The EF-4C Wild Weasel IV was a development of the F-4C, designed in parallel with the F-105 Wild Weasel III program. This aircraft, like the modified F-100F and F-105F, was intended to detect and attack North Vietnamese surface-to-air missile sites. The EF-4C designation was not official.
These EF-4C aircraft were modified F-4Cs which were fitted with electronic equipment that was designed to detect, identify, and locate enemy surface-to-air missile radar installations. The EF-4C aircraft were fitted with the AN/APR-25 Radar Homing and Warning System (RHAWS) with antennae mounted on the top of the vertical fin as well as inside the empty infrared seeker fairing mounted underneath the nose. This system could give the direction of threats and could assign priority to them. An AN/APR-26 SAM launch warning system was also fitted, with a blade-like omnidirectional antenna installed underneath the nose just behind the infrared seeker fairing. An ER-142 electronic countermeasures receiver was installed. Frequently, the EF-4C carried a Westinghouse AN/ALQ-119 noise and deception active electronic countermeasures pod underneath the forward fuselage.
The F-100F and F-105F had always been viewed as interim *Wild Weasel* aircraft, pending the availability of the Wild Weasel IV EF-4C Phantom. However, the entrance of the EF-4C into combat in Vietnam was delayed by numerous problems. Among these were insufficient internal space to house the electronic equipment, electronic interference between the various components of the system, and mechanical vibrations of the panoramic receiver pod that was mounted in the starboard rear Sparrow recess. It was not until 1969 that these problems were fully resolved.
36 F-4Cs were ultimately modified to the Wild Weasel 4 configuration. Serials were 63-7423, 7433, 7437, 7440, 7443, 7447, 7452, 7459, 7462, 7467, 7470, 7474, 7478, 7481, 7508, 7512, 7513, 7565, 7567, 7574, 7594, 7596, 7607, 7615, 7623 and 64-0675, 0741, 0757, 0781, 0787, 0790, 0791, 0815, 0840, 0844, and 0847.
The first EF-4Cs entered service in June 1968 with the 4537th Fighter Weapons Squadron, an operational conversion and tactic development unit based at Nellis AFB in Nevada. At that time, this squadron was part of the 4525th Fighter Weapons Wing. The 4525th was redesignated the 57th Fighter Weapons Wing in October of 1969, and at the same time the 4537th FWS became the 66th FWS.
Overseas deployment of the EF-4C Wild Weasel IV began in March of 1969 with the 80th TFS, 347th TFW at Yokota AB in Japan. However, these planes were transferred in March of 1971 to the 67th TFS, 18th TFW based at Kadena AFB on Okinawa. The 67th TFS relocated to Korat RTAFB in Thaliand in 1972-72 to take part in the Linebacker raids.
The EF-4C was intended to detect and attack the Fan Song track-while- scan radar that was used to guide the SA-2 Guideline surface to air missiles. The primary armament of the EF-4C consisted of the Texas Instruments AGM-45 Shrike anti-radiation missile, plus an array of cluster bombs and conventional iron bombs. The Shrike missile proved to be rather unreliable in service, since it had to be preset before takeoff in order to home in on a particular frequency. The EF-4C could not carry or launch the AGM-78 Standard anti-radiation missile.
In December of 1969, EF-4Cs were issued to the 81st TFS of the 50th TFW, stationed at Hahn AFB in Germany. The The 81st TFS was transferred to the 86th TFW at Zweibrucken AB in January of 1972.
In 1973, surviving EF-4Cs were retrofitted with the Itek AN/ALR-46 electronic countermeasures receiver which provided fast digital processing in a bandwidth ranging from 2 to 18 GHz. Antennae for this system were placed on the tailcone at the base of the vertical fin as well as on the lower fuselage immediately aft of the nose radar. It interfaced with a cockpit display and provided automatic control of jamming assets. In addition, an AN/ALR-53 long-range homing receiver was mounted which could guide aircraft toward surface threats.
After being replaced by later, more capable versions of the Wild Weasel Phantom, many EF-4Cs were returned to F-4C status and then turned over to the Air National Guard. These ex-EF-4Cs were turned over to the 113th TFS of the 181st TFG and the 163rd TFS of the 122nd TFW, both with the Indiana Air National Guard, which received these planes in 1979. However, neither squadron was actually assigned the specialized Wild Weasel mission, and both squadrons flew their EF-4Cs in the conventional strike role. Both Indiana ANG squadrons exchanged their EF-4Cs for F-4Es in 1988.