40m DC-receiver – VFO

So the receiver is alive and kicking and I have received amateurs from The Netherlands, UK and Italy on a simple 10m wire antenna. However, the VFO is comprised of a Siglent SDG1032X function generator from work. Hardly a self-contained solution!After an article by Bill Merea in the GQRP Sprat magazine, I’ve decided to […]

40m DC receiver – “It’s alive!”

With a three day Pentecost weekend and my wife away on a camping trip with my son, I had some time to look into the receiver again. With the previous series of tests, I’ve found that product detector was working fine and featured good conversion gain. The LO oscillator injection was flawed because the […]

Double-balanced cross-coupled product detector

The double-balanced cross-coupled product detector had a brief stint of popularity in the 70s and 80s. It’s popularity quickly faded once integrated product detectors like the Plessey SL640, Motorola MC1496/1596 and the CA3028A came on the market. Offering ease of use and further integration. My attention was first drawn to the cross-coupled product, when […]

Brickwall audio filter

For my 40mDC receiver, i was looking for a good audio filter that I might reuse for multiple receivers. While browsing in old magazines I came across a filter designed by Robert Penfold. It was featured in an article in Ham Radio Today March 1986 (see download section).

The brickwall audio filter […]

40m DC receiver (2)

After my previous attempt at building a 40m DC receiver failed (I received nothing but noise while at my Kenwood HF receiver, plenty of signals were heard), I made some changes to improve the sensitivity and to add some features that were desperately needed..

[…]