Missing antenna wires

I recieved an 820c from Arrow last week. It’s missing the two wires on the backside, and I get no scan results from WiFi and Bluetooth. Can anyone confirm they get WiFi/BT signal without these wires?

They definitely need the wires.
Unfortunately, it looks like some batch received by Arrow is missing those jumpers. The first two boards I received had them, third was missing. I spoke to Arrow and convinced them to give me a substantial partial refund in order to “buy the tools and parts needed to make them”, but you can buy appropriate jumper wires on amazon for a few $.

The schematic lists the connector part as a Murata MM4829-2702B. This data sheet indicates the cable part would start with MKHKxxHKxx:

No sign of this cable anywhere, and the data sheet states only use the mating connector. I suspect something else will work with an insertion loss.

What third party cable are you using?

I will contact Arrow in the AM. This is silly.

When you need to buy an extension cord to run a vaccum cleaner, do you search for a part number or do you search for “extension cord”? You’re looking for an IPEX4 pigtail.

Good luck with arrow. They won’t be able to figure it out.

Hi Joel:

This has been discussed before here: GPS and WIFI antenna and in the app note https://developer.qualcomm.com/qfile/29467/lm80-p0436-42_add_ufl_ant_and_valid_gps_on_android_app_note.pdf

Of course this is for the 410C, but if I remember correctly the 820 is similar.

Or maybe this is what you need: https://www.mouser.com/ProductDetail/Siretta/ASMG015G113S13


I don’t think those will work, and the situation is a bit different on the 820c vs 410c.

On the 820c, the wifi is on a separate module, and there is no antenna pin on the module soldered to the 820c board, which means that in order to connect the PCB antenna on the 820c board to the module requires a short jumper wire with IPEX4-M on both ends.

Your link looks like it would be for connecting the module to an external antenna, instead of the onboard PCB antenna.

See red lines I added to the following;

The hardware user manual shows the jumpers on page 9:

IPEX4 I can manage. I wasn’t aware the connector was a standard. The only thing for female to female I found was on EBay - 20CM, also ordered IPEX4 to Antenna.

Next problem is GPS.


@doitright thanks for the picture and reminding me what the 810c looks like, it has been a long time since I looked at it.


you need IPEX MHF4 female to female. I found the cables here: MHF4 Female to Female Cable: 2-inch, 4 in, 6 in, 8", 10", 1FT, 14", 18-inch I would suggest a 2inch and a 3 inch cable.

The actual cables were ‘custom’ built with the insulation removed from the co-ax where the clips are. this holds the cables down neatly, and ties the shields to the ground plane which might improve performance by a fraction of a dB.

The cables are not on the first level BOM, hence likely the reason the boards were built missing the cables.

For an external GPS antenna, The process is similar to the 410C, you add the connector, and install a 22pf capacitor C430 instead of a zero ohm resistor. If you use a powered GPS antenna you will need to install L31.

@ljking Nice! Just ordered these. That’s a great resource.

Thanks Lawrence. Hope things are good.

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I just populated the IPEX MHF4 cables @ljking referenced (data-alliance). Two 2". One fits perfect (longer path), the other sticks out slightly.

BT and WiFi is now working like a champ.

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