RFM98W - TCXO

Hi Guys,
I was wondering if the RFM98W module has a TCXO or just an XO on board.
If only an XO, can you describe how we can add a TCXO. Or better yet, just send the schematics, we'll do the rest J
I'm interested in the really low bandwidth applications of the module, and this requires a TCXO according to the datasheet.
Thanks.

This message was edited 1 time. Last update was at 21/03/2016 09:08:56

Hi Yariv,

There is same interest in similar situation using the RFM95W.
Here is the link for it:
http://forum.anarduino.com/posts/list/110.page

HopeRF has agreed to manufacture special transceiver using 2ppm TCXO for the RFM95W, but I will inquire to see if they can do the same for the RFM98W.
We have just received sample crystals and will evaluate and test later this week.

The new transceiver with the TCXO will be available for purchase soon, the cost will be only about $0.20 more than the regular 10ppm XO.
We will be purchasing these in volume and making them available for sale as soon as possible.

Cheers,
-Rick

Hi Rick,

I've been waiting to buy some TCXO equipped RFM98Ws. I was excited to see your news, has there been any progress?

Thanks,

Herb

Hi Rick,

Any update on the RFM95W module with 2ppm TCXO. We are developing a product that will use this part and are very interested in getting some modules for evaluation. We will use for US ISM application working in the 902 - 928 MHz band.

I have given up hope of getting TCXO fitted to these devices in the short term.......

TO overcome this problem i replaced the 32MHz 3.2x2.5mm SMD crystal with a 10ppm part myself:-

Here is a suitable 10ppm 32HMz crystal that can be directly replaced - ideally using a tweezer soldering iron
[url]
https://uk.rs-online.com/web/p/crystal-units/6754920/
[/url]

I have done a straight swap for the above without any other changes and the unit work fine although i have yet had the time to check more reliable communications with BW<62.5KHz

Currently have the following modem settings working ok at 868MHz

Ideally i would like to fit an oscillator module (TCXO) instead of a crystal to get the ppm down to 2ppm and open up the possibility of using the very narrow bandwidths:-

Here is a suitable TCXO but you will need to modify the miniwireless pcb to allow this to work as the current RFM95/98 module are fitted with a SMD crystal and NOT an oscillator!!

[url]
http://www.ebay.co.uk/itm/191830861745
[/url]

To make this mod the output of the TCXO needs to be connected to pin XTA and XTB needs to be open circuit (so a track cut as currently both XTA and XTB are connected to either side of the crystal) The TCXO will need to pick up 3V3 power from somewhere also.

have a look here for the TCXO connection to the SX1276 chip

[url]
www.semtech.com/images/datasheet/sx1276_77_78_79.pdf
[/url]

Hope this helps.

Cheers

Dan