Category Archives: operating

Satellite Operating Tips for FLSPOTA

With just 5 days to go until FLSPOTA weekend, now is the time to start preparing for getting the 35 point satellite bonus! While some of you may be experienced satellite ops, if you haven’t worked sats since the AO-51, AO-27, or even the RS-* days, it might be a good idea to read up a bit and practice some LEO ops before contest day. The current fleet of LEO sats, including AO-85, AO-91, AO-92, and SO-50 (all FM repeaters),  and FO-29, the XW-2* sats, AO-73, EO-88, CAS-4B and a couple of others are fast passes (12 minutes or so from horizon to horizon), and require tuning for Doppler shift. Operating full duplex is not required – but is HIGHLY recommended! For FM sats, nearly any HT will work for a transmitter. When operating full duplex with two separate radios, you can use something like a Baofeng for a transmitter, and a higher-quality receiver; Yaesu, Icom, and Kenwood rigs don’t “desense” or overload in the presence of the strong signal transmitted by the other radio. Full-duplex mobile rigs like the FT-8800, TM-D710 and others are also a good choice – and one you may have already in your car!

Here are a few tips:

  1. Listen to some passes over the next few days, especially if you have never made a satellite QSO or it’s been a long time. Listening will help you get the hang of the “flow” of satellite QSOs. They’re typically short, only exchanging callsigns and locator information (and of course for FLSPOTA, your park ID).
  2. If you can, schedule a pass with someone you know is a good satellite op. It’s helpful to get over that first try if you know there is someone listening for you! You can find quite a few sat ops on the very active Twitter and Facebook AMSAT communities. You can find me on twitter at, feel free to give me shout if you want to try a QSO!
  3. Practice!!! Don’t roll up to the state park on Saturday expecting to make your first-ever satellite QSO successfully. It may go well, but it probably will not without some practice 🙂 Weekend passes tend to be very busy, so having some experience under your belt will help everyone have fun!
  4. Operate full duplex if possible. You can use a single radio that has this capability (like the Kenwood D72), or two separate radios, one for each band. It makes it a lot easier to operate and tune if you can hear your own downlink signal while transmitting – you can also make sure that you don’t accidentally transmit over another station’s QSO in progress. This is a huge etiquette issue on satellites!
  5. Use iPhone apps like GoSatWatch, Hamsat, or SatSat, or Android apps like ISS Detector or AMSATDroid. They’ll help to plan which passes to try. Make sure you update your Keplarian elements, and GPS location in the app so you have accurate pass times!
  6. AO-91 and 92 are good choices because they’re easy to hear and easy to get into. They do tend to be busy on the weekend, so SO-50 is another good option that tends to be a little quieter. AO-85 works well also, but sometimes it takes more transmit power to get into (10-15w). The others are easy to work with 5w or less.

For more info, there is an excellent guide written by Sean Kutzko, KX9X located at

Portable Power

There are a lot of options for powering your station while operating in state parks! Here are a few that I’ve personally used.

Deep Cycle Lead Acid Batteries

These are a great, general purpose option if you aren’t limited by weight. For the price, they’re hard to beat if you want a lot of capacity. Marine batteries, tractor batteries, golf cart/RV batteries can all work great. The downside? If you can’t drive right to your operating spot, the weight makes it really hard to justify. Lugging an 80lb battery along with all your other stuff can really cut down on your motivation to get out and activate parks.

I primarily use mine when I’m going to be operating from my vehicle. Many of you probably have the same problem I do – when my car is on, I have S6-8 noise levels on HF. That doesn’t help much when trying to pull out a weak station! So, I’ll load my big Exide deep cycle AGM into the backseat of my car (something like 45AH of usable power at 100w SSB/CW duty cycle) When I get to a park, I shut off the engine, put the battery and radio on the tailgate or a picnic table and start operating.

One word of caution – be careful with the charger you use. An AGM like the one pictured above has fairly strict charging voltage requirements. Even though some big box store chargers claim to have an AGM setting, when I’ve checked them they have not been anywhere near the correct charging voltage. Check your battery’s manufacturer for their recommended charging voltage, and make sure your charger is supplying it. I use a high quality Noco brand charger

Lithium Battery Packs

Different brands of LiFePo4 batteries

This is what I use most of the time. The main reason?  A very high power-to-weight ratio. A 12AH LiFePo4 battery weighs less than my radio! There are other benefits too. LiFePo4 batteries maintain a very stable voltage until they are nearly discharged. That means you can use most of the battery’s rated capacity before your radio reaches it’s voltage cutoff threshold (normally 13.8v, +/- 10 or 15%). A lead acid battery’s voltage will tend to drop as you use it, so even though it has a similar or higher rated capacity to a given lithium pack, you may not be able to use it as long before your radio starts to complain.

Bioenno 9AH LiFePo4

They do take a special charger, some of which will depend on the brand.  Bioenno makes a great line of self-contained LiFePO4 packs which have built-in charging circuitry, overcurrent protection, and discharge protection. You buy the battery and a wall-wart style charging cable, and you’re all set. But…all that convenience comes at a cost. Expect to pay ~$150 for one 12AH battery and charger. For me? It’s worth it because everything is built into the pack. They’re available through Amazon, HRO, and various other retailers.

Charging a Zippy 4.2AH 4S2P LiFePo4 pack, with a balancing charger

An alternative is to use R/C plane batteries, like the Zippy brand sold by Hobby King. They are less expensive (around $60 for an 8.4AH pack), but do require a special balancing charger. You’ll also have to install your own connectors. I use Anderson powerpoles for all my power connections, which make everything interchangable between all my gear. They can be a bit tough to install on the r/c packs, since the power cables tend to be larger gauge (10 or 8 AWG), and very, very fine stranded almost like welding cable. The open sided 45 amp powerpole inserts make this process much easier. The primary benefit of the Zippy packs is more flexibility in charging rates, and their lower cost. I used these for a number of years before eventually moving to the bioenno packs.

Internal Batteries

Windcamp batteries installed in an FT-817

Some radios, like the KX2/3, and FT-817 have a place to install internal battery packs. These can be NiCd, NiHm, or lithium packs. I’m not a big fan of using the stock NiMh internals like those in the FT-817. Some people like them, but in my experience they don’t have enough capacity to be useful doing much more than listening. I replaced mine with some aftermarket LiPo packs sold on eBay by Windcamp. They aren’t too expensive ($70/ea), and have to be charged through a supplied battery cover instead of through the normal rear plug on the 817. But they work great! Each one is 3AH capacity, which lasts for a week or more worth of satellite passes (which is primarily what I use my 817s for these days). It’s nice to have everything self contained in the radio – and they charge much faster than the stock batteries.

The downside? They ship direct from China, so expect to wait up to 2 months for delivery. Don’t wait until the last minute to order them before a trip!

Other Tips

Don’t forget battery maintenance! If you aren’t using them often, make sure your lithiums and lead acids are stored at the proper voltage – letting them drop too low can severely damage the battery, leading to diminished capacity or even needing a replacement.

Use standardized power connectors like Anderson Powerpoles. Being able to interconnect all your gear to whatever power source you choose to bring along for an activation is worth the trouble of installing the connectors! Do yourself a favor and buy one of the purpose-built crimping tools. They aren’t expensive and make the job easy.

An anderson powerpole power splitter (homemade)

Something else that would be a perfect for for sunny Florida is solar power! That’s on my list to experiment with. I do know at least one ham who operates often using an FT-817 and two Harbor Freight solar panels. Some of you might already operate using solar power, or have other tips I haven’t mentioned – if so, share some pics and your ideas with us on Facebook!

73 de nj4y