在對 this answer的評論中引用的論文中，在1950年代，具有便攜式天線的射電天體位置如何如此精確，可以將其分配給昏暗的光學對等物（類星體）？
1963年的論文是Accurate Measurement of the Declinations of Radio Sources（單擊小的PDF圖標），並且在下面引用了包含短語"晶體混合器"的兩個摘錄以及框圖。
當我聽到"晶體"時，我想到的是振盪器的石英晶體，或者帶有氧化物表面的金屬晶體（例如方鉛礦），用於使用cat's whisker contacts來製造二極管，但是對於混頻器中的二極管檢測，真空管和固態半導體二極管存在於1960年代，儘管我不知道960 MHz下的性能。
The arrangement of the components of the receiving equipment is shown by the block diagram of Figure 1. The receivers were of the superheterodyne type, and the crystal mixers were connected by short lengths of cable to the antenna feeds without any pre- amplification at the signal frequency. The local oscillator frequency was 960 Mc/s, and the center frequency of the IF amplifiers was 10 Mc/s, with a band width of about 4 Mc/s. No attempt was made to reject the image response of the superheterodyne. Note that the IF amplifiers were split into two sections. The IF preamplifier was located at the prime focus of the paraboloid along with the mixer and amplified the signal sufficiently to allow it to be fed through a long connecting cable to the remainder of the receiver, which was located in the laboratory building.
The local oscillator power for each half of the receiver was supplied by a separate klystron oscillator, which was phase-locked by a closed-loop servo system to reference signals of a common, central origin. The high-frequency refer- ence signal power required by the system for a satisfactory lock was about six orders of magnitude weaker than the available local oscillator power required by the crystal mixers of the superheterodyne receivers. The problem of getting phased local oscillator power to the two antennas when they were being used at large separations was thus greatly simplified.