For your 6.6685 GHz methanol-line receiver, the best Mini-Circuits connectorised choice is probably:
Mini-Circuits ZX60-14LN-S+
- Frequency range: 50 MHz–10 GHz
- Gain: approximately 22 dB
- Noise figure: about 1.5 dB typical, and specified below 2 dB to 7.5 GHz
- Supply: 6 V, approximately 72 mA
- Connectors: SMA
- 6.7 GHz lies comfortably within its low-noise operating range.
Other suitable choices include:
| Model | Frequency range | Typical gain | Typical noise figure | Assessment |
|---|---|---|---|---|
| ZX60-14LN-S+ | 0.05–10 GHz | 22 dB | ≈1.5 dB | Best overall choice |
| ZX60-83LN-S+ | 0.5–8 GHz | 22.1 dB | ≈1.4 dB | Excellent, but 6.7 GHz is nearer its upper limit |
| ZX60-06183P+ | 6–18 GHz | 24 dB | ≈1.6 dB at 6–8 GHz | Good, with useful coverage for other microwave projects |
| ZX60-06223LN+ | 6–22 GHz | wideband LNA | roughly 2 dB class | Extremely wideband but unnecessary for a dedicated 6.7 GHz system |
Mini-Circuits lists the ZX60-83LN-S+ at about 22.1 dB gain and 1.4 dB typical noise figure over its 0.5–8 GHz range. The ZX60-06183P+ covers 6–18 GHz, provides approximately 24 dB gain, and has a specified typical noise figure of 1.6 dB from 6–8 GHz.