Track Movement of Milky Way With Amateur Radio Telescope

I've got a really nice LNA that I used with my old reciever.... but don't use it with the SDR. The concept is this: by mounting the SDR directly on the yagi, you eliminate the coaxial losses..... and since one of the main reasons for the LNA is to overcome those losses, you can do away with it from the system without nearly as big a penalty as one would expect.

The portable rig in the pic is GREAT for satellites. I'm in the middle of building a 2m / 70cm antenna..... each one with it's own feed harness. That would make it simple to switch between uplink / downlink in less than a second usin the same radio.

overloading the LNA / detector has always been a problem in RA, and the SDRplay is no exception. With an LNA, you can overload the SDR quite easily, especially with the yagi since they exhibit side lobes. Even a nearby weak signal outside the beam looks like a fireball on the FFT / Waterfall screen. I run the SDR without an LNA to avoid that problem.

 

The OP only has intro and exit text from the Spectrum article. However there was a link embedded in the title to view its entire contents. Details in that material include this info that may pertain to your questions,

"I purchased the dongle from Nooelec.com ($37) because that company had also recently started selling a gizmo that seemed perfect for my application: It contains two low-noise amplifiers and a surface-acoustic-wave (SAW) filter centered on 1420 MHz ($38). The dongle itself provides power for the amplifier through the coaxial cable that connects them, a 30-cm (12- inch) length of coax purchased on Amazon.com ($9). The dongle just sits on the ground next to my horn and is attached to a Windows laptop through a USB extension cable."

Link to LNA spec's etc -> https://www.nooelec.com/store/sdr/sdr-addons/sawbird/sawbird-h1-barebones.html

FYI - the author and radio telescope maker Dave @N2LVD may not respond on this forum, however I received a quick reply via this email address -> david.schneider@ieee.org

 

They are not Lids; QSX split UP UP UP ! on 4462.35 MHz (H x Pi)

 

The original article has a nice photo of the "pin" (monopole) antenna and precise directions of why and where to place it within the "can" waveguide. A cute little 1/4w ground-plane vertical.




Chip, with such an antenna on a celestial target are there any effects from polarization on observations? Could there be a benefit to add a second "pin" placed on the adjacent can side, 90 degrees opposite to the first antenna?

For not much more $ that could be a totally separate path to its own separate LNA and SDR, with the two signals combined after detection. The HDSDR software apparently may be configurable to perform diversity reception in real-time, interleave the two paths at the I/Q level.

73, John

 

Just as I thought.

Yeh, you could add a second monopole and second receiver and 'total power' the two on the computer. But the 21cm hydrogen line is generally unpolarized, or weakly polarized.

Better just to time average longer rather than double the electronics.

'Horn' type antennas are far advanced since these early designs--unabashed plug: just got the patent on fractalized, shrunken, broadband horns. Hot 5G antenna for the lower bands ;-)

Building a simple horn is fun and quite gratifying. Keep in mind a modified horn of this type discovered the 'Big Band' 3 degree background (CBR).

 

yes it can be. The only real problem with them is that as the frequency gets lower, they tend to grow to very large proportions, which makes them difficult to steer / aim.... thus you are limited to sweep scanning.

 

THIS is too, too cool!

 

I hope not have you seen the news lately?

 

Brilliant article! We need more insipiration like this.