tinySA Ultra Spectrum Analyzer and Signal Generator

What's in the Box

The unit comes nicely packaged in a solid, attractive box with excellent packaging to secure the contents inside. In addition to the device itself, there are two (!) jumper cables with dual male SMA connectors, as well as a SMA barrel connector, telescopic antenna, USB-C cable, and a stylus. Unlike many devices which require an additional purchase of a Micro SD memory card, a 32G(!) card is included already in the slot. There is also a strap with a guitar pick attached which can be used as a stylus in a pinch.

tinySA Ultra ZS405 Basic Specs

(From the tinySA wiki Page)

• Screen size 4-inch
• Spectrum Analyzer for 0.1-800 MHz or, with Ultra mode enabled up to 5.3 GHz, level calibrated up to 6 GHz. Can observe signals up to 12 GHz
• Signal Generator with sine wave output between 0.1-800MHz or square wave up to 4.4GHz or RF test signal output up to 5.3 GHz when not used as spectrum analyzer.
• Switchable resolution bandpass filters from 200 Hz to 850 kHz
• Built-in 20 dB optional LNA
• Color display showing max 450 points providing gapless covering up to the full frequency range.
• MicroSD card slot for storing measurements, settings and screen captures.
• Input Step attenuator from 0 dB to 31 dB (cannot be used in combination with LNA).
• A built-in calibration signal generator that is used for automatic self-test and (low) input calibration.
• Connected to a PC via USB it becomes a PC controlled spectrum analyzer or signal generator
• Rechargeable battery allowing a minimum of two hours of portable use
• Max input level +10 dBm.
• The generator function cannot be used as a tracking generator as you cannot use the spectrum analyzer and generator functions at the same time.

Spectrum Analyzer Mode

As mentioned, there are two basic modes to this tinySA ultra: a spectrum analyzer mode, and a signal generator mode. I'll first look at the spectrum analyzer side, and then at the signal generator side.

When turning on the tinySA ultra, it will default to the spectrum analyzer mode. Attaching an antenna like the one included in the box, you will see the ambient noise level based on your location. For example, if you open it in your living room, you're likely to see a very low noise level with an occasional spike. There is an automatic marker which shows when a spike, or several spikes register, with the marker showing the strongest signal. At the top of the unit, you can see the frequency and decibel reading of that spike. You can also configure the analyzer to place markers on all of the spikes which rise to a specified noise level through the menu options.

Operation

I would recommend going to the tinySA Ultra wiki either by scanning the QR code printed on the box materials, or by going to the tinySA.org page, and follow the startup self-test and calibration instructions before using the unit for actual testing. This will ensure proper calibration as well as indicate any problems with the unit before you depend on the results of your testing. This is also where you can find the instructions to activate the Ultra mode when you're ready.

Below is an overview of the self-test and calibration setup. When running the self-test, you should end up with a message that says the self-test passed and then a message to "touch screen to continue."

If something fails, before you fear there is something wrong with your unit, run the calibration process, and then run the self-test again. That likely will clear up any issues. Note that you do not have to perform the calibration check each time you use the device. This is basically for first time use, or if you suspect the device has lost calibration for some reason. The same is true for the self-test.

Note that there are two calibration processes. One is from 100 kHz to 5.34 GHz, the other is a calibration process above 5.34 GHz. If you don't plan on using the tinySA above 5.34 GHz, you can ignore that 2nd calibration process altogether.

As the instructions indicate, you will want to connect one of the jumper cables to each of the two ports, the RF port and the CAL port.

This presents a loop to the unit allowing it to test itself and calibrate accordingly. When the calibration is complete, you will get a message indicating that and the instruction to "touch the screen to continue" just as with the self-test.

Local Noise

Right now, in my radio room, I am reading an ambient noise floor of approximately -90 dBm (decibels in milliwatts), with a spike at 460.88 MHz. You will notice I have arbitrarily narrowed the spectrum analyzer frequency range to start at 250 MHz and stopping at 500 MHz, with two smaller (lower dB) spikes showing. By narrowing the search range, two things happen. First, the scanning time is faster. Second, the indicated signal becomes wider in the display, allowing the unit to give a more precise reading.

As an aside, while it might go without saying, this unit in no way compares to the level of accuracy possible with units costing thousands of dollars. If you need the closest absolute precision you can get, you likely already know this is not the unit for you. However, for SWL, amateur radio, and basic calibration usage, this unit is perfectly capable of giving you acceptable results. And did I mention it's extremely portable?!

A nice feature of the software is the pause function, which can help identify a frequency or range of frequencies, or study more of a signal's characteristics. While paused, you can also use the wheel at the top to scroll through the frequencies to identify other peaks and their signal strength and frequency location. If you want to save the screen, you can go to the menu and tap on "save capture."

Using the menu, you also have the option of displaying multiple markers. If you have two or three signals coming in, you can bring up the menu, tap on marker, and choose 2, 4, 6 or 8 markers to be displayed as needed.

First Test/Activation

A simple test you can do right away is to measure something like your key fob. I measured mine and it showed a frequency of 434 MHz. An easy test, but effective to show the unit's ability to identify a signal (and there is no danger of overloading the tinySA on your first test!).

What then happens when you test a handheld radio, for example? While you can connect the radio directly to the RF input using one of the cables provided, the power, even from a handheld, could damage the unit unless you put an attenuator (or more than one if needed) between the radio and the device.

The tinySA Ultra can handle about 6 dBm input strength. More input power than this risks damaging the unit. However, if you test your handheld 10 or 15 feet away from the unit on low power with its included antenna connected, you will be able to get sufficient readings, indicating the primary frequency as well as one or more harmonics, assuming the scan range is set to cover the possible harmonic frequencies.

If you want to connect a transmitter directly to the tinySA Ultra, please see the recommended attenuation required in the notes below in the Safety Issues section.

For example, I have a low-power handheld (Yaesu VX-3 1.5W) set to 146.670 MHz which, with offset, transmits on 146.070.

As you can see in the photo as I transmit, the fundamental frequency is 146.070 MHz, with a signal strength of -37.9 dBm. In the second photo representing the 2nd harmonic, you can see the frequency is 292.29 MHz, with a signal strength of -57.9 dBm. The 2nd harmonic of a fundamental frequency is 2x that frequency, so if you set your analyzer stop frequency above this multiple, the tinySA will display that 2nd harmonic as shown here.

A really nice feature of the analyzer is that you can directly measure multiple harmonics of an input signal by going into the menu and choosing "measure" and then tapping on "harmonic." You then set, as the center frequency, the transmit signal from the radio. You can then set the span for how far away from the fundamental frequency you want the measurements to be taken above and/or below that fundamental frequency. This allows you to see multiple harmonics.

Spectral Purity/Deviation

Another useful feature of the tinySA Ultra for amateur radio operators is to test the spectral cleanliness and deviation of a transmitted signal, say, for example, of your handheld. This would also apply to GMRS and Family Radio Services radios as well. This will help ensure you are not creating splatter which, of course, goes against FCC regulations, but also just ensures you have the cleanest signal possible.

For FM, frequency deviation is optimized for voice clarity, typically 5 kHz, which means the transmitted signal can have roughly a 5 kHz width to carry voice, digital signals, etc., which can then easily be understood through a repeater or in simplex mode, radio-to-radio.

Without getting in too deep, basically what we look for using a 5 kHz deviation is an additional 3 kHz of typical voice range, making a width of 8 kHz. Since this can be 8 kHz plus or minus, we actually double that to 16 kHz. We also want a little extra room to cover pops or higher pitches from certain letters, like "S" or "P" sounds, and so when we test a radio for splatter, we want to try to hold the signal to within roughly 18 kHz, which gives us about 95% clarity. Enough technical talk! The main point is that we can check our likely signal clarity by measuring it with the capabilities of this device.

Obviously, there are many other features associated with a spectrum analyzer function, but I will stop here to keep the article manageable. Besides, I suspect many reading this will find unique or otherwise untested uses for this function!

Signal Generator Mode

To switch from spectrum analyzer mode to the signal generator mode, you'll tap on the "menu mode" button, and then select "signal generator."

The signal generator will start with a default setting of 10 MHz. This can be adjusted using the stylus by sliding back-and-forth to change the frequency, or, and more useful typically, tapping in the center and entering a specific frequency.

Beneath the frequency is the dBm setting, which can be adjusted in exactly the same way as the frequency. It defaults to the highest level of -17.5 dBm, and you can slide back-and-forth to set a general range, or tap the set option on the slider to enter a specific dBm.

You can modulate a tone in either AM or FM, set the frequency of modulation, depth, deviation, and even set a sweep generator to sweep along a certain frequency range. Again, all of this is explained in the wiki pages, and demonstrated by various YouTube videos. This is an overview of the analyzer/generator capabilities, and as such, we don't want to get too deep in the weeds for this article.

Testing the Signal Generator

An easy test of the signal generator is to set a frequency on the generator and match that on a radio receiver. Transmit the signal with the tinySA's antenna connected and transmit the signal with the default -17 dBm signal setting on AM, remembering to set the radio receiver to the same mode. If you attach a simple short wire antenna to the receiver, or use a built-in telescopic whip with portable receivers, you should be able to hear a good strong signal at the designated frequency. If you reduce the dBm on the tinySA to something like -35 dBm, you should hear the signal weaken, just as if you were to move the tinySA antenna farther away from the receive antenna.

You can also connect the radio receiver directly to the tinySA and drop the dBm down to around -73 dBm, so as to receive an S9 signal on the radio. Again, we want to make sure we don't overload the radio receiver by generating too strong of a signal from the tinySA. (If you wonder why I keep mentioning this, it is simply that all similar devices, even expensive spectrum analyzers, are designed to work with very low input power. Likewise, radios receiving signals through an antenna are receiving very weak-powered signals by the time the signal reaches them, even from shortwave stations around the world starting out with 100,000 watts.)

If you want to test the radio above S9, you could add 20 or 25 dBm to increase the received strength at your receiver, by roughly the same amount. Likewise, if you reduce the signal strength using the dBm slider, you can see how low you can go before the receiver stops recognizing the generator's signal.

To reach a level where the receiver cannot hear the signal at all may require an attenuator, depending on the receiver's sensitivity. Of course, these are not hard and fast numbers, because your receiver's meter may not be calibrated exactly, or you may see different results using different radios because of the variance between their respective meters.

The signal generator function is also great for tightening up the alignment of a receiver, particularly older units, or when building your own receiver. By injecting a known frequency at various points, receivers can be aligned to show accurate frequency displays.

A Sampling of Additional Features and Uses

• There is a speaker/headphone jack which allows you to listen in on a signal such as an FM modulated station or AM modulated station (broadcast or shortwave) when you turn on the low noise amplifier, or LNA. It's not designed for impressive sound, but rather a down and dirty ability to hear a signal right from the unit.
• You can turn on a waterfall display, which can show you more information about various signals that are being received, much like modern SDR radios.
• RFI Tracking - The tinySA Ultra is very useful for tracking down radio frequency interference. One of the tricks for locating RFI is to attach a dummy load to the antenna connector so that you are isolating as many signals as possible from various sources like AM and FM radio stations, Wi-Fi, etc. When you are trying to track RFI in your shack or in your house, you do not want to have to figure out if what you are hearing is a legitimate signal.
• One thing many more advanced spectrum analyzers have is a tracking generator, which the tinySA does not have. However, I have seen plans on the internet for building one, so if that is of interest to you, you can do some research and possibly add that capability.
• You can also find tear-down videos on the internet, as well as videos from folks who have overloaded the unit and what they did to bring it back to life.
• For field work, I would recommend carrying both a NanoVNA and a tinySA Ultra in a case with various needed attachments. These two units combined will give you most, if not all, of the testing capability you will need to setup your radio and to make sure you are producing a clean signal, all while having minimal additional weight in your pack.

Software

There are several programs which can connect your device to a computer, which will allow you to operate on a larger screen. Not all features work through the software, but most of the main ones do. Of course, if you are out in the field, you may not want to carry the extra weight of a laptop, and so operating with just a stylus is perfectly fine as well. I have been using the tinySA software since it is the most common software being used to control the device, but you may like to try something else.

Safety Issues

From the tinySA wiki page regarding power limits on input:

Required attenuation between transmitter and tinySA

• For 100 W: between 60 and 70dB
• For 10 W: between 50 and 60dB
• For 1 W: between 40 and 50dB

The best approach is to ALWAYS use a 30 dB attenuator directly connected to the tinySA and to use power attenuators to reduce the output of the transmitter to the target input level of this 30dB attenuator, that is +10 dBm

So, you will need these power attenuators

• For 100 W output: 30-40 dB
• For 10 W output: 20-30 dB
• For 1 W output: 10-20 dB

Thankfully, there are Power (in watts)-to-dBm calculators on the web if, like me, you do not remember the analog way of calculating these conversions. An excellent site is at: www.everythingrf.com/rf-calculators

Also, the manufacturer recommends keeping the dust covers on the unit to avoid static discharge damage when not in use.

Pros and Cons

As I always do, below is a list of the Pros and Cons as I see them based on my experience with the tinySA Ultra. None of the cons are deal-breakers by any means, just mentioned as things of which to be aware.

Pros

• Portable, self-contained test instrument for use as a multi-featured spectrum analyzer and signal generator
• USB-C charging
• Headphone/speaker jack for listening to demodulated signals
• Ability to go into "Level" and "Unit" to change from dBm to watts to measure power units in watts
• The ability to flip the screen display so that the USB cable can be positioned at the top, making it easier to work with it when tethered to a computer.
• Using either the tinySA Ultra or the tinySA.app you can grab screen captures and save them either to the included memory card, or to your computer when connected and using the app. You can also load/save previous captures, traces, settings and more.
• Software operation - With the tinySA software, you are not limited to the small 4-inch screen of the unit, so the spectrum analyzer display can be much larger.

Cons

• All of the units I have used or seen used seem to require tapping toward the bottom of a menu item to activate the menu choice. It's not really a true "con" once you use the device for a bit, but it takes some getting used to.
• As you move the included antenna around it can become slightly loose. To be fair, this is a rather common problem with small antennas having a SMA connection. It's not so much a fault with the radio, but rather something of which to be aware.
• On my unit, the USB-C cable is a very snug fit on both ends. This can be a plus in that the connections will not come loose easily, but also a potential negative if one is not careful plugging in the connections. Since it is an almost ubiquitous connection, I may use another cable and keep this one in reserve.
• When entering information on the popup keypad, I have noticed the touch sensitivity is such that one can easily enter a doubled number without meaning to (e.g. 77 instead of 7). The solution is to carefully check your numbers before hitting enter. (Physician, heal thyself?!)

Conclusions

This has been a very brief overview of the capabilities of the tinySA Ultra. As mentioned above, the wiki pages, online user videos, and especially the short videos produced by the developer of the tinySA will be of great help in getting the most from the device.

As both a shortwave listener and an amateur radio operator (and occasional builder), I can see a number of uses this device can fill without having to spend massive amounts of money on bench testing devices. Shortwave listeners can tighten up receivers using the signal generator function; use the spectrum analyzer/waterfall functions to see what signals are coming in on a given band (very helpful for non-SDR receivers), and track local RFI sources that might not be obvious upon casual listening.

Amateur radio operators can test transmitters for splatter and deviation, harmonic levels, as well as finding signals through the analyzer and waterfall functions. If you're building your own equipment for amateur radio operation, a number of the tinySA Ultra features will come in handy for testing along the way. And if you do any amateur radio satellite work, or just like to listen in, the large frequency range of the tinySA Ultra can be a great way to identify signals out in the field. This device, along with one of the NanoVNA models, makes for a great POTA/SOTA activation kit, or a set of useful tools for field days.

I am impressed with the capabilities of the tinySA, its compactness, stability, and software making it easier on these tired old eyes. I also appreciate having a number of the most common accessories included in the box, rather than having to dig up cables and power cords to get things going. For long-term use I would recommend buying (or 3D-printing) a carrying case to protect the unit from damage, as well as carrying those accessories that one is likely to need in the field.

While I rarely comment on the looks of a product's packaging, I must admit when something is packaged properly AND stylishly, I think it shows pride of manufacturing. The tinySA folks seem to show that pride not only in their presentation, but also when reading through their wiki pages. They do not try to oversell what their product is, but neither do they apologize for what it is not. They have placed the device within a niche they believe delivers value as well as function, and I agree.

The tinySA Ultra is available here: https://www.radioddity.com/products/tinysa-ultra-spectrum-analyzer with a current price as of this writing of $199.99 USD