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NS-40 Class E Transmitter

Designed by David Cripe, NMS

Designer's Radio Bio

This Kit Has Been Retired
First time builders please note: This kit is an ideal first kit. It is inexpensive, has a small number of parts and the pc board is uncomplicated. Many first time builders have chosen this kit and wrote to say how pleased they were that it worked perfectly upon powering up the first time.

NOTE: NS-40 GROUP:   Bart Lawson, WIIT, has formed an NS-40 Yahoo Group.
Read his QRP-L announcement here
and click the button at the top of this page to join.
The NS-40 Transmitter is an upgraded version of the overall winner in the FDIM 2008 Homebrew Contest. It is a truly unique QRP transmitter design. NS stands for None Simpler, so this is the None Simpler 40 Meter Transmitter. Why is it called the None Simpler? Because there are only 14 electronic components, and NO TOROIDS or COILS of any kind to wind - NONE! All inductors are incorporated directly on the PC board as etched spirals.

This is an ideal first kit for budding homebrewers and will also appeal to the seasoned QRP'r due to it's innovative design. Just because this is a simple transmitter, doesn't mean that there is a compromise in performance. The transmitter incorporates a two transistor MOPA (Master Oscillator-Power Amplifier) circuit, with a 2N7000 crystal oscillator driving the IRF510 Class E final. Both are keyed for a clean, click-and-chirp-free signal. The innovative Low Pass Filter (LPF) provides harmonic rejection to greater than -50 dBc. The signal is a clean 5 watts into a 50 ohm load.

Using the rugged and low-cost IRF510 MOSFET this transmitter utilizes a CLASS-E final amplifier for maximum efficiency and reliability. The 2N7000 oscillator easily drives the final to a full 5 watts out while running at comfortable temperatures. The PA heat sink helps the final accommodate accidental high SWR (>5:1) excursions while tuning or trying out a new antenna. NOTE: Our Stand Alone VXO. the SAVXO, will drive the NS-40 to full output and provide frequency agility. See the link in the documentation below for detailed instructions on incorporating this Super VXO design into your NS-40 transmitter.

As mentioned above there are no toroids or other coils to wind. That's because David has incorporated all necessary coils as PRINTED CIRCUITS on the PC board, i.e. SPIRAL-PC-TRACE INDUCTORS. While this may be common at VHF and UHF, we believe this is a first for a 40 meter application. You have to see and build it to believe it.

The PC board is the size of a post card - and actually has a blank QSL card form printed on the back. You could put a stamp on the bare board and mail it!

The kit comes with all components, 7030 kHz crystal, pc board, mounting hardware, and heat sink. All components are through hole mounted. This is a very easy kit to build and populating the board will take an experienced builder only about 20 minutes. The size of the pc board drives the cost of the kit. Board prices, including tooling costs, continue to climb so the price of the kit came in a little more than we had expected, but it is a great kit anyone will enjoy building.

Power Output: Strong 5 watts at 13.8 volts
Power Supply: 9-13.8 volts depending on output power desired.
Harmonic Rejection: better than 50 dB
Crystal Controlled Oscillator: 40M crystal supplied.

Assembly Manual
Connecting the SAVXO to the NS-40 Transmitter.
Parts List
Builder's Notes, Modifications, and Feedback
Keying Circuits  Use one of these, a straight key, or the Magic Box
Educational and Supporting Information, Including Class E Design
Elecraft's Excellent Capacitor Identification Page  Posted with permission.
Electronics 2000 Resistor Code Graphic calculator  Posted with permission.

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