Adapter board V.3.4 for the construction of a KW Transceiver with the Red Pitaya.
Updated version 26.07.2019


The Red Pitaya enjoys the amateur radio community of increasing popularity. Meanwhile, an improved 16-bit version with 50 ohm inputs and outputs meets the requirements of radio amateurs. The board described below is compatible with the new 16 bit Red Pitaya version.
Anyone who has ever worked with the Red Pitaya, certainly knows the problem with the not very elegant cable connection of the two extension sockets E1 and E2. I have already set up some transceivers and the problem too well known for me. To operate it as a KW transceiver, various connections of E 1 and E 2 have be led out and connected to periphery. There are several ways to get connected to the port pins, but unfortunately most of them are unsatisfactory. Wiggle contacts or even short circuits may limit the function. You need a lot of luck not to have the Red Pitaya burned. Soldering is not a good solution either. The connection with the specified 26-pin flat cables and the plugs is not satisfying, too. Pressing a connector to the cable requires the appropriate flat cable, connector, tool and high accuracy. In some cases the cable may end as trash because it was not pressed correctly into the plug. A visually elegant solution isn’t it, too. The aim was to have the RP placed directly on the Mainboard 100x160mm without any cable connections and to integrate part of the necessary peripherals for the control of external assemblies at the same time. A simple construction with easy-to-procure components was the main focus. Replication does not require special knowledge or skills. No special tools were needed.
The advantage of such a structure is that the complete wiring of the Red Pitaya is done directly via the post connectors on the board. Wiring errors are impossible. You no longer need to search for pinouts on the Internet and study wiring diagrams. And the inconvenient flat-ribbon connection cable is completely eliminated.
A compact unit is immediately available and can be operated immediately with all functions. I think this is an incentive for all newcomers to get more involved with the Red Pitaya.
The specifications for the board were to integrate a simple and variable accessibility of the required connections, as well as parts of the necessary peripherals equal to on the board.

Properties of the adapter:



On the board can be found: two miniature relays 2 x Um including the control transistor and a status LED for PTT. Relay 1 is provided with two potential-free outputs for the PTT control. Relay 2 switches 5 V to control additional relays. The 5 V voltage input is indicated by an LED and is protected by a TVS diode 1N5908 and a Micro-Fuse 1.6 A. The diode protects against overvoltage and wrong polarity.
The Red Pitaya is mounted with 4 pieces 25 mm high spacer bolts and is connected via the two post connector directly to the board. No cables are needed.
The required plugs unfortunately are not available everywhere. These are so-called "GPIO Header Extra 2x13 pin. Female" 25mm for the Raspberry Pi.
It is necessary to relieve the solder points on the track side during insertion of the Red Pitaya. This should be done by inserting two thin acrylic strips. The strips with the dimensions 33 x 13 x 2 mm should be pushed between the two contact rows. Finally, the small black plastic strips (supplied with the pin strip) should be plugged back on and fixed with some of superglue. This reliably prevents the solder points on the adapter board from being pressed out of contact when inserting the RP. The FPGA of the Red Pitaya has a distance of 15 mm from the adapter board, so that a 10 mm high fan still finds enough space between them. A fan with the dimensions 40 x 40 x 10 mm with 12V is used. To have the fan run almost noiseless it shoul be operated by only 5V. The cooling is quite sufficient. For fixing the fan you may use small insulating rings for power transistors. This results in an exact centering of the fan with the 3 mm screws in the 4 mm holes of the fan.
For the other connections, multipolar pin headers of the PSS 254 series with a pitch of 2.54 mm were used. These are inexpensive and easy to procure. This ensures that the required connections are easy to make. The audio codec board is mounted on a 10 pin male connector. It can also be soldered directly to the board. The board is attached with 10 mm spacers. The Red Pitaya itself was deliberately placed all the way back on the board. This makes it possible to plug in the network connector directly when installed in a housing. With large cut-outs in the rear wall of the housing, the USB ports are easy to access and a replacement of the micro-SD card is possible without opening the housing.
I have developed a corresponding board for the project. This professionally manufactured board can be obtained from me, including the two connectors and the acrylic strips. I can also supply various components or ready-assembled and ready-to-use board if required.
Please send inquiries to: Payment via PayPal is preferred.
My special thanks goes to Sandor DM4DS for support and many helpful hints.

The construction:

You will find a lot of useful information about the Red Pitaya, as well as instructions for building a shortwave transceiver with the RP and downloads at:
Equip the circuit board with care, a desoldering of components is difficult and succeeds only with a special hot air desoldering station.

Parts and suppliers: Download Partslist






Adapterplatine für Red Pitaya



Stapelleisten 2 x 13 pol. 25 mm hoch



Audio-Codec-Board WM8732
Entwicklungsboard MikroElektronika MIKROE-506



Audio Codec-Board WM8732
Entwicklungsboard MikroElektronika MIKROE-506

1221370 - 62


Lüfter 12 V  40x40x10 mm  Hersteller ( Sunon EE40101S1-000U-999 )




Finder Relais 2 x Um  Typ  5Volt



Distanzhülsen 3 x 25 mm 1 x Innengewinde / 1 x Außengewinde



Distanzhülsen 3 x 10 mm 2 x Innengewinde



2 pol. Stecker

PSS 254/2G


2 pol. Kupplung

PSK 254/2W


3 pol. Stecker

PSS 254/3G


3 pol. Kupplung

PSK 254/3W


4 pol. Stecker

PSS 254/4G


4 pol. Kupplung

PSK 254/4W


6 pol. Stecker

PSS 254/6G


6 pol. Kupplung

PSK 254/6W


PSK Kontakte für Kupplungen

PSK Kontakte


Buchsenleiste 10 polig RM 2,54 Höhe 5,0 mm

BL 1X10G 2,54


Kleinst-Sicherung 1,5 A Flink RM 5,0 oder 7,5

FRT-F 1,6A


TVS Diode 1N5908



Ker. Kondensatoren 4,7 nF RM 2,5

Kerko 4,7 N


Ker. Kondensatoren 100 nF RM 5,0

Kerko 100 N


NV-Elko 470 µF /16V Ø 10 mm H12,5 mm  RM 5,0

RUBY 35PX470MT81


Universal-NPN-Transistor BC 547 o-Ahnl.




Widerstände ¼ W RM 10



Download Circuit Diagram V.3.4

Download Component Schema V.3.4

Board equipped with Fan and Connectors.


Circuit board with Red Pitaya and Codec-Board.


Download V.3.4 all