[time-nuts] Troubleshooting an HP 58503A

Matthew D'Asaro medasaro at mit.edu
Sun Oct 14 20:05:37 EDT 2018

Thanks for the (important) suggestion. I will make another trip to the hardware store for some rubber sheeting or similar.


> On Oct 14, 2018, at 4:57 PM, jimlux <jimlux at earthlink.net> wrote:
>> On 10/14/18 4:42 PM, Tom Miller wrote:
>> ----- Original Message ----- From: "jimlux" <jimlux at earthlink.net>
>> To: <time-nuts at 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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