Before I begin, I would like to first thank Comrade Li (BD4XNS) and Professor Rong (BH3PTS) for their technical guidance during the DIY process.
This document will not go into detail about the JUMA TX136. Those interested can find more information on their own. In short, it is a DIY radio operating at 136 kHz (for amateur use) with a maximum transmit power of 50W. The link is as follows:https://www.jumaradio.com/juma-tx136
First, let's start with the enclosure. The original project used an enclosure that was only available from Mazoe, and it cost over 400 dollars for a standard metal box. This clearly wasn't necessary, so we decided to use Jia Li Chuang's design and manufacturing instead.
For cases where I don't have the original PCB design engineering files, my preferred method is: import Gerber files into KiCad to create a PCB project, then import it into EasyEDA. Manually recreate the BOM (Bill of Materials) and the 3D model of the PCB, and finally import them into JiaLiChuang's order assistant tool for aluminum alloy case design. Based on the 3D model, select and drill the appropriate case.
The design drawing is shown below:
After the design is complete, it's usually not directly sent to production. Instead, a 3D model is exported and printed to check if the hole positions are suitable. Here, Li helped me with the printing and assembly testing, which was quite good. Then, it can be sent for mass production.
The prototype casing that was returned:
Next, you need to bypass the magnetic ring. This requires patience, followed by installation, powering on, and debugging.
The hardware work is complete; the next step is testing.
The monitoring station in Shandong Province was unable to test the long-wave radio, and therefore could not issue a testing report. As a result, it returned to its original location for testing.
The equipment used for testing by Linyi 無委 (local radio regulatory authority) is an Agilent N9020A.
All equipment parameters passed excellent tests, with test frequencies ranging from 0 Hz to 1 Hz, and even exhibiting frequency variations. The personnel from 無委 (local radio regulatory authority) also praised the equipment's accuracy in maintaining its specified frequencies.
The maximum power of the spurious frequency component in the test is -43.8 dBm, which is less than -90 dBc compared to the 50W carrier wave of the device itself (47 dBm). The results are particularly impressive.
Finally issue the test report.
This might be one of the few longwave test facilities in China that are also registered?
Finally, conclude with a flourish and leave the future to the antennas and the 2200 MHz band.
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