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gary stout
| | Posted on Thursday, October 04, 2001 - 5:53 pm: | 
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just got in the new skylabt233. it is set for 10 meter band. how do i set for 11 meter or inbetwen the two? |
Marconi
| | Posted on Friday, October 05, 2001 - 1:00 am: |
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Gary, is this antenna like an old Starduster? I have heard some bad reports about some of these knockoffs. Hope you have one of the good ones. I have not seen the bad ones, but as I get the picture, it may have a stud built into the hub and the stinger fits onto the stud. It is told to me that this setup does not fit well and the stinger is loose and flops around. The good ones have the stud built into the stinger and this stud and the base part of the stinger then screws into the hub, making for a tight fit.
If the stingers are drilled and uses a sheetmetal screw to fix them together, then do as Tech181 suggest, make it a little longer. Maybe 1/4" to 1/2" may be enough. You will just have to experiment here. You may find that this antenna is so broadbanded that it won't make any difference. I know they say it is a 10 meter antenna and you want to use it in 11 meters. The 10 meter claim may only have to do with the story about the banning of all metal antennas in America.
If you feel the need to adjust it, when you get it resonant at the frequency you want, mark it. Then re-drill the smaller piece thru the larger tub hole already there. This cuts down on the extra holes in the stinger. Then clean out all the burrs or these burrs may cause the elements to stick or bind when trying to remove or adjust it later. Be careful not to over tighten. I use lock-tite and set the screw firmly but modestly so as not to deform the aluminum inside the tubes which could also cause binding on removal later.
I also use a little Pentrox or at least a good chassis grease (lithium type) to dress the connecting tubes and cut down on corrosion.
BTW, if this is a knockoff of the old SD'r then you should know that they have a weak spot. This spot is at the top of the stud where the stud goes into the stinger, the part that screws into the hub. Water can collect in this area and has no way to get out. This can cause deteriation of both the stud and the aluminum tubing and cause early failure. Get a very small diameter drill bit and carefully drill a small hole just at the top of the stud inside. You will of course have to guess where this point is, but if you look carefully at the crimp marks you can tell. Also, if your PL-259 does not seem to want to fit into the SO-239 inside the hub, then file and sand down the tip of your PL-259 a bit for fit. It is better than trying to drill out the SO-239 some. If you get it to loose a little solder on the sanded tip will fill it back out.
Be sure and plas-tie the coax as it comes out of the supporting 9' or 10' mast, the mast that sets in the hub. This takes the weight off the PL-259 and the coax fitting.
Just some tips.
Marconi |
Marconi
| | Posted on Friday, October 05, 2001 - 7:35 pm: |
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Tech181, I noticed that you're selling this Skylabt233 at CE. I note some problems with some of these knockoffs in my post to Gary. Can you identify what I am talking about regarding the stinger/stud assembly in the hub and the SO239 misfit?
Marconi |
Tech181
| | Posted on Saturday, October 06, 2001 - 12:23 am: |
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Marconi,
As far as the stud problem you mentioned. Are you speaking of the vertical radial collecting water? If so the Skylab comes with a plastic cap for the top most radial to keep water out. The bottom most portion of the radial is permanently mounted to the hub (by "hub" I mean the apparatus at the bottom where all the parts meet and the SO-239 is).
I do agree the SO-239 connector on mine is very tight. It is almost impossible to get the PL-259 the entire way in. Filing down the PL-259, or as a last resort, drilling out the inside diameter of the SO-239 can remedy this problem.
And yes, since the coax hangs freely from the SO-239 connector inside the mounting mast, you will need someway to support the weight of the coax.
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Marconi
| | Posted on Saturday, October 06, 2001 - 3:52 am: |
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Yes, the bottom section of the vertical radiator is prone to getting water inside. For years I would see these broken off near the hub, often leaving the stud sticking out. I wondered why. After looking closely at several radiators that broke and fell off, I noted that each was powdery, corroded, and pitted inside the tubing where it broke. So I figured water had been standing in there.
Of course you should use the caps that come with the kit and maybe even seal the middle joints somehow. However, these little cheap plastic caps and the sealer can waste away also.
Even if the top seal remains water tight, water can enter where the two elements go together. Even if sealed tight, over time, I would bet condensation can also produce water standing inside the tube. If so, there needs to be a way to get this water out and that is the reason for my drain hole recommendation. I don't like drilling holes in aluminum either, it causes weak spots that can break. So keep the drain hole small.
My M400 knockoff came with the hub assembly as a individual unit. Sounds like the Skylab you have comes with the hub and bottom portion of the radiator tubing element permently attached. This suggest to me that your SD'r is probably not the one described as having a loose and wobbley radiator problem.
The M400 style makes an excellent antenna but they are a little problem handling during installation due to the down radials and the coax inside the support mast, so just be careful. |
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