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Project Yamhill Preliminary Architecture
First Pass Specifications
In order to honor the lineage of this new project, I decided to go back to the well of using Oregon geographic names, as I did with a number of my projects from about a decade ago. Therefore, I am dubbing this endeavor Project Yamhill, in honor of the Yamhill River and Yamhill County, which is my new home.
Below you’ll find a rough first draft of specifications for this new radio learning project. Some things are incomplete and some things will definitely change, but you’re always got to lay down an initial stake, right?
Project Yamhill is the successor to the Willamette Transceiver, also known as the qrp-l Group Project. The purpose of this endeavor is to provide a platform to learn about radio electronics at a system level. Modules that correspond to the blocks of a block diagram will be the basis upon which different types of radio designs will be created. A modular 3D printed backplane will be the chassis, user interface, and power supply for the radio experiments. The desired goal is to have a high-performance CW QRP transceiver at the end of the main project run, however there would be the capacity to build many other types of radios from the blocks as desired, such as a SSB transceiver, run more transmit power with a linear amplifier that can provide 20 watts or more, data radio, simple receiver, different architectures such as a phasing receiver, etc.
All designs and code will be permissively open sourced so that an end user is able to build one by himself if desired. All radio design specifications will be published, along with detailed information about how the user can make his own measurements with affordable test equipment to ensure that his radio is performing as expected.
The Yamhill backplane will be the foundation of every radio experiment in this project. Designed to be printed on a consumer-grade FDM 3D printer, it will hold all of the necessary block modules open-air in a reconfigurable grid, have an integrated power supply and power distribution system, have rear connectors needed for a complete transceiver, and house the front panel with the user interface, including microcontroller, LCD display, buttons, encoder tuning knob, etc.
Possibly two sizes, but we're going to start with the largest and see if there is demand for a more compact version.
Block Module Grid
A grid of mounting holes for M3(?) screws to secure block module PCBs to the backplane will be spaced at 4 cm in each axis, with allowance for 5 mm of margin from the outside board edge at each mounting hole, with a 1 cm x 1 cm x 1 cm cable management channel being provided between each row and column of mounting holes.
Therefore, allowable PCB sizes will be 5 cm x 5 cm, 5 cm x 11 cm, 11 cm x 11 cm, 11 cm x 17 cm, etc.
DC power is to be provided by and distributed through a PCB that integrates with the backplane. Channels to be provided in the backplane (1 cm width?) for easy and neat distribution of other signals.
On-board Rear Panel Connectors
DC barrel (5.5 x 2.1 mm)
3.5 mm TRS (x2)
USB-C (for UART)
A front panel PCB will hold most of the user interface and brains of Project Yamhill. This PCB will be populated with:
Color LCD display module
Large tuning encoder
Two smaller encoders (for multifunction, possible AF gain)
AF gain pot if not encoder controlled
A plethora of microswitch pushbuttons
A handful of status LEDs
Two 3.5 mm TRS jacks
Microphone jack (RJ-45?)
Speaker (not sure if front-firing or chassis-mounted)
The front panel PCB will have a USB connection for programming the microcontroller, as well as at least two UARTs available for rig control, debugging purposes, etc., signal routeable to the back panel USB connector.
Block modules are self-contained PCBs that will perform the functions of a block on the block diagram of a radio. Most components will be SMT, and those modules sold by Etherkit will have the SMT components installed by the manufacturer. Through-hole components such as toroidal inductors and board connectors will be installed by the end user.
PSU/Power Distribution (special case, backplane integration)
12 V rail, derived from exterior PSU, minimum 1 A
5 V rail, minimum 500 mA(?)
3.3 V rail, minimum 500 mA(?)
(optional) Li battery boost and charge
50(?) dB AF gain
Able to drive a 1 W speaker or phones
AF gain control
~40 dB AF gain for use in a DC receiver
Double-balanced Diode Ring Mixer/Modulator
Option for higher than level 7?
Crystal Ladder IF Filter
Various bandwidths available for SSB, CW, roofing
IF Amplifier with AGC
Receive Bandpass Filter
Transmit Low-pass Filter
Most likely Si5351C, but open to options
QRP Transmit Linear Amplifier
Maximum power output 5 W
Higher Power Transmit Linear Amplifier
Maximum power output 20 W
10 MHz ref out
1 PPS out
Inter-module RF Signal Interconnects
Inter-module DC/AF Signal Interconnects
Proposed Learning Units
Direct Conversion Receiver
QRP CW Transmitter
Superheterodyne CW QRP Transceiver
Superheterodyne SSB/CW QRP Transceiver
QRP CW Transceiver Target Specifications
Expected Required Test Equipment
Spectrum analyzer such as tinySA
VNA such as nanoVNA
I’ve started a GitHub repo for the project here, which will contain all of the basic documentation. You can follow along there for future updates on the status of the architecture. I’ll also start posting design files there as they are generated.
I’d love to hear any constructive feedback about the preliminary design. Please comment below!
I Need Your Assistance!
If this project looks interesting to you, I could certainly use your assistance. Please share my post with friends directly, or post to your social media. Thank you!
Expect a drawing, rendering, or some kind of visualization of the Yamhill backplane. I’ve got FreeCAD loaded and ready to go on my laptop. The 3D printer will be coming out of storage very soon.
Also, I’ll be nailing down the PSU requirements and getting started on an initial design, since everything else will depend on this. This will be a unique module in that it will have a special, dedicated spot on the backplane.
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