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Si5351A VFO/Signal Generator
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1. Introduction
This is the operation manual for the VFO/Signal Generator kit. Please read it in conjunction with the
assembly manuals for building the kit:
VFO/Signal generator assembly manual (the controller PCB, rotary encoder, buttons and LCD)
Si5351A Synth assembly manual, or OCXO/Si5351A assembly manual if you use the OCXO
QLG1 GPS assembly manual, if using the QRP Labs QLG1 GPS to discipline the oscillator
Note that the output of the Si5351A are squarewaves at 3.3V peak-peak. Please read the Si5351A
datasheet, linked from
http://www.qrp-labs.com/synth
. If you require a sinewave output, then you
could fit a QRP Labs Low Pass Filter kit
http://www.qrp-labs.com/lpfkit
to the main PCB, to filter away
the squarewave harmonics. This would be effective over only a limited band of frequencies but may
suit your application.
The LCD may be configured to show not just VFO frequency, but also your callsign or other text, and
if you have a GPS connected (for disciplining the oscillator) you may display GPS parameters such
as date, time, latitude, longitude, altitude, satellite reception status, and Maidenhead locator.
2. Operating instructions
When you have just built the kit and have not yet configured it, upon power-up the kit will enter
“Diagnostic Mode”. If you can see this message on the screen, all is well. Press the Left button to
continue. If you do not see this message or any writing on the LCD, please refer to the
troubleshooting web page.
On power up (and after leaving the diagnostic mode, if any), the LCD displays the firmware name and
version number for a few seconds, then loads Preset 0, and enters VFO tuning mode.
2.1 Modes of operation
There are four modes of operation. The usual running mode is the VFO tuning mode, in which the
Clk0 frequency is displayed on the screen, and the rotary encoder tunes it.
VFO tuning mode (default at start up)
Select preset mode
Select tuning rate mode
Configuration menu editing mode
