[mythtv-users] Connecting to external cable box

[fkamp at comcast.net]

Kevin Kuphal wrote:
> John Dressler wrote:
>>> 2.  Regular TV output.  Here you need something to
>>> record the output (PVR-150, etc.) from the s-video or
>>> coax output from your box and then you need something
>>> else (IR blaster or serial port) to change channels 
>>> when needed.  In the capture card setup you specify a
>>> channel changing script that is called whenever Myth
>>> needs to change the channel.   That script either
>>> sends commands to the serial port or manipulates the
>>> IR blaster as needed.
>>> 
>> Yeah, I'm option 2 (using the serial wire and I have
>> the cable connected via coax). Can you explain to me
>> how I would do this. What do I set Video device and
>> default input to?
> 
> If you're using a PVR-150 type device, the coax connector
> is the Tuner. Now that I write, I'm not sure you can use
> the coax connector because being a Tuner, it is expecting
> to tune to a channel.  I suppose this would work if the
> cable box has an option to set the output to a particular
> channel (like channel 3 for the old days of VCRs).  Once
> you configure the external channel script, Myth will no
> longer try to tune the tuner and just leave it on the
> default channel you set up.
> 

I have to use the same setup.  I have a PVR 250 and a 
Dishnetwork cable box.  I use the coax (RF) output from the 
cable box on channel 3 as input to the PVR 250 antenna 
connection.  The PVR 250 remains on channel 3 at all times. 
  Mythtv sends commands through the serial port to an IR led 
that switches channels on the cable box.  IR led setup is a 
two wire connection (ground and DTR) so it could be driven 
with coax, but it plugs into the serial port on the 
computer.  The IR led is located close to the IR receiver in 
the cable box.  Works great, even using an ordinary red led 
instead of a real IR led.  Guess the red leds give off 
enough IR to activate the receiver in the cable box.  The 
voltages coming off the serial port are enough to drive the led.

Regards,
Frank Kamp