The HX Files 014

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.

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.



The HX Files 13

Hello and welcome to xtract 13 of the HX files.

In this issue I would like to talk about the new mobile unit I am making .
After operating /m for many a time I decided to make a new mobile unit, It was taking the fun out of setting up /p when I had to connect the tx unit to the amp, the monitor, and their dc leads, and having to disconnect the aerial and connect it to the rx .As you /per’s know the cables seem to have a life of their own and seem to knot  together, and by the end of the experimenting, and that you would have a ball of wires at the end of the day. 
 This unit would be an all in one; it would have a transmitter, receiver, and a small monitor installed, also I would be installing a 25 watt amp as well.
 This unit will save me a good bit of time as when I get to the site all I have to do is connect the aerial, camera and the dc, and I am good to go. And when the fun is  over I would be on the way home in a few minutes, and not spending ages taking everything down and packing it away while the base station I just worked only has to switch off and head for the tea.( the lucky #*!>*<^<).
 I was looking for a suitable project box in a Maplin store, and the ones they had were a bit too pricey for the size I wanted (and my pocket). So I had a look in my own stores, aka the shed, and after a while of digging in the shed I found the one you see in this issue. The first job was to make chassis for the parts, (this was made from some of the computer panel’s I had cut up that I mentioned in a previous issue) and to layout the parts for the best use of the project box and that the layout was as serviceable as it could be so I could improve on the design by adding other parts in the future. (Like a pre amp) laying out the parts took a few tries as I had to make sure the parts would be easy to get to adjust if needed and I would also be able to add or remove a faulty unit on it’s own and not have to a complete teardown.
 The first job I did on the project box was to fit the monitor, speaker, led’s and switches to the front, (Photo 1) a few pages were used in drawing the mock-up for this.

Photo 1

 The next job was to checkout how the heat sinks would perform under test. I had a small slab of aluminium plate that could be mounted on the back panel (Photo 2 below) or one that was much bigger and this one had fins as well.








Photo 2
First test

The amp was mounted on to the heat sink, after some compound was used as this was only a test I held the amp onto the plate by cable ties. After only 5 minutes the temperature rose to 44 degress, way to hot, and when second heat sink was used (photo 3) this was the best, as after 35 minutes this was only 33 degrees


Photo 3

. 


Cool running



 (Photo 4 on the right) These tests were done without any cooling fans this heat sink was drilled and cut to size and was used as the back panel of the unit. A small piece of metal was used to make a panel to mount onto the back of the heat sink; this would be used to accommodate the aerial socket (N type) and audio/video sockets (phono) and the 12v dc line (a gland would be used for the cable to go through safely).

Photo 5

 (Photo 5 on the left).The first couple of layouts of the parts (Photos 6 ) were setup with some wires and coax attached, in photo 7 you can see more of the cables and leads, and I decided to put as many of the wires under the chassis as this could make the unit look tidy .

Photo 8 shows some of the parts in their final location, but as always this could be changed as the project developed as this is photo type 001 and who knows what would happen when the unit was up and  running.




Photo 6

 

Photo 7

Photo 8

Photo 9 on the left shows the finished back panel but without the fan guards and the dc leads. After a few hours of transmitting both into a dummy load and on air, I did some modifications of the parts, one been the relay, it was running hot so it was mounted on some heat sink, (see photo 10 before I found the right bolts) the other been the coax from the N type to the relay. It was decided to use some hard-line coax as the transmitter was losing power, the original seemed to be intermittingly loosing power and if it was not for the watt meter I would not have known, and who knows I could have let all the smoke out in a few weeks of usage.

Photo 10

 It was only when the connections were been rechecked and tightened that it was noticed when the coax was held that the RF power dropped. When I decide to install the pre-amp and a different relay I will be making a new chassis out of metal again as the prototype one was getting like a sieve, and I will paint it to match the outside of the unit, or it could be made from a piece of Perspex .
As a point of interest the tools I used in constructing this project were, a cordless drill, various drill bits, including a stepped one that is shaped like a cone, a hole punch, various files, and a tap and die set, most of these tools are available in your local  hardware store.

 And finally
 Thanks to Michael EI-5-GG for his help in some of the drilling and taping on the project and of course his years of experience in the construction field. 
73's and may all your signals be P5.
  

The HX Files 12

The HX files.

Hello and welcome to extract 012 of the HX files.

D’oh.

Since the last HX files I was operating /P, I went to a site that was just over 15 km’s line of sight from the QTH of Mark (EI-9-FX) 

Photo 1

The location had a good take off and but it was down a lane that was not used often and was more or less a dirt track. I was brave because of the location, high and overlooking the area around Mark’s location. I said to Mark that I would not be bringing the 1.2 GHz equipment, and I would only bring the 10 GHz gear.(D’oh) The aerial I used was a horn aerial, photo 1, (the business  end of the horn antenna is 20cms x 20cms and is a total length of 5ocms) I started to transmit to Mark, and I slowly started to at first, pan across were I though Mark was, and then tilt the aerial and kept doing a couple of passes but all to no avail, Mark was not getting a thing from me. I guess I should have brought the 1.2GHz equipment with me to help me find Mark’s location , so, if you know of a village in need of an idiot, you can E-mail me and let me know.

 After awhile I decided to give up the trials for the night, and even on the way home from that failed attempt, I was talking to Mark on 2m, and I could not understand how we had such a bad outcome. The following day I decided to setup my 10GHz gear at home to see if I had a dodgy transmitter, or a faulty connector, or lead. so I setup in the sitting room of my home, and hey presto the picture and sound were there on my screen, so I was (@~¬*^#*) glad that I had a transmitter that worked, but because I was operating so close to the receiver I could have easily pickup my transmission at any power level, so I decided to use the Power meter (photo 2 ) to check that I still had my 500mw’s of Tx power,( or any mw watts at all, and I was relieved to see I had still got my full power .



Photo 2



Take 2.

One week later, and here I was back at the scene of the failed attempt, to try again, this time I decided to bring the 1.2GHz equipment .The first thing I did was to get set up that equipment, and then Mark and I could try and get each other on 1.2 GHz, and when we had that done we had an idea were our 10Ghz aerials were to point. Even though we were only over 15km from each other (again we will not be setting any records until we put a nought or two on the end of that figure). Mark was using a 10 watt transmitter and a 35el tonna aerial, and I was using 15watts and a 21el tonna at first, and then a Flash Gordon aerial later, see photo 3. With either of the aerials I used, both Mark and I could do no wrong; we could get each other with ease. In my case I was pointing the smaller aerial ( the Flash Gordon one) at the Moon ,Australia and even pointing it inside the car Mark was still getting me .We were just about to start using the 10Ghz equipment ,when we were joined on 145.400,by Tom (EI-9-CJ)who had heard us talking on 2m, and then Mark and I done a few test’s on 1.2Ghz with Tom with both of the aerials first on 15 watts and then with 750mw ,and just like Mark, Tom could get me every bit as good .(Tom lives in Rockmarshall, Dundalk and was around 27Km’s from me).



Photo 3
Flash Gordon Aerial



 10 GHz.

Tom stayed on the radio monitoring our 2m feedback, and then I started to transmit on 10 GHz to Mark. Using the horn aerial again, and balancing the aerial using the top of the door to take most of the weight and to hold it steady I started to transmit a signal, and shock and horror after a few seconds Mark got my signal, success at last.

Disc element Aerial

 (So what was wrong with last week’s attempt, did someone knock a shed or open a window?

I was in the exact same spot from the week before, as in the lane that I was on, it was the only spot that I could turn my car and not have to reverse about 2km to get back to an asphalt road). While I was still transmitting, Mark decided to retransmit my signal to Tom on 1.2GHz, as I was transmitting on 10GHz to Mark, Tom would be talking back on 2m and letting me know if my Armstrong rotator was drifting off Mark, because Mark was in another room away from his shack, as he had the 10 GHz gear setup again in the east wing, and he was using the audio he could hear from Tom telling me on the 2m rig to stop moving ,and then Mark would peak my signal and Tom would have a P5 (excellent)picture.

 I don’t know what if anything was in the path between us the previous week but at lest we were successful this time.

What’s next?

The next thing Mark and I have to do is to use our  10GHz transmitters with our dishes and transmitters attached to our tripods, photo 4, and try from a couple of hill tops. I will be bringing the 1.2GHz equipment with me for sure this time.

 A lesson learned indeed, anyway that’s it for another issue .Thanks yet again to Thos (EI-2-JD) for the photo studio time.

As usual may your signals be P5. 73’s, Pat.