W6YX - June 18, 2005 Work Party

Station Engineer John Fore, W6LD/P40L, reports another successful work part on Saturday June 18, 2005 at Site 530:

Yesterday, we were able to get the 2 and 6 meter yagis and the 1.2 GHz yagis mounted together with a multiband discone at the top of the mast (after introducing a "mast extension).

This is a temporary set-up for FD and the balance of the summer. The plan for later this summer is to use brackets I purchased commercially to mount a rotator and 14' mast on the telephone pole to the North of the shack and to move the 6 meter yagi there. At that time, we will also put the 440Mhz yagi on the new tower.

Over the summer we should plan on a number of next steps to finish off this project. These are:

  1. Construct and mount feedline thru-plate in wall at base of tower.

    Lars and I worked out the location and design of the thruplate. It will be an plate mounted on the inside wall of the shack about a foot above ground level to the left of the tower base (when viewed from inside the shack). The hole in the shack wall will be 7" x 12". It will be centered vertically on the temporary 3" hole that Mark Lawrence put in the building yesterday. Horizontally, the right half of the hole should be centered on the temporary hoe. The plate will be 9" x 14" to allow 1" of overlap. In addition, there will be an aluminum box welded to the plate that will seal the wall of the building and extend approximately 1" beyond the exterior wall (at it's thickest points). The dimensions of the plates that will be used to construct the "box" are: 2 plates - 4 1/4" x 12" and 2 plate - 4 1/4" x 7". The thru plate will have ten holes drilled in it, 9 of which will have N-type bulk head connectors installed and the last hole will be used to pass through the rotator feedline.

    Materials: we have the aluminum stock at the shack. I have put two sheet aside near the base of the new tower. The thicker material is for the thru-plate, and the thinner material is for the construction of the box. The bulkhead connectors have been ordered by Harry M. and should arrive on the 22nd.

    Construction: Lars has volunteered to drill and weld the components. We need a solution to cutting the aluminium though. Randy or Mark, do one of you have access to machines that can be used for this? Otherwise, I will have to take our aluminum stock to Allen Steel and overpay to have it cut up.

    Installation: Should be fairly easy. I hope that Randy or Mark can assist with that. Essentially, need tools to cut the hole. Possibly need file it down a bit. Then install thru-plate/box in hole with some kind of sealant and probably four screws into the inside wall of the shack.

  2. Install 6 meter antenna on telephone pole and install of 440MHz yagi on new tower:

    We have all of the major components for this job - brackets, thrust bearing, mast, rotator.

    Need to test and locate the best rotator. May make sense to purchased a used small Yaesu rotator for this application since so much easier to use than old Hygain rotators.

    Also, need hardware and appropriate drill and drillbits for installation of brackets. May want to modify brackets for a couple of large bolts that would go all the way through the telephone pole, instead of a larger number of smaller bolts per their existing design.

    Implementation: biggest challenge is getting to the 21' level on the telephone pole. Randy, do you think we could safely use a combination of the scaffolding on wheels assembled to work on the 21' dish, plus a ladder, all lashed to the telephone pole for stability? Alternately, we could put in place a full scaffolding set-up, although that'd be a lot of effort for a pretty small project.

  3. Raising VHF/UHF mast in new tower 5-6' by raising rotator base.

    This will require making modifications to the rotator base (cutting slots) so it can be fitted 4-5' down from the top. This will give us 50% more mast which I believe everyone agrees would be a good thing. We can do this later this summer after the 6 meter yagi has been moved.

  4. Permanent feedlines:

    Once things settle down, we will want to put new Heliax on all the yagis to optimize performance. This will also entail running Heliax out to the telephone pole to the North of the shack, which will necessitate some repairs to the old conduit system running out to that pole, something we desperately need to do anyway. BTW, that feedline will end up entering the shack through the box where all the HF feedlines enter, unless we make further modifications/improvements to open that conduit at the base of the VHF/UHF tower as well.

Item 1 above is the highest priority. I'm thinking late July/August timeframe for the 6 meter yagi, unless someone else wants to get it started earlier.

Thanks,

John, W6LD


Click here to return to the W6YX Homepage.


Stanford Amateur Radio Club - W6YX / w6yx-info@w6yx.stanford.edu
Contact the Webmaster at webmaster@w6yx.stanford.edu