Tohtsu CX-520D Coaxial Relay
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Tohtsu CX-520D coaxial relay purchased from ebay Nov 2025: Specifications: Three x type N female connector, has a common and a NC contact. Max input power: 300W pp at 1000…
Radio observation in hydrogen line (1420MHz)
Better to use a portion of signal spectrum as reference signal, rather than image shift.
From Alex Pettit, via SARA Mailing List, 5/11/2025: Andrew, see if this analogy helps : The Top 3 Data/Drift Pair shows using an image shift to measure system or sky…
What if any is potential benefit for adding filtering and amplification at antenna in meteor scatter detection arrangement at 143.050 MHz?
What if any is potential benefit for adding filtering and amplification at antenna in meteor scatter detection arrangement at 143.050 MHz? Short answer: yes—put a low-noise preamp at the antenna…
Potential Small Radio Telescope Drift Sources
Following from Alex Pettit by email 4/11/2025:
Best method to obtain reference samples for Hydrogen Line work
On 2025-11-04 03:27, ‘Andrew Thornett’ via Society of Amateur Radio Astronomers wrote following in bold, then Marcus Leech responded with answers in italics. Hi All, Interesting discussion on the resistor…
Three versions of Nooelec SAWBird H1 LNA
I made following comment on SARA mailing list 3/11/2025. “I was talking about the Nooelec SAWBird H1 LNA, which it turns out has 3 versions. Worth saying that it is…
Real life test results comparing amplifier performance at 1420 MHz
These results were presented by Andrew Sutkowski at the BAA Hydrogen Line Sub-Group Meeting 3/11/2025. His preference is the WVURAIL ones, which are designed as part of the DSPIRA project,…
In the design of a cantenna for 1420 MHz radio astronomy, how far from bottom of can should be monopole be located?
In a cantenna for 1420 MHz, how far from bottom of can should be the monopole? Short answer: place the monopole about a quarter of the waveguide wavelength (λg/4) up…
Does it matter what the monopole aerials inside a waveguide such as a cantenna waveguide are made of?
Andrew Sutkowski checked his feed and found monopole probe made of 1/8 inch copper tube far better at picking up 1420 MHz hydrogen signal than bare copper wire (information from…
What is a Kumar choke for radio frequencies?
A Kumar choke (often called the VE4MA or Kumar feed/choke) is a choke-ring / cavity around a horn/feed that suppresses unwanted surface and coaxial currents and “traps” or reflects energy…