I think you are running into what all of us have experienced. Noise is just a fact of life, there's no simple way of getting rid of the majority of it.
Your dipole/doublet is a balanced antenna, it doesn't need a counterpoise, or the 'other half' (ground) to work. End fed wires are not a balanced antenna, they do require a counterpoise/ground/'other half' to work -IF- you transmit on it, not is you are just receiving (it certainly wouldn't hurt thought).
Tuning the antenna, making it resonant on the frequency of interest, is a good idea. It's also NOT very easy or cheap. It typically means an impedance matching device at the feed point of the antenna, which in most cases is very inconvenient/expensive (but they are available). Another way is make the feed line part of the antenna and put that tuner at the radio. That also introduces a gob of potential problems with 'extra' noise. Any electrical device that feed line/antenna is near can introduce more noise.
A very rough 'ROT' (Rule of Thumb) is that antennas would rather be above metal than beside metal and hate being under metal. Another one is that the higher and longer the better until it get's completely ridiculous. The 'best' antenna you can have in your particular set of circumstances isn't the one that's commonly considered to be the 'best', but the one that works best for you considering all your limitations. What works for you and the 'best' aren't always the same thing.
I think trying a few different configurations is probably your best bet. Don't get too 'fancy' to start with. For receiving, a balun isn't all that necessary at all. That "balun" of coiled feed line isn't a balun, it's a choke. It can certainly help in particular instances but it's not a 'cure-all'. They seldom hurt so try it, it may help. Coil up a few feet like you would a rope, that can give you an idea if it'll help. Where you put a choke is variable. Near the feed point of the antenna is a good idea. Another one at the radio end can do some good too sometimes. Those chokes affect what's on the outside of the feed line not what's on the inside (the signal).
This is getting too long so I'll quit. There are lots of things that can be tried...
- 'Doc
