The Baofeng series of radios – our recommended best choice for most prepping purposes.

The General Mobile Radio Service – or GMRS for short – has evolved since its original establishment in quite different form in the 1960s.  In 1987 it evolved to essentially its present form, with business use specifically excluded, with a set of eight channel pairs for repeater operation, and seven single channels for non-repeater ‘simplex’ operation.

In 1996 the FCC created a new product – the Family Radio Service or FRS for short.  This was sort of ‘GMRS-lite’ and almost literally was squeezed into the ‘gaps’ between GMRS channels.  It was designed as a low power service for handheld walkie-talkie type radios only, and unlike GMRS there was no licensing requirement.  Anyone could buy FRS radios and ‘play’ with them more or less as they wished.

Because the FRS and GMRS frequencies were sometimes the same and sometimes only very slightly different, radio manufacturers started selling dual-purpose radios that could work either as FRS or GMRS radios.  In theory, this was illegal, but in practice, it was so widespread that the FCC chose to do nothing.  This created a confusing mix of frequencies and channel numbers, and we previously explained the implications of this in our earlier article explaining the confusion of frequencies between FRS and GMRS.

Finally – 21 years after this all started to become a mess, the FCC has acted to try and clear things up, publishing new rules and frequencies in September 2017, taking effect from late October 2017.

Unfortunately, things are still far from clear, but they are perhaps slightly less messy than before.  In particular, there will soon no longer be any more dual purpose radios – something we discuss in our article explaining the changes in FCC regulations about FRS and GMRS radios.

Here now is the new improved official list of channels and an explanation of what each channel can be used for.

Let’s first look at the most relevant list of channels for many of us – the FRS channels.

Table 1 :  FRS Channels and Power

Note that all FRS channels require a radio with NFM – ie, 12.5 kHz bandwidth.  And, as you can see, the numbering of the channels seems somewhat illogical and out of sequence with the order of the frequencies, as does the different power requirement for the 467 MHz frequencies.

Note also that the FCC assigns official channel numbers to these channels.  Whether new radios will follow the official channel numbering or not is anyone’s guess, but the list, as above, is the ‘gold standard’ FRS frequency/channel list taken directly from the FCC’s own website.

The FCC believes it all makes sense, and helps to fit the FRS frequencies more consistently into the GMRS frequencies too.  So let’s now look at the GMRS frequencies.

In the case of GMRS, not only do we show the frequencies and power, we also show what types of GMRS radio can use each frequency, and explain the frequency pairs for repeater use.  On the other hand, there are no official channel numbers.  Yes, it is quite a lot messier than the simple table above.

Table 2 :  GMRS Frequencies and Conditions

As you can sort of see from this table there are several differences between the GMRS and FRS services.  Although the FRS channels 8 – 14 are essentially identical with both services, the FRS channels 1 – 7 are restricted to 2 watts whereas the same GMRS channels allow 5 watts, and the channels 15 – 22 can go up to 50 watts with GMRS service but only 2 watts with FRS.

Plus FRS radios are limited to small handheld radios with fixed antennas, whereas the GMRS radios can have external antennas and be ‘base’ stations with greater power and/or repeaters.

In the power column, we show power of 50/15 for some frequencies.  In these cases 50W can be used for mobile, base and repeater radios, but only 15 watts for fixed stations.

So what are these different types of radios?  In the usage column we list them as :

B :  A Base radio station – a station located at a fixed location that communicates with other base and mobile stations

C :  A Control radio station – a base station that communicates through repeaters and can control the repeater

C* :  A Control radio station transmitting through a repeater

F :  A Fixed radio station – a base station that only communicates with other fixed stations

H :  A Handheld portable radio

M :  A Mobile radio station (ie in a vehicle)

M* :  A Mobile radio station transmitting through a repeater

R :  A Repeater radio station – ie one that receives (in this case) on one of the 467 MHz 50 watt channels and automatically/simultaneously retransmits it on the 50W channel that is 5 MHz lower (ie the matching 462 MHz channel)

Note – these definitions are per the FCC Part 95 regulations and seem a bit strange.  On the face of it, it seems that handheld units can’t communicate via repeaters, but we suspect this is not actually the case.

Simplifying the GMRS Frequencies

The key difference between the GMRS and FRS frequencies is there are an added 8 GMRS frequencies that are intended to be used only for repeater inputs (in the 467 MHz range).

Otherwise, the frequencies are the same, but power levels are different, and also in the high power channels, GMRS can use wideband FM as well as narrowband FM.

Most of these differences are automatically taken care of in the radio sets themselves.

The strange mix of frequencies sort of makes sense with this graphic illustration published by the FCC.

The FCC’s pictorial explanation of the new FRS and GMRS frequency allocations, which still quite literally leaves gaps or holes in their frequency allocations and reasoning

Summary

The new FRS frequencies and power allocations are much better than the original 14 frequencies and 0.5W power limit.  This is a good reason to get new FRS radios, and/or to reprogram your Baofeng or other radios to conform to the new frequencies and power limits.

It is possible the FCC may now start to lightly enforce some of its rules for the FRS and GMRS bands, so it would be wise to generally comply with the new requirements, now they are in effect.

Lastly, and as mentioned in the other article about the 2017 FCC changes to FRS and GMRS, you might prudently choose to get some more Baofeng or similar multi-purpose radios prior to their probable banning, early in 2019.

An example of a signal strength reading from a $25 SDR receiver and using free software on your PC. Essential for testing your Faraday cage.

So you’ve built your Faraday cage, and are ready to fill it with the precious electronic spares you want (need!) to protect against an EMP.  Well done.

But there’s one thing you really should do before closing it up and moving on to your next project.  Even if you’ve built a simple small and apparently 100% compliant cage, don’t you think you should check and test its effectiveness?  You’re placing a huge amount of reliance on this cage and its ability to protect its contents from an EMP, so isn’t it worth spending a bit of time and maybe a few dollars to check that it works as expected.

The interesting thing is that a Faraday cage is not an ‘all or nothing’ thing.  It isn’t like putting heavy blackout curtains across your windows and blocking out all the light from outside.  It is more like pulling a medium weight curtain across, and then having a searchlight shine on your window from outside.  Some light will get through, the key issue is how much.

The same with a Faraday cage.  It will reduce the strength of the EMP (the technical term is ‘attenuate’) but it won’t block it out entirely.  So how much attenuation will it provide, how much do we need, and how do we measure it?

How Much Attenuation is Desirable

First, how much attenuation do you need?  More is always better than less, but after a point, you reach a realm of vanishing returns and unnecessary extra protection.  We suggest you should look for 40 dB (dB = decibel) of attenuation, and ideally over 50 dB.

What do these numbers mean?  If you reduce something by 30 dB, you have reduced its power 1,000 times.  If you reduce it by 40 dB, you’ve reduced its power 10,000 times.  If you think to yourself ‘every ten dB adds another zero to the number of times the signal is reduced’ then you’d be correct.

So, after the lesson, the test.  How many times would the strength of an EMP be reduced if it had a 50 dB attenuation?  Please tell me that you answered 100,000 times.  Clearly that’s a lot, isn’t it, and probably it is enough.  Let’s see why we say that.

A strong EMP effect will induce voltages in the order of 50,000 volts/meter (it is difficult for EMPs to exceed this – anything higher than that and the sky sort of ‘short circuits itself’, although there are rumors of some ‘super EMP’ weapons that have found a way to create higher voltages).  If we reduce 50,000 by 40 dB, it is down to a trivial 5 volts/meter, and if we take it down by 50 dB, it is down to a hard to measure 0.5 V/m (ie 500 mV/m).

To put this into context, a strong radio signal ranges between 1 – 100 mV/m.  So after about 56 dB of attenuation, the strongest probable EMP is no more harmful than a strong radio signal – ie, totally utterly harmless.  And we’ve at least 10 dB of overload above that and probably 20 dB before there needs to be significant concern about EMP damage to electronic circuits that are switched off.

Measuring Attenuation – Decibels and Frequencies

There is an interesting complicating factor.  An EMP has a mix of different radio frequencies, and Faraday cages block different frequencies by varying degrees.  In general terms, the higher the EMP’s frequency, the less the attenuation.

So that begs the question – exactly what frequencies are likely to be found in an EMP?  The short answer is ‘all of them’, which isn’t very helpful, is it!  A better answer is ‘most EMPs are expected to concentrate most of their energy in frequencies below 100 MHz’.  To put 100 MHz into a meaningful context, it is right in the middle of the FM dial.

That is actually a bit of welcome good news.  The lower the frequency, the better most Faraday cages work at blocking it.  So if we test the cage at 100 MHz, we know that its blocking will be better at lower frequencies and that the 100 MHz result is getting close to a ‘worst case’ scenario.

There are a number of ways you can do this test.

Test 1 – The Phone Test

This is the easiest of all the tests, and is also the least valuable, but as a quick rule of thumb test, it can tell you if your Faraday cage might fail, although it probably can not tell you if the cage for sure will succeed (testing for failure and testing for success are surprisingly different things).

Take your cage and your cell phone to somewhere with good cell phone coverage.  Ideally, go somewhere where the cell phone is receiving on the approx 850-900 MHz range of frequencies, rather than on the 1900 MHz set of frequencies.  You can do this by using the excellent antennasearch.com website – put in your address, and then download all the different transmitters it finds close to you (chances are you’ll be surprised at how many there are!).  Use the tower map to find a tower belonging to the wireless service you use and which has only 900 MHz not 1900 MHz transmitters on it, then go to it to test.

This is more difficult than it sounds, and probably you’ll compromise by simply testing at home.  That is okay, but to get a helpful result, make sure that your cell phone has four or five bars of signal strength before putting it in the cage.

Close up your cage, and call your phone.  Maybe you’ll be able to hear the phone ringing inside.  If the phone rings, you know your cage is probably not working well.

If the cage material insulates the sound, simply check to see if the phone reports a missed call when you open it up again.  If it shows a missed call, that suggests your cage isn’t fully optimized.

Your cell phone can probably receive signals down to a signal strength of about -115 dBm.  You can probably get your phone to tell you the strength of the signal it is receiving if it is an Android or iPhone – here’s a good article on how to do so, and if you’re interested, this article tells you more.

So if your phone was showing a signal strength of -85 dBm before it went into the cage, and it didn’t ring, you know that the cage is probably providing at least 30 dB or more of attenuation (ie dropping it from -85 to -115 or more) but you don’t really know how much more than the 30 dB it is giving you.  And with only 30 dB of attenuation, that is close to a ‘failure’ so not hearing the phone ring, in this case, isn’t as positive as you’d think.

And if your phone is showing -55 dBm before going into the cage and still rings, you know the cage is providing less than about 60 dB of attenuation, but you don’t know how much less.  At 60 dB of attenuation, having the phone ring can still be considered a ‘success’, although you mightn’t think so by hearing the phone ring

So you need to interpret your phone results with care and caution.  You may be getting either false positive or false negative results; it helps if you know the signal strength the phone was receiving before going into the cage, and what the minimum signal strength is your phone will work on.

Plus, you are ‘torture testing’ your cage by checking its effectiveness at 900 MHz or 1900 MHz.  There is unlikely to be significant energy in an EMP at those sorts of frequencies, and the cage will probably offer better protection at lower frequencies.

So let’s now look at a slightly more helpful test.

Test 2 – Two Walkie Talkies

If you can walk inside your cage, go in with a walkie-talkie and have someone outside with a second one.  Close the cage up and see if you can communicate between the two of you.  If you can, that is suggesting a ‘fail’; if you can’t, that is suggesting a ‘pass’ for your cage.

The walkie talkies ideally should be on the MURS frequencies (about 150 MHz).  If you don’t have MURS capable radios, then FRS or GMRS (about 450 MHz) will work in a pinch, as well.  CB radios would not give as meaningful a result.

If you can’t walk inside your cage, that’s okay too.  In slightly simplistic terms, a cage not only blocks external signals from traveling into the cage, but also blocks internal signals from traveling out.  So all you need to do is use a rubber band to hold down the transmit key on a walkie-talkie, put it into your cage and close it up, and see if you are receiving any signal on the other walkie-talkie outside.

Note that walkie talkies sometimes have a ‘timer’ that stops their transmitting after a period of time.  Check that, when you reopen the cage, the walkie-talkie inside is still transmitting.

This is a good test with fewer ambiguities than the cell phone test.  You can be reasonably certain that if you can’t get a walkie-talkie signal through your cage, then it will block an EMP too.

But if the radios can still communicate with each other, is that necessarily a fail?  It depends on how much the signal strength has dropped.  If one of the radios has an accurate S-meter on it, this is helpful.  In theory, each ‘S unit’ on an S-meter represents a signal strength change of 6 dB, so you would want to see a 7 S unit movement or more between the two signals.  However, particularly, with inexpensive walkie talkies, they either have no S meter at all, or the S meter they do have is woefully inaccurate.

It is not prudent to rely on S meter values, even on quite expensive receivers.

Test 3 – Walkie Talkie and SDR

Good news.  You can actually do a very accurate test of the efficiency of your cage with very inexpensive items.  You want to have a walkie-talkie to place inside your cage, and use a SDR to measure the signal strength, accurately, on the outside.

For the walkie-talkie; if you don’t have a bunch of them already, get a Baofeng UV-5R.  While it is some years since we reviewed these lovely units, and while there have been later models released, the standard UV-5R, at a cost of around $30 each on Amazon, still remains an unbeatable value and excellent performer.  Tune it to a frequency around 145 – 155 MHz, it doesn’t really matter what.  You could tune it down to a lower frequency (they work down to 136 MHz) but best to keep it around the radio’s ‘sweet spot’.

But what is an SDR?  The acronym stands for ‘Software Defined Radio’.  Instead of a traditional radio with knobs and dials and everything, a SDR is a computer device – often in the form of a USB stick that connects into your computer, and which is then controlled by a computer program rather than by old-fashioned ‘analog’ controls.

These are amazing gadgets that can be had for as little as $25 (actually, you can get ones for even less than $25, but this specific $25 SDR is the best performing/best value unit until you start going way over $100).  Download the free SDR+ (pronounced ‘SDR Sharp’) software from here, plug the unit into your computer, and run the SDR+ software.  (If you have a Mac, you could try this free software.)

SDR radios have many uses for preppers, particularly as broad-band multi-mode scanners.  We’ll write more about them in future articles.

Tune to the same frequency as your HT (walkie talkie), make sure that you’ve zeroed out the RF gain and turned off the AGC, and you can get information on exactly the dBm signal strength that is being received by putting the cursor on the top frequency display.  If the signal is too strong – ie, you don’t get a nice single peak on the SDR’s display, but a whole series of peaks and a general lifting of all the frequencies being monitored, take the antenna off the SDR and maybe replace it with just a very short piece of wire.

Then stick the HT into the cage, close it up, and you’ll see exactly the drop in signal strength.  Maybe you go from +5 dBm to -40 dBm, or something else.  In such a case, clearly the cage has provided you with 45 dB of attenuation.  How easy (and accurate) is that!

In this screen shot (a larger view of the image at the top of the article), you can see that the display is monitoring a signal at 145.330 MHz, with a signal strength of +2.5 dBFS (forget about the FS, it means ‘relative to full scale’ – a concept which is not relevant to our needs).  That is a very powerful signal, and as you can see, it ‘stands up’ a long way above the random background ‘noise’ (the other data tells us the background noise is 56.2 dB below full-scale, and so in total, there is a separation of 58.7 dB between the background noise and the measured signal) and some other weak signals that you see small peaks for.

After getting your ‘out of cage’ reading, which this is, you then simply put the radio in the cage and get a second ‘in the cage’ reading.  The difference between the two dBFS readings is the amount of attenuation, and hopefully it is reporting more than 40 dB.

Summary

You shouldn’t assume your Faraday cage is giving you the protection you need and are relying on.  Fortunately, there are some relatively easy ways to test its functionality.

Ideally, you should be getting more than 40dB of attenuation from your cage.

The new Baofeng BF-F8HP looks very similar to the UV-5R, but is a genuinely different and improved model.

For several years, the small-sized and even smaller priced Baofeng UV-5R has been the most popular budget HT ‘walkie-talkie’ radio transceiver.  Although primarily intended for licensed radio ham operators, many of them have been purchased by people to use as ‘super’ FRS and GMRS radios, a (mis)use that is notionally illegal but almost never enforced by the FCC.  We’ve written several articles about this lovely radio, see, for example, ‘The Best Radio for FRS/GMRS‘ and also read through our articles on Communications in general for a lot of resource.

Baofeng have released a somewhat confusing variety of other models of radio (in particular, the UV-82 series), none of which have been compelling ‘upgrades’ to the core UV-5R radio.

Confusing the matter further, their various distributors have often rebadged and repackaged the UV-5R and given it new names, or implied it to be a new, improved, updated, enhanced subsequent model.  As far as we can tell, none of their claims have any foundation in truth at all, and no matter what the outside case of the radio, and no matter what its alleged model number, all such versions of the UV-5R are almost exactly the same, other than for occasionally updated versions of the firmware inside them, and all perform essentially identically.  Resellers also make varying claims about being official and sometimes the only official dealers for ‘real’ Baofeng radios, and these claims are also to be taken with a degree of open-minded skepticism – as best we can tell, Baofeng will happily sell their products to anyone who will buy them, and will slightly alter them as major customers may request.

To make it more confusing, the Baofeng radios are also sometimes called Pofung radios (this spelling more closely indicates how the underlying Chinese word is pronounced).  Again, there is no difference.

But now a truly new model has been released, and it truly is better than the standard UV-5R.  This is the model BF-F8HP.  Already, we are seeing a confusing diversity of model numbers surrounding this new radio type, as well.  The F8HP designation seems to be the official default designation, but there are other variants such as F9-V2+ (which seems to attempt to imply it is a later model than the F8) and the F8+ (which is actually a UV-5R).

There are three key differences between this new radio and the earlier UV-5R series, and one very important similarity.

1.  The new F8HP has three power settings rather than two.  The UV-5R had two power settings, and on high power was nominally claimed to be outputting 4 watts of power, and typically was closer to 4 watts on the 2 m band and 3 watts on the 70 cm band.  The F8HP has a low power that is similar to the UV-5R low power setting, a mid power which is similar to the UV-5R high power setting, and a high power which nominally gives you 8 watts and has been tested to give about 7 1/2 watts on 2m and 6 watts on 70cm.  That’s an appreciable boost in power, and may give you a slight increase in range in some settings.

2.  A new battery with more capacity.  The UV-5R typically had a battery claiming about an 1800 mAh capacity (and more realistically giving you 1500 mAh).  The new F8HP has a battery with a rated 2100 mAh capacity and good for about 2000 mAh.  The battery is the same size, but uses newer cells that have higher capacity.  You can never have too much battery, especially if you’re now using it at a much greater rate on the high power transmit setting.

3.  The new F8HP has a greatly improved antenna provided as standard.

The new style antenna is on the left, the old style is on the right.  This truly does make an appreciable difference to the radio’s ability to both send and receive signals a longer distance.

4.  The similarity :  All accessories that work with the UV-5R series also work with the F8HP.  That includes batteries as well as external microphones and speakers, and of course, antennas too.  So whatever you’ve bought already can be repurposed for the F8HP.

There are a few other minor differences too.  The new radio has some slightly improved internal circuitry, and a much better written 76 page manual.  Oh yes, it is also more expensive (but still great value), and currently can be found on Amazon for around $63, which is almost exactly twice the price of the UV-5R (which remains available for sale, too).

The F8HP operates on the same frequencies and has the same wide range of features and options, and can also be programmed through the same programming cables and the excellent free CHIRP software.

So – should you buy F8HP radios or twice as many UV-5R radios for the same amount of money?  We’re always keen to get the latest and greatest and best of everything, but the truth is that many times, the UV-5R will be all the radio you need.  If you get clear and reliable communications when using UV-5R radios, and especially if you are using them in low power mode, then there’s not really any need to get the F8HP.

If your UV-5R radios are struggling to connect to each other, then a better investment might be improved antennas on the UV-5Rs, rather than junking them and buying F8HPs.  A UV-5R with a good antenna (a Nagoya 701 or 771, for example) will generally give you comparable performance to a F8HP with its standard antenna.

But if you still have range issues, then, yes, you should get the F8HP.  A F8HP, on high power, and with an improved antenna, will beat the UV-5R every time.

As for us, we’re not junking any of our collection of UV-5R radios, but future purchases will all be of the F8HP.  Who knows what evolving needs and scenarios might come to pass, and you can never have too much range or battery life in your radio (although note that the UV-5R can also accept the same battery, and both can also use the extended battery or battery eliminators too).