Ham Radio Hacking: Thinking Inside The Box

There are two ways to deal with improving ham radio receivers, or — for that matter — any sort of receiver. You can filter and modify the radio frequency including the radio’s intermediate frequency, or you can alter the audio frequency output. Historically, RF and IF techniques have been the most valued because rejecting unwanted noise and signals early allows the rest of the radio to focus on the actual signal of interest. However, audio filters are much easier to work with and until recently, DSPs that could handle RF frequencies were expensive and uncommon. However, [watersstanton] shows us how to make what could be the cheapest audio enhancer ever. It is little more than a modified cardboard box, and you can see and hear the result in the video below.

On the one hand, you shouldn’t expect miracles. On the other hand, you probably have box laying around and can try it in the next three minutes so why not give it a go? You can hear a bit of difference when using the box and not using the box.

In particular, you can tell, too, a difference in the position of the box. He also encourages you to experiment with different materials. He likens it to cupping your hand around your ear to direct sound flow. We’ve actually seen passive amplifiers for phones that are not much different than this.

We are firm believers that ham radio doesn’t have to be an expensive hobby. You can scrouge quite a bit of gear using almost nothing.

19 thoughts on “Ham Radio Hacking: Thinking Inside The Box

  1. When the IC-7300 was first being released, there were vendors selling ‘scoops’ that you would place over the top of the radio to funnel the sound forward, rather than straight up.

    They were popular for a while, but soon anyone that wanted better/louder audio simply went out and attached a forward-facing external speaker.

    For example:


    1. Likewise… for me it’s a car speaker attached to a piece of plywood with a 3.5mm cable to plug into the radio.

      One of the radios (Yaesu FT-350AR) I use for a base radio at horse endurance ride events actually can take stereo speakers… it’s a dual-receive radio so if someone talks on the left side you hear it on the left speaker and vice versa.

      The thing has a single mono speaker in the body, the head unit has pissy near-useless small speakers in it… I plug in an old unamplified set of speakers from a SoundBlaster 16 sound card… works great.

      Prior to me bringing those speakers along, I recall once trying to hear operators in a major storm… grabbed a Bluetooth speaker I had laying around, plugged speaker-out to aux-in… that worked well too. Nice and clear.

      1. I used a pair of 4 ohm 8 inch car speakers wired in series in a wooden cabinet. they were a cheap low power type with a fake high power rating.

        The large size is much more efficient than the stock speaker, which gives an improvement in audio fidelity.

        One issue that’s not commonly mentioned is the non linear audio amps give a constant hiss at low volume, this i removed with a pi network resistor attenuator pad, of around 3db.

      2. For Field Day work where there could be generators running, I found US Army surplus Bose Triport headsets. You can also purchase a general aviation version for a lot more money. They have active noise cancellation and a directional boom microphone. They’re intended for use in high noise environments such as the intercom in an HMMV. If you go looking on an auction web site, be sure you find units which include the the boom microphone and interface cable. They aren’t much use without the cable (as I learned from experience). The molded connector on then cord is a mil-spec that is a bit expensive, or you can cut the connector off and wire something more convenient.

  2. I had a “fake stereo” setup for a mono tape player… I was between boomboxes… I got this 4″ cardboard tube, about 3ft long. Maybe a mailing tube, can’t remember. I cut an offset notch in it to sit snuggly on the speaker on top of the tape player, with about a foot one side and two feet the other (would have been more like 9″ and 21″ considering width of tape player if it was 3ft) and cut off the ends at 45 degrees (to point them more at your listening position)… and what happened was on the poppy crap I was playing was that the drums and bassy stuff came out the longer side stronger and the lead and vocals more out the shorter side… so kinda fake stereo like the band was arranged like that on stage. Improved the tone quite a bit in general.

    1. I have records where the original recording was mono, but they “re-processed” it to make it sound stereo for those with stereo turntables.

      Sounds weird through a set of headphones.

  3. Many had to do this back in the 50’s when the no fancy wooden console “big screen 20 inch+” TV’s had the speaker on the sides or occasionally both sides. Cigar box lids worked well. Now everyone could hear Desi & Lucy.

    Today the big wonderful flat screens have the speakers on the back or the bottom. Good grief! In paper thin walled apartments the next unit can hear the dialogue if its hung on the dividing wall.

    I drilled a hole at the small end and made a L shaped holder that my phone speaker fits up to out of a car rearview mirror aero-shroud . It is a horn shape with one flat side and has quite a bit of gain.

    1. Got that problem with a 90s color portable, speaker in the side. Person using it would have to max out the volume to get everything, whereupon it could also be heard perfectly in the adjacent room the speaker was pointing at. So had to stand a box beside it at 45 degrees to direct sound at user, rather than everyone else, and volume could be turned back down a bit.

    2. Have to remember to try stuff like that with any I find on the side of the road. Possible I’ve got one in my garage somewhere, had to replace whole unit when the alloy frame got broken and it wouldn’t mount up, but the plastic was intact.

  4. ok,

    for normal use, the speaker is good enough for me. For serious work, I use headphones. And no not the imho crappy heil things or dr dre’s stuff. Don’t even use the external speaker(s) that can be bought for the rig.

    I use RP-DJ1200; you can swivel away earpieces, good closed audio and has a high input level limit. (It’s a DJ headphones)

  5. I have done this when in a pinch
    Now I use my Sony noicecanceling headphones retune the nocecanceling while listening to a clear freq, then when I tune to a busy freq the talk is all that goes through….
    DSP by Sony…. Haha

  6. This is somewhat dumb Clickbait. Go to goodwill, buy a decent sized 4 to 8 ohm stereo shelf speaker. Preferably made with wood and with a 3.5 mm male already on it. The internal speaker is there as opposed to not having any internal speaker. There is zero baffling or audio quality thought put into it at all. Thats why most commercial 2 way one piece radios have a front firing speaker now. That and it negates the problem of requiring an external speaker when mounting the radio INTO the dash or modular center console.

  7. Well, lots of comments, but I must say, this “Cardboard Box Trick” is really a slick idea, and I just implemented it for free, by retrieving a little box out of my recycle bin. Thanks. In this day of $1,000+ radios, it seems a bit tricky to see someone re-aim the audio, and knock down that hissy hiss with a piece of paper. Gee., one might say, why didn’t the manufacturer of this fine equipment do something like this. Hey, how about a tone control implemented with one knob, and a little sound reflector that tilts up an an almost no cost hinge. Hmmm, and leave it up to someone to do this with a piece of cardboard, in 5 minutes.
    Well, excuse me commenters, while noise canceling earphones or Bluetooth speakers, or store bought speakers engineered into a cheap enclosure – ish plywood thing will work, I think you might have given this gentleman a warmer reception of his zero cost 5 minute idea… Just saying. Oh, and having studied audio acoustics in college, and done some work with it on the job, this has prompted me to get out my pencil and calculator, and see if I can have some fun with cardboard and maybe another free material… Fun stuff…

  8. I use my vehicle speakers for ham radio and CB. I mount them between the top of my seat and the headrest. It’s a great location. I can hear the contacts and my wife and other passengers, the conversations don’t drown out the radios. I bought 5 of them.

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