This 5W HF PA kit features an IRF510 MOSFET as the amplifier. But it also includes a discrete component power modulator (like a voltage regulator), which is controlled by an 8-bit Digital to Analogue Converter (DAC). A microcontroller can load a 74HC595 shift register with a sequence of DAC values which closely replicate an ideal raised cosine RF envelope. This makes a very clean CW transmission, practically eliminating key clicks.
Features:
- Approx 16dB of gain at HF
- IRF510 MOSFET PA stage providing 5W or more RF output from 200mW drive (varies by band)
- Raised-cosine keying envelope generation
- Option for standalone envelope shaping, without external microprocessor control
- 80 x 37mm PCB, compatible with Ultimate3S transmitter kit
- Discrete component power modulator with foldback current limiting
- Designed for typically 12V or 13.8V operation
- Large heatsink
- Supports RD15HVF1 transistor substitution for VHF/UHF operation
The kit is on an 80 x 37mm PCB, the same size as the Ultimate3S transmitter kit and relay-switched filter kit. It can be used with the Ultimate3S transmitter kit. Firmware versions v3.12 and above are capable of generating the raised cosine keying envelope. The connections required for use with the Ultimate3S transmitter kit are described in App Note AN004. Requires Ultimate3S firmware v3.12 and above.
The kit can also be built in a standalone mode, with onboard raised cosine envelope keying generated by an optional ATtiny84 microcontroller. This is plugged into the IC socket on the PCB instead of the 74HC595 shift register chip. The ATtiny84 is programmed to produced the raised cosine RF envelope and also provides a key-out signal which can be used to key a driver stage. This application of the kit is perfect for use in your homebrew transmitter projects. It is described in App Note AN005, which also includes discussion of a 5W CW transmitter built using the QRP Labs VFO kit and this 5W HF PA kit. The programmed ATtiny84 microcontroller is available as an option.
Finally, one or more circuit blocks may be bypassed. A simplified assembly manual details a simplified way to assemble the kit, without using the power modulator and raised cosine keying generator circuits. This may be suitable for people who wish to build a more simple PA that does not include the raised cosine keying facility.
More details, assembly instructions etc are on the QRP Labs 5W HF PA kit page.
5W HF PA kit
- Product Code: PA
- Availability: Out Of Stock
-
$20.00
Available Options
Related Products
Ultimate3S QRSS/WSPR kit
The Ultimate3S QRSS/WSPR Transmitter Kit transmits various QRSS, Hell, Opera, PI4 and WSPR slow-signal modes on any LF, MF, HF or VHF band (all amateur bands from 2200m to 2m or 222MHz). Thi..
$35.99
Ultimate relay-switched LPF kit
This relay-switched LPF board kit can have up to five additional LPF's plugged in, permitting the Ultimate3 and Ultimate3S QRSS/WSPR kits to sequence between 6 bands (including the LPF on the main U3/..
$16.00
VFO/Signal Generator kit
Full description on the QRP Labs VFO kit page. The Si5351A VFO/Signal Generator kit provides two independent output freqeuncies, 3.3V peak-peak squarewave and in the range 3.5kHz to 200MHz (Si5351A..
$35.99
RC1 Raised Cosine Keyer chip
Raised Cosine Key Shaper chip that can be used with the 5W HF PA kit to make a standalone PA with raised cosine RF envelope shape for click-free CW keying. Please refer to App Note AN005 for details. ..
$4.00