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PTT from TNCPi2 to FT-2DR

 

I'm having problems getting my PTT to work. ?I followed both the Signalink diagram from my radio (since I have one of those cables), and the FT-2DR with the mic/speaker adapter from Yaesu. ?I see the TNC (PiGate) receiving APRS packets. ?When using the signaling cable, manually pressing the PTT on the radio gets me a tone (on another radio I'm using for monitoring) and I can also hear the packets go out. But I can't get the PTT to work from the TNC2. I am using pin 3 per the manual.

The capacitor and resistor values for the signaling and Yaesu are different and I tried both versions.

Any ideas?

Thanks in advance.

Carlos
N3RDR
 

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Hello Carlos,

Your email is a bit confusing since you're mentioning "Signalink" though it seems you're really using a TNC-Pi which uses a completely different cable type.? Anyway, when you think the TNC should be transmitting, do you see the PTT LED light up on the TNC?? If you don't see that, you have to solve that first.

--David
KI6ZHD


On 05/20/2020 08:20 PM, KC3CCD wrote:

I'm having problems getting my PTT to work. ?I followed both the Signalink diagram from my radio (since I have one of those cables), and the FT-2DR with the mic/speaker adapter from Yaesu. ?I see the TNC (PiGate) receiving APRS packets. ?When using the signaling cable, manually pressing the PTT on the radio gets me a tone (on another radio I'm using for monitoring) and I can also hear the packets go out. But I can't get the PTT to work from the TNC2. I am using pin 3 per the manual.

The capacitor and resistor values for the signaling and Yaesu are different and I tried both versions.

Any ideas?

Thanks in advance.

Carlos
N3RDR

 

I am using a TNC. I made a DB9 to RJ45 adapter in order to reuse the signalink cable to my FT-2DR.

Yes, I see the red LED light up. I can also connect my UV-5R and it works fine.

Sent from my ?

On May 21, 2020, at 2:31 PM, David Ranch <rpi4hamradio-groupsio@...> wrote:

Hello Carlos,

Your email is a bit confusing since you're mentioning "Signalink" though it seems you're really using a TNC-Pi which uses a completely different cable type. Anyway, when you think the TNC should be transmitting, do you see the PTT LED light up on the TNC? If you don't see that, you have to solve that first.

--David
KI6ZHD
 

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Hello N3RDR,

I am using a TNC. I made a DB9 to RJ45 adapter in order to reuse the signalink cable to my FT-2DR. 

Yes, I see the red LED light up. I can also connect my UV-5R and it works fine.

Ok.. good to hear the TNC is thinking it's asserting the PTT signal.? The FT2D uses a TRRS connector while a UV5R uses the Kenwood-style dual-prong connector.? To me, it sounds like you incorrectly made the cable for the FT2D.? Double check your connections.

--David
KI6ZHD
 

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I verified operation on the FT-2DR to the Pi. Packets received, tones transmitted. Before that, I checked continuity, and impedance (yup, even capacitance). All checked from the pin on DB9 to the 4 connector single plug the FT-2DR uses. Even on an o-scope.?

I do admit I’m not sure what to expect from the PTT signal. I am using pin 3 from DB9 but I really could not see much difference on that pin to other unused pins. I saw a similar signal that audio TX had from the TNC but 180 degrees off. ?Very clean tones too! And it was all riding on a 60 Hz signal that I’m guessing is from power but the only thing with 60 Hz power was the scope which has not provided that type of leakage before. ?DC/AC coupling made no difference.

On May 21, 2020, at 4:34 PM, David Ranch <rpi4hamradio-groupsio@...> wrote:


Hello N3RDR,

I am using a TNC. I made a DB9 to RJ45 adapter in order to reuse the signalink cable to my FT-2DR. 

Yes, I see the red LED light up. I can also connect my UV-5R and it works fine.

Ok.. good to hear the TNC is thinking it's asserting the PTT signal.? The FT2D uses a TRRS connector while a UV5R uses the Kenwood-style dual-prong connector.? To me, it sounds like you incorrectly made the cable for the FT2D.? Double check your connections.

--David
KI6ZHD
 

PTT should go to ground when active


On Thu, May 21, 2020 at 1:50 PM N3RDR <kc3ccd@...> wrote:
I verified operation on the FT-2DR to the Pi. Packets received, tones transmitted. Before that, I checked continuity, and impedance (yup, even capacitance). All checked from the pin on DB9 to the 4 connector single plug the FT-2DR uses. Even on an o-scope.?

I do admit I’m not sure what to expect from the PTT signal. I am using pin 3 from DB9 but I really could not see much difference on that pin to other unused pins. I saw a similar signal that audio TX had from the TNC but 180 degrees off.? Very clean tones too! And it was all riding on a 60 Hz signal that I’m guessing is from power but the only thing with 60 Hz power was the scope which has not provided that type of leakage before.? DC/AC coupling made no difference.

On May 21, 2020, at 4:34 PM, David Ranch <rpi4hamradio-groupsio@...> wrote:


Hello N3RDR,

I am using a TNC. I made a DB9 to RJ45 adapter in order to reuse the signalink cable to my FT-2DR. 

Yes, I see the red LED light up. I can also connect my UV-5R and it works fine.

Ok.. good to hear the TNC is thinking it's asserting the PTT signal.? The FT2D uses a TRRS connector while a UV5R uses the Kenwood-style dual-prong connector.? To me, it sounds like you incorrectly made the cable for the FT2D.? Double check your connections.

--David
KI6ZHD
 

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That’s what I though. Let me see if I understand. ?Ground normally manes zero volts. In this case, PTT is shared with the TX Audio. I was able to simulate it since it is a simple circuit and the output is actually what I saw on the scope (sans the 60 Hz).

I simulated the radio with a 2k Ohm load that I turned on and off just to see the output. ?The PTT switch is the going to ground part:

Here the voltage at the 2K resistor is the load


Closed the PTT, simulated 2 K ohm load

Assume open circuit (no radio connected)

In my mind, unless one is using VOX, this will not trigger a PTT on the radio since there is no separate line for that.

So, there must me something else to this PTT business. Correct? I think someone on some threat mentioned some feature is used on some chip with a particular tone that triggers a PTT?

The radio does not give me the option to use VOX (or none that I could find in the manual or menus).

What am I missing? It’s always the simple things…

Carlos
N3RDR

On May 21, 2020, at 4:57 PM, N5XMT <dacooley@...> wrote:

PTT should go to ground when active

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