking the ctcss on to the cos line as a test?

The data board in the radio is not the standard data option for these radio’s it appears to be a third party board, both the tait t2030 radio that I have their previous life was in gps location reporting for a company here in my town. This was third party proprietary equipment that was in use.
The schematics that were supplied to me with these radio for the db9 pin out show there is a line in and out and data in and out currently using the line in and out not to sure where they are running back to on the logic board? Any details would be handy of the points to tap on the logic board, it was fun just finding where to tap the cos, had to tap that in as there was no cos on the schematics / pinouts.

The BC639 has the base and collector reversed when compared with the 2n4401, so I think your fob is ok. I used the schematic here to determine my tap points. I was looking for discriminator audio and pre emphasized tx audio, so the audio points might be different for you on simpleusb. The points I used were S13-1 for discriminator audio, S13-8 for TX audio, S14-6 for PTT, S14-4 for COS/CTCSS (depending upon radio programming) and S13-11 for ground. S13 and S14 are the connectors that go to whatever option board you have installed.

OK thank you guy’s for you help,
we now have a working node.
followed the points on the board for the radio plus also taped the ctcss in to the cos line
now it is operational.
Now to move to a raspberry pi2.

Glad you got it sorted out.

And thank you for and other for your help,
now to workout why asterisk will not run at all on raspberry pi2
will work on a pi 3