[RTTY] Problem with MMTTY, more

[Robert Chudek - K0RC]

Ed is most likely referring to the PDF file I posted here: 
*http://tinyurl.com/27z3bf3*

I also use an older laptop (Dell C640) with a docking station for my 
contesting setup. The problem with PTT during initialization has always 
been an issue, even when using one of the tweaks that Joe mentions. You 
will get key-down until the OS is finished loading and the reset utility 
is executed... I have not found an equipment friendly solution to this 
problem.

So I added a toggle switch in my interface to eliminate the key-down 
problem. Of course that only works when I remember to flip the switch 
after I'm done with a RTTY session.

PTT is the primary problem of this cheap interface that is properly 
dealt with in the commercial interfaces.

Also, be aware if you are using an older laptop like I am, the USB ports 
might not support USB 2.0 with its higher transfer rates. One solution 
is to add a PCMCIA card with USB 2.0 ports. Most laptops have a slot for 
this style of card. It allows you to add serial ports, soundcards, and a 
variety of other items.

73 de Bob - KØRC in MN


On 12/22/2010 8:59 AM, Joe Subich, W4TV wrote:
> That is the way Windows initializes the serial port (the data port
> is initialized high).   You might look into using Strobe (pin 1)
> for PTT to see if it is initialized low or look for one of the old
> "set LPT" utilities and run it in an autoexec file at start-up to
> reset the LPT data lines (D0-D3 and D4-D7) low.
>
> 73,
>
>      ... Joe, W4TV
>
>
> On 12/22/2010 9:23 AM, Edwin Karl wrote:
>> I probably should have been more detailed in my description.
>> I use LPT1 with a laptop/ docking station. It makes for a convenient
>> workstation when on the air or contesting. Normally I use the desktop
>> for normal logging, etc. It is not connected to the radio in any way.
>> I use the serial port to connect to the radio for PSK and other such
>> modes through a Rigblaster. There is no space for an additional
>> serial card adapter.
>>
>> Now I use the circuit that K0RC and JA7UDE publish. An NPN
>> transistor sinks the voltage from the back of the radio. The transistors
>> are tied to the computer thru a 3.3k resistor. On my docking station
>> pin 25 does not go to ground, So I use pin 20. Pin 2 for FSK, Pin
>> 6 for PTT. (K0RC)
>>
>> Once the computer wakes up, and I open MMTTY the PTT lifts and the
>> radio is now in receive. It sure sounds like a software issue (?).
>>
>> Thanks for all that replied.
>>
>> ed K0KL
>>
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>>
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