70 cm Preamp Follies

Last weekend Al KB2AYU and I (Al really did the work) put a Mirage 70 cm preamp up on the satellite antenna tree. Once installed we tested it and found that it made no difference in the received signal. So I had another identical preamp that I had tested and found working, so we swapped it out tonight - and found the same result. We had the control box that provides 12v to the preamp connected between the antenna switch and the antenna, and in that position it didn't work. So I decided to move it to the radio side of the switch and installed it with the control box input coming from the SDR radio and the antenna side of the box connected to the switch (the switch selects either the SDR radio or the 847 to be connected to the antenna). Strangely, this configuration worked! The noise level jumped about 20 db when the preamp was powered up, and a NO-84 PSK pass showed a much clearer signal on the downlink. Neither of us could explain why this configuration worked and the previous one didn't - the only difference was the position of the antenna switch along the line. So if you visit the clubhouse and see this configuration, don't change it!

Comments

Post a Comment

Popular posts from this blog

How We Built the GOES Reception Project

Image
How We Built the GOES Reception Project Updated 12/1/18 Building our functional GOES 16 receiver was a process of broad web research and cobbling together the experiences of many other successful experimenters. We found lots of individual articles on antenna selection, software, and many other topics, but nothing that really pulled everything together. Hopefully this article will provide a comprehensive overview of our project. If you've found other tips that were useful or have questions or comments about the project, please leave them in the Comments box below and we'll try to reply when possible.  Thanks to the many experimenters whose work we copied and implemented in making this project work. Location (QTH) Our station is located at the "clubhouse" of the Gloucester County Amateur Radio Club, located in Mullica Hill New Jersey. The clubhouse provides a dedicated location for radio experimentation and radio operations, complete with a 100 foot tower for VHF
Read more

GOES Satellite Reception Project

Image
We're getting interested in listening to the GOES geosync weather satellites, so this page is a collection of links to help get started with that project. We'll report on progress as it happens. https://www.rtl-sdr.com/setting-up-a-goes-weather-satellite-antenna-system/ https://www.rtl-sdr.com/receiving-goes-weather-satellite-hrit-with-an-sdrplay-and-2-4-ghz-wifi-grid-antenna/ Detailed article: https://www.teske.net.br/lucas/2016/10/goes-satellite-hunt-part-1-antenna-system/ Good building options: https://www.rtl-sdr.com/building-a-low-cost-goes-weather-satellite-receiver-with-an-rtl-sdr/ Here's the link to an antenna:  https://www.amazon.com/1850-1990-Parabolic-Antenna-Die-Cast-15dBi/dp/B06ZYJ3P82/ref=sr_1_2?ie=UTF8&qid=1536255463&sr=8-2&keywords=parabolic+grid+antenna+1.9 Link to antenna pointing from W2MMD: https://www.satellite-calculations.com/Satellite/Catalog/catalogID.php?41866 Info on GOES 16, the east-coast satellite: https://en.wikipedia.
Read more

Building the Raspberry Pi NOAA Satellite Station

Image
Building the Raspberry Pi NOAA Satellite Station After building the station to receive the GOES geostationary weather satellite, constructing the NOAA satellite station was a relative breeze. The NOAA series of satellites (NOAA 15, 18 and 19) are much more similar to amateur satellites than the GOES satellite – they operate in the 137 mhz band, are in low-earth orbits and transmit analog images rather than the complex error-corrected digital images of the GOES satellites. I simply followed the “ Instructables ” project design and it mostly worked the first time. The overall concept is simple – the project uses a inexpensive RTL-SDR radio and a Raspberry P i computer along with free software that you install on the Pi. There are several components to the software – first it uses the Gpredict program to set up times (cron jobs) for each satellite based on the next pass for each of the three satellites. At the scheduled time the Pi runs a script that will enable the RTL-SDR receiv
Read more