Pete
The reality is there are almost two many variables to predict the outcome
1) Proximity of the ham antennas vs the GPS antennas (obviously farther
away is better)
2) Polarization of the ham antennas may or may not play a role
3) Direction the ham antennas is pointing. Pointing away from the GPS
antenna is typically better.
4) Power levels , which in your case are modest
5) How "clean" the ham transmitters are (harmonics, spurs etc)
6) a direct harmonic at a particular VHF/UHF freq which appears in the
pass band of the GPS receiver I haven't done the math but you might
find you have a problem at 145.60 but not at 146.90 as an example
My guess is your unlikely to have much problem with at least 10' of
separation between the ham antennas and the GPS. In my prior location I
was running a KW on HF and 20-50 watts on VHF/ UHF and 10W on 1296. My
GPS antenna was on the same tower about 20' below the ham stuff . I had
two GPS antennas the 58532A and a Motorola ( cant remember the number)
and I never had a problem YMMV
Dave
On 4/14/2016 5:01 AM, Pete Stephenson 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
--
Dave
[email protected]
www.ArtekManuals.com
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