Hi there, I thought some of the readers of SWLing post might be interested in my reception of Mayanmar Radio, Yangon, during a late-night DX’pedition in Oxfordshire, UK. I managed to catch them on 5985 and 7200 kHz; the latter was a personal first and perhaps further confirmation that my 200 metre longwire is contributing in a positive way to my mobile listening post. Subscribers and regular visitors to Oxford Shortwave Log on YouTube will know that I am forever trying to push the performance of my vintage portables to the limit of what’s possible, in the hope that I might hear something very exotic. it’s happened once or twice and thus worth all the effort in the small hours. Thanks for watching/ listening.
Clint Gouveia is the author of this post and a regular contributor to the SWLing Post. Clint actively publishes videos of his shortwave radio excursions on his YouTube channel: Oxford Shortwave Log. Clint is based in Oxfordshire, England.
My new Elecraft KX2 tuned to Radio Australia this morning.
I’ve only had my Elecraft KX2 since Monday evening and have been so busy, I’ve only had an hour or so to tinker with this pocket transceiver. Monday evening, before putting it on the air, I updated the KX2 firmware to the latest Beta release which includes the new AM mode.
I’ve had so many questions from readers about the KX2’s AM audio already, I thought I’d do a quick comparison with the LNR Precision LD-11.
I set the LD-11 to a bandwidth of 9.6 kHz, and the KX2 to 5 kHz: their widest AM filter settings. Keep in mind, this is not an apples-to-apples comparison, but it does showcase each radio’s potential AM audio fidelity.
I tuned both rigs to the Voice of Greece last night on 9420 kHz around 00:30 UTC. VOG’s signal was strong into North America.
I made the following recordings with my Zoom H2N digital recorder, by feeding in-line audio patched from each radio’s headphone jack. I tried to balance the audio levels between the two rigs.
Note: Some Elecraft radios have an audio effects mode which includes a “delay” function. Elecraft describes it as “a quasi-stereo effect intended to provide depth and space to the received audio.” On an AM broadcast signal, it makes it sound wider and gives it almost a stereo depth.
I think the results from both radios are impressive. Since the LD-11’s bandwidth can be widened to 9.6 kHz, strong signals like this one sound pretty amazing. In truth, I actually prefer a filter width of about 8.2 kHz on strong signals, but VOG was wide enough to justify 9.6 kHz. I believe the LD-11 would rival many dedicated tabletop receivers.
The Elecraft KX2, in normal audio mode, sounds flatter and narrower than the LD-11 of course, but still very pleasant! In the KX2’s “delay” audio mode, the signal sounds much wider than 5 kHz, though the effect adds a little graininess to the audio. That’s okay, though–I love having the “delay” audio option in my tool bag.
Here’s what amazes me as an SWL and ham radio operator: both of these QRP transceivers offer excellent HF broadcast listening opportunities.
Please comment! Which audio sample do you prefer? Do you like the “delay” audio effect on the KX2? Keep in mind this is only one comparison and doesn’t address sensitivity or selectivity.
Paul, I hope you’re enjoying the good weather while it’s still summer! I imagine the days and nights are getting cooler already and soon, that beautiful stretch of Yukon will be frozen.
I’m happy to see you’re employing the ZM-2 tuner; it’s an effective little antenna manual tuner and doesn’t need a power source. Plus, if you ever get your ham radio license, you can use it in the field with QRP equipment. You’ve got a great setup there with quality components!
I just noticed that John (AE5X) has updated the firmware on his KX2 and made a short video of a shortwave band scan. On his blog, he notes:
Before getting my ham ticket, I was a SWL and am very happy that AM capability has been added to the KX2, making a fantastic radio even better.
[…]We have a very powerful AM broadcast station near my QTH on 740 kHz. I was not able to receive it at all with the KX2. Unlike some, I see this as beneficial – it tells me the 80m filters (the KX2 doesn’t operate on 160m) are doing what they were designed to do.[…]
I used the RTL-SDR Quick start guide at RTL-SDR.com/qsg. While I did not see any mention of Version 3, I hoped that the software that was linked would be adequate. As I am using a Windows 7 laptop, I downloaded the Zadig driver installer, along with copies of SDR# and HDSDR.
Getting the dongle going was pretty straightforward. And right away I was receiving VHF and above signals. The I/O driver defaults to Quadrature demodulation and this was what is used to receive VHF. But what about HF?
It took me awhile to figure out that you select Direct Sampling in the setup screen for the driver. In SDR# software this is found by clicking on the gear wheel icon.
Under sampling mode select Direct Sampling (Q branch).
In HDSDR you select the EXTIO icon.
Here you select the Q Input under Direct Sampling.
Note that with both you must use the Q input.
With the telescoping antennas included with the dongle, I received very few signals (of very poor quality). But I had read that the unit can only receive HF with a substantial antenna, so I moved the laptop to my hamshack.
I use an ELAD antenna distribution amplifier for my HF receive antennas.
It was easy to use a spare output from the ELAD ASA15 to drive the antenna input of the RTL-SDR V3.
Wow, what a difference!
First up was international shortwave. Here’s a shot from my Alinco General Coverage receiver on 9955 kHz this morning using my 260′ beverage antenna (pointed toward Europe). S9 on the Alinco S Meter.
And here’s the same signal on SDR#.
There was a delay in the audio coming from the PC versus from the receiver, but other than that, reception was identical. Audio quality was very good.
I then moved to the 20M Amateur Radio band. USB audio demodulation.
The little dongle worked! It is not what I would call my first choice in receivers, but it will demodulate AM and SSB just fine.
I did not try it on CW as I ran out of time.
I also tried the HDSDR software, which worked equally as well (but I think I prefer SDR# for ease of use).
All in all, if you have or can put up a good antenna for HF, the little $25 dongle is in, my opinion, worth trying out.
Thank you, Gary, for not only giving a quick evaluation of the RTL-SDR’s HF performance, but for describing how to setup HF reception via SDR# and HDSDR.
Over the years, I’ve gotten probably hundreds of emails from readers who would like to try their hand at SDRs, but were cautious about investing. For many years, a 3rd generation SDR would set you back at least $300-400. At $25 shipped, the RTL-SDR V.3 is an SDR receiver that is accessible to anyone who can afford a fast food meal or a few cups of Starbucks coffee. My how times have changed!
Once I get a few transceiver reviews off of my table, I might do some side-by-side HF comparisons between the RTL-SDR and a few of my other SDRs.