At the moment, I scan the 70cms band on a pretty regular basis and every so often, the radio will stop on 433.475 and 433.525 MHz. The signal sounds like a weak digital transmission and it's only there occasionally.
I thought perhaps it was due to an out of band signal and the receiver was being overloaded. Having said that, the Alinco 605E seems like a reasonable radio and the front end doesn't seem to be wide open like some of the handhelds.
After a bit of digging, I discovered that there is an allocation for low power device on the 70cms band. It's called LPD433... https://en.wikipedia.org/wiki/LPD433
This is the frequency chart which as you can see goes from 433 to 435 MHz.
I knew that some car key fobs and remote devices were using the band but I hadn't realised it was so extensive. Perhaps that is the reason behind the mystery signals?
What I didn't know was that in Europe, this allows licence free voice communications on 70cms.
"LPD hand-held radios are authorized for license-free voice communications use in most of Europe using analog frequency modulation (FM) as part of short range device regulations, with 25 kHz channel spacing, for a total of 69 channels."...from Wikipedia.
I noticed that Amazon are selling a dual 446 / 433 MHz radio as well...
Considering how easy it is to buy a radio, I wonder will there be more unlicenced operation on the 70cms band in future?