K6LCM LiFePO4 PowerBank Battery Box

I experienced some disappointing results with a portable 12-volt jump-start lead-acid battery at Field Day this year. David, AC9AC, saved Field Day for me by bringing by his 30 amp-hour LiFePO4 battery to our operating location at Shoreline Park. Impressed with its capabilities, I decided to upgrade my portable power. There are a number of vendors on Amazon and Ebay selling high-capacity LiFePO4 batteries at low prices. LiFePO4 batteries are impressive. Without going into too much detail, the main advantages are that they are up to 70% lighter than lead acid batteries, will continuously supply 13-14 volts under high-current draw conditions and can be completely discharged without damage. Most LiFePO4 batteries include a battery management system inside the sealed plastic battery itself, making them nearly a drop-in replacement for lead-acid applications. In fact, many new 12-volt chargers include special modes for optimally charging LiFePO4 cells. If you search online, you’ll find many pre-made power stations. The problem is that most of them are designed with general consumers in mind. Your average power-hungry electronics guru mostly needs a 5-volt USB power connection and a 120-volt AC outlet. These premade power stations typically lack higher current connections such as Anderson Powerpole sockets. The designers of these pre-made power stations were probably thinking: “Who would want to draw 20-30 amps at 12 volts?” Hams would of course! My requirements when designing the K6LCM PowerBank were that it would support typical 5-volt USB connections and a 12-volt DC cigarette lighter connection for running mobile chargers. But my design added two 12-volt DC Anderson Powerpole connections for supplying up to 30 amps of current to various rigs that are capable of transmitting up to 100 watts of RF. Below are some photos of the build and a parts list. I mounted the binding posts inside the top compartment of the Harbor Freight ammo box as shown. Using 12 AWG wire, I connected the battery itself (using the blade fuse connector with a 30-amp fuse) and all of the power outlets to the positive and negative posts respectively. In addition to the fuse, the positive battery lead passes through the master switch on its way to the positive binding post. The only connection that does not pass through a binding post is the positive (7.5-amp fused) connection between the charging port on the back and the battery. Since I intend to use this setup as portable… Continue reading

FM Simplex Node Frequencies in Santa Barbara

  Over the past few months there has been a renewed interest in AllStarLink FM simplex nodes among our members. These low power devices allow users to connect to remote VoIP nodes and repeater systems using an internet connection and an HT. Most opt to buy or build a device on 70cm. A couple years ago, during the initial DMR hotspot craze, SBARC expert consultant Matt W6XC identified a few frequencies around 431 MHz that were useful for digital hotspots like the OpenSpot and ZumSpot. HOWEVER, these frequencies are NOT appropriate for analog FM nodes. We must use a different part of the 70cm band for FM emissions. Matt suggests the following options for low-power, analog FM usage: 440.000/445.000; 446.860/441.860; 446.880/441.880 may be used as pairs for a low-power duplex node or as separate simplex node frequencies. Please listen to these frequencies with low squelch settings and no CTCSS for a few days before permanently parking your node here to see if and how these frequencies are used. FM simplex nodes are best PL/CTCSS protected, especially if they are left connected to a system like K6TZ or WIN System. Definitely avoid 446.000 altogether. This is the National Calling Frequency for 70cm. 446.500 and 446.520 are “General Simplex” frequencies. Others many want to use these for simplex QSOs or other itinerant purposes so please don’t park your node on any of these three frequencies. Also note that 432.000-439.999 MHz is allocated to weak signal, Amateur Television and digital emissions only. 440 is tough given the lack of simplex allocations. It’s a truly stuffed band! Perhaps just as important as which frequency you choose for your node is setting the PL/CTCSS tones. In Santa Barbara and Ventura counties, DO NOT use 131.8 or 88.5 127.9 or 131.8 Hz as a tone for your node. Picking almost anything else will ensure that you don’t inadvertently open the receiver of a repeater on the same or nearby frequency. If you are interested in these FM VoIP nodes, consider the ClearNode and SHARI projects.   Levi, K6LCM K6TZ Trustee

ZUMspot Raspberry Pi Info and Setup

ZUMspot Raspberry Pi Info and Setup Here’s some info on what it took for me to get my ZUMspot up and running, updated with new things I’ve learned recently.  This doc is a bit wordy but I’m hoping this will let you know what you need to successfully get your ZUMspot Rpi working using a Windows PC.  Don’t think the below is a lot of work – it’s really not. I’m pretty impressed with this product which all in is about half the price of the SharkRF Openspot  but with built in Wi-Fi and the possibility of adding a display.  I found configuring the ZUMspot to be as easy as the Openspot and I’m not a Linux person. Hardware Needs ZUMspot Rpi ($80 + $10 shipping) Raspberry Pi, either the Pi 3 Model B ($35) or the Pi Zero W ($10) If you choose the Pi Zero W you may want additional accessories mentioned later Micro SD card, 2GB or greater. (you likely already own this or <$10) 5V power supply for the Pi with micro USB connector (you likely already own this)  Software Needs  Latest Pi-Star software image from the internet (free) A windows tools to ‘burn’ the above image to your micro sd card (free) A PC on your network to configure Pi-Star   Hardware Details ZUMspot Rpi The ZUMspot Rpi is fully assembled and tested and comes with a short antenna.  It is purchased via email from Bruce Givens, VE2GZI (ve2gzi@gmail.com).  Send him an email stating you’ll like to buy one and he’ll reply pretty quickly (for me in just a few hours).  He produces them in batches so you might be put on a waiting list.  He ships from NY and from the time I paid until it was in my hands was less than 1 business week.  Cost was $80 + $10 shipping. He does offer a kit consisting of the ZUMspot Rpi + Rpi Zero W + 2×20 header + 4GB microsd card with Pi-Star already on it for $110 + $10 shipping but you can do better putting your own kit together. Raspberry Pi With the Raspberry Pi and you have 2 choices – the Pi Zero W, or the Pi 3 Model B.  Make sure you get exactly one of these part numbers.  The older version of each do not have built in Wi-Fi. Raspberry Pi Zero W is the smallest, cheapest, and more power frugal of the… Continue reading