The UK based company SDRplay have just announced the launch of a new Software Defined Radio receiver product – the RSP1B.

The RSP1B is an enhanced version of the popular RSP1A 14-bit SDR which covers the RF spectrum from 1kHz to 2GHz. The RSP1B comes in a rugged black painted steel case and claims to have significantly improved noise performance.

The RSP1B has the following additional benefits compared to the lowest cost device, the RSP1A:

1. It is housed in a strong black painted steel case.

2. It has significantly improved noise performance below 1MHz (i.e. for MF, LF and below), and in the 50-60 MHz region. There are also noticeable noise improvements in the 3.5-5.5MHz and 250-320MHz spectrum.

3. It has improved signal handling at HF frequencies.

Some consumers don't like the fact that the older RSP1A has a plastic case coated in a conductive coating to screen it and many prefer a more solid steel case. The RSP1B addresses that issue.

I found it interesting that the performance at 50-60 MHz has also improved.

The RSP1B is expected to retail at approximately £106 GBP in the UK or $133 USD (excluding taxes or shipping) for US orders. 

Thanks to Brexit, the company can no longer ship to individual consumers in the European Union and has to go through the more expensive resellers network. This brings the price in the EU up to about €153 while the older RSP1A retails for about €133.

I suspect most people will opt for the slightly more expensive RSP1B but the price is now significantly more expensive that other SDR models available in the EU.

For more information on this new radio, please go to www.sdrplay.com/RSP1B

Learn how to update the firmware on your ATS 25 radio with this step-by-step guide. Follow the tips and resources provided by a radio repair expert to successfully navigate the process.

The ATS 25 Firmware Update: A Step-by-Step Guide

Are you a radio enthusiast looking to update the firmware on your ATS 25 radio? In this video, the creator takes us through his own experience of updating the firmware, sharing some useful tips and resources to help you navigate the process successfully.

About the Creator

This video was created by Radio Workshop, a YouTube channel dedicated to radio repair and restoration. The creator of the channel shares his experience and knowledge with viewers, providing useful tips and tutorials on how to repair and maintain a range of radios.

Key Takeaways

Here are some key takeaways from the video:

• Updating the firmware on your ATS 25 can be a challenging process, but with the right resources and guidance, it is achievable.
• Follow the links provided in the video description to access a useful video tutorial and firmware files for the ATS 25.
• The updated firmware offers new features and changes to the radio’s display and performance.
• The firmware update can make the radio work more efficiently, with changes such as a more responsive S-meter and a new scanning function.
• Use the up and down buttons to scan the radio quickly.

Step-by-Step Process

• Here is a step-by-step process for updating the firmware on your ATS 25 radio:
• Follow the link provided in the video description to download the firmware file.
• Read the instructions carefully before beginning the update process.
• Use the Arduino software to upload the firmware to your radio.
• Once the firmware is uploaded, power on your radio and explore the new features and changes.
• The creator advises viewers to be patient and to take their time with the process, as it can be challenging, but ultimately rewarding.

Resources

The following resources are mentioned in the video:

• Tony Albus’s video tutorial on updating the firmware on the ATS 25.
• 9E1C’s website with firmware files for the ATS 25.

The YouTube tutorial [1] provides a step-by-step guide on how to update the ATS-25 firmware, while the SWLing Post article [3] provides some information about the new ATS-25 SI4732 receiver, which might be useful when updating the firmware. The GitHub repository [5] contains the firmware update code and instructions on how to perform the update.

My Best Advice

Take your time with the process of updating the firmware on your ATS 25. Follow the instructions carefully, and if you encounter any difficulties, refer to the video tutorial and firmware files provided in the video description.

FAQ:

Q: Is updating the firmware on an ATS-25 radio worth it?

A: Yes, updating the firmware can improve the radio’s efficiency and add new features.

Q: Is updating the firmware on an ATS-25 radio difficult?

A: Yes, it can be challenging, but if you follow the instructions provided in the resources carefully, you should be able to do it.

Q: Where can I find the firmware file for the ATS-25?

A: You can find the firmware file on 9ew’s website, which is linked in the video description.

Q: How long does it take to update the firmware on an ATS-25 radio?

A: The process can take anywhere from a few minutes to an hour, depending on your level of experience.

Q: Can updating the firmware on an ATS-25 radio damage the radio?

A: If you follow the instructions carefully, the risk of damaging the radio is minimal.

Learn the truth about two popular QRP radios, the TruSDX and QCX-mini, with three simple tests in this video. Understand the differences between the two radios and decide

Introduction:

The video compares two popular QRP rigs, the TruSDX and QCX-mini by QRP Labs, and conducts three tests to determine the difference between the two radios.

The tests include the silence test, the pain test, and the signal purity test. The video aims to provide a subjective opinion on the work of these two rigs without the need to be proficient in technical details such as decibels, microvolts, or dynamic range.

I found this video to be valuable because it provides a straightforward comparison between two popular QRP radios. The three tests conducted in the video helps understand the differences between two radios.

Linas, LY2H, the creator of the video, has a channel dedicated to amateur radio with over 13,000 subscribers. Linas shares his knowledge and experience in the field of amateur radio, provides tutorials, and reviews various radios and equipment.

Key takeaways from the video include:

• The TruSDX radio produces far more internal noise than the QCX-mini radio.
• The QCX-mini radio is quieter and produces fewer birdies than the TruSDX radio.
• The TruSDX radio has a slightly better signal purity than the QCX-mini radio.

Here are the steps followed in the video:

Silence Test:

• Connect both radios to a Bluetooth speaker with no antenna connected to either.
• Both radios should be set on CW mode 200 Hertz of filter with the AGC off.
• Listen to both receivers and note the internal noise produced by each radio.

Pain Test:

• Connect both radios to a dummy load.
• Increase the sound level on each radio and listen to the internal noise produced by each radio.

Signal Purity Test:

• Connect a Tiny SA to each radio.
• Tune the frequency to the signal generator and choose the frequency for the signal generator to transmit on.
• Adjust the level to the level of S9 for both radios.
• Listen to the signal on each radio and note the quality and purity of the signal.

Resources mentioned in the video include:

• TruSDX
• QCX-mini
• Bluetooth speaker
• Dummy load
• Tiny SA

My best advice for beginners in amateur radio is to start with a simple radio and work your way up to more advanced radios. Always conduct tests and experiments to understand the capabilities and limitations of your radio. Join a local amateur radio club and seek guidance and advice from experienced operators.

FAQ:

Q: What is a QRP radio?
A: A QRP radio is a low power amateur radio transmitter with a maximum output of 5 watts.

Q: What is a dummy load?
A: A dummy load is a device used to simulate an antenna load for testing and tuning a radio transmitter.

Q: What is a Tiny SA?
A: A Tiny SA is a low-cost spectrum analyzer that is used to measure the frequency and strength of radio signals.

Q: What is signal purity?
A: Signal purity refers to the level of interference or noise in a radio signal.

Q: What is a birdie in amateur radio?
A: A birdie is an unwanted signal that is generated within a radio receiver due to internal mixing or local oscillator leakage.

Conclusion:

In conclusion, when comparing the TruSDX and QCX-mini radios, it is important to consider the internal noise and birdies produced by each radio. The TruSDX radio produces more internal noise, while the QCX-mini radio is quieter and produces fewer birdies. However, the TruSDX radio has a slightly better signal purity than the QCX-mini radio. Ultimately, the choice between these two radios will depend on the user’s specific needs and preferences, as each has its own strengths and weaknesses.

As noted in a previous entry of this blog where I discussed the "Raspberry Kiwi" SDR - a (near) clone of the KiwiSDR - there is also the "FlyDog" receiver - yet another clone - that has made the rounds.  As with the Raspberry Kiwi, it would seem that the sources of this hardware are starting to dry up, but it's still worth taking a look at it.

I had temporary loan of a FlyDog SDR to do an evaluation, comparing it with the KiwiSDR - and here are results of those tests - and other observations.

Figure 1: The Flydog SDR.  On the left are the two "HF" ports and the port for the GPS antenna.  Note the "bodge" wires going through the shielded area in the upper left. The dark squares in the center and to its right are the A/D converter and the FPGA.  The piece of aluminum attached to the oscillator is visible below the A/D converter. Click on the image for a larger version.

How is this different from the Raspberry Kiwi?

Because of its common lineage, the FlyDog SDR is very similar to the Raspberry Kiwi SDR - including the use of the same Linear Technologies 16 bit A/D converter - and unlike the Raspberry SDR that I reviewed before, it seems to report a serial number, albeit in a far different range (in the 8000s) than the "real" KiwiSDRs which seem to be numbered, perhaps, into the 4000s.

The most obvious difference between the FlyDog and the original KiwiSDR (and the Raspberry Kiwi) is the addition of of a second HF port - which means that there is one for "up to 30 MHz" and another that is used for "up to 50 MHz" - and therein lies a serious problem, discussed below.

Interestingly, the FlyDog SDR has some "bodge" wires connecting the EEPROM's leads to the bus - and, unfortunately, these wires, connected to the digital bus, appear to run right through the HF input section, under the shield!  Interestingly, these wires might escape initial notice because they were handily covered with "inspection" stickers. (Yes, there were two stickers covering each other - which was suspicious in its own right!)  To be fair, there's no obvious digital "noise" as a result of the unfortunate routing of these bodge wires.

Why does it exist?

One would be within reason to ask why the FlyDog exists in the first place - but this isn't quite clear.  I'm guessing that part of this was the challenge/desire to offer a device for a the more common, less-expensive and arguably more capable Raspberry Pi (particularly the Pi 4) - but this is only a guess.

Another reason would have been to improve the performance of the receiver over the KiwiSDR by using a 16 bit A/D converter - running at a higher sampling rate - to both improve dynamic range and frequency coverage - this, offering usable performance up through the 6 meter amateur band.  

Unfortunately, the Flydog does neither of these very well - the dynamic range problem being the same as the Raspberry Kiwi in the linked article compounded by the amplitude response variances, choice of amplifier device and frequency stability issues discussed later on.

Observations:

Getting immediately to one of the aspects of this receiver, I'll discuss the two HF ports. Their basic nature can be stated in two words:  Badly implemented.

When I first saw the FlyDog online with its two HF ports, I wondered "I wonder how they selected between the two ports - with a small relay, PIN diodes, or some sort of analog MUX switch, via hardware?" - but the answer is neither:  The two ports are simply "banged" together at a common point.

When I heard this, I was surprised - not because of its simplicity, but because it's such a terrible idea.  

As a few moments with a circuit simulator would show you, simply paralleling two L/C networks that cover overlapping frequency ranges does not result in a combined network sharing the features/properties of the two, but a terrible, interacting mess with wildly varying impedances and the potential for huge variations of insertion loss.

The result of this is that the 30 MHz input is, for all practical purposes, unusable, and its existence seriously compromises the performance of the other (0-50 MHz) port.  Additionally, if one checks the band-pass response of the receiver using a calibrated signal generator against the S-meter reading, you will soon realize that the resulting frequency response across the HF spectrum is anything but flat.

For example, one will see a "dip" in response (e.g. excess loss) around 10 MHz on the order of 20 dB if you put a signal into the 50 MHz port, effectively making it (more or less) unusable for the 30 meter amateur band and the 31 meter shortwave broadcast band.  Again, there is nothing specifically wrong with the low-pass filter networks themselves - just the way that they were implemented:  You can have only one such network connected to the receiver's preamplifier input at a time without some serious interaction!

Work-around:

Having established that, out-of-the-box, that the FlyDog has some serious issues when used as intended on HF, one might be wondering what can be done about it - and there are two things that may be done immediately:

• Do microsurgery and disconnect one of the HF input ports.  If you have the skills to do so, the shield over the HF filter may be unsoldered/removed and the circuit reverse-engineered enough to determine which component(s) belong to the 30 MHz and 50 MHz signal paths - and then remove those component(s).  If you wish to retain 6 meter capability, disconnect the 30 MHz port.  Clearly, this isn't for everyone!
  

• Terminate the unused port.  A less-effective - but likely workable alternative - would be to attach a 50 ohm load to the unused port.  On-bench testing indicated that this seemed to work best when the 50 MHz port was used for signal input and the 30 MHz port was connected to a 50 ohm load:  The frequency of the most offensive "null" at about 10 MHz shifted down by a bit more than 1 MHz into the 9 MHz range and reduced in depth, allowing still-usable response (down by only a few dB) at 10 MHz, and generally flattening response across the HF spectrum:  Still not perfect, but likely to be adequate for most users.  (In testing, the 30 MHz port was also shorted, but with poorer results than when terminated.) 

In almost every case, the performance (e.g. sensitivity) was better on the 50 MHz port than the 30 MHz port, so I'm at a loss to find a "use case" where its use might be better - except for a situation where its lower performance was outweighed by its reduced FM broadcast band rejection.

This issue - which is shared with the RaspberryKiwi SDR - is that the low-pass filter (on the 50 MHz port) is insufficient to prevent the incursion of aliases of even moderately strong FM broadcast signals which appear across the HF spectrum as broad (hundreds of kHz wide) swaths of noise with a hint of distorted speech or music.  This is easily solved with an FM broadcast band filter (NooElec and RTL-SDR blog sell suitable devices) - and it is likely to be a necessity.

Other differences:

• Lower gain on the FlyDog SDR:  Another difference between the FlyDog and KiwiSDR is the RF preamplifier.  On the KiwiSDR and Raspberry Kiwi, a 20 dB gain amplifier (the LTC6401-20) is used, but a 14 dB gain amplifier (LTC6400-14) is used instead - a gain reduction of about 6 dB, or one S-unit - and the effects of this are evident in the performance as described below.  Was this intentional, a mistake, or was it because the 14 dB version was cheaper/more available?
  

Clock (in)stability:

The Flydog SDR uses a 125 MHz oscillator to clock the receiver (A/D converter) - but there is a problem reported by some users:  It's a terrible oscillator - and it's bad enough that it is UNSUITABLE for almost any digital modes - particularly WSPR, FT-8, and FT-4 - to name but a few unless the unit is in still air and in an enclosure that is very temperature-stable.

Figure 2: Stability of the "stock" oscillator in the Flydog at 125 MHz in "still" air, on the workbench.  The amount of drift - which is proportional to the receive frequency - makes it marginally usable for digital modes and is too fast/extreme to be GPS-corrected. Click on the image for a larger version.

Figure 2, above, is an audio plot from a receiver (a Yaesu FT-817) loosely coupled and tuned to the 125 MHz oscillator on the Flydog's receive board:  Due to the loose coupling (electrical and acoustic), other signals/noises are present in the plot that are not actually from the Flydog.  The horizontal scale near the top has 10 Hz minor divisions and the red has marks along the left side of the waterfall represent 10 seconds.

From this plot we can see over the course of about half a minute the Flydog's main receiver clock moved well over 50 Hz, representing 5 Hz at 12.5 MHz or 1 Hz at 2.5 MHz.  With this type of instability, it is probably unusable for WSPR on any band above 160 meters much of the time - and it is likely only marginally usable on that band as WSPR can tolerate only a slight amount of drift, and that's only if its change occurs in about the same time frame as the 2 minute WSPR cycle.  The drift depicted above would cause a change of 1 Hz or more on bands 20 meters and above within the period of just a few WSPR - or FT8 - symbols, rendering it uncopiable.

"The Flydog has GPS frequency correction - won't this work?"

Unfortunately not - this drift is way too fast for that to possibly work as the GPS frequency correction works over periods of seconds. 

What to do?

While replacing the 125 MHz clock oscillator with another device (I would suggest a crystal-based oscillator rather than a MEMs-based unit owing to the former's lower jitter) or apply a stabilized, external source (e.g. a Leo Bodnar GPS-stablized signal source) are the best options, one can do a few things "on the cheap" to tame it down a bit.

While on the workbench, I determined that this instability appeared to be (pretty much) entirely temperature-related, so two strategies could be employed:

• Increase the thermal mass of the oscillator.  With more mass, the frequency drift would be slowed - and if we can slow it down enough, large, fast swings might be damped enough to allow the GPS frequency correction to compensate.  With a slow enough drift, the WSPR or FT-8 decoders may even be able to cope without GPS correction.
  

• Thermally isolate the oscillator.  Because it's soldered to the board, this is slightly difficult so our goal would be to thermally isolate the mass attached to the oscillator.
  

To test this idea I added thermal mass:  I epoxied a small (12x15mm) piece of 1.5mm thick aluminum to the top of the oscillator itself.  The dimensions were chosen to overlap the top of the oscillator while not covering the nearby voltage regulator, FPGA or A/D converter and the thickness happens to be that of a scrap piece of aluminum out of which I cut the piece:  Slightly thicker would be even better - as would it being copper.

The epoxy that I used was "JB Weld" - a metal-filled epoxy with reasonable thermal conductivity, but "normal" clear epoxy would probably have been fine:  Cyanoacrylate ("CA" or "Super" glue) is NOT recommended as it is neither a good void filler or thermal conductor.

Comment:  If one wishes to remove a glued-on piece of metal from the oscillator during experimentation, do not attempt to remove it physically as this would likely tear it from and damaging the circuit board, but slowly heat it with a soldering iron:  The adhesive should give way long before the solder melts.

The "thermal isolation" part was easy:  A small piece of foam was cut to cover the piece of aluminum - taking care to avoid covering either the FPGA or the A/D converter, but because it doesn't produce much heat - and is soldered to the board itself - the piece of foam also covered the voltage regulator.

The result of these two actions may be seen in the plot below:

Figure 3: The stability of the oscillator after the addition of the thermal mass and foam.  Still not great, but more likely to be usable.  (The signal around 680-700 Hz is the one of interest.) Click on the image for a larger version.

I'll try to put together a breakdown of IC-7300's sections and how much power those use and try to see how Icom could've tweaked those to make the architecture "portable" for the IC-705.

Since getting back into amateur radio and also looking into SDR I've needed some antennas to really get the best out of both hobbies. My ground floor tenement flat is not conducive to good reception. Usually it's recommended that you make your own antennas at first so you can get an idea of how things work, learn some more about propagation, wavelengths, elements (driven, undriven and reflective) etc. - all pretty useful.

The best thing about antennas is that some of them are pretty simple. The kind of reception I was after - VHF and UHF mainly - can be done with some fairly relaxed tolerances and can be nothing more than a piece of wire with a few extra bits attached. Antennas for HF reception - which are limited to being quite large (unless you make a loop, which I may try next) - are beyond scope right now for me, as are satellite antennas (although I'm definitely trying that in the future).

So, what are the kind of antennas I've made and what are they for? And, crucially, are they any good? Let's look at them all. Most of the home-made antennas were constructed by attaching them to the end of a length of RG58 coax cable (good enough at these frequencies) and terminated at a BNC plug. I have a BNC to SMA adapter to fit both the SDR dongle and my handheld radio - which technically loses you some signal gain, but not too much. The elements themselves are made of some cores from a standard mains cable. Thin enough to work with, thick enough to radiate well (which is important).

ADS-B Antennas

The good thing about ADS-B antennas is that they are really tiny. At the standard frequency of 1090 MHz a half-wavelength is 13.75 cm. A quarter-wavelength is therefore 6.875 cm. I took some major inspiration from this page for deciding what to make: https://lucsmall.com/2017/02/06/making-antennas-for-1090mhz-ads-b-aircraft-tracking/

In terms of received signals I was getting one, maybe two planes every half hour or so? I live pretty close to an airport, which is both a blessing and a curse. At that location most planes are low to the ground. That, coupled with my ground floor location, severely compromised my ability to pull in decent signals. At this high a frequency the line-of-sight needs to be pretty good.

VHF antennas

The first thing I tried to do was make a VHF dipole antenna for use on the 2 metre amateur band. The most popular mode used in this band is a vertically-polarised FM signal. This is basically the normal type of FM voice (and sometimes data) transmission used elsewhere outside of the amateur bands for walkie-talkies, taxi and bus radios, pagers, and loads of other stuff. Vertically polarised antennas are much easier to erect than horizontal ones and usually the job requires nothing more than sticking it on the end of something and getting it high up. The dipole was literally just two pieces of wire cut to quarter-wavelengths of the middle of the amateur band (145 MHz), one soldered to the core and one to the shield.

Performance was orders of magnitude better than a rubber duck antenna, and I was able to get tens of miles with relatively low power. Sadly given the lack of structure to the elements I was unable to get it really high. I had to tape it to a fence post, as you can see.

I mentioned that telescopic antenna earlier and I used that on the same hill. I seemed to get a much greater distance and a better readability of my signals over my inefficiently-made dipole. I was able to get higher by standing on top of things like big rocks and trig points, and this also improved the distance. I managed to make a contact with somebody in the Lake District on top of Helvellyn for a straight-line distance of 89 miles on 5 Watts of power.

UHF antennas

The same types of antennas can be used for UHF signals by modifying the element lengths to match the wavelength required. The higher frequency and shorter wavelength of UHF signals means that line-of-sight starts to get more important as those signals won't get bent as much by buildings or the surrounding landscape. Therefore I wanted to do something to improve the gain of my outgoing signal as well as make receiving of weaker signals possible.

I chose to make a type of directional antenna called a Yagi - much easier to do with element lengths this short. It features multiple undriven (not attached to the radio) elements of varying lengths to "focus" a signal and a reflector at the back to help even more. The driven element in the middle is basically like a dipole.

The first thing to do was to demonstrate that it was at least made properly and giving gain in the proper directional pattern. So I aimed the antenna in the general direction of the nearest repeater, moved the antenna around, and checked to see if the signal went up and down. And it did, massively. And with a handheld you can talk with one hand and aim the antenna with the other.

A major problem is that nobody uses UHF analogue anymore, though. Digital radio is popular, but I have no gear for it. So there was little point to this other than as an exercise and it went well. I could use it for other UHF frequencies though on the SDR or for scanning. Not perfect, but better than a rubber duck and the gain may be required sometime.

Where next?

I was really chuffed with how all of this turned out. Having never done this before I was surprised how easy it can be to make something useful. Of course you can make them as complex or as involved as you want, improve the materials, the construction methods, etc. Lots of people use PVC pipe to hold their elements and cap the ends, making things somewhat waterproof.

In terms of future steps it seems the best thing to do is to make a good quality vertical with a ground plane and get it high up on a fibreglass mast. It's easier to handle than a dipole and the performance is much the same. Can't see the point of dipoles unless you're using a yagi for the gain. Much easier to bung a telescope on the end of a bit of cable and get it nice and high. So I'll be looking for some pipe to do this. Unfortunately it'll be a metre long so I need a way to make it out of sections for easy packing. Detachable ground rods too would be a bonus.

ADS-B seems to be out unless I can get a decent position for a receiver. One day... And UHF? Meh.

Thing is, there isn't a "best" antenna because they're all for different things. No ground plane may be ok if I'm in a field. A Yagi may work if I can mount it to the side of something and aim it easily. And the dipole... actually I'm struggling to see why they're useful unless in Yagi configuration, and the angle of radiation isn't great for distance. Am I missing something? They have a specific lobe pattern you may want, I guess.

Lots to think about, then. And a long-term goal of making a nice travel-capable 2M portable antenna. Probably a ground plane with some removable elements.