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Radio Bug Cache


AK0B
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Under FCC Part 15 rules it would be easy to construct a 13.554 MHz 2 milliwatt beacon. I built one of these using a EPSON programmable osc from Digi-Key. I obtained the circuit from K0LR longwave Part 15 site here on the web.

 

With some of these new HF- UHF radios such as the TH-6 etc it might be fun finding a radio hidden cache.

 

de Stan ak0b

 

Stan-AK0B

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I thought Part 15 required type acceptance?

 

I had always thought that hams could only experiment in the ham bands. Put your transmitter in the 20 meter band on a beacon freq and you can run more power.

 

I do agree, however, that this sounds more like a fox hunt than a geocache.

 

My two cents worth, refunds available on request.

 

Dave_W6DPS

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> Sounds like fun but it also sounds like a fox hunt and not a geocache.

 

You could have the GPS get you close enough to get the signal and then follow the signal to the cache. Or you could have a traditional cache with a note inside indicating the frequency to track on to find a second cache (so that traditional geocachers are not left out completely).

 

In any case, it would be a combination search using both the GPS and the tracking receiver.

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Problem with the 'combination' is you would have to decide how far away from the location you would switch. With terrain masking, reflection and other considerations what would be the switch point? Then you would have to have a long term power source, or again this would be a 'short term' cache...aka foxhunt. I thing the detractors outweight the benefits. Of course, this is only an opinion.

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quote:
Originally posted by Erawa: Then you would have to have a long term power source, or again this would be a 'short term' cache...aka foxhunt. I thing the detractors outweight the benefits. Of course, this is only an opinion.

One solution fo the "short term power problem" would be to make the beacon solar powered or make a solar powered battery charger and charge the batteries

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The idea I am setting up is for those hams that want to play with fox hunt can and for those non-hams they can reap the rewards also and maybe encourge non hams to become hams also.

So fox hunt or geocache? 2b or not 2b? Lets just have fun.. icon_biggrin.gif

 

Rich Conn

kd5jxu@arrl.net

145.130 -

146.500 simplex

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I think that this is a wonderful idea. I think that some folks aren't thinking far enough outside the box though. You can design the RF beacon so that you must be within 100ft or so of the cache to even RX that beacon. I recommend doing this somewhere in the 147Mhz simplex portion of 2m. Why? Because most amateur operators own a device capable of RX 2m but, the same can't be said for 13Mhz. Also, non amateurs can buy a very inexpensive scanner to RX 2m - the same can't be said for 13Mhz.

 

Something else that you might consider doing is have the beacon send hints via CW or a digital playback device for phone mode.

 

Solar power could operate the device for a daytime only cache or one could implement a charging controller and batteries with it to have a 24hr beacon/cache.

 

The panel may be a bit more difficult to hide while ALSO giving it a good shot to the sky to do its job.

 

Something else is that this represents a much more significant investment that you are deploying to the field. It would be a serious bummer to have someone find your beacon/cache and decide to claim the entire beacon/cache as their prize.

 

- EnterZone

K4WTF

WPXT826

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Hi group

I just finished the construction of a rock 2 meter beacon. it weighs 18 oz and emmits 275 mw. I have it transmitting on 146.500 every 5 min. with a 1 min. tx. I have it powered by a series of nicad 9 volt batteries and a solar charger. I will be doing test for the next month and see how the progression goes. I will keep all posted.

frog.gif

 

Rich Conn

kd5jxu@arrl.net

145.130 -

146.500 simplex

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All you need is a tech ticket, that is the beauty of it. I found my plans through ARRL and did some mods to it with the help of an engineer from where I work. if it works out I will post it

 

quote:
Originally posted by F_22:

Just out of curiosity, where are the plans for this transmitter? And could I opperate it with a tech license?


 

Rich Conn

kd5jxu@arrl.net

145.130 -

146.500 simplex

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If Billy Joe Jim Bob stumbles upon it is it still geocaching. at least chasing a beacon you are searching for it

 

quote:
Originally posted by Mopar:

Sounds like fun but it also sounds like a fox hunt and not a geocache.

If you CANT find it using a GPS, is it still a geocache?

N2GZG

 

+ _Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon. _


 

Rich Conn

kd5jxu@arrl.net

145.130 -

146.500 simplex

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Here's an idea...Have a traditional cache and a hidden transmitter cache. In the traditional cache, have a frequency (2m), and a dtmf code. You simply tune up to the proper freq, enter the dtmf code, and it would start the radio cache transmitting. It would continue transmitting unitl either one of two things happen: a "found" button is pushed on the cache, or a specified amount of time has elapsed. It could be solar charged, and would only transmit when needed. This way, non hams can find the traditional cache, and hams can find both.

 

Whaddya think?

 

Bill KD5PGX

 

"Those who think that they know everything are especially annoying to those of us who do." ;-)

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We used a transmitter that emitted a tone when somebody found our cache. When you opened the lid on the ammo can the plunger switch (now converted to roller tip)activated the device. The signal is only detected by a receiver hooked up to a scan recorder program on an old computer. Time, Day, Date and duration of lid opened was all recorded...

We thought about recording what was said by the "finders" but we respect the laws governing private conversations and such.

GOOD idea! We already had complications of getting a "radio bug cache" approved since it detracted from primarily using a GPS, Compass, Maps etc. The only way to get it approved is by indicating the use of GPS be the prime (but alternate) method of preference. For those who wish to use radio detection other than or in conjunction with GPS (etc.) by all means do so. Build it and they will come...GOOD LUCK! KD7KYU

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quote:
Originally posted by GeoCan:

FRS channel #2 with privacy code #35


 

You may want to check various brands and models - I've heard, but have not confirmed, that not all units use the same privacy code number to specify the same sub-audible tone. I'm curious on what you did for batteries and how long they last.

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I like "Kordite's" idea. A combination like that could be quite enjoyable. But I'd hope to know what band to expect when I uncover the frequency in the initial cache. Otherwise I'm liable to carry the wrong receiving equipment.

 

"Today's truth remains valid only as long as it withstands the test of tomorrow's discoveries" - George Hicks

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I (poikää) am a HAM and our local HAM group have a FOX every Wednesday evening from April to October. We have several Geocachers in the bunch and we are trying to come up with a combination cache / FOX placement. I think both would work with the cache listed as normal but having a new Icon for a radio / beacon geocache. (Markwell?)

HAMs could find the general area as to the page then DF it as the beacon comes in "view". A PIC controller could be used to turn the rig on es off to save batteries or it could be a solar / battery type. FRS would work but you do not need a license to listen to a radio signal!

 

poikää es butterfl

 

Pain is weakness leaving the body

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Here is my combo idea: construct a CW beacon transmitting on low power FM band and instruct seekers to bring their FM walkman's with them, and a printout of the cache page that has morse on it. The cache page coords lead them to an area where they pick up the signal, and the CW coords lead them to the final/next location.

K-ID is $8 preprogrammed, and those little FM transmitters can be had for around $15. For power, maybe a solar panel? I can find 5v 180mA for $16.

I'd love to do this, but would need some help from you electronic circuit experts.

Will connecting the "sidetone" to the input of one of those cd-player/fm transmitters do what I expect?

What is the effect of the power fluctuations of a solar panel on the transmitter and the beacon chip?

What is the effect of outdoor temperatures on the whole thing?

Can a suitable hiding spot be found where you have a decent chance at retrieving it?

Legal?

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