Topics

How to bring "down" PTT?

Steve McGrane <temporarilyoffline@...>
 

I'm chasing this PTT issue on my 2m unit and I'm not sure where to go from here.  I'm out of parts or ideas or both.

The DRAWS hat will signal PTT and the radio will open transmit and send as it is supposed to.  When DRAWS is done, DRAWS PTT will shut off, but the radio still transmits.

What can I put "in-line" in the PTT wire to get the signal closer to "zero"?

Am I asking the right question?

- Steve

kc9dfk
 

What kind of radio are you trying to setup? What are circuit are you to use?


On Sun, Jun 2, 2019, 11:39 AM Steve McGrane <temporarilyoffline@...> wrote:
I'm chasing this PTT issue on my 2m unit and I'm not sure where to go from here.  I'm out of parts or ideas or both.

The DRAWS hat will signal PTT and the radio will open transmit and send as it is supposed to.  When DRAWS is done, DRAWS PTT will shut off, but the radio still transmits.

What can I put "in-line" in the PTT wire to get the signal closer to "zero"?

Am I asking the right question?

- Steve

Steve McGrane <temporarilyoffline@...>
 

This is a Kenwood TM-281a.  It does not have a DIN connection and I am making up a break out cable that connects DRAWS to MIC+Rear Speaker.

I have everything working except the "release the PTT button on the mic" on the radio side.


On Sun, Jun 2, 2019 at 1:59 PM kc9dfk <kc9dfk@...> wrote:
What kind of radio are you trying to setup? What are circuit are you to use?

On Sun, Jun 2, 2019, 11:39 AM Steve McGrane <temporarilyoffline@...> wrote:
I'm chasing this PTT issue on my 2m unit and I'm not sure where to go from here.  I'm out of parts or ideas or both.

The DRAWS hat will signal PTT and the radio will open transmit and send as it is supposed to.  When DRAWS is done, DRAWS PTT will shut off, but the radio still transmits.

What can I put "in-line" in the PTT wire to get the signal closer to "zero"?

Am I asking the right question?

- Steve

 

The PTT Output on DRAWS is an open collector NPN Transistor. It expects the Radio to have a pullup to Positive voltage, typically 5-12V.

If the PTT LED goes off then the SW has done its job.

Measure the voltage on PTT when yo power up, then again when you PTT and release.

Bryan K7UDR

Steve McGrane <temporarilyoffline@...>
 

The PTT line is 4.94v when the radio is on and the DRAWS/Pi is not

When the Pi comes on, the PTT line goes negative.

I have PTT line on draws connected to PTT line on Radio... but I'm thinking they both produce 5v and they should be connected in a crossover fashion?


On Mon, Jun 3, 2019 at 8:23 AM Bryan Hoyer <bhhoyer@...> wrote:
The PTT Output on DRAWS is an open collector NPN Transistor. It expects the Radio to have a pullup to Positive voltage, typically 5-12V.

If the PTT LED goes off then the SW has done its job.

Measure the voltage on PTT when yo power up, then again when you PTT and release.

Bryan K7UDR


Steve McGrane <temporarilyoffline@...>
 

Ok, so now it works... magic I guess.

DRAWS => RADIO
AFOUT => MIC
PTT   => PTT
GND   => MIC GND
AFIN  => Rear Speaker TIP

Sep Non-insulated GND in DIN cable => GND in RJ-45 Bundle

I'm not really sure why this works, all I did was change around the ground alignment.  Before I was marrying all the grounds, now I have the MIC/MIC GND isolated to the DRAWS GND

If anybody can explain this, I'm all ears.


On Mon, Jun 3, 2019 at 12:48 PM Temporarily Offline <temporarilyoffline@...> wrote:
The PTT line is 4.94v when the radio is on and the DRAWS/Pi is not

When the Pi comes on, the PTT line goes negative.

I have PTT line on draws connected to PTT line on Radio... but I'm thinking they both produce 5v and they should be connected in a crossover fashion?

On Mon, Jun 3, 2019 at 8:23 AM Bryan Hoyer <bhhoyer@...> wrote:
The PTT Output on DRAWS is an open collector NPN Transistor. It expects the Radio to have a pullup to Positive voltage, typically 5-12V.

If the PTT LED goes off then the SW has done its job.

Measure the voltage on PTT when yo power up, then again when you PTT and release.

Bryan K7UDR


 

Hi Steve,

Here’s a link to a Ham that direct connected to his TM-281:


Bryan K7UDR

Steve McGrane <temporarilyoffline@...>
 

I saw that... and it might be in my future... or I might get another rig.

I got to the point where I MUST GET THIS WORKING... and now I have... but when the dust settles, this isn't the radio for a "go kit" since its only 2m, and you can't do voice without disconnecting digital and vice versa... we'll see...

Thanks for sending that over.
- Steve


On Wed, Jun 5, 2019 at 10:47 AM Bryan Hoyer <bhhoyer@...> wrote:
Hi Steve,

Here’s a link to a Ham that direct connected to his TM-281:


Bryan K7UDR