Building a Sandwich from pre-assembled Boards

NEW: Pre-assembled Boards (and more) are available from the following suppliers with our permission:




Here´s the Information you need to complete the Rig.

Let´s start with the modified iBOM´s. Every Part that´s already on there, is checked as sourced and placed. The Amount of remaining components to source can vary over time. It depends on PCB-Revision and source of the PCB´s.

So you just have to take care of the Rest.

Explaination / How to use: The iBOM is a (downloadable) interactive html-file, that shows you which component goes where. It is helpful, to keep track of what you are doing. Schematic is also available as reference and sometimes contains some additional information.

For critical parts I´ve tried to provide a link to the related item in a shop (either reichelt or mouser) Those are no affiliate links. They are just thought as help for you, to get the right parts !

When it´s sold out at that vendor, you need to look for other sources. But at least you know the exact Part, you need to look for.

OLED IO-Board:

You just need to source and place the THT Components.

Here´s the Schematic for the OLED IO-Board:


D1/D2 Standard 1N4148 Diodes

SW4 (rotary encoder) use EC11B13 (Unlike other rotary encoders, this one is known to work without trouble and comes at a reasonable price)

SW1-SW3 you can use for example these

MK1 (on-Board Mic) for example this one (watch for polarity !!!)

J4,J5,J6 use these

J1 and J2 are male jumper connectors, nothing special

J3 is Place Holder for OLED Display, like this one (if you buy another one, watch for the right order of the Pins)

J7 and J8 are Female Pin Sockets, with bent contacts for horizontal mount. Nothing special.

2 Diodes already soldered in, Rest waiting….
(Almost) everything placed on the Top Side
Here I prepare a Socket to Plug in the OLED
I´ve shortened the PINS of the OLED Display, so they will fit in flush.
OLED Socket soldered, and Inter-PCB placed and soldered
For the programming Interfaces, I use left overs of the long Adafruit Male/Female Stacking headers (See Mainboard for Details). I cut them to required length, bend them and solder them in.
Last thing is the rotary encoder. Now the IO Board is ready
Bottom View


You just need to source and place the Si5351 and the FST3253 SMT IC´s and the THT Components. JLC-PCB do not have the IC´s in Stock and cannot place them for us.

Here´s the Schematc of the Mainboard:


D1/D2 Standard 1N4148 Diodes

U4 is 74ACT00 in DIP-14 Package

U6 is ATMega 328 in DIP28 Package use Socket for that

U3 is LM4562 in DIP-8 Package

U5 is Si5351 in MSOP-10 Package

U1 is FST3253 in TSSOP-16 Package

U2 is 7805 in TO220 Package

Y1 Crystal 27MHz

Y2 Crystal 20MHz

Q1 BS170 in TO92 Package

J2 and J3 are cut from Male/Female Stacking Header Set

J1 is Terminal Block by Phoenix Contact, can be replaced by anything with5,08mm Pin-Spacing

Start with soldering U1 and U5 on the pre-populated board.

SMT IC´s waiting to be soldered on

Here are some tips how to solder that without special tools:

SMT IC´s soldered on. This is actually all on the SMT Side.
Now we take care of the THT Side. Pretty self explaining.
Next, I cut off 2 pieces of a 36Pin Stacking Header at the 15th Pin. This Pin will be lost.
Left: fresh cut at 15th Pin / Right cleaned up a little towards 14th Pin.
Then simply solder them in
After you´ve put the ATMega in the Socket, the Mainboard is ready. (You still need to screw in Power Supply cable and Program it later)

8-Band RF Board

Comes naked, so it will be dealt with on the Main Page of this Board:

8-Band RF Board


The latest Software can usually be found here

But you need to activate and deactivate some options in order to work properly with your Sandwich. (Band Relay Support, OLED etc)

I´ve prepared that for you:

OPTION 1 (use while building, testing etc – includes Error Messages, but NO CAT Control)

OPTION 2 (Workhorse, when your built is finished, Including CAT CONTROL, but without Error Messages)

Unfortunately there´s not enough Space in the ATMega to have both….

Help, how to install the Software can be found here:

In case, you still hear noise from OLED (change in Noisefloor when you unplug OLED)

Try another ATMega. Sounds stupid, but I had the case, that one ATMega would create audio humm (from OLED) the other not. Seems, like there is also Tolerances involved in their ADC Quality….