Thanks, Ray.
I checked my silent carrier coming in at S9+20db at NW Ireland kiwiSDR and the two subcarriers were barely if at all traceable on the waterfall now, despite the very strong signal, but they were indeed certainly noticeable earlier this afternoon. I will keep an eye on it and see if I can improve it further. Ultimately, I will never get the signal as perfect as with professional equipment, but as long as it's listenable.. I too have heard the hum previously. Your antennas do seem to be picking up my signal quite well though, which is good as it's only 50w. Thanks.