I have a rather beginner question, hope that's okay.
I use my Quansheng to listen over 50 MHz, and I have heard that one can hack the firmware to go down to 18 MHz, but I really want to listen to the LF, MF and HF frequencies so I bought a cheap RTL-SDR with two antenna inputs: 100KHz to 30MHz and 25MHz to 1.7GHz
Now I have to decide what to do for the antenna, preferably without buying them outright, so I have consulted this link: https://www.sdrplay.com/antennasuggestions/ and it looks like a good starting point is this configuration:
100KHz - 30MHz
20 Metre / 66 Foot long fine speaker/transformer copper wire strung from house to nearby tree, insulator at the ends fashioned of garden hose to limit grounding into tree when wet.
25MHz to 1.7GHz
771 whip antenna
Homemade vertical whip antenna
So my question is around connecting those to the box. I can't put the SDR box outside so I can't stick the end of the antenna into the BNC as some people suggest, I could insulate the wire in tape or hose and bring it inside the house through the vent. Or I could wire coax to the outside corner of the house and connect it.
I know my SDR box has a balun on the mainboard, but do I need to put another one at the interface of the coax and the antenna wire?
Do I absolutely need to drive a ground stake to connect to the shield of the coax?
I know my long horizonal antenna should be 66 foot long but how long should the vertical whip be, and can it be constructed in the same way? Would it be better just to locate a stock 771 antenna outside and connect it with coax back to the box, and again would an additional balun be necessary at the connection between coax and antenna?
I'm going for a cheap and cheerful setup if you haven't guessed, so absolute idyllic operation isn't required, just best as can be achieved with about €50.