A Beverage Story
As usual I was chatting to Ken on the radio link between our two houses. He was telling me how he missed having the beverage in the open space next to the permanent beverage in the woods. Rather excitedly he was telling me that the farmer wasn't going to be using the field until the end of February, and that he could put up a straight and in the clear beverage around 500 meters or so long.
So the next evening about half an hour or so before dark we set out with wooden supports for the wire and 4 drums of cable and about 100 meters or so of loose cable. The reason we left it so late was so we weren't seen by young kids who would only be too happy to have a pull or swing on it etc. One thing I must say is don't ever walk down wind of Ken just after he has had his dinner, and walking a narrow path way beside a river didn't give me an escape route..!!
Armed with the compass we started to survey the field. We decided to put the aerial a little more north west than the beverage in the woods, and by doing this, the end of the beverage wouldn't finish inside the same woods as the other one. By this time it actually was getting quite hard to see so we planted the supports every 5 meters or so and left it until the next day to have a look. We also rolled out 400 meters of wire so we could get stuck into it the following evening as well.
We set out a little earlier, and this time I was in front of him this time smelling the country air, and not what Ken just had for his dinner. We stood at the feed point and boy were we wrong about the direction. Serves us right for not doing that part in the day light. So up came the supports again and this time I was walking with the compass. Ken was planting sticks behind me as we walked. The only hard part of this is when we came to a small clump of trees and shrubs. About 20 feet of the beverage had to go through this, and it was actually quite hard to see if we were getting our line correct or not. So both of us with squint eyes and a lot of shouting and waving right or left we managed it.
Again it was starting to get dark so we attached the already rolled out 400 meters roughly to the supports. We then put two copper ground rods down, one at the feed point and one at the end for terminating the beverage. The next day we set out and attached the wire more securely to the supports at around 7 - 10 feet high (more on this later) and added more supports as necessary. We also had to solder the remaining 100 or so meters to the 400 meters we already had run out, and add a 600 or so ohm terminating resistor to the end of the beverage. Next was the feed point and I already had a balun made up, a standard 33/11 turn overlapping balun. (33 turns to the beverage and ground. 11 turns to the coax.)
The connections were then plastered with grease to keep the water out. We set out to get the coax out of the way of dog walkers, deer etc, by putting a couple of the poles up to keep the cable out the way of a rough path which is often walked.
There was only one more job to be done before we could have a listen live, and that was to solder the coax coming over the river to the coax going into Ken's shack and I must admit this was the thickest coax I have ever seen. It must be the thickness of my arm. So after this job was done, Ken made the coffee before the initial test. He decided to use the NRD 515 for this first trial and at the very start I predicted that with the balun, 981 Star would be down on the new beverage, as hopefully it would be more directional. (I forgot to say that after day 1 Ken told me that he didn't have a balun installed on his beverage at the wood end, but has one in the shack end, which did surprise me. But boy does it work well without it. Would it be better with one at the feed point though??? )
First Ken tuned to Radio North on 846 on the wood beverage. It was S9 +20 db. On the new beverage it was pegging the meter at S9 +40 db. Now my reputation was on the line he tuned to 981 using the wood beverage and Star was a little over S9. He then switched to the new beverage and I held my breath... YES it was s7 so it "seemed" that the new beverage was more directional than the wood beverage. He checked various other stations eg faroes on 531 etc and they were all some s points up on the new beverage. But the REAL test would come at night when the USA and Canada would come in.
At around 22.00 local we were talking via the radio link, and both of us noticed that Canada was starting to come in on 1400 khz. The time had come for the dx test. Ken reported that on 590 on his wood beverage there was next to no splatter but on the new beverage there was quite a bit of european qrm and splatter. So some bad news on 590. Ken invited me over to his place to see for myself, and while I was there I did see that there was much more qrm from Europe on the new beverage compared to the old wood beverage which surprised us both. The wood beverage has a much longer feed line, many joins where the cable has been damaged throughout the years, and it's not what you call particularly straight. It also runs up and down over hills through dense woodlands etc but here it was, rejecting Europe much better than a nice new beverage in the clear, in a straight line, less of a length of feeder etc.
There was some good news though. At the hf end of MW, from roughly 1200 khz, the new beverage beats the wood beverage quite easily. Some stations that were very weak and noisy on the wood beverage were in the clear, and quite strong on the new antenna. So something was just not quite right. Could it be the balun was not ok? Well in my opinion it wouldn't be bad in one part of the band, and good in the other. It would either be bad all over, or good. The antenna is receiving OK. The problem is the Euro QRM. Would a balun have an effect on the back null ??? Was the terminating resistors ok? I did do some home work and read that if the termination value was not ok, it would send the signals back up to the feed point and this causing a reduced back null which sounded like our problem.
The next evening we took down a volume control and pre tuned kens radio to 639 a czech station, and we were able to remotely listen to this at the end of the beverage. I also took with me a switching unit that Ken had made up for a test with one of my loops. We could select a 470 or a 1000 or a 1500 ohm resistor. I tried this first. With the 470 ohm resistor, yes there was a dip and we could hear another station in the background. Then we tried the 1000/ 1500 ohm resistor but there wasn't much difference. So with the 470 ohm almost working, was Kens original 600 ohm resistor not suited?
So on went the variable resistor and ken tuned it for a null which he not only found, but managed to make the Czech station disappear altogether, and leave a Spanish station in its place. So now we had found the correct termination value Again everything was greased back up and the test was done again in the shack. The Czech station was being received on the wood beverage, but when we switched to the new beverage there was the Spanish station. We had a definite null. Again at 22.00 local the Canadians started rolling in again, but again Ken reported bad euro splatter on the new beverage. This was certainly strange. We had achieved a definite null on the new antenna, but yet we were still getting bad euro qrm. Could the problem be that the beverage is too high? We put it 7 - 10 feet high to keep out the way of walkers and wild life. Could this height be bringing in more European QRM and would it help if we put it to say 3, 4 or 5 feet high? Is the balun doing ok? I suggested taking the balun off and feeding it direct to see what that does. We will do various tests over the next few days, but any suggestions can be e-mailed to Ken, or leave a reply on the message board, or why not chat with us live on skype. Just search for me "tvdxrools", or Ken "scottish_dxer".
Many thanks
David H