Radio For Everyone new Posts: RTL-SDR Accessories, 5 Easy Mods, FAQ, Legal/Moral Issues and Portable SDR

Akos from the radioforeveryone.com blog (previously sdrformariners/rtlsdrforeveryone) has recently added several new posts. The first new post is a beginners guide to RTL-SDR accessories. In this post he shows and links to his reviews of various RTL-SDR accessory products such as upconverters, baluns, filters, preamps and adapters.

In the second post he shows a guide to 5 easy mods that can be performed on RTL-SDR dongles which will improve their performance. The mods include using a ground plane, using a wire antenna, extending the coax, removing the IR and LED diodes, and putting the dongle into a metal tin.

In the third post he discusses portable software defined radio and shows exactly what products and software you need to set up a an Android or Raspberry Pi based mobile SDR station.

In the remaining new posts Akos has created an RTL-SDR FAQ and a guide to understanding the legal and moral issues of SDR. Finally the last new post we saw is where Akos tests a cooled RTL-SDR V3 vs a stock V3. His results appear to show that the cooled dongle achieves slightly more (avg. 3.73%) position reports.

Akos' guide to RTL-SDR Accessories.
Akos’ guide to RTL-SDR Accessories.

4 comments

  1. snn47

    Thank you for your reply.
    Variation of ambient temperature and airflow across the preamp and/or SDR, will improves heat exchange by up to 20%, and therefore can influence the results.
    Since it it is of interest to identify if cooling will improve performance significantly, I proposed placing one SDR outside in winter if it is below -20° C. A freezer allows year around measurements, however since mine is in the cellar, this would require additional cable which, which introduces additional cable loss and increases the noise figure.
    The first stage noise has the most impact on the overall noise figure, therefore cooling the preamplifier will have the largest impact.
    If you have access to dry ice, try cooling the preamp and/or SDR with dry ice to identify, if cooling will improve sufficiently to warrant any further tests.
    I did a few tests with peltier elements for cooling, using air and watercooling.
    Unless you use a two stage = two peltier elements back to back, the temperature difference is limited to less than 30° C temperature difference. The the warmer the outside air is the less temperature difference you’ll get. Watercooling peltier elements is therefore the better solution compared to cooling peltier elements via airflow, especially during summer.
    If you have access to a well, than the cool ground water will improve cooling even more due to the lower temperature you start with. Even only a low trickle of water from a water tab is more efficient than air cooling in the summer. Even a single peltier get you below 0° C this way.
    A large problem with peltier cooling is condensation and if you get below 0° C freezing of the condensated water. Constructing sufficient isolation for the cool side of the peltier and the preamp/SDR from the warmer outside air to avoid condensation and turning the condensated water into ice is quite difficult.

    • Akos Czermann

      Lower temperatures work, see here for independent observations:
      http://discussions.flightaware.com/ads-b-flight-tracking-f21/pro-stick-plus-and-orangepi-pc-at-16c-t38295.html
      Condensation is not an issue if electrical components are encased in oil.
      http://www.radioforeveryone.com/p/cooling.html
      I’ve done all the possibilites you list above, which I consider Intermediate level, adds 7-9 % for ADS-B. No offense, I have a water reservoir with fish called aquarium, 300 gph hour pump, watercooled dongles with and without Peltiers, breaking the 10 percent barrier is impossible without going below zero celsius.
      New gear with preamps is a different story, I ordered a Plus just to test as a reference against circulating antifreeze with Peltiers cooling a reservoir. Direct chip cooling, heatsinks on tuner and ADC converter, and so on, an absolutely pointless exercise when an Uputronics preamp is yours for $60 shipped, and I’m sure that I can count on one hand the number of people who will spend evenings assembling such a cooling system.
      My site is called radioforeveryone, because attaching a heatsink is easier than cleaning up antifreeze, and strapping heatsinks can be done in a few minutes.
      If you have more ideas, I’d love to hear from you, here or via email, I might have overlooked a simpler path, and you sound like a felllow soul.

  2. Akos

    These two stock v.3 dongles when tested earlier had 0.9 % difference, which is noted in the post.
    Placing dongles in different locations will introduce one more variable by altering the operating noise environment. Receivers under testing are right next to each other now.
    I’ve written a post on my ADS-B testing methodology and problems encountered separately, available at:
    http://www.radioforeveryone.com/2016/09/ads-b-testing-notes.html
    If you have any suggestions or recommendations (I like the two identical heatsinks idea, maybe I’ll do something similar with a Peltier-based air cooling, but air cooling is low efficiency), I’m more than happy to do any further testing – in fact, I’ve just ordered one more Pro Stick Plus to get more position reports as a comparison basis and to get figures with advanced cooling methods with the latest equipment, so I’m open to suggestions.
    I’m much more into water cooling and sub-zero temperatures at the moment, because air cooling with heatsinks is really basic and not a real challenge anymore. V.2 dongles reliably operate at -15 Celsius case temperature (measured with infrared thermometer which can be off but it’s consistently off for comparisons), but preamps add heat – e.g. a Pro Stick Plus in the same case runs at 32 degrees whilst a v.3 runs at 26 degrees. Removing that heat and getting more reports is the next step, but maintaining -10 in a 20 degree room without leaks is somewhat complicated.

  3. snn47

    cooled vs a stock V3
    There is no information that allows to conclude that it was the heatsink that improved performance.
    Both SDR should have received the same heatsink, but placed in different ambient temperatures e.g. during winter. One SDR placed inside, the other to a temperature <20° C e.g. outside during winter or in a freezer.
    Then redoing the test by reversing both SDR locations/ambient temperatures, to ensure that the SDR with the heatsink didn't provide better performance to begin with.

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