The Jammers

Shown here are the more common airborne jammers used during the war, along with links to expand on the individual pieces highlighted. Code names were assigned to each of the jammers to enhance security and make it easier to remember the growing array of capabilities that was represented by the various models. Beginning at upper left is an AN/APT-3, with the AN/APT-2 and AN/APT-1 to its right.

On the second row is an AM-18/APT Class B linear amplifier, used to raise the power level of jammers in the 140-210 MHz range to 100W. In the center is a training version of the APQ-2 jammer, and to its right, an AM-14/APT - another Class B linear designed to work in the 85-150 MHz range, also with a power output of 100 watts.

The third row, left to right, starts with one of a series of five jammers aimed at disrupting German tank radio traffic, the ART-6 through ART-11. This particular one is an ART-7, which covers the 10 meter ham band. To its right are three pieces covered on another page, the ARQ-8. Both that ART-7 and ARQ-8 were intended as communications jammers, targeted towards German capabilities, but represent an entire series of such jammers. Two more (not shown in this bay) were the AN/ARQ-1 and the AN/ART-2. The ARQ-1 was one of the first integrated spot jammers made for communications jamming, incorporating a receiving capability to determine specific threats and then switching to jamming mode. It joined a variety of conventional AM transmitters that had noise sources added to them but needed sometimes complex tuning procedures before the jamming was effective. Since its development was parallel to other more capable systems, its operational use was rather short. The ART-2 had a higher output power but was rather specifically designed for installation in single seat carrier fighter planes for use as a barrage jammer against Japanese walkie-talkies.

The bottom row, left to right, displays the AN/APT-5, APQ-9, and AN/APT-9 jammers.

Most of these jammers respond to minor reversible conversion to AM or DSBRC operation on the ham bands, though their stability is sometimes not the greatest. Frequency setting can be a bit of a chore as well.

The antennas used with these jammers can form a daunting collection effort all by itself. The more complex ones represent a sea change in understanding the physics of wave propagation and impedance transformation to open air. Below are some of the more common antennas that were designed and deployed in WWII for this equipment:

AS-251 fishhook antenna, used with APT-2, APT-5, APT-9, and APQ-9 jammers

AS-69, the predecessor to the AS-251 - part of the Carpet jamming system against Wurzburg radars

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