Copy of email sent to me by Ted Cline October 2025: How are coaxial relays controlled from the computer to allow software like SDR Sharp to collect calibration data vs…
Shows some hydrogen – need to complete full 24 hours and re-analyse. Note altitude and azimuth may be incorrect in these plots.
Short answer: you can make a cavity “as big as you like,” but past a sensible size you don’t gain performance—and you often make things worse (more spurious modes, weight,…
Adding more digits (fingers or resonators) in an interdigital RF cavity filter has several important advantages and disadvantages, depending on what you are optimizing for (selectivity, insertion loss, bandwidth, physical…
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For 1420 MHz (the H I line at 1420.4058 MHz), the “best” cavity filter depends on where you place it in the chain (pre-LNA vs post-LNA) and what you need…
Good — that’s a nice setup for remotely switching antennas, receivers, or feed chains. Let’s outline how to get both coaxial relays (12 V and 26 V types) under PC…
Short answer: use the quietest DC you can. In practice that means: Why (and how) Hydrogen-line work is extremely sensitive to conducted and radiated hash. Switching PSUs produce combs that…
Here’s a concise, technically balanced comparison of SAW (Surface Acoustic Wave) filters and Cavity (Resonator) filters — especially relevant to radio astronomy, RF front-ends, and communications receiver design. 🧩 1.…
The attachments mentioned in the discussion below are available in following downloadable ZIP archive: https://www.astronomy.me.uk/wp-content/uploads/2025/10/Comparing-dish-sizes-performance-H-Line-311025.zip Here’s a practical comparison for your dish sizes at the HI line (1420 MHz), assuming…
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