[time-nuts] Troubleshooting an HP 58503A

jimlux jimlux at earthlink.net
Sun Oct 14 19:57:56 EDT 2018

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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