Thanks for your info and advice BB and Mike. They are invaluable to me.
At the end of the day, these real life info and advice what we are coming here for, to read and learn.
I still haven't managed to build MW Loop yet. I am planning to order some wire first. I was looking for some thin wire for the turns around the plastic box, but the lengths of the wires I have is not enough. And I must find a variable capacitor from the tool box too. I think that is all I need for the parts.
But I managed to buy a PALSTAR AA30 Active Antenna, and connected the random wire into it, and I was listening to XHDATA radio with it. It definitely makes huge difference in reception. I am really happy that I got the AA30, and recommend it to any HF DXing SWLs.
What it does is, it brings out weak signals from the noise and make them audible. And when the weak signals are fading or unstable, this AA30 makes it more stable to listen to. Sometimes the difference is phenomenal. Sometimes it is only marginal. If the signal is already strong, then the AA30 will not make much difference, but when the signal is weak, and when powered on, it then gives noticeable boost in the reception in most cases.
If the signal is just too weak and the QRM is too bad, then it will not be much help. But then nothing will help in that case. I am not sure if most up to date design receivers with best functions and devices and parts in their bells and whistles will do the job even without any aids, for the signals under most poor propagation situations. But on 70 usd XHDATA radio, it is not bad, the AA30 works great.
But yes, I get Mike's point where passive loop antenna works better than the active ones. I feel that any MW DX antenna must be rotable ones too. Because most of the MW signals are very much directional, my random wire simply doesn't work well even with the AA30. But even builtin ferrite core antenna works better when positioned to the direction where the signals are coming from.
I read some of your reviews on the NRD 545 535 radios on eham, and glad that I didn't buy them. They are very pricey radios, and of course they might be excellent radios, but when they develop faults, it is impossible to repair them by myself. And when they are no longer supported by even the manufacturer, what chance have we got? I am not sure if they can hear the signals that this 70 USD XHDATA cannot hear on the same antenna? I doubt it.
I once had an old NRD525, and yes it was an excellent radio. But it wasn't much different from other radios I had at the time. It was just NRD name, and nice looking and good ergonomics, and yes it received great, but so did other radios too. Anyhow, you could tell us more about your thoughts and experiences from the high end radios compared to low end or vintage radios on the performance comparisons.
Thanks & 73
Al