Thanks for your reply Phil.
I've mounted the IR sensor on the rear of the Driver's compartment bulkhead so the remote can see it through the access door when propped open.
In running mode, as opposed to set up, my Sony TV remote volume button will make a marginal difference to the volume but cycles round on to full volume and down again.
In doing so it also makes a "rushing sound" which I guess is the air release, also the horn (on constantly like a buzzer) and will also introduce some quite significant interference noise.
In addition the channel up button will increase the engine speed up to full speed (although the wheels are not turning) and also introduce interference noise and another sound which sounds like a non-British emergency services siren.
The Fosworks Omni Tx-2.0 has the two-tone horns set up on F1 & F2 and F3 turns the sound off & on.
When switching the loco on the engine is running immediately.
Pressing F3 fades out the sound nicely.
Pressing F3 again and the sound goes through an engine start up procedure.
I'm assuming something is not right, but notwithstanding I didn't buy it new, I'm not impress that it seems to have gone defective in a little over two years.
The perils of eBay !
Regards,
Joe