Diplexer with integrated Bias-T (Triplexer) for QO-100 and X-band microwave reception using LNBs

This article shows how to build a simple Triplexer (Diplexer plus integrated DC Bias-T) for use with commercial TV LNBs for QO-100 or X-band microwave experiments. Introduction When using modified, commercial LNBs for reception of the QO-100 amateur radio satellite or X-band microwave experiments, it is necessary to pass a clock-reference signal, a DC supply […]
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Universal Clock Translator using Renesas VersaClock 6E Devices

Due to the popularity of the QO-100 geostationary amateur radio communication satellite, precision GPS reference frequency sources (GPSDO) are becoming more and more common in home labs. The desire to derive different, fixed frequency signals from a GPSDO has similarly been increasing as different devices requiere different reference clocks with different frequencies. Therefore, this article […]
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LNB Modification for 10 GHz QO-100 Satellite Reception

This article shows how to modify an inexpensive LNB to accept an external LO-reference signal in order to be used as a K-band downconverter for QO-100 (Qatar Es’hail 2) amateur radio sattelite reception, radio astronomy or similar K-band experiments. This article is a shortened version of a scientific paper that I wrote as the lead […]
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JFET-based infinite impedance detector for AM-demodulation

The so-called “infinite impedance detector” is a circuit that was commonly used in the old days of vacuum tubes. Since vacuum tubes can be somewhat considered to be heated JFETs, it is evident that such a circuit can also be built using a more modern, silicon-based approach. This article covers my first experiments with a […]
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SITOR-B / NAVTEX Test Signal Generation

This article shows how to generate valid NAVTEX message bitstream using an Arduino. The Arduino implements proper CCIR476 character encoding, SITOR-B forward error correction, synchronization and phasing signals. An entry-level function generator is then used as a FSK modulator on 518 kHz where it can be received by a NAVTEX receiver. UPDATE: There also is […]
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VHF LDMOS Power Amplifier Experiments

The NXP MRF101 series high ruggedness N-channel Enhancement-mode lateral MOSFETs promise over 100 Watt CW output power and slightly over 20 dB gain from 1.8 MHz all the way up to 250 MHz. Their mismatch insensitivity for a VSWR of greater than 65:1 without significant device degradation makes these devices extremely interesting for amateur radio […]
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ICS501 / ICS501 VHF Experiments

The ICS501 / ICS511 from Renesas are easy to use, fully integrated clock multipliers for output frequencies up to 200 MHz. What makes them particuarly interesting is the integrated crystal oscillator circuit and ability to produce some fractional multiples, such as 6.25 or 2.5. So let’s find out if they’re interesting for the hobbyist who […]
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Lumped-Element Wilkinson Splitter / Combiner Design

This is a supplemental article to two of my videos on my YouTube channel about the theory and design of Wilkinson splitters and combiners. A Wilkinson divider is a specific class of power divider with high isolation between the output ports. This feature is particularly useful when used as a combiner. This article will show […]
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850 MHz Scanner Preamplifier / Filter Project

This article shows how to use off-the-shelf parts to improve the performance of a radio scanner in the 800 – 900 MHz band. Furthermore, it shows how to expand radio coverage by using two different receive antennas at the same time. For some reason, my new BCD996XT scanner wasn’t working as expected on the statewide […]
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