This page is a record of recent radio related projects I have undertaken that may be of interest or use to others - enjoy!
My main interest in amateur radio is in the VHF/UHF/Microwave parts of the spectrum. I none the less have odd sorties onto the HF bands just to see what they are like. Below are details of some projects I have undertaken recently ( or at least those that have got the length of being written up in some form or another! )
Spectrum Analyser Repair
One of the most useful bits of test gear for RF and microwave work is a spectrum analyser. I have an HP141T/8552B/8555A analyser. A few years ago mine inexplicably lost sensitivity. I found that the mixer diode had died. I suppose that I must have done something to damage it but I was not aware of it. Having nothing to loose I dismantled it and attempted a repair. This was quite successful and I wrote it up as an article which appeared in the September 2002 UK Microwave Newsletter and others might find it useful if they have an ailing HP8555A plug-in. The article is available below:
Repair of the mixer in the HP8555A spectrum analyser plug-in
Time and Frequency Measurement
In order that I can measure frequencies accurately at microwaves I maintain a GPS frequency standard. It is a Hewlett-packard Z3801A. These units were used in the North American cellular phone system to synchronise cellsites. The have become available on the secondary market in fairly large numbers and often appear on Ebay where I obtained my unit. The unit runs continuously and I monitor it with a PC. Here is the status of my Z3801A.
The N2PK Vector Network Analyser
Recently I have been interested in the N2PK vector network analyser and have had one put together. This is a very useful piece of test equipment that has all the functionality of a professional instrument, covering the frequency range 100KHz to 60 MHz. This project was created and designed by Paul Kiciak, N2PK and is a very interesting and novel design. I recently gave a talk at the Lothians Radio Society (my local radio club.) Here are the PowerPoint slides I prepared for this.
The original design was controlled from the parallel pot of a PC. Here is a description of how I powered it off the USB port and made it communicate over the USB port using G8KBB's software.
One of my interests is in UHF/Microwave portable operation. One useful facility for this is to be able to connect to the internet when portable to arrange QSOs. Her is how I did it. How to set up Pay-as-You-Go GPRS Internet access for the ON4KST reflector when out portable.
Some time ago I gave another talk at the Lothians Radio Society on the history and development of RF connectors. Here are the viewfoils I prepared for this. This is one for real radio geeks!
Here are the foils for a talk I did on the measurement of noise figure using natural noise sources.
8th November 2006