Products

This version of the PG-TIA amp follows the original Hayward and Kopski design by being bidirectional. By powering the left to right amplifier, the signal goes that way. If powered right to left the direction is ...

The performance of a receiver or transmitter depends on careful impedance matching between its sub-systems: its mixers, filters, and amplifiers. Mismatches can cause loss of signal strength, inter-modulation ...

Adding automatic gain control to a TIA IF amp makes the audio volume of a receiver as predictable as the impedance of the amp itself. AGC keeps strong signals from blasting-out your eardrums ...

The Hayward-Damm design (published in the December 2007 issue of QST) has long been extolled as excellent, but its complexity has discouraged a number of would-be builders ...

A general purpose, discrete-component audio amplifier with selectable three or four pre-amp stages. Based on a design by Richard Andersen, KE3IJ (SK). Live a little . . . use something other than an LM386 ...

The operational amplifier–the "op-amp"–was created to do by analog means what we now do digitally: to simulate mathematical operations. In application, though, op-amps have long been used for so-much more ...

The Mini-Circuits MAR-6SM+ MMIC is small but powerful. It has a bandwidth from DC to 2GHz, a gain of 22dB at HF frequencies, a very-low noise figure of 2.3dB, and--wait for it--a termination-insensitive I/O of 50Ω ...

I wanted to replace the drifty VFO in one of my rigs with a digital solution, but my hand-wired solution was messy, fiddly, and prone to ground loops and digital noise. So I designed a PCB ...

IN DEVELOPMENT: An all surface-mount Universal Digital VFO/BFO Module a quarter the size of the through-hole versions currently available. A Raspberry Pi RP2040 microcontroller and Si5351A clock generator will share the same small PCB and, like ...

A clean, ripple-free and narrow-skirted "xtal" filter is essential for excellent performance, especially in a receiver. They are, however, among the most difficult builds for a home-brewing amateur to pull off ...

In Development: A PCB and kit for single-band low-pass filters based on the "CWAZ" (Chebyshev with a zero) design by Jim Tonne, WB6BLD, and popularized by Ed Wetherhold, W3NQN. The virtues of this design is that ...

Protect yourself from reverse-polarity mayhem and from the assault of noise coming in through your DC power input. At the same time, you can monitor the current draw of your homebrewed rig. Here's three versions of ...

After several months of development, MDRF is pleased to offer this kit version of N6QW's P3ST SSB transceiver for 15, 17, or 20 meters (it can be built or modified or any one of these). It's ...

J310 JFET transistors in through-hole versions have not been manufactured for years, but SMD versions still are. These little half-inch breakout-boards combine two surface-mount J310s into a single dual-gate JFET. They are useful for a number ...

Dual-gate MOSFETs were once common in Ham radio designs, but no through-hole versions are now available on the market. These little half-inch breakout-boards with pre-soldered SMD versions might make ...

A breakout PCB for the BFR106 NPN 5GHz transistor. It’s proven to be useful as a “hotter” replacement for more-commonly used devices. With an transition frequency at 5GHz, there’s a lot more gain available for the ...

The circuit of a diode-ring mixer is simple, but making one with good balance, high isolation between inputs, and low-insertion loss is not trivial. It's absolutely doable for a home-brewing Ham, but a wise person chooses ...

The Mini-Circuits MAR-6SM+ MMIC is small but powerful. It has a bandwidth from DC to 2GHz, a gain of 22dB at HF frequencies, a very-low noise figure of 2.3dB, and--wait for it--a termination-insensitive I/O of 50Ω ...