Author: sq5bpf

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Adding an INA219 power monitor to a chinese USDX+ transceiver

The (tr)uSDX has hardware to measure the power amplifier voltage/current/input power. Since the output power is also measured, it can calculate and show efficiency. This is very useful for tuning the class-E output stage, and is also useful in the field to see battery voltage and other parameters.

I have an uSDX+ transceiver from China. Let’s add the power monitor to it too. This description should apply to other radios based on the uSDX.

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Demo of a working replica of the Great Seal Bug on the 23cm band

This is a demo of a working replica of the Great Seal Bug.

As far as i know this is the only attempt to make a working replica, not only a nicely looking prop.

I am a licensed radio amateur (callsign SQ5BPF), therefore the device dimensions were scaled to make it operate on the amateur radio 23cm band (1240-1300 MHz).  Please see my other articles about this device.

 

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The Great Seal Bug. Part 3: Building a working copy of The Thing

This is the third part of articles about the Great Seal Bug (also called “The Thing”). These articles will cover: history, theory of operation and a practical reconstruction of this device. This part is about building a working copy of the Great Seal Bug

To my knowledge this is the only publication about making a wirking replica of the Sreat Seal Bug. https://www.vintagespycraft.com/ shows a beautifully looking model, however the emphasis was on making it a nice looking exhibit, and not on making it work (but look at this site anyway, the model is a work of art).

In 1945 this was super-secret, ultra-novel military technology. Building and operating it required special materials and access to ultra-secret hardware. So is it possible to do this in 2022 on an amateur budget? Surely not.

But radio amateurs have a long history of doing “impossible” things, part because of their ingenuity, and part because of their ignorance (they simply don’t know something can’t be done). So lets try anyway 🙂

Continue reading “The Great Seal Bug. Part 3: Building a working copy of The Thing”

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The Great Seal Bug. Part 1: history

This is the first part of articles about the Great Seal Bug (also called “The Thing”). These articles will cover: history, theory of operation , a practical reconstruction of this device and a working demo.

This device, even 75 years later, is still often mentioned at security publications and conferences.

Great Seal Bug
https://commons.wikimedia.org/wiki/File:The_Thing_Great_seal.jpg

Continue reading “The Great Seal Bug. Part 1: history”

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Astec AA21660 power supply modification for 13.8V output

Astec AA21660 power supplies can be modified to give 13.8V / 24A.

They are specified to 24A @12V and 27A @5V, with 400W max continuous power. It is used in various  Engenio (former LSI Logic) storage products, which are OEM-ed by many companies: IBM (TotalStorage DS4xxx and DS5xxx line), NetApp etc. The IBM FRU is 19K128.

The following mods change the overvoltage protection to 14.4V, and set the voltage to 13.8V.

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SV9/SQ5BPF with uSDX part 2

So I’ve tried to operate from Platanias / Crete (see SV9/SQ5BPF with uSDX part 1).

Threw a wire on a palm palm tree, stretched a counterpoise on the ground, tuned it, and made the first CW QSO on 40m with Zygi SP5ELA. So next I’ve tried to tune the antenna on 80m, and the uSDX transceiver failed with a short circuit.

It seems that the smd PA transistor died on 80m (it also dies on 10m). Fortunately I’ve had two IRLML2060 transistors with me, but no soldering iron and other tools.

So is there any hope that i will be able to make more than one QSO?

Continue reading “SV9/SQ5BPF with uSDX part 2”