[time-nuts] GPS Timing Antenna Failure - Long

Larry McDavid 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.

Larry


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.
> 
> Dana
> 
> 
> On Sun, May 13, 2018 at 12:23 AM, Hal Murray <hmurray at megapathdsl.net>
> wrote:
> 
>>
>> 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
>> residue
>>> 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
>> installed,
>> or maybe decay slowly over time as something changed.
...


-- 
Best wishes,

Larry McDavid W6FUB
Anaheim, California  (SE of Los Angeles, near Disneyland)


More information about the time-nuts mailing list