Friday 10 April 2015

New Receiver Shield

The new Kanga / m0xpd Rx Shield is here...

I stuffed the first production PCB yesterday evening and had it running on 40 in a matter of moments!

There are no great surprises from the original "Sudden Rx Shield" from way back in 2013 - but I've done some tailoring of the audio frequency response and we've been forced to change to an SMD package on the SA602 due to supply issues.

The shield retains the external audio processing loop, which allows the introduction of everything from volume controls to filters and audio processors and includes software-controlled Rx muting.

You can see the new shield on the Kanga stand at the NARSA show, where it is being launched this Sunday

in the luxurious surroundings of the Norbreck Castle Hotel in Blackpool.

I was going to say "Sunny Blackpool", but they tell me our recent spell of settled weather is going to change this evening, so all bets are off.

See you on Sunday!

...-.- de m0xpd


  1. Many thanks for your blog, it has inspired me to have a play with an arduino based receiver. I am a developer by trade making that hardware the bigger challenge.

    I have both the Si5351 and RX Shield kits from Kanga (half built), however, I am wondering what would be the best way to feed the Si5351 RF source into the spare [] pin on the RX Shield. I don't have the TX Shield (with buffer amp etc).

    Kind Regards

    1. John

      There is loads of level coming out of the Si5351 (without amps etc) - if you stick the (CLKx_AC) square wave straight into the '602 on the Rx shield it will technically over-drive the '602 (no doubt the reason for your question) but it will almost certainly still work. However - ideally - you ought to drop it down with a resistive pad to somewhere around 600mV (if memory serves).

      In my experience the particular voltage isn't critical. Also, the operating impedance of the resistor network isn't critical - certainly not to the Si5351 and (to a lesser extent) to the '602, so a pair of resistors will do.

      Purists might want to use this resistor network as opportunity to filter (as the harmonic content of the square wave will have the d.c. receiver sensitive on more than one band) but the purists probably wouldn't be doing this in the first place! And - if you're going to use more than one band, this filter design isn't going to be fixed :-(

      I will try to get a post together on using the Si5351 shield with the Rx at some point.

    2. Thank you, this is a big help. I look forward to the Si5351/Rx post.