One of the good things about the amateur radio hobby is its diversity. If you begin to become bored with one particular activity there are always plenty of other things to try. And so I decided to try something completely new (for me anyway) – HF Slow Scan Television or SSTV for short.
I downloaded the mmsstv software from http://hamsoft.ca/ and read through the instructions on setting up. All very simple really, much like setting up JT65, RTTY or any other soundcard based system/software. It does come with a few standard templates so I used these for a while until I got my head round the file size and clipping tools to create my own.
fig 1. My transmitted SSTV CQ message and control panel.
I have now made several contacts around Europe and Russia and the variety of images received is quite amazing. Contrary to popular belief, they are not pictures of nakedness – they are images of nature, wildlife or screen grabs from cartoons.
fig2. Image received at M0CVO from SP5SMY.
For many radio amateurs, myself included, being able to build our own kit – be it receivers, transmitters or test equipment – has always been an important part of the hobby. One important component of many of these items has always been the polyvaricon or small AM tuning capacitor. These are used to tune radio receivers, or as part of a low power / QRP antenna matching/tuning unit (AMU / ATU). Unfortunately it now appears that they are no longer being manufactured and whilst there are a few left on the surplus market, supplies are likely to come to an end. It seems that in this age of digital radios and push button tuning there is now no call for them – who listens to AM radios anyway? Of course there are those of us (radio amateurs) who will always want some form of small tuning capacitor such as this for the radios that we build, won’t we?
Small AM tuning capacitor
Of course being resourceful amateurs we will soon find an alternative (I am sure). One possibility of course is to use small trimmer capacitors but then the ease of adding a small tuning dial would be gone. This would bring the need for holes drilled in cases above said component and the use of trimming tools to tune them. Not the easiest of ways to retune your receiver or “net” your CW contact.