Review of Deepace KC9531B USB RF Power sensor

[mehdi]

I got a Deepace KC9531B USB RF Power meter for review, and I decided not only to do a review of the device, but also compare it to my other USB RF power meters from Mini Circuits and Anritsu, to see how this new product compares to more established brands and models (spoiler: I'm surprised how good it is for the price!)



Disclaimers:
1. I am not an RF expert. I work on automotive cybersecurity as a profession, and RF and ham radio are my hobbies, so I use and review devices from a security engineer/RF hobbyist perspective.
I also use RF T&M equipment in my job for things like antenna testing, modem testing, jamming and spoofing tests, etc. Please let me know if you find inaccuracies or areas of improvement in my approach to the review.
2. I am under no obligation from Deepace for this review. What you read is my honest unbiased review.

Intro
You need an RF power meter to measure the output power of a device that emits RF signals (e.g. a transmitter, or the output of an amplifier or attenuator). For example, if you measure a signal strength before and after an amplifier (in its input and output), and measure an increase (let’s say by 20dB), you’ll know if the amplifier is working as expected and according to the datasheet or not.

KC9531B
This is a newcomer to the RF power meter world. I know Deepace from their portable spectrum analyzers and VNAs.
The original retail price is $499, but currently is listed with ~20% off, selling for $385 on their website. It measures power for input signals from 100MHZ to 4GHZ, and the measurement range is -30dBm to +20dBm.
I was happy to find out it uses USB-C vs many other devices on the market that either use their proprietary connectors, or use older USB types like microUSB or USB type B.
The software used for measurement is also from Deepace, named KCSDI.
The device has 3 connectors: a USB-C to connect to the computer (and also as power), a RS485, and the RF input which is male N-type. There are also 3 LEDs on the device labeled POWER, DATA, and ALARM.
The device is well-built. I can’t complain about the physical build, neither can I find signs of quality compromise. It’s not as good as Anritsu, but I can’t compare a device with something almost 10x the price!
Everything with the software went smoothly (download links, driver setup, device connection, etc). There’s no learning curve; the UI is easy to navigate.

Spec comparison
Here’s the spec of my other USB RF power meters. It’s important to point out that these devices are not comparable 1:1 (for example my Anritsu measures power for frequencies up to 8 GHZ), so, I will only look at the features that all 3 devices share (e.g. I will only measure power for frequencies between 100MHZ and 4GHZ which is supported by all 3 devices). The only reason I am doing this comparison is that I already had those 2 USB power sensors (I have 2 more power meters, but they’re stand-alone devices, not USB sensors, so I excluded them from this comparison)







Test setup
For the first test, I used my GenComm GC747A LTE Analyzer’s built-in RF signal generator, as I didn’t need signals beyond 4GHZ (and also I found it to be  the most accurate signal generator I have access to in this freq range https://x.com/mehdi0x61/status/1708532932229390524] [url]https://x.com/mehdi0x61/status/1708532932229390524[/url])
I used a SMA to N-type adapter, and used a very low-loss cable from Gore PhaseFlex series.
I chose 4 frequencies for the CW signal and generated each 2 times, once with -30dBm and once 0dBm, and measured the signals with each power meter.



Here’s the measurement results:




As you see, it’s extremely close to the pricier and calibrated RF power meters, and also within specs.

Here’s a screenshot of each software:








For the 2nd test, I generated a 10MHZ-wide LTE signal (FDD) using SignalHound VSG60A vector signal generator.

I picked 3 frequencies and only generated them at 0dBm:



I think the reason Anritsu’s and Deepace’s readings are similar is due to their sensor type (they’re both RMS)

For the last test, I wanted to test the power meters at the higher end of their measurement range (+20dBm). Unfortunately SignalHound VSG60A can only generate up to +10dBm, so I had to use an RFExplorer Combo signal generator that can generate up to +15dBm (I don’t have access to a wideband power amplifier that can generate signals beyond +15dBm on all the desired frequencies for this test)

Here’s the results:



Who should buy it?
If you need a portable and accurate RF power meter for your home lab in the 100 MHZ- 4 GHZ and within the offered dynamic range, this is amazing for the price. If you're a ham radio operator working on HF bands, then it’s not suitable for you.
I only know of one other RF power meter in the sub-500 price range, but it’s not as accurate as this one: the immersionRC power meter which is only calibrated for certain frequencies (35, 72, 433, 868, 915, 1200, 2400, 5600-6000MHz) and doesn’t offer computer connection, but is more portable.

My wish list for areas of improvement or new features:
1. It would be great to protect the USB port. Although it uses a more modern and replaceable connector/cable compared to MiniCircuits and Anritsu, but those have protected the cable against accidental breaking which could easily happen in a crowded lab bench or during field use (look at the picture below)



2. Would be really nice to have another model that covers frequencies below 100MHZ, so it’s more appealing for ham radio use in the HF range (and maybe beyond 4 GHZ as well)

3. The datasheet should include more details. There are many important specs that are missing (e.g. SWR for different ranges, linearity, input damage level, DC voltage at RF port, whether the device requires calibration, etc)


Bottom line
I am impressed with the quality and also measurement accuracy of Deepace KC9531B for the price it’s offered, and I think it fills a gap in the RF T&M market: a device that’s not built for hobbyists only, is accurate enough to be used in a personal or small lab, doesn’t compromise on build quality, and yet offered in an accessible price range. As you saw in my tests, it punches beyond its weight, and I recommend it to anyone looking for a USB power sensor without breaking the bank.


Product/datasheet links:
Deepace KC9531B : https://deepace.net/product/kc9531-usb-rf-power-sensor-4ghz/
Mini Circuits FCPM-6000RC: https://www.minicircuits.com/pdfs/FCPM-6000RC.pdf
Anritsu MA24108A : https://www.anritsu.com/en-US/test-measurement/products/ma24108a



Mehdi / DF2HF, NM9A