PTT problem

PTT problem

[Vittorio Vallero]

Hi all,
I Have a problem with the PTT on the serial port
/dev/ttyS0. 
The PTT (RTS etc) line goes high
as soon as soundmodem (gmfsk as well) is loaded or the
soudnmodeconfig utility is put into
diag mode.
It is resolving packets perfectly on RX and it makes
the right TX noises.
Only the PTT is the problem.

I am running Slack 9.1 with kernel 2.6.4

Any help is appreciated
Thanks 
73 Vittorio IK1RAC



	

	
		
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Re: PTT problem

[Rodolfo Brasnarof]

---
On 28 Apr 2004 at 11:48, Vittorio Vallero wrote:

> Hi all,
> I Have a problem with the PTT on the serial port
> /dev/ttyS0. 
> The PTT (RTS etc) line goes high
> as soon as soundmodem (gmfsk as well) is loaded or the
> soudnmodeconfig utility is put into
> diag mode.
> It is resolving packets perfectly on RX and it makes
> the right TX noises.
> Only the PTT is the problem.
> 
> I am running Slack 9.1 with kernel 2.6.4

I had similar problems and solved them by compiling the 
package myself. The original package seems to be bad.

Re: PTT problem

[Vittorio Vallero]

Thanks to everybody !
You were right! I had just to recompile the packages.
It seems that Ham packages for Slack 9.1 do not match
my setup.
73s


	

	
		
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PTT problem

[Gordon Croft]

Hello list,
I'm new to packet radio and am not as good at circuit design as I should 
be!!:)

I've built a circuit to interface the serial port RTS signal to the 
radio PTT line.
The radio is an old ICOM IC-20 and I checked to make sure it has a 
positive voltage (+12V) on the PTT line .  If I ground the PTT lead, it 
keys the transmitter, so I think the radio is working correctly.

The circuit I built uses an opto Isolator (NTE3040).
I tried to send the circuit lay-out but the server rejected my message...

When I check the current flow on the PTT side of the opto isolator with 
the computer trying to key the transmitter, I see about 14 mA and the 
transmitter on the radio does not operate.  If I just connect the PTT 
line to ground through the ammeter, I see about 125 mA and the 
transmitter does send.  Is it possible that the opto isolator is 
presenting too high a resistance and there's not enough current flow to 
activate the transmitter?  If so, how could I correct the problem?