THE HISTORY OF GB3XG 10GHz REPEATER

Amateur Television known for short as "ATV" has been going around for years. Not a lot of Credit ever gets paid to these very dedicated guys who design build and Experiment with ATV to try to send to each other and other Groups picture information. One of the most noticeable asset you will soon learn about an experienced ATV chap is the help he will always give to a new person to this Hobby. There is a lot of effort required and Technology has now made it easier and cheaper to get going on ATV... Years ago skeptics said about ATV and its frequencies such as 10GHz you wont work far with that. I can tell you they was and are wrong just a few m/W will go many miles with a full FM Colour High Definition Picture with Sound.............

A very Active group is the SEVERNSIDE ATV GROUP who first put up GB3ZZ at Filton north Bristol and has been worked well for what will be now decades. The group is well known World Wide and it is not very expensive to join at which you get a News Letter four times a Year called "P5".

I moved down to CLEVEDON about 11 years ago and joined the Group as a member soon after I found out about STV Group. Alas I moved into a hole as far as ATV is concerned and have had to live with the problem I am surrounded by industrial units........

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GB3XG was first started with Ted G3JMY in Bristol then I took over from Ted and produced a Logic unit in a small 19" rack to control the system. I designed a 4 way Video Switcher and all the other 6809u/P and Sound cards and DTMF interface also a 16 channel A/D multiplexer and PSU..... The repeater had additional inputs so that it could operate to other Repeaters in the Area... Because of the large amounts of RF from nearby Transmitters I fitted RF filters everywhere so we would not get RFI problems. The Original output power was 300m/W later changed to 1 Watt.. Nigel G7JZP and Ivor G1IXF produced the OMNI DIRECTIONAL ant's for RX and TX and these were about 14dbd gain one above the other up a JEWSON's Drain pipe that showed little if any RF attenuation. In addition up this pipe were multipole filters to give TX to RX isolation Ted's times nine multiplier and an LNB . Lastly a 23c/m Halford slot..... Nigel set up all the filters and LNB..... Ivor did all the rigging with a few more of the "A" Team whom had had experience with GB3ZZ all this was new to me.... We waited and waited and waited for the License to be given and I think it was Viv G1IXE the Chairman of the Group who chose XG... and the story is that "X" means ten in roman numbers and "G" equals Gigahertz...... So it was Born...after working Ken our ATV standards Guy we turned pots up and down until correct Sound and Video levels and Sound injection was obtained.... Ted G3JMY was the first station to work through the repeater....... I can tell you it's a Lot of Work by a lot of people and backed up with the Capitol of the Group and its dedicated men and women and children....... One other unusual thing I did with XG was to track the noise floor value on the RX during a 24 hour period it changed and I used this to our advantage..... Because the RX setup was OMNI-DIRECTIONAL the Sun's solar noise came into play and seemed in general around 2pm the noise floor went up and was lowest around 4am.... I actually tripped on a sudden increase in the noise floor and by using several Test cards with a "SIGNAL BAR" going across acted as a tuning aid to new stations only when you then drop out and come back with video syncs does it let you through a very useful feature. This function was driven from the AGC line on the Sat RX and taken to my logic unit A/D converter... I soon learned that I had to clamp this line to 5Volts so as not to blow up my A/D 5V chip when a strong local station sent the AGC line up to maximum well over 5Volts we all had a good laugh about that one and was something I had not anticipated but we learn.... Each Year they have a Christmas Party, Junk Sale and a Raffle to aid funds....... The Group has always gone to LONGLEAT RALLY mid summer...... Each of us grow on the backs of those gone before and is a super hobby.... GB3XG has been worked through several times by a Station in Bolton "Winter Hill "Lancashire in Winter........ G3RFL