Category: Hardware

What could go wrong if you buy a broken retro machine for cheap just to repair it and make it shine again with VIC-IIe colors and sing with glorius 3 channel SID chip? It’s not as easy task as I thought earlier and this repair went for much longer and costed me way more as compared to my previous Commodore 64c repair. Despite all the time, money and effort I put into it I don’t regret it at all. This repair allowed me to learn A LOT about electronics and electronic repair.

My mighty fixed Commodore 128 in it’s full glory.

A few years ago I bought the original dual port Airspy HF+ and was amazed by it’s reception quality. I’m using this sdr receiver up to this day for both HF and FM DX-ing and couldn’t find any other affordable yet so good receiver. Back in 2021 I bought Airspy HF+ Discovery as a replacement in case my dual port receiver is struck by ESD during lightning storm or something else.

Most noticeable differences are lack of metal casing which if present, could be useful in noise and interference reduction, and it has only a single SMA port which is fine for simple setup with single wideband scanner antena, but it’s definitely problematic for someone using separate HF and VHF antennas for better gain and performance. Similarly to dual port model, this device also uses micro-USB port which can potentially cause some troubles. If you stumble upon a connection problem when your computer doesn’t detect a device, or does detect but for some reason SDR software can’t connect to it, please check your usb cable. In my experience even good looking cables with no visible damage to the plug can be faulty, that’s why I’m using my trusted high quality cable filled with ferrite chokes/beads.

During last Black Friday I bought Raspberry PI 4 on Aliexpress for just $36. After initial tests I’ve found out that a good cooling case is definitely a must have. The SoC quickly reaches 80°C under a full load and then throttles from 1.5 to 1.0 GHz per ARM core to maintain the temperature limit. So, I ordered a very nice Chinese aluminium case for just $7.5. I love PoE devices – my new toy must also support Power over Ethernet – and it does!

I took a cheap LM2596 DC converter and installed it together with the board in the aluminium case.

I’ve been lately looking for a small 10/100M Ethernet switch with a USB and both PoE input and output port (Power over Ethernet). The MikroTik RouterBOARD hAP (RB951Ui-2nD) looked pretty good, so I ordered one. The 2.4 GHz Wi-Fi interface was unnecessary, but the price was acceptable anyway, as I found a used device in excellent condition at just $25 including shipping.

As usually, the first thing I did after receiving the package was the teardown. The PoE ports are usually dedicated for some remote devices connected with long Ethernet cables and located outdoors. Therefore, a special protection should be included in the front of the controller (QCA9531 SoC in hAP). Unfortunately, this is not the case of RB951Ui-2nD. Although the engineers designed the PCB of this device with TVS diodes on both PoE input and output ports, the final product does not contain them. Protection for other ports was not planned at all.