We've just moved in to a new house and there's a huge 2.4m c-band dish here. Is it possible to pick up truevisions with this if we fit a ku-band lnb?

Yes, I fitted my C band antenna with a combo C-band/KU band LNB for my TrueVisions and C-band reception. It gave much better signal strength/gain than the small TrueVisions disk due to the much larger C-band dish....even in the nastiest thunder storms I still had my TrueVisions satellite signal coming through. I also had another KU band LNB mounted on the C-band antenna to receive NSS6 KU band transmissions. I still have that antenna/LNB setup for C-band/NSS6 reception but now use TrueVisions cable TV & internet.

Can you recommend an LNB? I read somewhere you can't use a universal LNB with truevisions/

Is the dish solid or mesh, and if mesh, how large are the gaps?

The TrueVisions branded DVB-S2 receiver may require a standard or universal Ku-band LNBF.

Check this True Corp website page for the requirements and setup directions for your specific receiver

TrueCorp > TrueVisions > Setup and Use > LNB Settings for TrueVisions Set Top Box

link includes setup instructions for:

ADB ABS-3Q76

ADB ABS-8976

ADB ABS-9877

ADB ABS-9976

Humax IR-H100S

Humax IR-H101S

Humax IR-H102S

Jiuzhou JZ-DTS5418

Topfield IR-T200S

Topfield IR-T401S

Topfield TF-6300IR

True Digital HD - Skyworth HD-SK1000S

Can you recommend an LNB? I read somewhere you can't use a universal LNB with truevisions/

I used a combo C/KU band LNB and not a universal one...the KU LNB portion was fixed a 11.3GHz....even the KU band only TrueVision LNBs are fixed 11.3GHz LNBs (or use to be). But a universal KU LNB will work...just need to set the settop box up correctly like in RickCor's post.

My particular model was a Idea Chun 830C/KU with the KU LNB fixed for 11.3GHz vs a universal one....I bought it at a Bangkok Store for Bt890 in 2010...still up on the dish. Idea Chun may have got bought out by Idea Sat...not sure. I wouldn't worry about the mess gap...my 1.7M C band dish is a mess dish...I've never seen a mess dish in Thailand with mesh gaps so large it wouldn't work with KU band...in fact all the C band dishes I've seen have the same mess gap.

Anyway, here's a snapshot and link to an Idea Sat combo C/KU band LNB....two C band outputs and one KU band output (TrueVisions only uses the Horizontal frequency polarization). The KU port is the one on the end of the LNB. No shortage of various combo models.

http://www.idea-sat.com/products/lnbf.html

Thank you, that's very helpful!