[time-nuts] GPS Antenna Feed Line Decision

Glenn Little WB4UIV glennmaillist at bellsouth.net
Sun Sep 3 23:41:26 EDT 2017


I work with a broadcast station.
We just had a HD FM radio transmitter upgrade done.
In the upgrade package from GatesAir was a GPS antenna with a F fitting.
The provided feedline was RG-223 with a TNC on one end and a SMA on the 
other.
Also provided was a TNC to F adapter.
The new exciter has a GPS receiver installed to provide 1 PPS to the 
exciter.
There was also another piece of equipment that required 1 PPS and they 
provided an antenna and no feedline with that one.
Either piece would output 1 PPS, so the second antenna was not needed.

So you wonder what the "professionals" had in mind with the adapters.
Low bidder for the antenna??

73
Glenn
WB4UIV

On 9/3/2017 10:09 AM, Wes wrote:
> On 9/2/2017 4:48 PM, Clay Autery wrote:
>> Thanks for the response...
>>
>> Not sure why you and the other guy both recommended RG-6 75-Ohm cable
>> and F-connectors, when the nominal impedance of literally everything
>> else in the system is 50 Ohm, including the antenna and the HP GPS
>> Distribution Amp....  And then adding N to F adapters?
> As "the other guy" (I think) let me say that the impedance mismatch is 
> immaterial and in my case I have one GPSDO with an SMA connector and 
> another with a BNC and an antenna with an SMA.  So I "adapt" no matter 
> what I do.  Because I understand the cascaded noise figure equations, 
> I know that I don't need an active distribution amplifier to feed just 
> these two devices, so a $5.00 "F" connector splitter is adequate. 
> (https://www.markertek.com/product/201-232/2-way-2-4ghz-90db-satellite-splitter-dc-power-passing-to-one-port)
>> Doesn't make any sense unless one has $$ as a top priority, already has
>> a spool of RG-6 quad shield, etc...  but I specifically stated that $$
>> is not a top priority....  Not really even in the top 5 or 10...
> Then by all means you should use L-band waveguide. :-)
>
> Wes
>
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-- 
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Glenn Little                ARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIV            wb4uiv at arrl.net    AMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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