NDB reception

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Paul
Posts: 236
Joined: Fri Feb 17, 2017 9:52 am

Re: NDB reception

Postby Paul » Mon Nov 20, 2017 12:17 pm

Hi 13dka
Thanks for all the information.
Were I to "sacrifice" the HI-Z port to achieve the best LF/mf signal on the mini-whip (which definitely outperforms my simple end-fed long-wire in this area), I would disadvantage myself with respect to reception on the long wire (9:1 balun in line) and not be able to take advantage of the mf/fm filter available on Port A.
However, antenna experimentation here will doubtless continue and your impressive results definitely illustrate an avenue going forward.

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13dka
Posts: 136
Joined: Sun Feb 14, 2016 8:40 am

Re: NDB reception

Postby 13dka » Mon Nov 20, 2017 7:51 pm

CaptainNemo wrote:can you post some details about your loop? horizontal I suppose...


Yes, horizontally polarized (so physically a vertical, "upright") loop, center-fed (vis-a-vis the apex) which is not ideal (high main lobe elevation angles), but this way I could easily conceal the coax in the hedge and the loop is entirely invisible in the tree. Note that for LW/MW, even a 20m/60ft loop is still a "small" magnetic loop (SML), so the main reception lobes are perpendicular to the pane of the loop and I have no idea what their elevation angle would be.

The reason why I use 2 of these antennas (I christened them the "crappole" and the "craploop") that the loop configuration is pretty noisy above 5MHz at least at my QTH. This can be seen in this GIF:

Dipole_vs_delta-loop_7500-14500.gif
Dipole_vs_delta-loop_7500-14500.gif (111.02 KiB) Viewed 1088 times


Paul wrote:Hi 13dka
Were I to "sacrifice" the HI-Z port to achieve the best LF/mf signal on the mini-whip (which definitely outperforms my simple end-fed long-wire in this area), I would disadvantage myself with respect to reception on the long wire (9:1 balun in line) and not be able to take advantage of the mf/fm filter available on Port A.


Yeah, the BC filter not available on the Hi-Z input and the Hi-Z being the only full-sensitivity input on VLF can be pretty inconvenient. I have to swap antennas and inputs all the time due to that. I really wish the BC filter would be selectable on any input, and the bee's knees would be an internal antenna switching matrix, so each of the 3 physical antenna ports could be internally switched to any of the 3 inputs. At least I have the Hi-Z input transformed to Low-Z and SMA using the NooElec 9:1 balun, so I only have to deal with screwing SMA plugs on and off.

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gearjamer468
Posts: 4
Joined: Tue Sep 26, 2017 4:09 pm

Re: NDB reception

Postby gearjamer468 » Mon Nov 27, 2017 7:16 pm

just for info

i am using an sdrplay rsp-pro2
my antenna is a ground mounted hustler 6 btv tuned for the ham bands, with 50 feet of rg 8x coax, a 4 to one balun on the rsp 2 pro i can copy the very low power airport beacons 60 mile away from me ... my qth is in a vally between two mountain ranges here in vermont .... the signals fade in and out, but, they are readable ...
Last edited by gearjamer468 on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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