Four State QRP Group

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A Super VXO Designed by
Jim Kortge, K8IQY

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Kitted and Offered For Sale By The Four State QRP Group

Sold Out and Retired.

SAVXO stands for Stand Alone Variable Crystal Oscillator. This is a Super VXO design which has it's origins in the Super VXO of the SS-40 receiver. It is crystal controlled yet combines frequency agility with smooth stable tuning, and NO perceptible drift - even from a cold start. It is ideal for driving your NS-40 or other crystal controlled transmitter or recever, and is also a great starting point for a transmitter strip of your own design. As kitted the SAVXO will put out over 250mW by itself, plenty of power to operate QRPp.

The SAVXO can be used on any of the HF bands, just plug in your crystals for your frequency of interest, and change the low pass filter values (see table below). The amount of bandspread available is approxomatly 8-10 KHz on 40 meters and increases as the freqency is increased. Approximately 15-20 KHz on 20M and about 35 KHz on 10M for example. The kit is supplied with 40M crystals and can be ordered with one of two crystal choices. 7040 KHz for those who wish to cover the QRP calling frequencies, and 7122 KHz for those ops wishing to check into the Four State Wednesday night 40M net. Choose the appropriate Paypal button below for the frequency of your choice.

First time builders please note: This kit is not difficult to build. All parts are thru hole parts, there are NO SMT parts. The parts are wide spaced on the board making installation easy and the tuning control is board mounted. After the parts are installed the board is complete and ready to try out.

Specifications and Design Features
Tuning Range Typically 8-10KHz on 40M, 15-20 KHz on 20M, and about 35KHz on 10M.
Tuning Control Varactor with board mounted single turn potentiometer.
Stability: No perceptible drift! Even from a cold start.
Adaptability: Easily and Inexpensively adaptable to any HF band 160M - 10M.
PCB: Extra series inductor positions provided for experimentation.
PCB: High quality 1.25" x 4.25" silk screened printed circuit board.
NS-40 Ready: Comes with the components and instructions for driving the NS-40.
Note: If you have some chirp when keying the SAVXO barefoot or driving the NS-40, put a 22K resistor at the R6 location.

Assembly Manual
Using the SAVXO as a Stand Alone QRPp transmitter.
Test Driving the SAVXO on 17M. A complete 17M transmitter design by K8IQY.
Connecting the SAVXO to the NS-40 Transmitter.
T1 Winding Tutorial
Schematic  See page 7 in the Assembly Manual.
Parts List  See page 6 in the Assembly Manual.
Board Layout
Picture of Finished Board
Photopage   Check out Jim's 17M transmitter.
Low Pass Filter values for each HF band, 160M-10M.
W5USJ, Chuck Carpenter's SAVXO Page
K9PL's Review  in the K9YA Telegraph  (posted here with permission)  Thank you Philip.
Download WB8RCR's Dial Maker A generic dial can make an effective
  frequency indictor when used with a calibration chart such as this one.
Elecraft's Excellent Capacitor Identification Page  Posted with permission.
Electronics 2000's Excellent Resistor Code Graphic Calculator  Posted with permission.
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