K2GWK Amateur Radio Projects

One of the benefits of Amateur Radio is that it gives you a great excuse to build things. I thoroughly enjoy designing and building stuff. By "STUFF" I mean anything from my Brewery, things around the house and yard and yes my beloved hobby of Amateur Radio. I will start documenting my Amateur Radio projects for those who are interested. I will document the builds as best as I can and I hope you take something useful away from these projects.

Project: Vector Network Analyzer S-Parameter Test Set

What a lucky guy I am. My wife is thrilled that I am a Ham. When I am on the air she often times just takes a seat in the shack to listen to my QSO's. To say she is supportive is an understatement. For Christmas 2013 she purchased me a VNA or Vector Network Analyzer. The VNA is a very handy tool for all kinds of RF measurements and every Ham would benefit from having one. In recent times a number of USB based VNA's have surfaced on the market for well under $1000. The VNA I recieved as a Christmas gift was the DG8SAQ VNWA 3.0E. The VNA was purchased from SDR-Kits.net for about $700 US and it included the Calibration Kit and Cables in a nice case. There are compromises on these inexpensive VNA's with one of the most glaring examples being able to measure only in a single direction or only measuring S11 and S21. You physically need to turn the device around to measure S22 and S12. I was very happy to discover that the DG8SAQ VNWA 3.0 has an output that can support an external switch which will in effect reverse the device for you so you can measure in the reverse direction for S22 and S12. I began to hunt around the Internet to see if there was anyone utilizing this feature of the VNWA 3.0 and indeed there were a couple. This project is my implementation of an S-Parameter Test for the VNWA 3.0 based on other implementations viewed on the Internet.

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Project: Vector Network Analyzer PL259/SO239 Calibration Kit

The most accurate way to measure the Loss and VSWR of a device is with a Vector Network Analyzer like the one described above. Unfortunately a Network Analyzer is almost useless without error correction ability. The Network Analyzer has the ability to correct for systematic errors like low directivity, port match and frequency response errors. The only way the Network Analyzer can make use of it's error correction technology is by measuring some known standards like a load, short, open and thru connection. The known load, short, open is our Calibration Kit or what I have built here. You need a calibration Kit for every different connector on the devices you test. Most connectors in the Amateur Radio world are either PL259 or SO239 so I decided to build a PL259/SO239 Calibration Kit. The next one I build will be for the Type N connector as I already have one for the SMA connector. It is a fairly straight forward build and should cost well below $50. The only caveat is that you will have to make some measurements on your completed Calibration Kit with a Network Analyzer. Remember I said they had to be known standards. That is really the only challenge in this build but I know you will overcome it.

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Project: 6 Way to 2 way Antenna Switch

In my shack I have three HF tranceivers and in my back yard I have two HF antennas, one being a beam on a tower and the other a ground mounted vertical. I decided it would be advantageous to be able to switch any of the three HF rigs to any of the two antennas and to do it without breaking the bank. I also wanted the ability to switch in a Vector Network Analyzer for antenna test and tuning. I could have purchased a fancy antenna switch from DX Engineering or any of the other manufacturers but what would be the fun in that and they tend to be a bit spendy. For this simple project my design goal was to build something that could be controlled from the operating position, the switch would reside in the shack and the cost would be less than $250.

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Project: FTDX-3000 Tune Button

One of the neat things about the Elecraft K3 is the Tune button on the front panel. When this button is pressed, a CW carrier is output for tuning an amplifier or antenna tuner. When purchasing my Yaesu FTDX-3000 I found no such function to allow for tuning up an amp or antenna tuner. Sure I could put the rig in CW or FM, adjust the power and key up microphone, but that all takes time and is cumbersome. I happened on an thread on eham.com discussing this exact thing and a response from W6GX nailed it. He mentioned that by grounding the TX REQ jack on his FTDX-5000 it would initiate a tuning signal. I had a look at my FTDX-3000 and found the TX REQ signal on the Linear connector on the back of the rig. I grounded it and sure enough it worked. I then proceesed to build a little bracket with a push button switch and changed two FTDX-3000 menu changes and I was in business. For under $10 I built the perfect solution for tuning with the FTDX-3000. Take a peek at this very simple project.

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Project: On-Air Sign with RF Relay

A Christmas or two ago my wife bought me a nice LED On-Air Sign for the shack. Up until recently I had the sign hooked up to the rig power supply so that when I powered up one of my transcievers the sign would light and let anyone entering the shack know that I may be on the air. That works well in theory, but one day I forgot to turn the rig power supply off while I was in the shack reading a QST article, and I think it annoyed the wife a little because dinner was ready and she was afraid to interrupt because she saw the sign lit up. Well, a happy wife means a happy life so I decided to do something that would prevent it from happening again. I figured the easiest was to accomplish the task was to switch a relay whenever RF was detected. I figured someone had to have done this before and came across an older QST article that featured such a device. The article can be viewed HERE.

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Project: RTL2382U based HF Receiver (In Progress)

If I am not talking on my radios while I am in the shack, I am listening. Listening to the radio tends to relax me quite a bit and my wife has caught me nodding off in my chair while listening more times than I care to admit. I am in a constant battle with insomnia, especially when I travel for work. When I travel for work I find it difficult to relax enough to fall a sleep for all the obvious reasons. I would do much better if I only had something with me that would help me relax and not cause a hangover.

I caught an article about the RTL2382 Dongle while reading QST and thought I may have something there. I could easily build a HF reciever that would be portable, hook up to my laptop and not cost an arm and a leg. This project is 85% packaging and 15% electronics as I needed an upconverter for the Dongle to receive HF and a preamp to improve it's sensitivity.

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