Yet another embedded Red Pitaya rig

Blockschaltbilder, Anleitungen und Bauprojekte zum Red Pitaya.
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Registriert: 29 Sep 2017, 19:13

Yet another embedded Red Pitaya rig

Beitragvon f6itu » 16 Jun 2018, 20:34

Hallo Red Pitaya Freunde

This Red Pitaya transceivers is using the SPI bus (Thanks to Pavel for this incredibly nice feature) and a personal retrofit of the Alexiares frontend, offering all the functions controlled by PowerSDR or LinHPSDR (filter section of the Setup menu)

red pitaya small.jpg

This filter is a combination of low pass and high pass, able to cover the whole 0/60 MHz spectrum without hole (and not only small portions restricted to the ham band as most bpf do)
This frontend also includes an attenuator, a low noise amp for the 6m portion, 3 antenna selector, several external filters, transverter and Pure Signal switched input
External control (penny menu) is also available to command and control an external sspa and it’s lpf (via the I2C bus this time)

I'll probably made a write-up of the whole system and integration next July
Most of the frontend architecture is described at ... s_Angelia#

Hope you'll enjoy it
Marc f6itu
filtres small.jpg
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Registriert: 26 Mär 2016, 21:12

Re: Yet another embedded Red Pitaya rig

Beitragvon DH1KLM » 17 Jun 2018, 13:59

Hello Marc,
looks great. Impressive work. I am looking forward to your next report about the whole system.
Maybe you could also post pictures from the innards.
73 de Sigi, DH1KLM
Beiträge: 29
Registriert: 29 Sep 2017, 19:13

Re: Yet another embedded Red Pitaya rig

Beitragvon f6itu » 17 Jun 2018, 21:27

Oh, certainly Sigy
I’ll try to be as precise as possible and will always answer (or try to answer) to any question
In a few words : We are a group of French hams who decided to build a series of “HPSDR compatible” rigs. Some decided to build an angelia pcb (anan 100D) from component level, others have chosen the Red Pitaya, and some have decided to build the KF7O’s Hermes Lite v2.0 (and I must admit, many of us are building the three configs)
This is the main reason why I tried to retrofit the Alexiares Frontend : “one filter to rule them all” , with some constraint :
- It has to be and stay “open hardware” (CERN licence for original designs)
- It must be 100% protocol compliant with the original HPSDR code
- It could be build by newcomers (all boards are using SMD component, but nothing under 0805)
- All design could be downloaded on github (kicad schematics and pcb)… Please fork as much as you want
- Dimensions must fit in the “cheapest” form factor sold by Chinese pcb makers (10x10 mostly)
- We could supply pcb for ham who don’t want to run a 10 pcb batch for each board (not yet in place, but it will)
- This must be a non-profit initiative for DIY addicts
The Red Pitaya “integration” is in fact the proof of concept and real life benchmark of these boards
Just some picture to illustrate (the box is a former 4 channel Gould oscilloscope)

inside up small.jpg

This is the upper layer of the rig. The piece of paper with some orange traces is a “dummy” to mark the size of a full size Angelia board. On top, the red pitaya, on the bottom, the SPI control board and the two filters, hpf and lpf. This picture has been taken before a neat wiring

inside dwn small.jpg

The next picture shows the “power” stage. In the lower right angle of the box, the blue pcb Is in fact an I2C board. A kind of DC2PD interface board, but with a dual buffer (ULN2003). This board could be used to control the two filters, but with less functionality compared with the SPI bus. I use it to control the “external” Penny connector
The small green and sqare pcb located close to the blue I2C interface is the Angelia OCXO (10 MHz). I’ll probably later add a specific ocxo for the Red Pitaya.
On the upper side of the rack, you can see 2 different switching power supplies. The big one is a 13,8V dedicated to the relay switching and the 20 W power amp (not on these pictures).The second -and smaller PSU gives a 8.5 volts
- for the 10 MHz ocxo (which has it’s own series regulators and filtering).
- For the Red Pitaya or Angelia 5V rail
- For the Angelia 3.3 rail
In fact, this PSU is able to deliver approximately 40 to 50 W. The 8.5 V is sent to a bunch of 3 series regulators (LM1084 for the 5, 3.3 and “whatever” output voltage) followed by a heavy-duty filtering board to avoid any switching noise coming from the PSU.

cpu up small.jpg

cpu down small.jpg

The last to pictures shows the CPU/display/USB audio board and partly the antenna switching system (not yet shielded when I took the pictures). The TX switching relay board can handle approximately 200W PEP.
As I already said, this UP board is just a proof of concept, for demo purposes and “quick and dirty” portable conditions. Most of the time, the computer part is shut downed and the rig uses like a “normal” networked radio station.
More enhancement are “under development” : an SSPA control unit (MCU, sensors, display), a new version of the Pure Signal coupler, a new design of the voltage regulation board… and I hope Manfred XQ6FOD will succeed building the EER (or ET) part of his amplifier. I’d definitely love to drive a “linear D class amp” :- )
If someone consider using my Github repository ( , please download the most recent “branch”. The “master” trunk is considered as an ever evolving project and could not be considered as reliable.
I couldn’t find the time to clean the gerber files yet… it will be done during this summer… I swear
Once again, I wish to thank Pavel for its efforts and the implementation of Phil VK6PH “alex” protocol. Very few ham are considering using the SPI bus… they really don’t know what they miss :-D
Vy 73’
De Marc f6itu

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