On 10/14/18 4:42 PM, Tom Miller wrote:
----- Original Message ----- From: "jimlux" <jim...@earthlink.net>
To: <time-nuts@lists.febo.com>
Sent: Sunday, October 14, 2018 7:07 PM
Subject: Re: [time-nuts] Troubleshooting an HP 58503A
On 10/14/18 3:03 PM, Matthew D'Asaro wrote:
All -
Thanks again for all the suggestions and advice I have gotten on
this project. It ran all night without loosing lock, so I am calling
it fixed. There is just one more order of business before I can use
it, and that is some way of "mounting" the GPS antenna on the roof in
a non-destructive manner, both to avoid damaging the (flat membrane)
roof and so that I can move it if necessary. See the attached photo
of what I have come up with. All the parts (minus the cable and
antenna) came from Home Depot.
The concrete block is a generic 1 sqft paver stone which cost all of
$1.18. This is to provide a heavy base and avoid tipping. Attached to
that is an upside-down PVC toilet flange from the plumbing section.
It is attached with 6x stainless steel machine screws and wing-nuts
that pass all the way through the paver and are counter-sunk on the
bottom so that the heads won't damage the roof. Nylon spacers
separate the toilet flange and paver block by about 1/4 inch so that
water can drain if needed and to provide a space for the coax feed
line to come out. Pressed into the top of the paver is a 3" to 2"
reducing adapter and pressed into that is a 2" to 1-1/4" reducing
adapter. The mast itself is just a 2-foot section of 1-1/4" PVC pipe.
The 58532A antenna is apparently designed to mount over a 1-1/4" mast
since its inner diameter is 43mm and the outside of a 1-1/4" pipe is
42mm.
Standard "non-penetrating" roof mounts use this technique - they have
a frame which you ballast, by bricks, pavers, or sacks of gravel.
After that it's more a matter of figuring out how to do the mechanical
structure - sandbags and plumbing fittings are a fine way to cobble
something to together.
Don't forget to place a rubber pad under the paver to protect the roof
material.
A scrap of carpet, plastic runner, or plywood works well. The carpet
gets pretty gross after a few years, depending on your climate, but it
keeps sharp edges from poking where they shouldn't.
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