Expanding the transmit range of an amateur radio transceiver is probably the most common modification. Because of its use associated with the Military Auxiliary Radio Service (MARS) or Civil Air Patrol (CAP), this modification is often referred to as MARS or CAP mod. This article shows how to perform this extended transmit modification on the […]
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Radio Frequency (RF)
FT-101E and IC-718 Repair Impressions
Over the past weeks I had KF5FBR’s Yaesu FT101E ad N5WSA’s Icom IC-718 on my bench for various services. The FT-101 needed a general health check and brand new capacitors. No output powers was the problem the IC-718. The latter was caused by burned out final transistors. While working on them, I shot some pictures […]
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L-Network impedance matching
Impedance matching is an everyday problem for RF circuit designers. The L-Network is one of the easiest lossless ways of matching a low source impedance to a higher load impedance. This article shows how they work and how to design them. Matching a transistor amplifier’s low output impedance with the higher impedance of an antenna […]
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Review: Analog Devices ADF4360 PLL Synthesizer
The ADF4360 series from Analog Devices is a a family of integer-N-synthesizer chips with on-board VCOs. Since the chips cover all amateur radio bands between 4m – 13 cm and are rather inexpensive, they are predestined to be used in homebrew amateur radio equipment. Not too long ago I reviewed ADI’s wideband PLL synthesizer ADF4351 […]
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Review: Texas Instruments CC2531 USB Evaluation Module Kit
The CC2531 is the second generation ZigBee/IEEE 802.15.4 compliant System-onChip with an optimized 8051 MCU core and radio for the 2.4 GHz unlicensed ISM/SRD band from Texas Instruments. But what good is it, really? To make the evaluation of the CC2531 a bit easier, TI put together the CC2531EMK. The CC2531EMK is a an evaluation […]
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DIY Passive Probe for the GHz range
Passive probes for the GHz range are costly and it’s usually not too economical to invest into one if you’re just a hobbyist. But regular, cheap probes will not work on signals in the GHz range. So is there a homebrew solution? Yes, there is, check it out! Every passive probe and every piece of […]
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Review: Analog Devices ADF4351
Frequency generation is usually a very critical part in every RF design. The higher the target frequency, the higher complexity. Usually. With the ADF4351, Analog Devices offers an effort-saving component level solution for frequencies up to 4.4 GHz. The ADF4351 from Analog Devices (ADI) is a modern wideband PLL synthesizer with integrated low phase noise […]
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Quick look at a BPSK31 signal
PSK31 is gaining more popularity among amateur radio enthusiasts. It’s extremely small bandwidth and excellent performance in weak signal conditions make this mode perfect for low power HF stations. PSK31 is a digital transmission mode with just about 31 Hz bandwidth. The signal conveys data at a data rate of 31.25 baud and is extremely […]
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Why PSK31 over FM is nonsense
The current issue of ARRL’s magazine QST features an article about PSK31 on 2m in FM. This article is going to show why this is an unnecessary waste of bandwidth and therefore nonsense. PSK31 is a digital transmission mode designed for minimum bandwidth and great performance even in weak signal conditions. Sending a PSK31 signal […]
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DSSS / BPSK Clock Recovery with the Abracon ABFT
Clock recovery in Spread Spectrum applications and BPSK modulated signals can be somewhat tricky. There are no commercial solutions available solely for this task either. Or are there? This article shows a great off-label use of the Abracon ABFT. Clock recovery in a Direct Sequence Spread Spectrum (DSSS) receiver can be quite a challenge. Because […]
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