These receivers, housed in dewar A admit beams which are, in Nasmyth coordinates, horizontally polarized.
The tuning band of the new A100 receiver (replacing the old 3MM1 (H polarization) receiver) is 83.5 - 115.5 GHz; its IF bandwidth is about 500 MHz. SSB receiver noise temperature is 80 K or less over the entire band; the image side band rejection is at least 20 dB.
The new A230 receiver (replacing the old 230G1) can be tuned between 200 and 255 GHz. SSB receiver noise temperatures range between 100 K near 220 GHz and 300 K at the highest frequencies. At 230.5 GHz, values near 150 K were measured. Image band rejection is of the order of 10 dB, the IF bandwidth is GHz at 3 dB.
Both receivers can be tuned entirely from the control room. Note however that little experience in operating the receivers exists at the time of writing. For more details see the report elsewhere in this newsletter.
A100 replaces receiver 3MM1 as the standard pointing receiver.