Thanks to chatting with Andy G1HBE and John MW1FGQ at the start of 2009, I've become interested in 13cm narrowband operation.
(my only previous operation on this band was with wideband FM-ATV equipment).
My first step was to acquire one of the MMDS downconverters which Andy was using.
This has a PLL-synthesized LO, which I moved down to 2176MHz to create a 2m IF (the modification entailed changing the reference crystal to 8.5MHz, and adding a small capacitance to the VCO tuned circuit).
The first signal which I received using this was the 16th harmonic of my 2m handie, just to check that it was working! But as my home QTH is surrounded by higher ground, all my 13cm contacts will probably be made when operating portable from the nearby hills.
I recorded my first success on 24-Jan-2009, when I received MW1FGQ's NBFM and USB signals at 59+ from Winter Hill, at a distance of over 60km.
John was using just a few hundred milliwatts into a selection of home-made antennas, and we used 4m FM for talkback.
I've since tried to hear him from home, but with no success yet.
My first plan to make a transmitter of my own is to modify a 2.4GHz band video sender to produce NBFM. This will require some self-training at I2C programming, to move its synthesizer down to 2320MHz.
I already have an old DL2AM PA unit from my ATV projects, so I'll be able to manage almost 1W of transmit power! And as I have two beam antennas, I'll probably end up with completely independent transmit and receive systems, and operating semi-duplex as my two oscillators drift apart!
If you'd like to try a sked on 13cm, then please get in touch.