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Variable-Frequency
Oscillator
Last Updated on:
Sunday, October 25, 2009 04:40 AM |
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Links to electronic circuits, electronic schematics, designs for engineers,
hobbyists, students & inventors:
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A Simple VFO for 80 & 160 Meters - This VFO is simple to build and is quite stable.
The VFO produces a two phase output (2 outputs), making it well suited to supplying a
signal to either single ended RF amplifiers, where only one ....(electronic design added
05/06/07) |
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Build a PIC Controlled DDS VFO 0 to 6 MHz - (schematic / circuit added 11/03) |
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FET Oscillators - This circuit comes from the Progressive Communications Receiver that
is in most of the recent ARRL Handbooks and the article "A Progressive Communications
Receiver", by Wes Hayward and John Lawson, QST, November 1981, Page 11…..(circuit added
10/09) |
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Huff-Puff Stabilizer - The credit for this circuit goes to Hans Summers, who developed
the circuit after my suggestion that magnetic coupling would work with a frequency
stabilizer. It uses a shift register (74HC4517) as a memory for the stabilizer and
provides excellent stability....(circuit added 10/09) |
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K7HFD Low-Noise Oscillator - This circuit appears in the ARRL 2000 Handbook, Page
14.18, and in Solid State Design for the Radio Amateur, by Wes Hayward & Doug DeMaw, Page
126. No buffer is necessary with this VFO. There is enough drive to go directly to a
diode mixer….. (schematic added 10/09) |
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NE602 VFO Oscillator - It's my opinion that the NE602 may have been overlooked as one
of the most stable VFO oscillators around. In the Signetics application note "Applying the
Oscillator of the NE602 in Low Power Mixer Applications", the NE602 is described as a chip
with three subsystems, a Gilbert cell mixer, a buffered emitter follower oscillator, and
RF current and voltage regulation.....(circuit added 10/09) |
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VFO Buffer Circuit - In the first design of the receiver, this buffer was used with an
FET VFO oscillator followed by a filter and a 2N5109 amplifier…..(designed added 10/09) |
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VFO/Buffer - It's basically a standard Hartley oscillator, followed by Roy Lewallen's
buffer (page 14.20 of the 2001 Handbook). Output is +7 dBm into 50 Ohms. Don't be tempted
to add a gate diode, this circuit doesn't need it, and it will degrade the phase noise
performance, according to Ulrich Rohde. It should be suitable.... (added 02/05) |
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VFO from 2001 ARRL Handbook, page 14.20 - (circuit added 06/07/08) |
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