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

Tue Feb 5 15:31:42 EST 2019

Hello Everyone,

First time Hackrf poster but long time reader.  Chuck is correct.   I just went through a project where i added external antennas to my WIFI router.  The following links below are from EBAY to purchase the adapter to goto  RP-SMA from SMA or vice versa and are only a dollar or two each.  If you were to get the correct adapter you could make the cable you need.  Ebay has cheap adapters from china but it might take a month to get in the mail.

https://www.ebay.com/itm/SMA-Female-To-RP-SMA-Male-connect-SMA-to-RP-SMA-RF-Connector-Adapter-USA/111516107525?hash=item19f6e0c305:g:-UkAAMXQVERSrf1P:rk:2:pf:1&frcectupt=true

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=2x+SMA+male+plug+To+RP-SMA+female+%2F+male+center+Straight+RF+connector+Adapter+EC&_sacat=0

Thanks, Tom

________________________________
From: HackRF-dev <hackrf-dev-bounces at greatscottgadgets.com> on behalf of Chuck McManis <chuck.mcmanis at gmail.com>
Sent: Tuesday, February 5, 2019 2:21 PM
To: cliff palmer
Cc: hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] How to tell if antenna is faulty

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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