That's what Jane's says:

"The China National Precision Machinery Import and Export Corporation (CPMIEC) Hongqi-2 (HQ-2, Red Flag-2) was the
result of a redesign of the HQ-1 system. The basic HQ-1 system was purchased from the then Soviet Union in the late
1950s, and was known as the System-75 Dvina.
On arrival in Chinathe system was renamed HQ-1. Shortly after arrival of the system and system components, China
and the USSR diplomatically fell out. Chinawas therefore forced to reproduce spare parts for its operational systems.
Furthermore, copying and reverse engineering resulted in a modified HQ-1 incorporating anti-jamming techniques this
system became known as the HQ-2.
In April 1965, co-ordination of the system development was assigned to the No 2 RA of the 7th Ministry of Machine
Building. An accelerated development programme then followed which resulted in the weapon passing its type
certification by the end of 1966. In July 1967, the complete system received its design certificate approval for
production. It was then used operationally to shoot down a Lockheed U-2 in September 1967.
The HQ-2 saw combat service with the People's Liberation Army Air Force in the late 1960s against Taiwanese-flown
U-2s; the missiles claimed five U-2s, one in each of the years 1967, 1968 and 1970 and two in 1969."