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I've looked at 23cm transmitters and receivers in kit form but this is a mode I know very little about. I was thinking of building a receiver from kit for my 2e exam what do people think?
23cms is a good band to start on as a) there is plenty of kit available and b) there are plenty of test signals to receive (aka repeaters).
I guess the easiest way to get started on 23cms ATV is to buy the Comtech modules (see http://www.13cm.co.uk) they are under £40 each and give you transmit and receive without any hassle. If you want to do some DIY then you can build the controller yourself (see http://www.radio-kits.co.uk/) or buy it ready made from http://www.13cm.co.uk and of course there's the challenge of putting it all in a nice box and sticking the labels on straight
You will also need an aerial - what kind depends on where you are located with reference to your nearest ATV source, the simplest would be a "twin quad" and is easily built yourself (see CQ-TV 210 p.44) and gives a reasonable amount of gain. If you need more gain then you will probably need to make or buy a yagi or helix, again there are plenty of designs on CQ-TV for either type (let me know if you need to know which issues).
Of course at 23cms you need low loss co-ax for the downleads - I use LMR400 which is rather thick and unwieldy, but is very low loss, for short runs you can get away with satellite cable, particularly if you use a masthead pre-amp. Speaking of which, a low noise pre-amp is essential on 23cms for any kind of DX and was my first homebrew piece of kit when I first got into ATV.
I hope that helps, but please feel free to ask more questions if you need clarification, if I can't answer I'm sure there will be someone who can.
Chris - G1FEF
However, I could do with sorting out a couple of things, such as...
What additional equipment is needed? I presume some kind of camera and an antenna, of course, but what else would people say a basic, start-up station should have?
What are activity levels like and where are the main centers of activity? I live in Bolsover, Derbyshire, in a reasonably good location. I already use 23cm CW (mainly) and voice modes (sometimes) and I think there used to be someone in the area who was active, but where is the best place to listen for other ATV users?
I did, once, have an old satellite receiver, which could be modified to be a 24cm receiver, but I gave it to someone who was already 'into' ATV some years ago. Are these sorts of receiver still about and what would people recommend looking out for, or even avoiding? With the imminent shut down of analogue commercial TV, what bits of kit might be worth salvaging when people start throwing old gear out when the analogue transmissions are shut down?
Thanks in advance for any help or advice.
If this goes well, I may ask for the 13cm pack for my birthday later in the year...
I also decided to get the 18 Watt PA as well, just in case a bit more power was needed.
The next job is to beg/borrow or make a suitable antenna I guess. I've seen a few designs for bowtie antennas and various Yagi/Uda beams, so I'm sure I can do something.
The next unsolved question is some form of picture to send. Anyone any ideas? I have a digital camera which has a 'TV' output, but needs a bit of a repair to the battery cover, or a 6 volt supply, which might do I guess? I suppose some form of pattern generator might help?
Is there some way of taking an output from a webcam?
Thanks for any help.
The most difficult part, for me, is always drilling the holes and making the boards fit in the box, but it's almost finished now.
I'm planning to have it all up and running for the local ATV activity night on Friday.
I also decided to get the matching 13cm transceiver boards and have another box sorted to put that in, but I now need to make up an antenna, or maybe two since I have no change over relay for 13cm as yet, so I will either have to manually swap over, or just make two antennas...
I wonder if most people on 13cm are using Yagi/Uda beams or dishes? I'll also probably need to be out on a higher spot to get a signal to and from one of the 13cm repeaters as I will only have about 200mW available at first.