Phase Locked Loop Frequency Synthesizer Demonstration Board - This document details the evaluation procedures and usage of the Hewlett-Packard HPLL-8001 demonstration circuit board and evaluation software. All operating conditions and electrical characteristics of the HPLL-8001 are described in the current version of the data sheet__ HP Application Note 1145 Phase Shift Radio Direction Finder - Similar to the system used in modern aviation where an antenna array modulates the phase of an incoming signal. The commercial system is known as Commutated Aerial Direction Finding (CADF) where a ring of 18 identical antennas are each switched on in sequence, just like winding a rotary switch round and round so that one antenna is always connected to the receiver. __ Designed by Harry Lythall-SM0VPO
Pi Filter has Sharp Notch - Simple filter network makes a great low-pass filter having a sharp notch just outside paSSBand. Can be implemented as active filter using GIC circuit. Use this component calculator to determine resistor and capacitor values. Voted best of issue! __ Designed by Jim Haggerman, Hagerman Technology LLC
Pic-Plot GPIB to RS-232 converter - Get rid of dry plotter pens or unclear camera snapshots of test instruments when reporting your lab test session. This adaptor will capture plots or prints of your GPiB instrument to your PC through the serial port. __ Designed by Andrea IW9HJV and Johnny IW9ARO
Pic-Plot2 GPIB to USB converter - Pic-plot goes to USB Without any additional adapter, the new Pic-plot2 directly communicates with your PC or laptop through the USB port. Gives faster downloads from your GPiB instrument and it is self-powered from the host PC: no need of DC adaptor. __ Designed by Andrea IW9HJV and Johnny IW9ARO
Plastic Pipe Finder - i used this circuit once to track down the location of a plastic pipe, buried underground. it transmits a weak RF signal, which can be picked up by a portable AM radio from about 6 feet away. . . Circuit by Dave Johnson P.E.-December, 2004
Pocket sized 20m (30m) CW QRP transceiver - i started to discover the 30m band by using an adapted version of my 80m single-board CW transceiver. The first impressions were quite encouraging, so I decided to build a portable transceiver for this interesting band. There was no dilemma about the modulation the transceiver has to support, since the SSB is on 30m not allowed. I also decided not just to adapt an earlier design, but to design a completely new transceiver. The goal was to make a gear that would be based on a superhet receiver, would measure less than 10cm x 10cm x 5cm and would include a digital frequency read out __ Designed by Aleksander Stare
Pop Free Microphone On/Off Switch Circuit - This circuit uses a simple technique to eliminate the usual “pop” sound when an electret type microphone is switched on or off. The circuit is completely passive and will work on dynamic and electret type microphones. . . Circuit by David A. Johnson P.E.-February, 2002
Popcorn direct Conversion receiver - schematic for a no-frills, relatively low-cost CW superhet receiver with a 4.00 MHz intermediate frequency. There is no AGC or RF gain control, however this receiver has good large signal handling capability. This receiver uses just 6 bipolar transistors and an op amp for reasonable volume into headphones. Much__
Post Mixer Amp - SSB Transceiver-Receiver Section: The post mixer amplifier, makes up for the losses in the passive mixer and i.F. port attenuator. The transistor is a 2N4427, if you don't have one, try a 2N3866, 2N5109, on any similar, medium power VHF transistor. The output transformer is 10 turns with a tap at 4 turns. The core is the same, high permeability ferrite ring, used in other parts of this project. The output supplies DC current for the RX/TX switching diodes at the SSB filter input __ Designed by EI9GQ homebrew radio
Precision measuring receiver (Selective Level Meter) - This receiver was designed to precisely measure communication channel power over a 90 dB or greater range. This is useful for monitoring and installation of radio communication systems. The basic design can be adapted to the low VHF region through 6 GHz. A TCXO and PLL synthesizer assure accurate frequency setting, while a precision Logarithmic Amplifier (Log Amp) detection scheme __ Designed by Steve Hageman
Programmable PLL (Si570) Local Oscillator for HF Receivers, Transmitters, Transceivers (PDF) - A new product has recently been developed by Silicon Labs, the Si570 DSPLL® programmable
frequency synthesizer, and it has great potential for use in many amateur radio applications.
Here we will explore some possible uses. Phase lock loop technology has been in use for many years, but the ability to use variable software-supplied loop parameters in PLL technology to directly generate square waves with frequency resolutions of 1 Hz or less is now possible. The Si570 immediately puts the new technology into the sphere of uses that has been recently been dominated by Direct Digital Synthesis (DDS) products.
__ Designed by Silicon Labs\
Protects Phone Line from Lightning Strikes - To build a circuit that will help protect your equipment from lightning strikes on the phone line. This circuit was actually designed to reduce or eliminate a very local broadcast AM radio stations signal from bombarding my parents telephone line, however it also turned out to be a really good lightning protector. __ Designed by Kevin Custer W3KKC
PSK Meter (updated 4'th of october 2005) - PSK-Meter is a controller board to prevent overload of a transmitted PSK-signal at the HF-bands (made in February 2004) __ Designed by Bjarke Korsgaard
PTT and soundcard interface for the TM255/455 - Ham Radio - Modems and Soundcard interfaces __ Designed by Guy Roels ON6MU
PTT and/or soundcard interface - Ham Radio - Modems and Soundcard interfaces __ Designed by Guy Roels ON6MU
Pulse Counting Receiver - Hi Fi quality, high sensitivity, and only one tuned circuitPopular in the UK but virtually unknown elsewhere __ Contact blehack @ yahoo dot com
Puxing radio serial interface schematic, easy to make - Schematic only, no circuit description given __ Designed by Thomas Scherrer OZ2CPU |