It is possible to tune in RTL using "Add Channels" on a Sky Digibox but you would need an LNB switch to select the Astra-1 LNB whenever you want RTL. This method is feasible but usually "upsets" the Digibox so it often requires a reboot.
Likewise, it should be possible to tune in RTL with a Freesat receiver but, again, it could cause problems.
The parameters to tune RTL manually (not usually necessary with a FTA receiver) are
12188 - H - 27500 - 3/4
You also get German Eurosport FTA (Free To Air on any ordinary digital receiver) which provides various programmes, including tennis in summer, with German commentary. The English sound on the encrypted Eurosport Biava (Hotbird satellite 13°E) is FTA and often matches the Astra-1 (19.2°E) transmission. Obviously, you'd need two receivers or a specially modified receiver to handle video from Astra and audio from Hot Bird.
If you don't have or want to use a Sky Digibox AND a FTA receiver for F1, you can use a Humax HD or HDR receiver by itself. In Freesat mode it will provide all Freesat programmes from the Astra-2 LNB. In non-Freesat mode it can control a DiSEqC switch to select the Astra-1 LNB.
That's all I know but feel free to send me information if you have already done this.
Note: Please don't ask "will your bracket fit my dish?" Our LNB bracket works with our dish. If you have any other dish then you are probably going to have to "bodge" something. Click on the link, above, to "our Sky minidish extra LNB page" for ideas.
Dave M. adds:
There are several other FTA German channels on 19.2 that also show sport (including boxing, German football, Champion League football, FA Cup matches ,winter sports and others. These channels include ZDF, Sat 1, Eurosport, Das Erste and Sport1. Lists of interesting FTA events can be seen here http://robssatellitetv.webs.com/liveftasports.htm football and other sports can be found here although it does list encrypted and FTA channels http://liveonsat.com/2_day.php
Chris R. adds:
I have done this exactly as you suggested, except that I have separate dishes for 19.2E and 28.2E, not two LNBs on one dish. My comment is that my attempts to receive Radio 5 Live over the internet have been doomed to failure. As soon as the qualifying or race commentary is due to start, there is an announcement that, due to rights issues, the F1 coverage cannot be received via the internet, and the programme switches to a discussion on football or similar. However Radio 5 Live via a second set-top box works just fine, and is little over a second ahead of RTL and French TF1 in synch.
No report is complete without a discussion of the pros and cons.
1. If you already have a Sky HD subscription, you can watch F1 at no extra cost.
2. If you already have a Sky subscription (not HD) it may be more cost effective, at least in the short term, to pay the extra for F1.
3. Setting up Radio 5 Live is an additional problem and you may find that the audio is not synchronised with the picture.
4. Radio 5 live might lose the right to broadcast F1 commentary.
5. RTL may lose the right to broadcast F1 racing.