Saturday, 19 March 2016

Adjustable Attenuator


This week, much to my surprise, a variable 50 Ω RF attenuator arrived in the post. Sent by my friend and photography mentor Peter G., I feel renewed appreciation to him for his support over the many years of our email friendship. Many thanks Peter.

I searched for the product website and learned its specs:  JFW Industries datasheet

Here are some photos and sweeps:

Peter found it at a HAM flea market and did not get time to test it. I love the SMA connectors, since I standardized to them 3-4 years ago. Below lies just a few of my many sweeps. I dialed in an attenuation and spanned it to observe the flatness and attenuation compared to the dial setting.

Wow.  This thing works like a charm! I immediately put it into my test equipment arsenal.

Above — To the left of my bench lies a flip-lid, 3 drawer box, I keep my fixed 50 Ω attenuators with both BNC and SMA connectors; 1 each SMA + BNC barrel connectors, 50 Ω terminators and  return loss bridge 50 Ω terminators in the top compartment — ready for quick access.

Above — Another view of the test equipment storage box that sits on the left edge of my bench. The new variable attenuator now sits in the middle drawer of this box.

Out Takes

I've not posted much this year and likely won't due to other competing interests. Most of my radio time gets spent reading and learning about radio frequency design theory.

Above —The output pulses of a phase-frequency detector.

Above —"Scope art". An oscillating PLL loop. Not nice to see in your synthesizer circuit, but nice to look at from an aesthetic viewpoint.