[time-nuts] Can a Symmetricom 58532A antenna and ham radio transmitters coexist?

[Tim Shoppa]

I have GPS antennas 500 feet directly under my HF antenna running full
legal limit. And GPS OCXO's in the shack just feet away from the legal
limit amplifier. Never ever a problem.

Now my 35-year-old garage door opener... it went bonkers when I got my big
boy amp and used it in a big RTTY contest! My wife came to me shortly after
the contest started and wondered if maybe I had something to do with the
fact the door was going up and down continuously for the past hour. After
the motor and starter cap blew up, I got a brand new garage door opener,
and it does a lot better when I'm transmitting :-).

Tim N3QE

On Thu, Apr 14, 2016 at 5:01 AM, Pete Stephenson <pete at heypete.com> wrote:

> Hi all,
>
> I recently acquired a pair of Symmetricom 58532A antennas and so far
> they work great with my setup (antenna --> Symmetricom 58535A splitter
> --> [1] Thunderbolt and [2] other receivers that I swap out
> occasionally).
>
> I'm also an amateur radio operator and am looking to mount the 58532A
> on a roof-mounted mast to get better coverage (right now it's outside
> a window). Would the presence of nearby (either on the mast or within
> 20m of the mast) HF (3.5-30MHz) , VHF (~145MHz), and UHF (~430MHz)
> transmitters cause any issues? My transmit power is typically around
> 5-20W on HF with peaks up to 100W and 1-5W on VHF/UHF. The HF antenna
> is a simple wire dipole, not a high-gain directional antenna.
>
> Naturally, I'd like to avoid damaging my GPS antenna or any of the
> downstream devices.
>
> Since the 58532A is currently mounted relatively close to the
> splitter, I'm using LMR100A coax (it's lossy, but the short lengths
> mean it's not an issue; the window mount makes the thinness of the
> cable important) but for the longer run from the mast I'd used LMR240
> or LMR400 as needed. I use the same type of cable for the HF radio.
> Those cables are well-shielded (braid-on-foil) with >90dB shielding
> attenuation, so I don't think signal leakage from or ingress into the
> cables will be a big deal.
>
> The datasheet for the 58532A specifies the out-of-band signal
> attenuation is around 60dB at +/- 50MHz.
>
> Many thanks in advance for the help.
>
> Cheers!
> -Pete
>
> --
> Pete Stephenson
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