Do you want to measure filter response (bandwidth or insertion loss), amplifier bandwidth, or antenna characteristics? This JTGP-1033 D6 network spectrum analyzer with RF generator makes it possible. It costs approximately €50, which is incomparable to a VNA or its direct competitor, the NWT4000.
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Principle of Operation and Application
The principle behind the JTGP-1033 D6 is simple. The device is equipped with a frequency generator and a spectrum analyzer (or at least one logarithmic detector), and the device under test (commonly referred to as DUT) is placed between the two. When scanning a frequency range, a series of measurements is performed, and in return, we obtain the DUT’s frequency response. It contains 2x ADF4351.
If you purchase this device, you will receive a PCB, a USB connection cable, 2 SMA connection cables, and a small bag containing three M810 integrated circuits. This serves as a spare in case you overdrive the spectrum analyzer’s input and damage the circuit.
If you also want to measure antennas, you’ll need a measuring bridge. You can build one yourself following the OK1UGA instructions or purchase one. For measurements, it’s also important to have high-quality loads, and in this case, it’s not worth skimping—choose a professional-grade product.
SNA Sharp is an excellent software tool. SNASharp is (free) software written in C#, designed to control (primarily) scalar analyzers compatible with the NWT software from DL4JAL: http://www.dl4jal.eu/
Measuring the patch feed for QO-100 (uncalibrated)
Supported analyzers
It has been successfully tested on the following analyzers:
- NWT70 sold by BG7TBL
- Simple Spectrum 35M – 4.4G sold by BG7TBL
- Simple Spectrum 135M – 4.4G sold by BG7TBL
- NWT500-1 sold by BG7TBL
- NWT500-2 sold by BG7TBL (The linear scanning feature is now available on the 2 NWT500 models)
- JTGP-1033 (D6 on AliExpress)
SNASharp integrated analyzers, but they have not been tested:
- NWT300 sold by BG7TBL
- NWT-4000
- NWT-6000
A measuring instrument like this is certainly of interest to many designers and antenna technicians, myself included. It was recommended to me by Pavel, OK1PHU. After unpacking it from the envelope, I connected the JTGP-1033 D6 spectrum analyzer with an RF generator to my HAM netbook, which has only an Atom processor with 1 GB of RAM. The SNA Sharp device was detected without any problems. Calibration is required, which is a very simple process, and the software will guide you through it. Then you can start taking measurements.
It’s important to know that the RF generator isn’t running continuously; instead, it’s turned on and off using a button on the circuit board. Since I was interested in measuring antennas, I connected the jumper and performed my first measurements. Everything worked perfectly!
Shortcomings of the JTGP-1033 D6
However, the JTGP-1033 D6 also has some drawbacks. According to https://vma-satellite.blogspot.com/2019/04/new-simple-spectrum-analyzer-device.html, the noise level is around -70 dBm, which is 10 dB higher than that of SMA/NWT analyzers. There is also mention of an input impedance deviation and the possibility of improving the dynamic range: http://alloza.eu/david/WordPress3/?p=542
Attenuation stage at the analyzer’s input D6
Attenuation stage at the generator’s output
The principle involves adding attenuation stages to both the RF generator’s output and the analyzer’s input, as well as adjusting the filter. This requires a bit of skill and a steady hand when soldering SMD components. The procedure is described at http://alloza.eu/david/WordPress3/?p=542. Even without these modifications, however, the JTGP-1033 D6 is an excellent measuring instrument.
I made these modifications myself, and repeated measurements do indeed come out slightly better. I mounted the JTGP-1033 D6 spectrum analyzer with an RF generator into a Hammond HA1455J1202 aluminum enclosure purchased from GM Electronics, which I naturally shortened. To enable turning the RF generator on and off, a button and an indicator LED were added to the front panel. The front and rear panels were designed in Corel Draw and printed on self-adhesive foil. The film was affixed to the panel, coated with several layers of clear varnish, and further secured with the original mounting brackets.
JTGP-1033 D6 Spectral Analyzer with RF Generator
Evaluation:
Measurements were taken of the DL7KM antenna at 435 MHz, an LTE filter, the LZ5HP PCB antenna at 2.4 GHz for QO-100, and a patch feed for the same purpose.
Measurement of the LZ5HP antenna tuned to 2.4 GHz
The JTGP-1033 D6 is an excellent tool that I recommend to every design-oriented VHF/UHF/SHF amateur radio operator. You can purchase it, for example, on eBay or AliExpress.