Comment by jacquesm

It is as good as impossible to run an oscillator based receiver that is also connected to an antenna that does not radiate. That's nothing to do with poor design, it's just physics. Zero coupling does not exist in practice. By design the mixer stage sits pretty close to the initial amplifier and it will result in some of the oscillator energy making it back to the antenna circuitry. FWIW I built a ton of transmitters and radio gear in my teens, it is pretty easy to take a theoretical stance here and declare that anything that leaks is not designed properly but that's about as 'true Scotsman' as you could get.