At last a day arrived when I had the energy and the weather to get the new antenna up. All it should take was an hour or so to assemble it and replace the co-ax plug ... ?
Aurora was predicted, so I was hoping for a quick job. The antenna is aloft now, but it did not go up there easily.
|PowAbeam 5 element for 50MHz now installed at GM4FVM|
It is hard to represent the difference between the antennas, so I took some photos ...
|The two antennas with car for scale|
|With the old Vine (left) you can see the 4m element remaining as this can be a dual band antenna|
Taking the old antenna off and installing the new one on the mast was simple enough. First snag then was corrosion in the co-ax. I had to take off the PL259 plug used by the Vine and replace it with the "N" type used by the PowAbeam.When I opened the self amalgamating tape which was covering the existing connection the PL259s looked bright and clearly no damp had penetrated the seal. On removing the 259 I noticed that the solder inside seemed to have softened and turned to mush. Time to investigate further.
Cutting back the outer sheath revealed corrosion on the braid.
|Corroded braid in the co-ax (note that the short length near the plug was relatively clean)|
As the plugs seemed clean and there was no damp this time, I think this is another sign of the problem noted last year. Possibly I just happened to cut back to a short clean bit last year. Maybe there was further corrosion then if I had gone far enough back to find it. So this time I cut back in stages and found it stretched quite a way down the braid. I eventually found reliably clean bright braid after removing the last metre or so of cable.
|Clean braid after cutting back a metre of cable|
That unexpected work took time, and to add to my frustration my mobile phone was constantly beeping to warn me of an Aurora. I also got a text from a local amateur to warn me. Infuriatingly I had to reply that my mast was tilted over and it was taking a while to get everything back aloft. I could have left 6m and operated on 4m and 2m, but once this job was started I though I had better finish. After all, the good weather might not hold.
When you want to get finished, I find that it is usually the last thing which lets you down. In this case it was the compression "N" type plug. It looked pristine, but when I took it out of the bag it turned out that there was solder on the brass centre pin. I must have used it before. I cleaned off the solder and tried to fit it. As usual, the two major issues I have with these plugs can to hold me up.
First, I cannot understand how you can effectively solder the centre pin. I know the theory, which is that if the pin is hot enough the solder will sink into the pin by capillary action and coat the cable centre. It is just that it never seems to work that way for me. With Mrs FVM diverted from some essential task to hold the co-ax I finally got it on somehow.
Then the second problem arose. As I so often find, it was impossible to start the lock nut threading into the barrel of the plug. As this compresses the rubber seal you have to do it, but in the process it is necessary to push the barrel one way, the nut the other way, and turn one relative to the other at the same time. As Mrs FVM had returned to whatever it is she does, I had to finish it myself. And it just would not go in. I knew that once I got the threads started it would be fine but ... grrr, it just would not start.
Eventually, of course, I got it going, got the mast vertical and the beam is now officially "up". Whether 2dB makes any difference remains to be seen. So does the question of whether it is indeed 2dB or a lot less. We shall see.
But progress has been made, I suppose. It took over four hours to do it.
The Aurora seemed to be over by the time I got back into the shack. Via Aurora I heard various beacons, and GM4VVX on 2m and GM4UYE on 6m. No contact resulted.
More Aurora is promised for later today. Now that I am ready, what chance is there of that happening?