[Hackrf-dev] How to tell if antenna is faulty
Jonathan Guthrie
ka8kpn at ka8kpn.org
Tue Feb 5 15:29:57 EST 2019
The MIL-STD-348 is available for download, by the way. You can get the
link from the Wikipedia article on the SMA connector.
On 2/5/2019 2:21 PM, Chuck McManis wrote:
> Technically there is only *one* SMA connector, it is defined in
> MIL-STD-348. There is also "RP-SMA" which has the same mechanical
> dimensions but swaps the pin and socket locations from the outer
> threaded version to the inner threaded version.
>
> That said, a vendor might confuse them and call some random connector
> "SMA" (I have seen TV types refer to the 75 ohm "F" connector as an
> SMA connector incorrectly)
> --Chuck
>
> On Tue, Feb 5, 2019 at 8:53 AM cliff palmer <palmercliff at gmail.com
> <mailto:palmercliff at gmail.com>> wrote:
>
> I tried to order a multimeter test lead that fits SMA connectors
> so I can have an easier time testing antennas.
> It turns out that "SMA Connector" can mean a lot of different
> sizes and types.
> Does anyone have the male and female core diameter for the SMA
> connectors used by the HackRF One?
> Thanks!
>
> On Thu, Jan 31, 2019 at 6:22 PM Michael Ossmann <mike at ossmann.com
> <mailto:mike at ossmann.com>> wrote:
>
> 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 <mailto: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 <mailto: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
> <mailto:hackrf-dev-bounces at greatscottgadgets.com>> on behalf
> > > of cliff palmer <palmercliff at gmail.com
> <mailto:palmercliff at gmail.com>>
> > > *Sent:* January 30, 2019 3:15 PM
> > > *To:* hackrf-dev at greatscottgadgets.com
> <mailto: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
> <mailto:HackRF-dev at greatscottgadgets.com>
> > > https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
> > >
>
> > _______________________________________________
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>
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