[Hackrf-dev] How to tell if antenna is faulty

[Michael Ossmann]

Cliff,

That sounds like a faulty ANT500.  Please contact your reseller for a
replacement.  Send a private email to me and info at greatscottgadgets.com
if you run into any problems with that.

The two most common faults of ANT500 and ANT700 are a short between the
center pin and shield ground or a break in continuity between the center
pin and the antenna element.  Both of these conditions can be tested
with a continuity tester.

The DC resistance between the center pin and the antenna element is
unspecified, but I think it should be stable and low enough to cause a
continuity tester to beep.

Michael


On Thu, Jan 31, 2019 at 09:45:58AM -0500, cliff palmer wrote:
>
> Jake, the reading between the tip of the antenna and the center pin varied
> wildly - so much that I borrowed another multi-meter to confirm them.  The
> readings went from zero to 160+ and back.  I did secure the antenna and the
> multi-meter leads to make sure my hands weren't the cause of the variation.
> It looks like the antenna is faulty.
> Thanks for the hint on CQRX.
> 
> I am using the Hackrf with the Ant500 as a starting place to learn enough
> about SDR to tap RF data feeds from NOAA Buoys.  These buoys measure water
> temp, wind speed and direction, wave direction, height and frequency.  The
> buoy data will be fed into an FPGA/RISC board to calculate and display
> marine navigation conditions, much like your local weather forecast
> includes a wind speed and direction display.
> There's no way that the Ant500 will be the right antenna for this.  I got
> it because I needed a starting place and a number of YouTube tutorials on
> SDR used it with the Hackrf.  Once I know more about what I am doing I'll
> be pestering you all again for advice on antennas.
> 
> Thanks again
> Cliff
> 
> On Wed, Jan 30, 2019 at 11:24 PM Gavin Jacobs <apriljunkbox at hotmail.com>
> wrote:
> 
> > Cliff,
> > I have a hackrf and an Ant500. With the antenna fully extended, you should
> > measure a very low resistance between the tip of the antenna and the center
> > pin of the connector. Mine was about 2 ohms. If you have 75 ohms, then
> > there is a problem. Try again between the center pin and the elbow (where
> > the extensions start) - it should be very low < 1 ohm.
> >
> > You should be able to use GQRX to receive an FM radio station, with almost
> > any antenna. Most common rookie mistake is forgetting to turn up the IF
> > gain.
> >
> > Tell us more about your setup and we can help you get started.
> >
> > Jake
> >
> > ------------------------------
> > *From:* HackRF-dev <hackrf-dev-bounces at greatscottgadgets.com> on behalf
> > of cliff palmer <palmercliff at gmail.com>
> > *Sent:* January 30, 2019 3:15 PM
> > *To:* hackrf-dev at greatscottgadgets.com
> > *Subject:* [Hackrf-dev] How to tell if antenna is faulty
> >
> > I have a Hackrf One with an Ant500 Antenna and I am having no luck with
> > multiple tutorials found on YouTube, including the ones at Great Scott
> > Gadgets.  I measured the resistance on the (disconnected but fully
> > extended) Ant500 Antenna using a multimeter (one lead on the metal part of
> > the antenna and the other on the male lead in the connector.  The
> > multi-meter measured up to 75 Ohm resistance.
> > I'm really new to SDR and so I don't know if resistance should concern me,
> > but it seems like an antenna should not have resistance.
> > I would appreciate some advice about how to determine if this is really a
> > problem (and the antenna is faulty) or if I am making a typical new-to-SDR
> > mistake.
> > Thanks
> > _______________________________________________
> > HackRF-dev mailing list
> > HackRF-dev at greatscottgadgets.com
> > https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
> >

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