[time-nuts] GPS Timing Antenna Failure - Long
lmcdavid at lmceng.com
Sun May 13 16:35:50 EDT 2018
I can't be completely certain the residual and ugly flux residue in my
Symmetricom GPS antenna was the cause of the antenna failure. I can say
that, after cleaning off the flux residue, the antenna worked again.
I did fail to explain that after verifying the GPS antenna splitter was
not the cause of signal failure, I verified the Symmetricom antenna was
getting 5 vdc power and also that the antenna was drawing about 20 mA
current from the 5 vdc source. That 20 mA is about right for this
Spectracom antenna, according to its spec. The 20 mA also indicates
there was no short or open circuit to the antenna. That surely suggests
to me that the antenna amplifier circuitry had no gross failure.
I worked in the precision scientific instrumentation design field for
over 40 years and I can't count the number of times flux and whisker
growth has caused problems in circuitry and connectors. I may be
old-fashioned but I still believe the best solder flux is a flux you
later completely remove!
Spectracom apparently agrees because they, in later versions of this
same antenna, added a shield over the coax termination and totally
removed all residual flux.
On 5/13/2018 4:15 AM, Dana Whitlow wrote:
> Flux can provide just the right kind of ionic leakage path that leads to
> whisky growth
> and eventual sudden shorts.
> On Sun, May 13, 2018 at 12:23 AM, Hal Murray <hmurray at megapathdsl.net>
>> lmcdavid at lmceng.com said:
>>> To make this very long story into a short one, I learned that the HP/
>>> Symmetricom 58532A GPS Reference (timing) antennas use a simple patch
>>> antenna instead of a quadrafilar antenna and that old solder flux
>>> will attenuate the even amplified GPS signal out of this antenna.
>> Flux seems unlikely to produce a sudden failure.
>> If flux was the problem, I'd expect it to work poorly when first
>> or maybe decay slowly over time as something changed.
Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)
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