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

[Chuck McManis]

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> 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> 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
>> 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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>>
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