[time-nuts] GPS antenna installation problem
bill at iaxs.net
Sun Mar 1 20:05:00 UTC 2009
My GPS time system consists of two Z3801A receivers with two HP cone
I built a mast from plastic pipe (6" base to 2" arms) that is about 16
The antennas are 4 feet apart, each 2' from the center of the mast. The
rises from a deck and is fastened 8' up at the roof line. The mast sits
3/4" sheet of high density marine plastic fastened to the deck with
hinges so that the antenna can be folded away from the house and brought
deck railing. The mast was put up in 2003.
The antenna cables are each half of a 100' coil of RG-8U. Each cable is
half in the house and half outdoors. N connectors are soldered to both
no adapters are used. The cables leave the house through a waterproof
fitting and travel about 5' under the deck to the mast. There's a
to allow the mast to be lowered, then the cables rise unsupported
mast pipe and branch out to the antennas, which support the weight of
Oh, and the location is Minneapolis, MN, USA.
The problem is loss of signal during cold weather. Last winter (07-08) I
the signal from one antenna during a cold snap, but it came back a week
later when it warmed up outside. This winter, I lost The North antenna
22 when the low was 15, and it didn't come back. Then the South antenna
away on Dec 24 with a -17 low and didn't come back. I'm still running on
I suspect that it's not a good idea to hang 20 feet of RG-8 from an N
without some kind of strain relief, but I don't know why that would be a
weather effect. Perhaps the center conductor shrinks more than cable and
braid, and pulls the center pin out. There's definitely an open circuit,
at the receiver end of the cable. There's no alarm from the Z3801.
Any thoughts, comments or ideas?
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