NBEMS using a Baofeng UV-5R on the cheap

Interface notes are a little way down the page - this first part is just me rambling about WHY I did this.

Why run NBEMS on an LCR (Little Chinese Radio)?

I participated in the Lindon City Drill Down for Safety preparedness exercise earlier this month. We had one ham radio operator in the EOC (Emergency Operations Center) and 3 area operators. Each area had neighborhoods reporting with scenarios that we were required to relay to the city EOC as they came in from runners or over the neighborhood radio nets (some of which were using FRS radios). This was accomplished admirably in the time allotted for the exercise (just over 60 minutes). I think we relayed close to 30 scenarios and a few other things as well. Had there been more scenarios, or other traffic (health & welfare, etc.) that needed to be passed over the net from the areas to the EOC, there would not have been enough time to get it done. As it was, the radio operator in the EOC was fully engaged in receiving, transcribing, and disseminating the scenario information to the participants at the city.

At the debriefing, the 4 of us who participated in the net talked about what could make things better and we decided that transferring the scenarios digitally would help in many ways (accuracy, speed, etc.). The next day Dave N7BAN sent out a link to the ARRL's page on NBEMS (Narrow Band Emergency Messaging Software). I started reading and was hooked. I setup the software and with the SignaLink USB interface I already had, I was able to make everything work. A couple days later Dave and I were successful communicating on the air with fldigi.

We talked about having this capability for our the exercise next year and how the police department had recently given us a hand-me-down laptop and printer for use in the city EOC. I really liked the fact that you can be successful using NBEMS in many modes (MT63-2KL is especially good) without any interface at all - just computer's speaker/mic next to the radio's speaker/mic and by holding the PTT on the radio at the appropriate times, it all works. In an emergency knowing how to operate like this could be very beneficial as equipment may not function correctly or even be available.

The city might be willing to get us a radio interface to the nice Icom radio they purchased a while back, but it seems to me that we need to also have systems in the field (at least 3, right?). Even though the computer speaker next to the radio mic would work, it would be somewhat cumbersome and would also introduce extra noise into the signal (not to mention the area where the radio operator will be located). Having an interface there would allow us to use two modes at once. We still need to work out the issue of having only one antenna. I'm not sure if the Icom radio will allow us to use 70cm for digital on one side and 2m voice on the other, or if we will need a separate radio and a duplexer.

Anyway, for use at a mobile station, I thought about purchasing another SignaLink. But then after more reading (this internet is a big place :) I realized that my new standard radio has VOX (voice operated transmit) that could be used in place of a switched PTT line and that it should work with a very simple isolation circuit. Well, I tested it and it does. Now, to the meat of this article, how to make the interface:

Creating the Interface

This interface works great on my UV-5Rs. It may work on Kenwood and other radios that use a similar interface. You would probably have to modify it for use with anything else.

I took a ground loop isolator and added a 10K ohm resistor and a 10uf capacitor then hacked a cable from the headset that came with the radio (this would also work) and soldered it to the circuit board in place of the original cable. I chopped the ends off the other side of the isolator and put on stereo 3.5mm plugs stereo 3.5mm plugs with the ground on the sleeve and the other lines connected to the tips (the rings were left unconnected). I ended up with a circuit like this:

Notice that there is nothing for managing PTT. That is because I'm using the VOX feature in the radio to key the transmitter when it detects input from the computer. This has worked very well in my testing. As you can see from the links to the parts above, I love Amazon and their Prime shipping program. I have 98 capacitors and 498 resistors left that I would be happy to share with anyone local who'd like to build an interface. :)

I took advantage of a couple of existing solder pads for the resistor and tried to put the capacitor in a place where it would not contact other stuff. The wires from the cable were very tiny, but soldered just fine without doing anything special.

A view of the isolation transformers on the other side of the PCB.

The finished unit from the bottom

Top view

Because my Macbook Pro only has a single connector for audio, I use a little USB sound card little USB sound card instead. This has the additional advantage of leaving the built-in audio device to handle regular sounds while this one can be dedicated to its purpose.

Although work and home are only 4 miles apart, there are some good sized hills in between. Also, work is in a building that is really good at blocking radio waves. At home I have a Comet GP-6 clone hooked to a Kenwood G-707A and the SignaLink interface I mentioned earlier. From inside my building at work, I can't hear the home radio consistently on 2 meters even at 50 watts especially from where my desk is located (bottom floor on the opposite side from my home). From outside in the parking lot, my truck's radio (a Yaesu FT-8900R and a Comet SSB-5) can talk to home with both ends running just 5 watts. If I set the rig in the truck to cross-band mode, I can use the HT inside the building on 70cm at low power to reach the truck and from there on 2 meters to the house. This works great so far.

All in all, I'm excited about the possibilities for using NBEMS along with normal voice operations for emergency situations. I believe it has more immediate value than HSMM or BBHN, which I have also been playing with, so I am shifting my focus for a time to learn and do more with digital over VHF/UHF. As always, there's plenty more to do (setting up NBEMS on my Raspberry Pi in my trailer for example).

Standardizing on the Baofeng UV-5R

Why I want to standardize

I currently have several different radios that I use on a regular basis. None of them are the same. It frustrates me that when I want to use a radio, I have to find the special accessories for that particular radio because many of the others aren't compatible (batteries, charging cables, headphones, antennas, etc.). It's not as bad, but, the difference in operating and programming methods is sometimes annoying having to remember each radio's idiosyncrasies.

I have decided that rather than continue down this path, that I want to standardize. I love standards but, there are so many to choose from that it really hasn't been feasible until now. I wouldn't mind standardizing on the VX-7R (it's a great radio), but the cost is prohibitive. The low cost of the Baofeng UV-5R has made it possible for me to have several radios that all use the same programming and operating methods, and the same accessories. I want one for everyday use. I want one that stays at work. I want one dedicated to a Go Bag at home. Etcetera.

What I have now (handheld radios)

• My oldest son and I have both had the VX-7R (after trading up from the 5R) since they were first released almost 10 years ago.
• HTX-202 to do some APRS and later Echolink activity
• Several HTX-420 HTs that I bought for my wife and children
• Kenwood D7-AG that I have used for packet and APRS
• I won an Icom V80 at a ham picnic

Compromises required

I decided that while I will have to make some trade-offs, it will be worth it to me in the end. In my research so far, I have read nearly all of the 10,000 messages on the UV-5R Group and scoured the net for reviews and comments. Based on what I knew, I ordered the radio from an outlet based in the U.S. It took over a week, but I finally received my radio in the mail. These are my thoughts on the pros and cons of following through with my plan of purchasing more of these radios and parting ways with my older ones. It is as much for me, to justify my plan, as it is to share with everyone else. There are many other reviews of the UV-5R available online and I'm not going to try to link to all of them here.

The UV-5R I'm using

The Baofeng radio I received is labeled as a "UV-5R+Plus" and has firmware version BFB281. As I write this, I am aware of two newer versions on the market (291, and 293).

Differences that matter to me

Most of these items are things that are different between the UV-5R and the other radios I use. Most often, I am making the comparison to my VX-7R since that is the radio I use the most. Some of these items may not be important to anyone else. I may come up with others as I gain more experience with this radio and I'll try to either make comments below or if there is a lot of stuff to talk about, I may update the article itself so the information stays in one place.

1. Display.
1. Signal strength indicator.
1. In receive mode, the little cell phone like indicator on the display is completely redundant since it only tells you if the squelch is open or not (just like the audio from the radio along with the backlight and the light on the front of the radio both tell you). If the number of bars changed with the strength of the signal, that might make it useful, but they don't.
2. When transmitting, the indicator does show the transmit power level (2 bars for low, 4 bars for high).
2. Can't see both Frequency and Name at the same time - even when operating with dual watch turned off. The other side still shows in the display even though it is inactive.
1. What I do to get around this:
1. In menu 21, set [A] to display the name.
2. In menu 22, set [B] to display the frequency.
3. Change to the same channel in both [A] and [B].
2. My other radios (except the VX-7R) make it difficult to see both the Name and Frequency also.
3. No battery voltage display.
1. This is handy to know how your power source is doing.
4. No barometric pressure display.
1. I never use this function, but it is available.
2. I doubt it is very accurate, since my VX-7R had the tendency to get pressurized during use. I sometimes have to pop the battery off to get it to sound right again.
5. No clock display.
1. Handy when I keep the time set correctly, but I rarely do.
2. Have to turn the radio off to see it.
6. Offset direction not evident.
1. "+-" shows for any frequency that has an offset, it doesn't tell you which direction.
2. Being in the frequency display mode and pressing "* scn" to activate the Reverse function will show the other frequency.
7. Backlight.
1. Screen is easily readable with the backlight on (my Kenwood is difficult for me to read with the backlight at night).
2. Backlight timeout delay is 5 seconds max.
1. Would be nice if it stayed on constantly when using the radio as a base station with external power.
2. A 30-60 seconds delay would be nice when using the radio at night.
3. Backlight acts a bit strange when monitoring.
1. If the frequency is quiet for longer than the backlight timeout period, the backlight turns off (normal).
2. When a transmission is received, the backlight does not turn on. (strange)
3. When a transmission ends, the backlight comes on (normal).
4. I'd love it if a firmware update made it so the backlight comes on whenever the state changes (in both 2 & 3 above).
2. Controls.
1. Channel control.
1. Buttons only - no knob.
2. Can't scroll through channels as easily as I'm accustomed to doing on the VX-7R.
3. I won't bump the channel accidentally as I often have because I forgot to lock it before putting it back on my belt (or in my chest pack, etc.).
2. Volume control.
1. I don't like that the volume knob is so easily rotated. I'm likely to accidentally turn it down to where I will miss stuff.
2. The clicking knob on the VX-7R is much better. My other radios (except the V80) also suffer from this problem, so it's not really that much of a difference, but I wish it had more resistance.
3. Lock function.
1. I can still turn the volume down when locked.
2. Most buttons will stop a scan when locked.
3. The Call button will still switch to FM radio mode when locked.
4. It does come back on in lock mode after cycling the power.
5. Autolock seems like a great thing to have for events. We'll see.
4. FM radio/Alarm button.
1. Why'd they put it there and call it a "Call" button?
2. Why is it orange?
5. Squelch.
1. The VHF side is separate from the UHF side.
2. Levels go from 0-9 on both sides, but the VHF side ignores any settings above 1 making the 2-9 options useless.
1. From what I've read, this is a bug in the radio.
2. At work around my computers, this is a hassle because there are several frequencies where the radio picks up a small amount of noise. If I could set the squelch up just a little bit higher, I think it would be fine. 
3. Fixing this particular bug would make it worth it to me to upgrade to a new firmware version.
3. The monitor button is slow to open squelch (so you can use the flashlight). It'll just take some getting used to I imagine.
3. Memory channels.
1. I find 128 channels somewhat limiting. I don't have room to store my most needed amateur and public service frequencies along with FRS, GMRS, MURS, CAP, repeaters from neighboring counties, places I visit frequently, etc.
2. No banks for scanning or other separation ([A], [B], etc.).
4. Transmit/Receive.
1. Can't hear two channels at once.
1. Not true dual receive. You can listen to [A] or to [B], but not both at once.
2. Probably helps with battery life.
2. Switching between Transmit/Receive seems slow.
1. This is just a feeling, not anything I've measured.
2. I've read about others having trouble with APRS (might need a longer TX Delay than other radios).
3. Reverse function.
1. Changes both [A] and [B] banks at the same time.
2. In Name display mode, it's not evident what frequency you are actually using (see previous item) even when transmitting.
3. Turns off after a power cycle (even if radio is in lock mode).
5. Programming.
1. Fiddly, but not too bad once you get the idea. A cheat sheet helps me.
2. Decent software available for free that is being actively developed.
3. My other radios were confusing at first as well. This will only get easier as I only have to remember one process.
6. Firmware.
1. Firmware is not updateable. Whatever you get, you have to live with it.
2. My radio was sold as "Latest version 2013" but what I received was a new looking radio (different face plate) with a slightly older firmware version. Since these radios are sold exclusively online (according to the label on the radio itself), it seems like it can be hard to know what you will get. Maybe this will improve as more domestic sellers start carrying these radios.
3. I sent my D7A back to Kenwood to be upgraded to the 'G' version, but I've never heard of a Firmware update for any of my other radios.
4. I like that things are improving with this radio. I'm sure there would be no problem selling (or donating!) radios with older versions.
7. Scan mode.
1. In comparison to my other radios, the scan mode is extremely slow.
2. It's got a weird quirk of skipping over channels using tones under 141.3 Hz, but I don't have any channels that need to tone squelch (TSQL, R-CTCSS, or whatever your radio calls it).
3. Does not resume after a power cycle (even in locked mode).
4. Can't program channel skip (channel lockout) in the radio.
1. You can do it in the programming software, but that doesn't help you in the field when you run across a problem frequency and need to take it out of the mix. This is something I really hope they remedy in a future firmware update!
8. Power.
1. Can't charge without drop-in charger (through the radio).
2. Extra chargers are cheap.
3. Battery eliminators are cheap also. They may be nicer than having a big plug sticking out of the radio with the possibility of it falling out and getting no indication (been there). I haven't used one before, so I'll have to report on this later.
4. As long as the drop-in charger is reasonably smart, I think the batteries will be better taken care of than my other radios. They won't likely be too hot when charging due to being used at the same time, or being charged through the radio while sitting in a hot/cold car, etc.
5. Can get multiple rechargeable batteries relatively inexpensively (read: "way cheap"). I can get several (or more) instead of always trying to charge the one or two I have whenever possible (like in the car, etc.).
6. Extended size battery packs are available.
7. Long reported battery life relative to most other radios. I'll need to report back on this.
8. Low battery warning sounds nice. Again, I'll have to report back since I haven't even run it down once yet.
9. No AA pack available.
1. A "AAA" pack only partially makes up for this as I try to only carry one type of battery.
2. Maybe someone can make one out of an extended battery shell? Extra size/weight is not important to me - I want the flexibility a AA pack offers in the field.
9. Light.
1. Turning it on while scanning requires two presses, one to stop scan mode, then one to turn the light on.
2. I wish I could turn the light off with a single press of the button instead of having to hit it twice (it cycles through On, Blink, Off).
3. My EDC flashlight is much brighter, but the radio's light would certainly let you see up close in a pinch (finding a keyhole, etc.).
10. Accessories.
1. Antenna
1. The stock dummy load is OK, but not much more than that.
2. The connector is backwards from all of my other SMA antennas and I'll be checking out the $4 antennas online that people have been raving about.
2. Some of my old Radio Shack/Kenwood accessories don't fit
1. The newer earphones I have fit fine. A couple of older ones do not.
2. An older Realistic speaker mic doesn't fit.
3. The new programming cable I got with the radio also fits (and works with) my D7AG.
11. Misc.
1. Multiple colors available.
1. I haven't decided yet if I think I might want something other than black (for the radio, or the battery pack). I can always label the radios to tell them apart, but when using two radios simultaneously (a strong possibility for me), different colors might be kinda cool. I'll probably start with camo - I just can't see myself carrying a bright red radio.
2. Size/weight.
1. With the standard battery, the UV-5R is the smallest and lightest radio I have.
2. Slightly narrower than the VX-7R, but about the same height.
3. I don't have the extended battery yet.
3. Water.
1. I haven't really read much about it's resistance to water. It doesn't appear to be sealed very well to me. I'll try to keep it dry, but if I fail, I don't lose much - and I get another antenna, battery, belt-clip, and charger with the new unit.
4. The A/B button on my UV-5R feels different when I press it. It doesn't activate in the same way with the same amount of pressure as do the other buttons. It feels sort of sluggish. It still works, it just feels odd.

I have not had much actual operating experience with this radio yet (only 2 conversations so far just to tell me that it does actually work). I only received it yesterday.

My bottom line

I'm not ready to give up my D7AG with it's APRS and packet capabilities quite yet (at least some of the accessories are interchangeable . I told my oldest son that his wife gets my VX-7R the day she gets her ticket. My daughter has her HTX-420 already as do middle sons 2 & 3. Daughter in law #2 will probably end up with the V80. Youngest son hasn't been interested yet, but I'll talk his future wife into being prepared and then he will be. :)

Programming Function Quick Reference

For now, this helps me.

21 - A-Display Channel/Name/Frequency 22 - B-Display Channel/Name/Frequency 24 - Autolock 27 - Create a memory channel (use [A])    2 - Transmit power    5 - Wide / Narrow band  10 - Receive DCS  11 - Receive CTCSS  12 - Transmit DCS  13 - Transmit CTCSS 23 - Busy Channel Lockout   Save twice (RX then TX) or use 25 & 26   25 - Shift +/-   26 - Frequency Shift 28 - Delete memory channel 34 - Dual watch display priority

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Notes on UPS units from UCARES picnic give-away

Since so many UPS units (~30) found new homes at the recent UCARES picnic, and because I didn't get a chance to modify this batch to add Anderson Connectors or put labels on them, I thought it would be good to compile a short list of notes that may help anyone who ended up with one make good use of it.

• All of them are used. They all used to work. I don't know if they work now or not. If you ended up with one that doesn't work, let me know - I think I can get a few more and can trade you.
• I have used them to charge and maintain 12 volt SLA batteries that were rated from 7 to 100 amps.
• Multiple batteries can be floated from a single UPS.
• They will NOT power a radio bigger than an HT for an extended period.
• You can use batteries (while connected) with higher drain radios without problems as long as the batteries themselves can handle the load.
• They provide about 0.75 A of charging current. A large battery will take a LONG time to charge at this rate.
• They float at about 14.0 Volts. A little on the high side (at the expense of battery longevity), but keeps the batteries fully charged and ready for use should there be a call-out, etc.
• SLA batteries can be left connected to the UPS indefinitely. I would expect about 3-5 years of life (a guess, not a formula) from a brand new battery if left connected and never used.
• They will work as normal UPS units and can provide backup power to a computer, etc. Just be sure to use large enough leads to the battery(ies) (at least 12 ga for full rated capacity).
• To turn the units on when 120 Volt power is not available, press and hold the power button until the unit beeps, then release the button while it's beeping.

Some of my other posts that may be helpful:

• Stuff about UPSs
• UCARES training item about batteries
• Be careful - batteries can do bad things

Last, here's a close up picture of the way I have modified these UPS units to put connectors on them for convenient use with my batteries:

I drilled a 1/2" exit hole for the wires (which are just barely long enough if you cut the original connectors off right at the end). I used hot glue on this one, but that wasn't the best idea I've ever had. You can see that it is loose now (3 years later) and doesn't keep the wires from moving in the hole. A grommet would have been better, but they are a bit of a pain to install and thread the wires through. I have had better success with using kneadable epoxy putty and just pressing it into place into the hole and around the wires. You may also choose to leave the original internal wiring intact and simply tap into the lines to bring a longer connection out the back. This would allow you to use an internal battery if you want as well as an external one if needed. Keep the wires as short as possible. At its full rated load, this UPS can draw over 30 Amps.

Getting APRS running again

I'm going to try to get my digipeater running again. I swapped the dual port TNC I was using for a single port that has APRS capable firmware. I won't be running an I-gate anymore, but there seem to be enough around here already. I just want it to provide extra coverage for the area.

This site in Finland is doing some really cool things with APRS. It's best to use your callsign as your username, but make something up if you don't have one, or don't want to give it.

So, the first thing I've got to do is get a USB to serial adapter to connect to the computer so I can program the settings in the TNC. Once I set it up, it can be disconnected from the computer (a major source of problems in the past) and run on its own.

The radio is a Phoenix SX 16 channel and puts out somewhere around 30 watts. The antenna is an 8 foot Diamond X200 clone installed on my roof about 30 feet up. Power is supplied by a home built power supply that float charges a 75 AH battery.

2007 Squaw Peak 50 Mile Trail Run

For several years now, I've been helping out at various aid stations for a couple of Ultra Marathons put on by John Bozung. Last Saturday, for the third year, I went to Windy Pass with a group of Aid Station people as their communications person. This year, I wasn't alone. There was another radio person to help this time which was a huge help! I actually had some time while there at the station to do something other than track in and out times of all the runners (201 passed through our station this year).

Since it was a low water year and the spring where we normally collect water for the runners was running very slowly, we filtered about 15-20 gallons of water with a hand pump so we would have enough for everyone. The other 30 gallons or so were collected directly from the pipe (installed by the Forest Service?) leading from the spring. The water from the spring runs into a trough which did a good job of collecting the water, it just had some pretty nasty looking stuff in it. Without pumping, we would have run out early, so I'm glad I brought my water filter with me (an MSR WaterWorks). The Katadyne Backcountry filter the other people had there was pretty well clogged (and useless) after they had pumped 3-5 gallons. They told me that it was new when they brought it up for this trip (glad I didn't buy that one!). The water itself looked clear (it was just sitting there in the trough - not zipping down a muddy stream or anything), but I had to clean my filter after every 2-3 liters to keep it running fast, so there must have been a lot of stuff suspended in it.

The runners had completed 40 miles when they got to our station and had just climbed 2000 feet up to us (at about 9000 feet) from the last aid station on a hot south facing slope. They were pretty tired. One guy at the end had the worst time of it. The course sweeper stayed with him until he made it to us, and for about 30 minutes alternated between laying down and leaning over a tree puking. He finally was able to drink a little of my still-frozen Powerade that I had stashed and some of an electrolyte drink called Emergency (reference needed) from some of the other aid station people. Although the Utah County Search and Rescue team was already busy on another couple of calls, they did send a team to assist us in case there was a problem. We knew we needed to either get him moving and have the SAR team help us with him if he couldn't make it or just call a helicopter to evacuate him before it got dark. He started feeling a little better and decided to try to get down on his own.

Here he is leaving the aid station. My red shirt looks absolutely huge on him but he sure looks a lot better than he did when he arrived.

After descending some and drinking more of the electrolyte drink, his condition improve quickly and soon he was running down the mountain ahead of the sweep. I believe he even finished the race.

Way to go Phil!

It was a lot of fun and between myself and another aid station person, we got a lot of pictures of the runners. I don't know if we got everyone, but we came close. I hope to be back up there for the Kat'cina Mosa 100K this August.

UCARES Training Item

Training Item given on the Utah County ARES net on 23 Jan 2006
(It was originally scheduled for 17 Jan, but was delayed a week)

[2006-02-03 Note: Eric Harrison KE7BQE send me an e-mail saying that he recorded the net and has posted it here: http://www.thirdpicket.com/plone/site/Members/eric/blogs/blog/archive/2006/02/03/battery-training-item Thanks Eric!]

I’ve played a lot recently playing with batteries and I thought I’d talk tonight about some of the many types of batteries we may encounter in the Amateur Radio world, and I’ll briefly mention a few of their characteristics.

First, the standard non-rechargeable types everyone has used are of course the Alkaline batteries that we get from the grocery store. These come in all sizes from N to D. One of the most important attributes of Alkaline batteries in Amateur Radio or Emergency Communications situation is that they are available almost anywhere. I’ll come back to this point later.

Non-rechargeable lithium batteries are widely available in 9v, 123 and AA sizes. Some of the advantages of non-rechargeable lithium batteries in commonly used sizes are that they are lighter than akalines and they last longer in devices like GPS units, flashlights, digital cameras, and so forth. Hikers, cavers, and others are often willing to pay a little extra for these high-performance batteries.

Rechargeable batteries in commonly available sizes come in two main chemistries, Nickel Cadmium (also referred to as Ni-Cad) and the newer Nickel Metal Hydride (or NiMH). A key advantage of rechargeable batteries over alkaline is that they cost less for the power that they provide over their lifetimes.

Rechargeable battery packs for Hand-Held radios come in three main types, NiCd, NiMH, and the newer Lithium based chemistries.

Other types of batteries I’d like to include as useful to Hams tonight are Lead Acid batteries. Car and Boat type Lead Acid batteries are most often the Flooded Electrolyte type (they have liquid that sloshes around inside them which can spill if they are tipped over). Sealed Lead Acid batteries – the kind that Hams like to carry around – don’t spill if tipped over and are often used in things like wheelchairs, electric scooters, those cordless 20 trillion candle-power spotlights, and so forth.

Rechargeable NiCd batteries have been in use for over 60 years. Sealed Lead Acid batteries have been around for 30-40 years. NiMH and Lithium-Ion batteries became widespread in the 1990’s. The new polymer based lithium batteries are barely 5 years old. And more types are coming I’m sure.

So now that I’ve mentioned a few different types of batteries, I’d like to talk a little about the advantages, disadvantages and care of each type.

First, back to the point I made earlier about batteries you can buy at a grocery store. If your equipment can run from these types of batteries, you will have a very good chance of being able to borrow some spares from someone else if yours happen to go dead sometime. Whether it’s a public service event or an actual emergency you will probably be able to get AA size batteries. While I have not always been completely successful, I have made an effort to make sure that all of my portable emergency communications gear can run from AA sized batteries. This way I don’t have to carry separate sets of spares for each device and my radio can share batteries with my flashlight if the need arises.

A little now about rechargeable battery packs like the ones on most handheld radios. I’m going to be fairly simplistic here as there is quite a lot of science behind these packs and yours may differ or contain a new technology or whatever; so IN GENERAL here are some tips to help your battery packs last longer and give you the most operating time per charge.

If you have a Nickel based pack (NiCd or NiMH), run it down at least every 5-10 times you charge it. If your radio automatically shuts itself off when the voltage drops too low, you are better off than some of us who have Kenwood radios that don’t do that. Some radios really will run a battery pack down completely – all the way to 0 volts if you let it go that far. This is particularly bad because a battery pack is typically made up of multiple cells. Running the pack completely dead will most likely damage one or more of the weaker cells inside. In short – run it down, but not dead every 5 to 10 times you charge it.

If you have a lithium based pack, charge it at any and every convenient time. Lithium based batteries do better if they are discharged partially and recharged multiple times than if they are completely discharged on each cycle. Lithium batteries will die within a few years whether they are used or not. Their chemistry is such that they are on a downward slope from the day they are made. Lithium packs cannot be charged with chargers that are not specially designed for charging them.

Cycling either Nickel or Lithium based battery packs in hot environments significantly shortens their lifetimes. Cycling them at 85 degrees, will reduce their life by about 20%, and their life may be reduced by as much as 40% at 100 degrees. That doesn’t mean that you will get less talk-time if you charge a battery while it’s at 100 degrees, it just means that you won’t be able to cycle them as many times. Sitting a radio on the seat of a car in the summertime and charging the battery pack while it’s at 120 degrees is hard on the pack. Some smarter battery chargers won’t even start to charge when they detect too high a temperature.

Sealed Lead Acid or SLA batteries, like Lithium based batteries, do great when they are charged as often as possible. Unlike the other types, SLA batteries do great when they are left on float chargers that are designed specifically for them. Unfortunately, car or boat float chargers, or motorcycle battery chargers are not designed for use with Sealed Lead Acid batteries. Let me repeat this in stronger terms. Hooking an SLA battery to a float charger not designed for an SLA battery could destroy the battery in a relatively short time. Most of the power supplies that we use with our Ham gear can (and often do) provide the perfect voltage for floating SLA batteries. However, caution is in order here in case you’re thinking of hooking up your battery to your power supply. Most power supplies are not designed as battery chargers and they may not work well if you try to hook up a battery (especially a discharged one). In this situation they may simply shut down if they have over-current protection built into them. If they don’t have this protection, they may blow a fuse or they may liberate some of their carefully stored smoke. Also, if you turn the power supply off (or lose shore power) the battery may be completely drained. I have found that a really great way to keep my SLA batteries charged and ready to go is to hook them up to a computer UPS. Most UPS units have chargers in them that are designed for use with SLA batteries (since they have batteries in them). I’ve got some pictures and other notes about doing this on my web log (http://kd7lrj.blogspot.com). I’ll post a link to the site on the ucares.org page as well.

The last thing I’m going to talk about is Self-discharge. Batteries that are left disconnected discharge slowly. For non-rechargeable lithium batteries the self-discharge rate is very low. They will easily last 10 years with only a small loss of charge. That’s why these batteries are so good for long term storage or very low drain devices like clocks and smoke alarms. Alkaline batteries can be good after several years of sitting around too – just check the dates they print on them nowadays. However, at the high temperatures encountered in hot cars even Alkaline batteries can lose half of their charge within a year. Nickel based rechargeable batteries have a much higher discharge rate of 1-2 percent per day. NiMH batteries can lose 10% in the first 24 hours and then another couple percent per day at room temperature. After a few weeks in a high temperature environment Nickel based batteries may be completely drained due to self-discharge. Lithium based rechargeable batteries fare much better than other rechargeables and only self-discharge at about 2-3% per month at room temperature. SLA batteries will self-discharge at about 5% per month. Self-discharge does not harm any rechargeable battery types except SLA. If you let an SLA battery sit around disconnected for long periods, it may destroy itself. Charge those jump starters in your trunk at least once every six months! If you have SLA batteries sitting around that you’d like to test, charge them up and get in touch with me – I have a tester that can measure exactly how much power a battery can provide.

Sources:

Powersonic: http://www.power-sonic.com/techman.pdf
Isidor Buchmann: http://www.buchmann.ca

Cadex: http://www.cadex.com

Many, many other web sites.

Mold your own ear piece

Steve (NV7V) just sent around this link: PodFitKit Home

Sure sounds a lot cheaper than paying a professional to come and do it for you. You can mess up quite a few times and still come out ahead!

Let me know if you or anyone you know trys it. (click the comments link)