Be Vewy Vewy Quiet, We’re Hunting Baofengs

In the world of ham radio, a “Fox Hunt” is a game where participants are tasked with finding a hidden transmitter through direction finding. Naturally, the game is more challenging when you’re on the hunt for something small and obscure, so the ideal candidate is a small automated beacon that can be tucked away someplace inconspicuous. Of course, cheap is also preferable so you don’t go broke trying to put a game together.

As you might expect, there’s no shortage of kits and turn-key transmitters that you can buy, but [WhiskeyTangoHotel] wanted to come up with something that could be put together cheaply and easily from hardware the average ham or hacker might already have laying around. The end result is a very capable “fox” that can be built in just a few minutes at a surprisingly low cost. He cautions that you’ll need a ham license to legally use this gadget, but we imagine most people familiar with this particular pastime will already have the necessary credentials.

The heart of this build is one of the fairly capable, but perhaps more importantly, incredibly cheap Baofeng handheld radios. These little gadgets are likely familiar to the average Hackaday reader, as we discussed their dubious legal status not so long ago. At the moment they are still readily available though, so if you need a second (or third…), you might want to pull the trigger sooner rather than later.

At any rate, in the setup that [WhiskeyTangoHotel] has outlined, the Baofeng radio is connected up to an MP3 player which is loaded up with a recording of your message and FCC callsign that plays in a loop. An Arduino and a relay module are then used to key the transmitter automatically by grounding out the microphone connector. As it so happens, the lanyard mount on the Baofeng is a convenient ground point and allows you to hook the whole thing up quickly with alligator clips.

If you’re looking for something a little more compact, we’ve previously covered a very nice wearable transmitter which can be used for fox hunting. We’ve even seen a gutted FRS radio stuck into a rocket if you want to take your hunt to the next level.

20 thoughts on “Be Vewy Vewy Quiet, We’re Hunting Baofengs

    1. The counterfeits and non-FCC compliant intial versions from a few years back did have some issues (or outright missing PA filters). Not sure if this applies anymore, given the spectrum analysis we did locally on the FCC stamped models did not show over-modulation problems (just barely inside the fcc & ic limit rules).

      Maybe someone has a more modern study available somewhere.

      1. Counterfeits? There are counterfeit Baofengs? That’s just funny. Why would somebody make the effort to counterfeit a $30 Baofeng when they could instead make the same effort and get 10 times the money by slapping a Yaseu or Icom sticker on it.

        For the non-hams out there that is kind of like claiming that there is a counterfeit k-mart branded underwear problem out there on the market. Or counterfeit Kia cars. Maybe counterfeit Harbor Freight tools!

        I don’t believe you.

        1. Think of it this way-

          Spend your time and money making a counterfeit Yaesu that will get smacked down by their lawyers and keen-eyed OM’s?

          Or:

          Spend your time and money making a cheap, popular with new ham, fast-selling radio that will probably never be discernible from the original until it gets purchased and hooked up to a spectrum analyzer?

          My money’s on the latter.

        2. Ridiculous but true,
          In some cases the clones were actually better quality, and digital codecs even met the standards.
          It is always a gamble unless you get equipment from authorized resellers.
          ;-)

  1. Following the US FCC crackdown, most Baofengs are now illegal to sell/import/possess for Canadian amateur license holders. =(
    http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf08449.html#s6.4
    https://laws-lois.justice.gc.ca/eng/acts/R-2/page-2.html#docCont

    Proving once again our local MPs have zero insight into the technological collateral damage caused by discarding modern wide-band technology in favor of concepts from the 1960s. Even Police band IT maintenance people are getting nailed these days due to the DMCA clone imported from our neighbors:
    https://www.cbc.ca/news/canada/manitoba/city-of-winnipeg-manager-in-charge-of-police-radios-arrested-after-2-year-investigation-1.5027975

    Oh well, at least China will get all the awesome new comm tech… not like we are legally able to use it anymore anyway.
    lucky… ;-)

    1. Err no your police guy got arrested for criminal fraud and breach of license. This has nothing to do with the DMCA and would have been illegal in pretty much any country including the USA and Canada before the era of the DMCA.

    2. If reliably confining one’s transmission to the actual desired frequency range instead of splattering all over the bands, potentially causing harmful interference to important services is a concept from the 1960s then you can call me Austin Powers.

      Yes, I know that SOME Baofengs are ok. Yes I know that they are affordable and the more reliable alternatives are overpriced. Yes, I agree that something in the Baeofeng price range SHOULD exist. But that does not make it ok to cause interference. A ham radio manufacturer that cannot RELIABLY keep their products within the ham bands and out of the public service frequencies should not be doing business. Baeofengs are like Cracker Jacks. You don’t know whats inside till you open it. If you tested a good one then congrats! The next one you buy might not usable.

      Note, I’m not talking about radios that can be tuned off-band. That can be up to the user to chose not to do or pay consequences if they go there anyway. I’m talking about when the frequency on the display is good but a greater than allowed percentage of the power out the antenna is going somewhere else.

      1. By law, a license here requires one own equipment to verify the radio output is within tolerance of the holders class limits.

        It is a $5000 fine and or 1 year in jail if you get it wrong.
        The IC/FCC stamp on the radio has nothing to do with this part of the rules.
        We’ll assume you can prove you own such equipment upon a site inspection. ;-)

        1. The FCC may care about a gaylord of them being imported but they could give a shit less about the ham bands on a personal level. They let the arrl’s hitler youth patrol them. The funny thing about that is they can only mess with you IF you are a ham and you ID yourself as such. About the most the FCC is going to do to an individual these days is ask them to knock it off. Now, if they don’t heed that warning they may get pounded upon, but the chances of getting that warning are pretty slim. They have like 8 employees world wide. They have much bigger fish to fry. I have heard it takes half their staff just to keep janet jackson form popping her other tit on the air.

    1. You’re just seeking the carrier, so the actual modulation doesn’t really matter. If you don’t modulate an FM transmitter, then it’s just putting out a carrier.

      You do need a means of measuring relative signal strength at the receiver. Some receivers will be better at that than others.

      Michael

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.