The Belkin Tunecast range of devices are reasonably useful for quick and dirty testing of VHF/FM stereo multiplex receiver-decoders. The 'auto-off after n seconds of loss of audio input' feature is a bit of a nuisance since it resets your output frequency preference back to tbe default
however, there is a smple and effective modification that can be done to prevent this. The search engine of your choice should track down the details fairly quickly.
I keep thinking that I ought to try and find an ex-BBC chum with access to one of the Designs & Equipment Department 'reference-standard' receivers, against which the performance of one of the above could be compared ...
"'Allo, 'allo, Evesham ... zis is Night-'awk calling ... are you receiving us? - ovair ..."
Guy