RTL-SDR BLog V3 (RTL2832U)  with 2.4 MHz bandwidth.  Receives frequencies up to 1700 MHz.   Connected to the Raspberry Pi USB port with a USB extender cable.

Combined filter and pre-amp for hydrogen line at 1420.4 MHz.

These modules are positioned as close as possible to the feedwire, via a 6 inch long SMA cable.  The black unit on the left is a Nooelec SAWbird H1 module (this is a  SAW filter and a LNA.)  The silver unit on the right is a wideband LNA (made by RTL-SDR)   Both are powered with a 5 Volt DC external supply (a small hole was drilled into each case to admit the power wires.)  A 6 foot long SMA cable connects the output of the wideband LNA to the input of the SDR.

I used a 12 Gauge copper wire for the 1/4 wave feedwire antenna (5.25 cm long.)  Rather than soldering this wire into a SMA coupling, I simply filed down the end of the wire and press-fit it into the female side of a BNC-to-SMA adaptor.  This adaptor is attached to the wall of the can using the supplied nut.  I did not solder any components.

This metal box contains the Raspberry Pi, as well as  two 5-volt transformers that require 120 VAC.  It is essential that these items be enclosed in a grounded metal box to prevent any electrical noise from entering the telescope.  Transformers and the Pi itself can be prodigious sources of EMI, even in the 1.4 GHz range!  A CAT5 ethernet cable (not shown) also feeds through this box, since the Pi WiFi is turned off during operation.  The SDR is mounted outside this box since it generates a significant amount of heat during operation, and does not emit any EMI by itself.

Shows the Raspberry Pi 4 with USB and CAT5 data cables.