Cutting-edge diy projects
I am now concentrating the bulk of my ham activities in the microwave region, and have CW EME and amateur DSN as my top projects. My goal was thus to install a relatively large prime-focus dish to be moved by a heavy-duty Az/El rotator.
In this whitepaper I describe how I modified a Tek2000.com 12 ft TVRO mesh dish so that it can be moved by a SPID BIG-RAS Az/El rotator.
Location of whitepaper: Tek2000 antenna on AzEl – N2QG
It’s July 20, 2019, and I am invited to a private screening of the CNN Apollo 11 documentary, followed by a party with my fellow nerds, so I don’t really have time today to work the sats. It’s 102ºF outside, so not a good day to tweak the antennas either, but I nevertheless wanted to do something space-related to celebrate the 50th anniversary of the Apollo 11 Moon landing.
As a compromise, I decided to test a Trivec-Avant AV2040-2 SATCOM antenna indoors to see if it would be suitable as a portable antenna in the VHF and UHF ham bands.
CLICK HERE for a detailed writeup with high-resolution pictures in .pdf format.
The GOES-East (GOES-16) satellite (GOES=Geostationary Operational Environmental Satellite) operated by NASA and the National Oceanic and Atmospheric Administration (NOAA) is exactly due south of my QTH and provides a view of Earth centered right at my longitude (75°W).
GOES-16 transmits two interesting direct services:
I wanted to experiment with receiving these services from the GOES 16 satellite, and to do so, I added a small grid parabolic antenna to the Az/El boom that drives my 12’ EME dish. I purchased this antenna on eBay®. It is an Altelix WiFi 24dBi 2.4GHz parabolic dish with N-male connector that sells for $30:
This is the latest addition to my antenna farm. It’s a 12 ft mesh parabolic antenna on a heavy-duty AZ/EL rotator. My intention is to use it for 23cm and 3 cm EME, amateur DSN, as well as for next-generation amateur satellites/CubeSats and (hopefully) planetary probes.
Fortunately, my wife doesn’t mind my weird hobbies, my deed doesn’t have HOA restrictions regarding antennas, and New Jersey has a specific law that prohibits municipalities from adopting zoning ordinances that prohibit construction or use of antenna structures by federally licensed amateur radio operators (Act from Assembly No. 3641 of the State of New Jersey, 211th Legislature, introduced January 10, 2005)!
Thanks to the nice people at the municipal office, I was able to get a zoning/construction permit from my township with no issue. The construction inspector already gave me approval on the footing, so now it’s time to load a feedhorn and start to QSO off the Moon. The antenna is smaller than the maximum I requested in my permit, so I can still grow it by another ~3 ft in case I feel the need for a few more dBs.
Of course, I’m already thinking about my next antenna project. My thought is a tall tower to support a very large 2m/70cm EME array along with a 6-element HF beam. According to NJ Act 3641 I can put up a 70ft tower, and then place the antennas on top of that:
“No governing body shall adopt a zoning ordinance that prohibits or has the effect of prohibiting the construction, maintenance or use of an antenna and support structure therefor by a federally licensed amateur radio operator. Zoning ordinances may reasonably regulate the location and height of those antenna structures for the purposes of health, safety or aesthetics; provided, however, that those ordinances permit sufficient height of those antennas and support structures so as to reasonably accommodate amateur radio communications by federally licensed amateur radio operators.
Restrictions imposed on such antennas and support structures by ordinances shall constitute the minimum practicable regulation necessary to accomplish the legitimate purposes of the governing body enacting that ordinance. For purposes of this section, it is presumed that any ordinance that prohibits or has the effect of prohibiting any antenna support structure that is 70 feet or less in height above ground level, exclusive of any antenna upon the structure, is unreasonable. No federally licensed amateur radio operator, applying for permission to install or modify an amateur radio antenna or amateur radio antenna structure, shall be required to pay an application fee that is in excess of that which may be assessed for residential variances generally, nor shall such applicant be assessed any amounts for legal, technical, or other consultation or advisory costs incurred by the reviewing agency in evaluating the application submitted.”
I love my wife and I love NJ!
Jason Meyers (KC2TDS) and I (N2QG) had a fun weekend receiving SSTV from the ISS. We tested many different radio/antenna configurations. Along the way, we once again found out that Amazon “China-Special” connectors are worthless. I’m trashing any connectors in my adapter box that are not real AMPs!
The real interesting finding from this weekend’s campaign was that the SDR-RTL (fancy version) does slightly better for this application than an AOR AR5000, ICOM IC-R7000, and Yaesu FT-736R! We also tried the FunCube+ Pro against the SDR-RTL against weak terrestrial signals, and saw just a tiny bit extra SNR (the FunCube+ Pro has dedicated SAW filters).
Antennas used: 2MCP8A and log-periodic on Yaesu 5500 rotator, and eggbeater with Mirage preamp.
I’m currently rebuilding and expanding my space communication antennas with the intention of being QRV on 23cm EME, as well as being able to receive deep-space probes on the DSN X-band this coming spring. My favorite way of calibrating the Az/El rotors is to use FTA geostationary satellites, and as a reference, I upgraded my C and Ku-band small-dish (120cm offset) with a heavy-duty horizon-to-horizon (HH, H2H) motor.
I found that my ZGemma H7 FTA receiver could not handle the current needed to operate the motor, so I built a simple power inserter just for the motor. The 1uF non-polar capacitor provides a low-impedance path for the 22kHz DiSEqC signal to the motor, while at the same time the 10uH inductor isolates the RF from the LNB from entering the motor supply. The 500uH inductor (rated for 4A DC minimum) isolates the 22kHz signal from being dampened by the filters in the power supply (an old IBM laptop power supply rated 16V @ 4.5A).
Clean schematic in pdf: H2H Motor Power Inserter
Construction technique and enclosure are not critical, but the connection between the LNB and RECEIVER ports must be kept short. My housing is the enclosure of an old DISH Network switch that I emptied out and modified to add a power connector compatible with my power supply.
This works like a charm! The H2H motor now moves quickly and smoothly without shutting down the ZGemma’s tuners.
This is the current state of the Az/El VHF/UHF array and FTA dish at N2QG:
The high-gain antenna on my space communications array is based on a Fortec Star 120 cm dish. This is a high-quality, large dish designed for motorized FTA reception of analog, digital, and high-definition programs on Ku band satellites. I built a feed that combines a KU band horn for free-to-air (FTA) satellite reception with a helical feed for transmission and reception in the amateur L-band (23 cm, 1,296 MHz).
Being a peace-loving atheist, I am not interested in the religious and radicalized political junk that is most prominent over FTA. Instead, I use the Ku-band transmissions from geosynchronous FTA satellites as known-Az/El beacons to calibrate the aim of my array.
Last week I posted detailed construction information for my rubidium atomic clock frequency reference. Besides that unit, I also built a GPS-disciplined 10 MHz oscillator to serve as a secondary frequency reference, as well as a source of GPS NMEA data for my ham shack instruments that can use precise location and real-time-clock data (e.g. for satellite tracking). I just posted on www.diyPhysics.com details about this 10 MHz GPS-disciplined standard. Continue reading
I just posted on www.diyPhysics.com about my 10 MHz rubidium standard based on a surplus Efratom M-100. It is a free-standing 10 MHz +/-5×10-11 frequency standard for frequency counters, as well as a precise calibration source. I use it to keep precise track of frequency when working on Earth-Moon-Earth (EME) communications, where even tiny errors in tuning can make the difference between success and failure to receive weak echoes. Continue reading
Our space-communicationsantenna array includes a camera that looks in the direction that the array is pointing. This camera helps us check that we are aiming directly at the moon during EME attempts. In addition, when it lets us see airplanes that may be the source of interfering signals when we conduct radio-astronomy observations. Continue reading
