SMA End Launch Connectors


#1

I’m experimenting with LoRa:

Adafruit RFM95W LoRa Radio Transceiver Breakout
Adafruit Feather M0 RFM95 LoRa Radio

If you want to fit an Antennae with an SMA connector, you need to fit an SMA End Launch Connector onto the PCB.

For the Breakout Board, I can find the connector on Farnell but they are asking £15 just for delivery as it’s US stock only. I can use Mouser or Digikey, but it will be a similar problem. Adafruit have it on their website but “out of stock” and it still has to ship from the US

I haven’t yet found the right connector for the Feather.

So, my question is, any suggestions on part numbers and suppliers at a reasonable cost in the UK for both boards?


#2

Granted I know very little about this subject matter (story of my life!), is this the part you saw on Adafruit’s site by any chance?


#3

Nope, I’m pretty sure this is the fellow I want: https://www.adafruit.com/products/1865.

There seem to be a few critical dimensions

  1. Thickness of PCB - 1.6mm seems to be required
  2. Space between the “prongs”. The “cheap” connectors from Farnell are about 9mm, the Tracks on the board are more like 6mm which matches what I can see in the data sheets for at least one part (£9 each and £15 shipping). Hence me asking the question!

I did later realise that the Feather actually has tracks for a uFL connector so that may be a red herring.


#4

I think you’d be lucky to find a specialist part in a quantity of 1 for a reasonable price, your best bet is some obscure UK re-seller, EBay or otherwise.

If you have a part number, you can track down distributors with Octopart, but I don’t think you’ll find particularly competitive prices: https://octopart.com/search?q=edge-launch%20sma%20connector


#5

Yup that was my act of last resort, however given Adafruit describe fitting such a connector and have it for sale (albeit out of stock), I hoped I wasn’t on my own trying to find one, after all not much point using LoRa without an external Antennae! Oh well, I shall research elsewhere, thanks


#6

hum, I’m still confused, I thought the whole point of the part I linked to was to bridge a SMA antenna to the uFL that the breakout board ships with (and I understand can be fitted to the Feather board too).

… I assume you would prefer a more compact solution and that’s the reason for you trying to source a PCB connector? or am I showing my abysmal ignorance about this again, lol?


#7

Something like https://www.wirelessthings.net/sma-pcb-straight-end-launch ?

Gordon


#8

Yup, that’s what I got at first before I checked the dimensions and the spacing between the two sets of pins on each side of the PCB is 9mm on that connector and around 6mm on the PCB


#9

I hate uFL connectors, great in a final project, but not so great connecting and disconnecting and just lying around on the bench in general. So

For the Feather variant, I have no choice and I’ll hunt down the PCB uFL connector and use a uFL to SMA adaptor cable.

If I have to I’ll use the same solution on the breakout board, but the proper SMA connector is just so much neater and robust (well it is to me anyway). I just need to find it at a sensible price. If it came back into stock at Adafruit themselves then that would work even with postage from the USA to the UK