This weekend’s detection: STEREO-A received on X-band using 1.2m offset dish:
Author Archives: David Prutchi
My First True-DSN X-Band DX: Bepi-Colombo at 15.2 Million km from Earth
Today I was able to receive my first true-DSN X-band DX from Bepi-Colombo at a distance of 15.2 million km (around 9.5 million miles) away from Earth!
The squeezed-tube feed was made by Jason Meyers KC2TDS based on a design by Micha? Zawada SQ5KTM :
The signal was received with the feed mounted on a 1.2m f/d=0.6 offset dish steered by a Yaesu G-5500 az/el rotator:
There is a Kuhne LNA-8000B low-noise amplifier connected directly to the probe, and the amplified signal is sent to the downconverter (LO=8GHz) mounted on the boom.
Downconverted signals (400 – 450 MHz) are received using an AOR AR-5000. The radio’s IF is sampled by a SDR-14 and displayed with SpectraVue.
Tracking of the probe is with PstRotator’s new DSN feature which downloads ephemeris data straight from NASA JPL’s Horizons:
Super-Kumar DSN X-Band Feed Ready for Testing this Memorial Day Weekend
I received a squeezed-tube depolarizer and super Kumar scalar ring from Paul M0YET (from uhf-satcom.com). Jason KC2TDS terminated it with a waterjet-cut copper disk and added a probe which he carefully tuned with the VNA to get <20dB return loss in the 8.4 to 8.45GHz DSN band.
My plans for this weekend are to take down the 23cm EME feed from the 3.5m dish and test this feed after taking some measurements with the horn that Jason KC2TDS built based on Michal SQ5KTM’s design.
DSN S-Band Helical Feed for 1.2m F/d=0.6 Offset Dish
I finally got around to building a 3.5-turn helical feed for the 1.2m offset dish to receive S-Band satellite and DSN signals. VSWR is quite OK (1.5:1 to 1.6:1) within the Near-Earth and Deep-Space S-band (2.2 to 2.3 GHz):
This feed works much better than the PCB LPA with which I started my experiments. Here is USA159 (DSP-21):
First light on S-band with low-gain (1.2m) offset dish
I have the aiming of the 1.2m offset dish calibrated, so it’s ready for receiving on DSN bands. I started by placing a WA5VJB wideband log-periodic array at the focal point followed by a Minicircuits LNA. I placed the filter/cable driver in the mast box to send the S-band signal via 100 ft of LMR400 to the shack.
With the Az/El under the command of NOVA for Windows, I set it to track DSP-F21 (USA-159). The satellite transmits using circular polarization, so I know that I’m wasting at least half of the signal by receiving with linear polarization, but this is the feed that I have on hand for this antenna. Nevertheless, the received signal is very clearly seen against the low noise floor:
Next: Mount the DSN x-band horn/lna/downconverter on the 1.2m dish and start to practice tracking of non-Earth-orbiting probes.
Decontaminating N95 Masks at Home to Extend their Use During CoVid-19 Pandemic
Remember that book that I wrote on UV Photography? Well, I ended up collecting/building a number of UV lamps, and some of them emit UV-C. I set them up as a makeshift decontamination rack for our N95 masks.
The effectiveness of using germicidal (UV-C) light to decontaminate N95 masks to extend their useful time is well established. In fact, use of Ultraviolet Germicidal Irradiation (UVGI) has been recommended as an emergency measure by the CDC. The limiting factor is that UV-C degrades polymers, so it will eventually cause failure to the mask’s structural integrity (Lindsley et al, 2015).
Our protocol at home, based on my understanding of CDC’s guidelines and the intensity of my lights is to use masks for up to 8 hours (of actual use time when outside of the house grocery shopping or running essential errands) and then expose them for 15 minutes per side to UVGI before reuse.
The link to my DIY Long/Med/Short UV lamp is available here. Or in whitepaper format here.
IMPORTANT NOTE: This post should not be construed as advice on the decontamination of PPE. Please refer to official information on this matter from the CDC.
WARNING: Midrange and short-wave ultraviolet radiation can cause permanent eye and skin damage. Do not look directly at midrange or short-wave UV radiation, even for brief periods. Take appropriate precautions with pets and other living organisms that might suffer injury or damage due to UV exposure at these wavelengths.
Defense Support Program (DSP) F21 2237.5 MHz Carrier as it Orbits
Click here for high-resolution version of the image.
DSP-F21 is a satellite of the US Air Force’s Defense Support Program (DSP) which operates the Satellite Early Warning System. The TLEs for this satellite (USA-159) are distributed by SpaceTrack. The satellite was launched in 2001 and is still used for missile launch detection. The satellite emits a constant carrier at 2237.5 MHz which sometimes becomes active with data during Early Warning and LEO SIGINT operations.
Adding an External Frequency Reference Input to the RFspace SDR-14
My favorite microwave receiver is the AOR AR5000. I have it locked to either my 10 MHz rubidium or GPS references. The 10.7 MHz IF output goes to an RFspace SDR-14 which I display using SpectraVue.
The SDR-14 does not come with a provision for feeding an external reference, but I know I had seen something about this a long time ago. I Googled it, and found out that Dave Powis, G4HUP, the originator of the mod had become SK. His web page is no longer active, but found it using WayBackMachine.
I successfully modified my SDR-14 and am feeding it 66.666,666 MHz from a Leo Bodnar Mini Precision GPS Reference Clock.
Click here for my writeup of the mod with pictures, as well as Dave’s original posting.
S-Band DSN (and Aerospace L-Band Telemetry) RX LNA and Filter Front-End
The CoVid-19 quarantine has given me the opportunity to revisit neglected home projects, so I decided to add another Az/El dish to my antenna garden. The main purpose of this new dish will be to serve as a low-gain testbead before moving an experiment to the 3.5 m dish.
My first experiment for the new dish will be on S-band DSN, especially to “learn the ropes” about tracking non-terrestrial-orbiting probes before I try it on the high-gain dish.
The S-band DSN frequencies are as follows:
The downlinks require the receiver to operate between 2200 and 2300 MHz.
1296 MHz EME QSO with 4X1AJ in Israel!
The highlight of my weekend was a JT65C EME QSO with Andrey 4X1AJ in Israel! That’s my personal longest EME DX. My 1296 MHz PA output was 600W, out of which I’m putting 400W at the feed of the 3.5 dish. In Andrey’s words, I was “booming” on his side (-17dB).
Very pleased with my current setup! THX Andrey for the QSO! 73