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40/20 trap dipole - Portable 40/20 trap dipole - Here's an easy to make trap dipole for 40 and 20 meters. I made this for portable operations, mostly for "to the field" type QRP contests. Being able to switch bands between 20 and 40 quickly and without re-adjusting an antenna tuner is a nice feature. The only problem is it's a little heavy with the feed line and all, and putting it up in the raw New England woods can be daunting. __ Designed by Steven "Melt Solder" Weber KD1JV A Dirt-Cheap, High Current Power Supply - Here's yet another use for that pensioned-off AT computer that's gathering dust in the corner.__ SiliconChip
Advanced VHF Power Meter - The DVM (Digital Volt Meter) also displays the correct polarity sign. There’s neither rocket science nor smoke and mirrors here folks: it’s all done simply with op amps and resistors! __ Designed by Prject Wes Hayward, W7ZOI and Bob Larkin, K7PUA that appears in QST, June 2001
Balanced Frequency Converter (Suitable for Frequencies up to 50kHz) - This circuit takes advantage of aliasing that occurs in any time sampled system. The output signal frequency is the difference in frequency between the input signal and the switch sampling rate. A 24KHz input signal sampled at 25KHz will be converted to a 1KHz output signal. in addition by using the LTC1992 fully differential __ Linear Technology/Analog Devices App Note, Mar 16th 2010
Bidirectional Current Source - The LT1990 is a differential amplifier with integrated precision resistors. The circuit shown is the classic Howland current source, implemented by simply adding a sense resistor. __ Linear Technology/Analog Devices App Note, Mar 31, 2010
Bipolar, Ground Referenced, Single-Ended Signal Interface to Unipolar, Differential Input ADC - Differential amplifiers are useful for providing the input to a single supply differential ADC from a bipolar ground referenced input source. All of the signal level shifting and gain requirements can be adjusted with external resistors. __ Linear Technology/Analog Devices App Note, Mar 16th 2010
Convert 2m VHF FM PMR Transceiver Motorola Radius M110 into an AM ateur Radio - Turn a professional 2m VHF FM PMR transceiver Motorola Radius M110 into an amateur radio __ Designed by Aleksander Stare
Dirt-Cheap, High Current Power Supply - Here's yet another use for that pensioned-off AT computer that's gathering dust in the corner.__ SiliconChip
Full-Bridge Load Current Monitor - The LT1990 is a micropower precision difference amplifier with a very high common mode input voltage range. it has pin selectable gains of 1 or 10. The LT1990 operates over a ±250V common mode voltage range on a ±15V supply. The inputs are fault protected from common mode voltage transients up to ±350V and differential voltages __ Linear Technology/Analog Devices App Note, Apr 5th 2010
High input IP3 mixer enables robust VHF receivers - 08/29/14 EDN Design Ideas: LTC Design Notes 515: An increasing number of applications occupy the 30MHz to 300MHz very high frequency (VHF) band. Television and radio broadcasting, navigation controls and amateur radios are a few examples. Modern RF component development is aimed at much higher frequency bands used for voice and data communications systems Design by Andy Mo
Low Noise AC Amplifier with Programmable Gain & Bandwidth - Two LTC6910 programmable gain amplifiers can be combined to provide independent gain and bandwidth control using two 3 bit digital words. The Gain Control PGA simply varies the circuit gain from 1 to 100. The Bandwidth Control PGA puts signal gain inside the feedback loop of the amplifier. As this gain is increased the effective value of feedback resistor R2 is decreased. This pushes out the upper low pass corner frequency of the ac amplifier. __ Linear Technology/Analog Devices App Note, Mar 16th 2010
LTC Design Note: High input IP3 mixer enables robust VHF receivers - 08/29/14 EDN Design Ideas: LTC Design Notes 515: An increasing number of applications occupy the 30MHz to 300MHz very high frequency (VHF) band. Television and radio broadcasting, navigation controls and amateur radios are a few examples. Modern RF component development is aimed at much higher frequency bands used for voice and data communications systems Design by Andy Mo
One transistor HF/VHF/UHF preamp using one BSX-20 transistor - The MAR6 (MSA-0686, 0685, 0885) is a high performance silicon bipolar Monolithic Microwave integrated Circuit (MMIC ) housed in a low cost, surface mount plastic package.
This MMIC is designed for use as a general purpose 50 W gain block. Applications include narrow and broad band iF and RF amplifiers in commercial and industrial applications. __ Designed by Guy Roels ON6MU
Parallel Port VHF FM Receiver - Use it to monitor the 144-148MHz amateur band, the 132-144MHz band or the 118-132MHz band.__ SiliconChip
Single Supply Video Line Driver (AC Coupled) - When AC-coupling video, the waveform Dynamics change with respect to the bias point of the amplifI er according to the scene brightness of the video stream. in the worst case, 1VP-P video (composite or Luminance + Sync in Y/C or YPBPR format) can exhibit a varying DC content of 0.56V, with the dynamic requirement being __ Linear Technology/Analog Devices App Note, Mar 25th 2010
TRF VHF Wireless Data Receiver - This receiver is little more than a crystal set with gain. Operating voltage range spans 3V to 5 V. The one on my bench runs down below 2.5 V. Why TRF? The beauty of this approach lies in its simplicity and lack of critical components. A transistor is used as an RF detector/amplifier, with the emitter and collector at AC ground (no such thing as Miller capacitance here!). All the gain occurs at baseband, and most of that gain occurs in a very inexpensive but good dual op amp. if the LC resonant frequency is pretty close to the transmitter's frequency, it will work. __ Designed by Dick Cappels
VHF 6 Meterband RF Amplifier - Ham Radio - AF Amplifiers - Schematic __ Designed by Guy Roels ON6MU
VHF Audio Video Transmitter - Build your own LC Meter and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for__
VHF Condor 16 transceiver modifications - Ham Radio - Other __ Designed by Guy Roels ON6MU
VHF FM TDA7000 Receiver - Very nice and simple design by Harry Lythall __ Designed by YO5OFH, Csaba Gajdos
VHF Receiver Converterer - For Q1 and Q2 I used a pair of 3SK45 dual gate FET's. Most VHF N-Channel dual gate MOSFETs should work fine. I have used 3SK88, BF961, and BF981 FET's in this circuit. if you decide to use a GaAsFET for Q1, you will probably need to use a Zener diode to reduce the drain voltage to a safe level. L1 is 5 turns of 1mm copper wire, tapped at 1 turn, coil diameter 7mm, L2 and L3 are 5 turns each. T1 primary is 9 turns on a Toko 10mm former (old iF transformer) T1 secondary is 2 turns. The screening can and outer ferrite cup are not used. __ Designed by EI9GQ homebrew radio
VHF Receiver for Weather Satellites - Build this compact 2-channel VHF FM receiver and pull in your own weather satellite pictures.__ SiliconChip
VHF transmitter - Schematic only __ Designed by Peter Jakab
VHF Video Transmitter 60-200 MHz - Here's a simple video transmitter for VHF TV channel will accept baseband video input, hence it can be driven by most CCD cameras and VCR video outputs. it ouputs roughly 80mW and when used with a 40cm telescopic antenna over 100 meters range is possible.__
VHF Wireless Data Transmitter - This project is only an example of what can be done. The legalities of building and operating radio transmitters are different in different parts of the world. Be sure to check your local laws before building or operating a transmitter like the one shown here. __ Designed by Dick Cappels
VHF/UHF Prescaler - The recommended Prescaler is ridiculously simple. it consists of just one IC , a TV tuner prescaler, the Philips SAB6456A, which can divide by 64 or by 256. This chip is widely available both new and in the surplus market at much lower prices than conventional divide by 10 prescalers. __
VHF/UHF TV Modulator - Simple oscillator that generates a frequency in the VHF or UHF region. The oscillator is modulated with the video signal and the modulated carrier wave thus generated is fed into the TV set's aerial input via a cable. Then all that remains to do is tune the TV to the correct frequency. __
Wideband Digitally Programmable Gain Amplifier - The LTC6910 is a CMOS
programmable gain (from 0 to 64) amplifier. The amplifiers provide for a differential input signal and for dc biasing the output into a precise voltage reference based level in a single supply design. __ Linear Technology/Analog Devices App Note, Mar 16th 2010
Wideband VHF/UHF/SHF 22dB RF preamp with MAR-6 or MAR-8 (MSA-0885) - The MAR6 (MSA-0686, 0685, 0885) is a high performance silicon bipolar Monolithic Microwave integrated Circuit (MMIC ) housed in a low cost, surface mount plastic package.
This MMIC is designed for use as a general purpose 50 W gain block. Applications include narrow and broad band iF and RF amplifiers in commercial and industrial applications. __ Designed by Guy Roels ON6MU |
