Mobile HF with SDRplay

Took a trip out to McKinney Falls State Park here in Austin, TX a few days ago during lunch to do some mobile HF operating with my SDRplay. I’ve always...

McKinney Falls State Park

Took a trip out to McKinney Falls State Park here in Austin, TX a few days ago during lunch to do some mobile HF operating with my SDRplay. I’ve always been interested in operating my SDR from a quiet & remote location. A state park was as close to that scenario that I could get, lol. You have to imagine that living in the 11th largest city in the United States, I’m bound to run into some RFI here and there. It occurs in the weirdest of spots too. Occasionally i’ll drive around with my HF rig on in Austin and especially in an urban environment, i’ll experience all kinds of interference, most commonly I experience it close to businesses & structures.

I scored a contact with W6VAH, the VA hospital out in Loma Linda, California, they hold a regular net on 20 meters, so snagged them on 14.258. Snagged a few others on 20 meters, but the bands as of late have been extremely noisy.

Speaking of noise… i’m currently considering investing in an active magnetic loop antenna for the home shack. I figured being in the HOA where I’m at, and my inability to get a full size dipole up in a flat top configuration, an active mag loop might help since its independent of ground, and it has the ability to null out interference. Usually if it’s interference that I’m experiencing, it’s coming from a nearby neighbor or company. I’ve tried regular transmitting mag loops before, and to be honest I wasn’t particularly impressed, but one that’s preamplified? I’m wondering if one is worth a try. They’re not cheap either… The Pixel loop from DXE is almost 500 bucks, the Wellbrook loop is just a tad less around $460 shipped from England. More to consider regarding my home QTH antennas! I refuse to give in to the QRM! Anyone with experience with these two antennas?


73 & Happy Friday


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No Comment
  • Mike Hohmann
    26 January 2017 at 9:51 PM

    Nice mobile shack, I’m jealous! 😉

  • Ken Ranous
    10 January 2017 at 11:37 PM

    Nice article! It’s amazing how much better SWL is when away from urban centers. I recently took an RTL-SDR camping to a mountain-top about 40 miles out of town. We strung up ~150 of wire zig-zag through some trees and fired up SDR#. At first we saw the MW & SW bands loaded with spikes and I thought oh no! But each of those spikes was a transmission, from all over the state, country & world. I was amazed at how packed the bands are when there isn’t so much noise to contend with. And to think that was just with an RTL-SDR in direct sampling mode.


    • K5ACL
      11 January 2017 at 1:15 PM

      Hi Ken,
      Thanks for stopping by! & thank you for the compliment! Interesting results with your RTL.SDR. Certainly makes for a portable receiver too with a small pc/laptop of sorts. Noise is the enemy! My next house will be in a nuclear bunker away from civilization, lol! if only… 73 -k5acl

  • Gene Silvernail
    27 December 2016 at 11:33 PM

    No experience with either but interested. The magloop is an interesting antenna because of the Q and the H field. I’ve read some stuff and need to read more because I believe this approach to interference is down the right path. BW while it’s its biggest downside its also its unique upside when looking all other antennas.

    The downside is mitigated with auto tuning and selecting appropriate L C ratios to attain effective BW for a modulated signal on the lowest freq. CW is near zero BW required. AM/SSB pushes achievable BW.

    The ideal ML would provide instantaneous or close tuning without memory lookup (maybe). Regardless, it comes down to changing capacitance quickly and repeatability over environmental conditions.

    I think most availables achieve resonance manually and those that have Auto-Tune do so with some limitations that distract from the antenna realizing it’s full usefulness and acceptance.

    It has a lot going for it…Size…Nulls…Noise rejection. Maybe current technology, 21st century dwelling environment and need will all meet and produce the next great innovation.

    Who knows??
    Just saying

    • K5ACL
      29 December 2016 at 6:34 PM

      Wow, thanks for your in depth insight to these antennas Gene, I think there’s an application for every antenna really, i’m definitely interested in them because of my lack of ability to put up a full size flat top dipole on just about any band. A year ago, I didn’t really know much about active antennas, but now i’m starting to realize their potential in a small space/HOA type situation.

      Great points! 73!