After upgrading to FC9, the previously working serial port channel-changer (bought from IRblaster.info) stopped working. None of the configuration had changed.
In addition to the serial port transmitter, there’s a receiver on the PVR350 card – handled by lirc_i2c
After much searching, an additional option came to light : softcarrier=1.
Here are the relevant parts of a [...]

The Situation
I have a Hauppauge PVR350 card, which includes an IR receiver (connected via a 2.5mm socket on the card), but I also need to control an external cable box via an IR blaster (bought from irblaster.info), and have COM1 free.
Actually, since I have a Belkin MediaPilot keyboard (mostly) working, I won’t need to use [...]

Simple schematic for building serial interface :
http://fly.cc.fer.hr/~mozgic/UIR/http://www.lirc.org/receivers.html
On 9-pin Serial plug :Ground : Pin 5Data : Pin 1 (actually DCD)
Existing Hauppauge interface :http://www.irblaster.info/hauppauge_ir.html
2.5mm ConnectorTSOP 2238 IR ReceiverTip VCCRing SignalShield Ground
VSOP (or Everlight) IRM2238http://www.datasheetarchive.com/preview/1808114.htmlVCC=5V, 38KHz
USB Pinout :http://pinouts.ru/SerialPortsCables/usb_cable_pinout.shtmlPin 1 : VCC (+5V)Pin 2 : Data-Pin 3 : Data+Pin 4 : Ground
Even simpler circuit for IR [...]