So far the Electronic Warfare made life more "interesting" for the SAM operators, but with experience and luck, they were still able to achieve...
... but it changed during the next year of the Vietnamese war, 1967
US EW agencies found out the frequency of the SA-75MK Dvina (SA-2B/F) missile beacon, and it turned out to be in a narrow 20MHz range.TAC
immediately started to send planes with two QRC-160-1/1A
pods, where one pod was solely dedicated for the missile beacon noise jamming
.For several months, all missiles were lost right after launch.
A new rule was enforced that before launch, the missile beacon channel should be checked for jamming.
If jamming was present, it was forbidden to launch.
As the situation become critical, Soviet experts were called in to find out and test the solution.
During 1969, Technical Bulletin-1 was released to all Soviet allies using the SA-75MK Dvina system.
It introduced several modifications:
- Adding the H<1 switch by modifying the missile guidance electronic, reducing the minimum effective altitude into 500m.
- Adding the RAB.po.K3 switch, in case of radio proxy fuse jamming. (this was feared by the Soviets, but never happened)
- Adding the PA-00 cabin "doghouse" at the top of the RSNA cabin for visual target tracking, in dense jamming environment.
- Adding the APP-75M instrument, to make launch calculations automatic.
- V-750VK missile FR-I5AK beacon output was increased from 20W into 80W.
After this bulletin was implemented, the beacon jamming become ineffective, and TAC stopped using it.
Quite interesting, that SAC never received hint of this modification, so the B-52 bombers were still trying to jam the missile beacon in 1972, using up valuable jammers for nothing.
Still in the same year (1967), the QRC-160 become official.QRC-160-1/1A E band Barrage Noise Jamming pod
become the AN/ALQ-71
, capable of jamming the S-25 Berkut (SA-1), SA-75MK Dvina (SA-2A/B/F), and the SON4, SON9 AAA systems. QRC-160-2 I band Barrage Noise Jamming pod
become the AN/ALQ-72
, capable of jamming the S-125 Neva (SA-3) system.
This pod was sent into the Vietnam War, but was never flown operationally proving that the S-125 Neva (SA-3) was never used by the Nort Vietnamese during the war. QRC-160-8 D..G band Barrage Noise Jamming pod
become the AN/ALQ-87
, capable of jamming the S-75 Desna (SA-2C), S-75M Volhov (SA-2E) beside the systems already covered by the AN/ALQ-71.
also prepared to face new Soviet SAM equipment in Vietnam, by fielding the AN/ALQ-49 G/H band Angle Deception Jamming System
, against the expected S-75 Desna (SA-2C) and the S-75M Volhov (SA-2E) system.
It complemented the already fielded AN/ALQ-51.