S-Band Neighborhood Enemy Electronic Defense


This is an attempt at building a proper pulse radar system using commonly available hardware store material, like copper plumbing pipe.  Really.  It will eventually be a full-blown Surface-to-Air Missle (SAM) system, but we have to start somewhere...

The pulse transmitter will be based around a design by John T. Zimmer (W2BVU) and Robert F. Guba (W1QMN) which was published by the ARRL in 1963(!)

It uses a 2C43 lighthouse triode operated as a re-entrant cavity oscillator with a resonant frequency of around 2.3 GHz for operation in the 13-cm ham band.

The 2C43 is high-voltage pulsed using an off-the-shelf marine radar modulator design and pulse transformer.

The 2C43 is designed for an average RF output power of around 2 watts, but by pulsing the anode voltage (approx. 2.7 kV @ 1 µs) it can reach a peak power of almost 2000 watts, depending on the particular 2C43's efficiency and output matching.

Using these old vacuum tubes is probably the easiest way to generate a large amount of peak RF power without being restricted to the frequency bands of commercially-available pulse magnetrons.  And it also avoids the hassle of having to parallel a bunch of solid-state modules to reach the same peak power.

The biggest drawback with this design is that the 2C43 hasn't been made for over 40 years, so you'll have to scrounge surplus tube websites, eBay, and hamfests for them.


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