Hello and welcome to epessiode 14 of the HXfiles.
I hope you all had a quite and uneventful Christmas, and I would like to wish you all a very happy and a peaceful new year, and that all you buy at the forthcoming rallies works.You can never have enough.
As usual I have made the same New Year resolutions, not to buy anything I have 2 or 3 of, but with the first rally of 2011, (Coolmines) only days away , (Rally date 20th-2nd 2011).
I found some space for a project box or two just in case I see any must haves at the rally, as over Christmas I did yet another stock take and found stuff I did not know I even had, so I won’t have to buy too much at the rallies this year as all my stock bins are full. You would think that with the dozens of different sizes of patch leads that you have, you would have years of stock to keep yourself supplied for all your projects, but after the project in the last issue, and its latest modification I used quite a few leads of around the same size and with the coaxial relay, and the now installed pre amp, I found out that a lot of leads the same size is not a bad thing after all.
7 GHz
This project in this issue is of a 7 GHz transceiver. All the parts were collected over a period of a couple of years. I bought the7 GHz horn aerials about 3 years ago with the intension of removing their flanges and grafting on a smaller 10GHz horn aerial to convert them to 10 GHz and then I would have a good aerial setup for 10 GHz. (as I Hadn’t got any Tx or Rx equipment for 7 GHz yet) But at the next rally I was at, I saw and bought a couple of 10 GHz aerials, and the 7GHz ones went into stock. The aerials were aloud to acquire some protective coating, (dust).A year later I came across a couple of transitions that would convert the flange at the end of the aerial to a N type socket, and they would give me some leeway with the aerials and the connections on the Tx/Rx units as I did not know what connections would be used, but at least I had some more parts, but as yet, no Tx or Rx units. After some more of the protective coatings had been laid down on the aerials and transitions (about 8 months worth) I came across some Tx/Rx units several rallies later, and I also purchased a 50mw amp.
The Tx and Rx boards came with a small panel aerial each (photo 1 on the right). I did a couple of test with the small panel aerial that came with them, and the horn aerials.
But for this test I would use the larger panel aerial.
Photo 2 below.
Photo 2 below.
shows the front and back of them.(Yes I have two of them) The tests I did involved leaving the RX board and the horn aerial on a 20ft (6m) pole, then using some dc and audio video cables connected to the video recorder. I had made sure everything was working before I left my home and that I was receiving a signal. So, with the equipment pointing to a nearby hill, off I went. This would not be guest work as I had done a few experiments like this before; the location I was using was a piece of land beside the QTH of the late Dermot (EI-2-AK). I would have loved to have been able to be doing the receiving and watching the signal as I drove along the route to the hill, but that would have been highly dangerous, and just a tad against our licencing conditions about operating an unattended station. So of I went with the Tx signal blasting out the mega watts
(photo 3 below, shows the Tx/Rx without cables)) and with the Rx connected to the video recorder at home, recording my signal as I drove along the route to the top of the hill.
The TX now has a power out put of 50mw, and the unit including the panel aerial was connected to the roof rack via cable ties (what would we and the police do without them).There is no picture of this as it was not a pretty sight, I would make a proper bracket later, I used a camcorder mounted on the dashboard at first.
Later on, I switched to the camera mounted on the towing eye of the car see photo 4 left. I would have a good idea looking back at the recording to see what the signals were like, how wide or narrow, and also how they would differ from the horizontal and vertical planes.
Alone all alone
The RX and TX units have only 4 frequencies to play with, but this should not be too much of a problem as the band is a little quiet at the moment, both of signals and operators.so I had to send a signal to myself ,(that’s not the first time I have talked to myself and maybe not the last) I decided to place the parts in the one box and make it into a transceiver and terminated it with an N type socket; the end of the horn aerial is finished in waveguide so I connected an N type to wave guide transition. This was not as easy as it sounds because the holes in the mounting flange on the aerial did not match the holes in the flange on the transition. After a talk with Michael (EI-5-GG) it was decided to make a plastic adaptor to hold the aerial and transition together and inline, while they were been marked for drilling, (the adaptor would be removed before final attachment) This was a tedious job cutting and filling to get a tight fit so the flanges both line up and be drilled correctly. With that job done (a couple of hours later) the next job was to decide how to attach the transceiver to the aerial and then to a pole.
Photo number 5 on the left shows the finished plate with all the gear attached. A couple of brackets were made to hold the transceiver to the plate rather than to bolt it direct to it as I only had the one TX unit at the moment, so I could go portable, as well as operate from the home. Another tricky job was the coaxial fly leads that were fitted to the boards; they had the SMA connectors the wrong way around (for me that is).I had a choice to change the lead or the relay, using the relay I have would mean using adapters, I had to decided what to do, to change the fly lead and to try and put a sma chassis socket on the board, or failing that a sma plug on a fly lead, or go with plan “A” and use the adaptors .So plan “A” it was. The adaptors would do as a short term solution as I would be only doing a few tests, and if I did not get a relay sooner rather than later I will have to get the soldering iron out and replace the fly leads. Installing the parts wasn’t too bad as the Tx/Rx boards were the same size and I decided to place one above the other using some small plastic spacers. It’s always a problem what to with all the connecting wires, whether to hide them or to leave them in view but tightly bound together so they look neat and tidy, It is nice to see but If you have to modify or replace parts you can find yourself making a new wiring loom, if you have put a chassis board in the box you can place the loose wires underneath and leave yourself with some room for manoeuvre if the worse happens.
That’s all folks.
That’s it for another issue.
Once again a happy New Year and I hope all your signals will be P5.
73’s de Pat.
