[time-nuts] GPS Antennas

[David G. McGaw]

Also, as I have found, some plastics don't just delay but actually 
absorb the signal.

David N1HAC

On 9/6/19 2:28 PM, Bob kb8tq wrote:
> Hi
>
> The gotcha with putting anything on top of a GPS antenna is that it impacts the phase
> shift from the sat’s. How important that is gets quickly into just how picky you happen to be.
>
> Bob
>
>> On Sep 6, 2019, at 11:07 AM, Nick Sayer via time-nuts <time-nuts at lists.febo.com> wrote:
>>
>> I’m late to the party, but my go-to antenna is the Gilsson marine antenna. If it has a downside, it’s that it has a flat top instead of a cone. I’ve got one mounted outside at our vacation home near Lake Tahoe, so we’ll see whether snow loading becomes a problem shortly. The fix would presumably just be a 3D printed plastic gnome’s cap, though even that might not be useful if we get snow like we did last year.
>>
>> It has a standard 14 tpi 1” standard thread, though I’ve managed to make do on more than one occasion with 3/4” NPT.
>>
>> Under normal circumstances, I routinely get 8 or more satellites with the top SNRs in the 50s.
>>
>> I designed a 3D printed mount for mounting it on a flat surface (which I needed to do here): https://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.thingiverse.com%2Fthing%3A3664978&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Cf3faa3a2e9ed46ead3fb08d732fc9785%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637033932771963548&sdata=IHu%2Fco9fp3KRNuoi0NNUBqR8dyWAw6rKl8Bpr8m0Gl8%3D&reserved=0 <https://nam05.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.thingiverse.com%2Fthing%3A3664978&data=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Cf3faa3a2e9ed46ead3fb08d732fc9785%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637033932771963548&sdata=IHu%2Fco9fp3KRNuoi0NNUBqR8dyWAw6rKl8Bpr8m0Gl8%3D&reserved=0>.
>>
>>
>>
>>> On Aug 30, 2019, at 11:35 AM, Denny Page via time-nuts <time-nuts at lists.febo.com> wrote:
>>>
>>> Could be. They sell a aluminum mounting rod for use with a magnetic base which mates with the unit perfectly, so I sorta assumed it was intentional. Tapering helps prevents over tightening / over extension which could damage the casing.
>>>
>>> Denny
>>>
>>>
>>>> On Aug 30, 2019, at 10:49, Bryan _ <bpl521 at outlook.com> wrote:
>>>>
>>>> Or a mfg. defect and thus why on the surplus market.
>>>>
>>>> -=Bryan=-
>>>>
>>>> ________________________________
>>>> From: time-nuts <time-nuts-bounces at lists.febo.com> on behalf of Denny Page via time-nuts <time-nuts at lists.febo.com>
>>>> Sent: August 29, 2019 7:39 PM
>>>> To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com>
>>>> Cc: Denny Page <dennypage at me.com>
>>>> Subject: Re: [time-nuts] GPS Antennas
>>>>
>>>> I think several people have run into that issue, including myself. It seems designed for a slightly tapered rod. Easy to fix with the right tool.
>>>>
>>>> Denny
>>>>
>>>>> On Aug 29, 2019, at 16:41, Ben Hall <kd5byb at gmail.com> wrote:
>>>>>
>>>>> Only issue with mine was that the thread wasn't fully cut, so I modified an old taper tap to be a bottoming tap with the bench grinder and finished tapping the hole to the bottom.
>>>
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