Category Archives: Accessories

Off-Grid Radio: Portable power recommendations?

This year, I have a lot of portable radio play in mind as I travel across the continent. At some point, I even plan to spend several days in an off-grid cabin on the coast.

In the past, I’ve powered my 12 VDC ham radio transceivers with a system comprised of three PowerFilm solar 5 watt foldable PV panels (see below), a Micro M+ charge controller and several gel cell type sealed batteries (a couple 7 Ah and one 20 Ah).

The system works well, but the batteries are a little heavy and unhandy when I want to hike into a remote site or play radio on the beach, for example.

In terms of receivers, my portables (like the Sony ICF-SW7600GR, Tecsun PL-660, etc.) simply use AA batteries which I charge with PowerFilm AA PV chargers (see above). My CommRadio CR-1a has an internal battery that will power it for hours at a time.

Power is much less of an issue with receivers because they’re quite resource efficient.

I mainly need a system to power my QRP ham radio gear, and that’s where I could use your experience!

Wish list

Charge controller

I need a new charge controller since my Micro M+ (no longer produced) is now being used to power a remote antenna tuner.

Of course, I’ll need an inexpensive charge controller that doesn’t produce RFI (radio interference).

It would be an added bonus if the charge controller could also charge my batteries when grid power is available.

12 VDC Battery packs

I’d like something relatively lightweight and safe.

Note: LiPo packs worry me, especially since I had one (an early GoalZero model) quite literally melt down and burn up on my bed only a few hours after bringing it back from an eight hour flight a few years ago. Scary!

Pure Sine Wave Inverter

I’d also like a small, efficient pure sine wave inverter that I I could connect to my largest battery and power my laptop for extended SDR spectrum recording sessions while off-grid.

I’d love a recommendation from someone who uses one and can confirm a model that doesn’t create radio interference while operating.

Recommendations?

Post readers: Please comment with your recommendations and include model numbers and links if possible. Thank you in advance!

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Guest Post: Using the HackRF One for DGPS Beacon Reception

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Many thanks to SWLing Post contributor, Mario Filippi (N2HUN) for the following guest post:

Receiving with a HackRF One, SDR#, and MultiPSK

by Mario Filippi (N2HUN)

The HackRF One is a Software Defined Radio manufactured by Great Scott Gadgets (www.greatscottgadgets.com) and has been on the market for a few years. Having used an SDR-Dongle for several years I felt it was time to “step up” to this wideband (1 MHz – 6 GHz) receiver to investigate a broader breadth of the radio spectrum, so one was purchased from Sparkfun (www.sparkfun.com).

Recently I performed a rudimentary evaluation of its ability to receive DGPS (Differential Global Positioning System) beacons found in the Longwave band between 285 – 325 KHz; this frequency range is well below the HackRF One’s stated lower receive limit of 1 MHz.

DGPS beacons, when tuned using SSB, emit a distinctive warbling sound, and at this QTH, depending on band conditions and time of year, can be heard as far away as the Midwest. Winter brings the cold weather but also excellent conditions for receiving these beacons, some of which were former marine radiobeacons retrofitted to provide greater DGPS accuracy.

The HackRF One, when used with SDR#, MultiPSK, audio piping software, and a good (43 foot vertical) receiving antenna was able to receive DGPS beacons, and two screen captures are below:

DGPS beacon from Sandy Hook, NJ. SDR# using HackRF One in foreground, MultiPSK software in background with decoded information. Click to enlarge.

DGPS beacon from Moriches, NY. Click to enlarge.

I was very pleased that the HackRF One was able to receive DGPS stations, though tuning them in seemed a bit trickier than with a standard RTL-SDR dongle. Since this time of year is not optimal for monitoring DGPS beacons, as well as the Longwave band in general, it’s reassuring to know that come winter I’ll be able to do some DGPS beacon DX’ing with the HackRF One. However, anyone with a shortwave radio and a good antenna can avail themselves of DGPS beacon hunting, just tune down between 285 – 325 KHz and listen for the distinctive warble.

To decode, look into an excellent program like MultiPSK (http://f6cte.free.fr/index_anglais.htm). 73’s!

Thank you, Mario, for another great post!

When Mario told me he had purchased the $299 HackRF One, I was hoping he would do some guest posts about this SDR–DGPS beacons was use I had never thought of. Looking forward to more of your guest posts, Mario!

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Aluminum foil: Larry’s simple AN200 antenna modification

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Many thanks to SWLing Post reader, Larry Caracciolo, who comments:

I bought the AN-200 in the spring of 2015 off of eBay. I was favorably impressed with the product. Comparing it to my old 9′ diameter tuned/shielded loop from 1992, there are some similarities and differences.

The Hallicrafters SX-96 (Image: Universal Radio)

I live in an apartment complex so plenty of radiated electromagnetic noise is present. I use a modified [Hallicrafters] SX-96 (AVC ckt was modified for improved modulation acceptance). The AN-200 does null out local static sources, somewhat, but not well enough to dig out weak stations. The tuning range for the loop is just at the bottom of the AM band (about 535 khz) to just over 1700 kcs.

On a whim, I wrapped aluminum foil around the loop and grounded it to the SX-96 chassis – in wistful hope of achieving some shielding from the RF has. As soon as I connected the aluminum foil ground clip to the rx chassis, all RF noise ceased and signals appeared from the mud. However, the tuning range is attenuated above 1200 kcs.

My favorite frequency on the AM band is 590 kcs. During the night, as many as seven different stations rose from the noise and provided station IDs at just the right moment. My best catch here in Everett, WA is KCSJ, a 1KW station in Colorado Springs.

From time to time, stations on the low portion of the AM band are accompanied with echoes – what I took for two stations and a small time delay between the same broadcast was actually multi-path to the degree that nearly 1/2 second separated the arriving signals. Short-delayed echoes, anyone? I’ve not observed this on frequencies above 1000 kcs.

Other sources of RF noise can come from the laptop, the cable modem, and even CFBs in other rooms. For truly noise-free listening environment, I place the laptop in sleep mode and unplug the cable modem. I’m quite happy with the AN-200 loop. Affordable, easy to use, easy to tune.

Thanks so much for sharing your experience with the AN200 loop antenna, Larry!

As anyone who grew up in the era of TV rabbit ears knows, aluminum foil can simply work magic in a pinch! There is no easier material to work with either!

As I pointed out in previous posts, the AN200 loop antenna is quite affordable. I just did a quick price search:

The Tecsun equivalent of this antenna (the AN100) is available from various sellers on eBay from about $15 – $30 US.
The Kaito AN200 (Kaito’s branded version) is available on Amazon for $30 shipped.
With the purchase of the Eton-Grundig Traveler III, Eton-Grundig Field, or Eton-Grundig Satellit, Universal Radio will include a free AN200 with your purchase.

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Guest Post: Building a magnetic loop antenna & broadband amplifier for your SDR

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Many thanks to SWLing Post contributor, Dave Gahimer (K9ZCE) for the following guest post:

Small Magnetic Loop Antenna with Broadband Amplifier for SDR Reception

by Dave Gahimer (K9ZCE)

Those with limited space, or antenna restrictions, might find a small 1 meter loop antenna a solution.

My son lives in an apartment. One Loop leaning against a wall gives him acceptable reception with the SDRPlay RSP on the ground floor–2nd or 3rd level flats should have very good reception.

Ten meters off the ground outside should give reception equal to any SWL antenna. We all with SDRs fight the image problem. Normal resonate ham band antennas show too strong reception of unwanted bands/stations. Did I mention noise? Loops are well known for –6 db noise reduction.

Then there is the possibility of SDR chip damage from your 1.5 KW station! In researching Loops we came across LZ1AQ. A Brilliant design /engineer (http://www.lz1aq.signacor.com/). Deep reading sometimes, but a great understanding of what makes a good receiving loop antenna.

Those who chase DX know that sometimes fading is caused by the signals’ polarization changing in the Ionosphere. Having both vertical and horizontal loops, and the ability to combine both signals diminishes this fading problem. Being able to filter the powerful, commercial FM transmitters diminishes image problems. Clipping strong signals at the antenna from very near powerful antennas/transmitters could save the SDR receiver from damage.

The LZ1AQ broad band Amp solves all these problems. http://active-antenna.eu/amplifier-kit/.

My son Ted and I built three, one meter loops from soft ½ inch copper plumbing tubing. One for his apartment, two for my crossed loops antenna. We weather proofed the Copper from corrosion by coating with outdoor clear spar varnish. We shaped the circle by drawing the tubing around a round glass top patio table.

The soft copper loop in held by white PCV plastic plumbing pipe. 1” or 1.25 inch schedule 40. Be careful to check that the PVC is schedule 40, thick wall. The thin wall pipe is not strong in the wind and will crack when you try to drill it.

Drill up to a 3/8 hole for the ½” copper tube to go through, then file out to fit. Here are some photos (click to enlarge):

Check out these links (all courtesy of LZ1AQ) to acquaint yourself with the loop construction and amplifier installation:

http://active-antenna.eu/tech-docs/2_ActiveAA_Mount_20.pdf

http://active-antenna.eu/tech-docs/1_ActiveAA_DandS_20.pdf

http://active-antenna.eu/tech-docs/3_ActiveAA_Antena_11.pdf

Many SDR receiver owners have seen improved noise and Image reduction by placing the plastic cased SDR unit on a small shielded/ grounded case.

The Amp needs 12VDC from in the shack. The Amp has two relays that you can switch, from in the shack, to select Vertical or Horizontal loops, or a dipole. The loop amp connects back to the shack via a shielded Cat 5 cable, Make sure you get shielded CAT 5 to reduce noise pickup. Make sure you provide an adequate good Ground below the antenna, less noise pickup and lightening protection.

Have fun!
Dave, K9ZCE
Retired from EE Dept @ Rose-Hulman Institute of Technology
Terre Haute, Indiana

Thank you so much, Dave!

Readers: yesterday I saw Dave’s loop antenna photos on the SDRplay RSP Facebook page. I was fascinated by his horizontally/vertically oriented loops and asked if he would write up a short guest post. He kindly obliged in a matter of hours!

If you have an antenna project you’d like to share, please contact me. So many SWLs and ham radio operators live in areas with restrictions and pervasive RFI–projects like Dave’s can revive one’s radio life!

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GODAR antennas

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Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who writes:

[Check out] this site I came by accidentally, small company, USA made antennas, most are OTA TV but he has a few shortwave antennas, quite reasonable. […] Also has old vintage pics. A little of this and that on the website, quite interesting company. He sells on Ebay too.

GODAR USA

Thanks for the tip, Mario. I love supporting mom-and-pop manufacturers like Godar. It appears–based on his eBay rating–that Michael Godar has very satisfied customers and produces quality antennas.

Thanks for the tip!

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Let’s talk Raspberry Pi 3 radio projects…

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I just received the recently released Raspberry Pi 3 that I ordered from MCM a couple weeks ago.

Now I’m plotting a few potential radio projects!

Recommendations anyone?

I’d love some input from SWLing Post readers as I’d like to feature a few Raspberry Pi projects here (and I’d certainly welcome your guest posts!).

I’d love to run my RTL-SDR or (better yet) SDRplay RSP with the Pi 3, but I’m sure there are a number of other projects I’ve never considered. I also have the original Raspberry Pi, but what I love about the Pi 3 is built-in wireless connectivity–of course, it’s faster than the original Pi, so I’m sure that’ll help with many radio applications.

Please comment with your suggestions and Raspberry Pi experience! I’m all ears!

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Ordering the CountyComm GP5/SSB from outside the US

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SWLing Post readers who are located in countries other than the United States, may have found it difficult (and pricey) to order the CountyComm GP5/SSB portable radio.

I’ve just learned about an eBay seller that ships internationally and works directly with CountyComm. The seller, Randy, is a ham radio operator (KB3GGC) and has a 100% satisfaction rating on eBay, so you can purchase with confidence. His price ($79.95) is also fair and shipping quite reasonable–certainly much better than many of the Tecsun PL-365 listings on eBay.

Click here to view his CountyComm GP5/SSB listing on eBay.

Randy also sells spare antennas and an adaptor that allows to connect external antennas to the GP5 series receiver.

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