Pirate radio. ;)

R

rigidigital

Senior Member
For my son starting boarding school next year! We have only built a kit from jaycar before. It had trouble reaching to the other end of the house. Its his idea to have a secret station at school. I think the simplest way is to buy an fm transmitter off a ebay, they seem to range from fifty bucks to five hundred bucks. They dont say what the range is. We are only looking for three hundred meters.

Then there is audio streaming, iused to log on to a site to listen to his commentary of f1 races. He only broadcast when there was a race on.

More in favour of the fm transmitter path though. If anyone knows much about fm transmitting id like to talk !

Thanks.
 
T

TheChief

Senior Member
Are you working for Ofcom or Comreg or some other such government agency?
Is this a PICAXE related question?
 
S

SAborn

Senior Member
It would help if you listed in your profile where you are located.

Many years ago i did buy a book on circuits for FM bugs, and built several of them with very good results, some gave over 500m range, others 100m, etc.

One that was reasonably easy and worked not too bad was this one.

http://www.talkingelectronics.com/projects/FM-Bug/FM BUG.pdf

Although there were better ones but i have not found a link to them.
If you try a google search for FM bug circuits you will find dozens of circuits.

Not sure about bugs in schools but you are his parent and that your call.
 
N

nick12ab

Senior Member
I think the simplest way is to buy an fm transmitter off a ebay, they seem to range from fifty bucks to five hundred bucks. They dont say what the range is.
Click to expand...
Generally anything marketed for car use has a range of about 3-15 meters.



It isn't a good idea to make something powered off batteries transmit with 50W of power when 1W (or less) is fine for this.

I have no experience with FM transmitting (except for having an FM transmitter like the one pictured and it having a short range) however I have experimented with UHF TV transmitting - short range obviously since I didn't want OFCON or any of the corporations they've flogged off our RF spectrum to coming round and complaining.

I tried an omni antenna that looked like this and a 10 element Yagi-type 'contract aerial' for transmitting and a crap set top loop antenna for receiving and the omni provided good to adequate picture only in my room whereas the contract aerial provided good signal throughout the entire house, so basically avoid any omni antenna for transmitting. The transmitter was just a satellite receiver connected to an RF modulator, then a signal booster, then the transmitting aerial.

How (omni) directional does his broadcasts need to be?

You'll have to use VHF antennas instead for FM but you will have the advantage of VHF's superior propagation-to-power ratio (or whatever the proper term is for that) compared to UHF and as there's no picture you don't have to worry about that either.
 
D

Dippy

Moderator
"You'll have to use VHF antennas instead for FM" - can you explain?

As long as no-one else is listening I would also go via the bug route.
I've had some impressive ones in the past, but mine ran out of steam at 50m plus a couple of brick walls.
I hope your son doesn't get expelled if found out? (Mind you, $50 on radio gear plus expulsion is probably cheaper than boarding fees :) )
 
R

rigidigital

Senior Member
SAborn said:
It would help if you listed in your profile where you are located.

Many years ago i did buy a book on circuits for FM bugs, and built several of them with very good results, some gave over 500m range, others 100m, etc.

One that was reasonably easy and worked not too bad was this one.

http://www.talkingelectronics.com/projects/FM-Bug/FM BUG.pdf

Although there were better ones but i have not found a link to them.
If you try a google search for FM bug circuits you will find dozens of circuits.

Not sure about bugs in schools but you are his parent and that your call.
Click to expand...
Was canberra, now bris. Thanks for the info.
 
S

SAborn

Senior Member
I guess half the fun is building the circuit with your son and both of you learning how it works.

Should you get stuck there is still some bugs around here, he can have if you care to pay the postage, the only problem is finding them as like most bugs they are smallish and hide well, and i have not used them for years, although did see them somewhere not so long ago. (just be bugged where they were)
 
S

SAborn

Senior Member
I've had some impressive ones in the past, but mine ran out of steam at 50m plus a couple of brick walls.
Click to expand...
Dippy well thats the problem, you used steam and not a battery, you and IWP must have the same electronics background as he uses the smell of an oily rag to run his picaxes. ;)
 
R

rigidigital

Senior Member
wheres the spel chequer :)

SAborn, can you remember what the total cost was for you to build the fm bug with near 500 meter range ? In anycse that site looks great. I just watcheda youtube video of a little village in asia with an fm radio station using one of the uits sold on ebay. It looked like the 50 buck unit, but a lot of them looked similar.
 
E

eclectic

Moderator
A genuine question:

Under Aus and/or QL statutes,
what's the legal position?

And indeed, what's the moral and ethical position?

e
 
P

Paix

Senior Member
Buy a couple of Binatone, or other pMR446 handhelds, it will give better range and still be legal, provide basic communications and not have enough battery life on transmit to get him into trouble from any form of unethical juvenile espionage.

Buy three and he and two mates can learn about circuit discipline and listening before speaking. Allow two to be stolen and then clandestinely listen to the perpetrators on the third one.
 
D

Dippy

Moderator
It crossed my mind too Ec.
I just hope Rigid Jnr doesn't get into trouble.

I have one of those baby FM things posted by Nick. Good quality and short range - maybe up to 10m so I'm not worried.

Though I think if my neighbour was using 300m power of cheapo crap that interfered with my listening to the Archers I'd be paying him/her a visit with my combined harvester :)
When I fiddled with radio bugs as a boy (when I was Nick's age) I had one that had terrible harmonics all over the shop which could have upset neighbours, so I gave it away (to someone who lived miles away!) . Even now it makes me cringe when people obsess with cheapness over quality with RF.
 
R

rigidigital

Senior Member
SAborn said:
Ok i just found the book of bug circuits.
Its been a while but i think it was "The amoeba" bug that gave 400-500m on 3 volts.

You are in luck as the kit is still listed by the books author.

http://www.talkingelectronics.com/AllKitsWithPics/AllKitsWithPics.html


Is about 2nd on the list of kits.

I never bought the kit and made my own PCB and found the components local.

The book is called " 14 FM Bugs to Build" by Colin Mitchell.
Click to expand...
Ta for all that effort. I am ordering the book and the amoeba. my last year in boarding school was 30 years ago. I wish I'd had a clandestine radio station. we would have driven the brothers and priests into a frenzy trying to find out who we were :) they were all a fairly highly strung bunch. But then i have to think who they were dealing with :) This has been a great thread for me, so thanks everyone. ten more characters needed..... .........
 
R

rigidigital

Senior Member
Paix said:
Buy a couple of Binatone, or other pMR446 handhelds, it will give better range and still be legal, provide basic communications and not have enough battery life on transmit to get him into trouble from any form of unethical juvenile espionage.

Buy three and he and two mates can learn about circuit discipline and listening before speaking. Allow two to be stolen and then clandestinely listen to the perpetrators on the third one.
Click to expand...
A thousand comedians outa workand you want to be one :)
 
G

geoff07

Senior Member
Best advice has to be to stay within the law, whatever that is where you are (Brisbane?). If you interfere with something important or breach someone's privacy you risk being stomped on these days. Not a good start to adult life. There will be plenty of ways to build legal gear if you choose the right freq and observe the erp limit. Playing with radio is however a great way to learn and it got me started on a career, so highly recommended.
 
R

rigidigital

Senior Member
geoff07 said:
Best advice has to be to stay within the law, whatever that is where you are (Brisbane?). If you interfere with something important or breach someone's privacy you risk being stomped on these days. Not a good start to adult life. There will be plenty of ways to build legal gear if you choose the right freq and observe the erp limit. Playing with radio is however a great way to learn and it got me started on a career, so highly recommended.
Click to expand...
Thanks, I agree you never know where it might lead to. having interests like this can only be a good thing. I do understand the legal side that people bring up but for such a low power /short distance transmitter that is planned i doubt there is any problem. But i say that out of what little commonsense I possess, not knowing anything about regulations. :)
 
M

manuka

Senior Member
Just pop into Jaycar & buy a few multi-channel UHF CB "("PRS") sets - they're totally legal & kids love playing "walkie talkie" spies with them. Their coverage & quality is outstanding for the cheapness, BUT best buy dockable versions (with rechargeable batteries) as AAA battery consumption will otherwise nickle & dime you to death... This has long been a serious woe with the cheap superregen. kids 2-way radios,as the 9V battery may only last a few days & cost more than the sets. Those things should be banned!

Extra: FWIW I've been pestered for decades by youngsters hankering for FM bugs & hidden transmitters.Aside from technical & antenna issues, my advice traditionally covers moralities (snooping may get you a punch in the nose),legalities(tight regulations & hefty fines may arise for pirate transmitters), budgets and -oh yes- the program content.

Who are your intended audience? In many places now the choice of AV entertainment is overwhelming, & no one may bother listening to your efforts! I recall a local student radio station that suddenly announced "A dozen beer to the next caller", yet NO ONE responded - rather implying they had no listeners...
 

Attachments

Last edited:
S

srnet

Senior Member
rigidigital said:
I do understand the legal side that people bring up but for such a low power /short distance transmitter that is planned i doubt there is any problem
Click to expand...
Rather depends where the transmitter and receiver are.

In the middle of the Australian Outback, probably no problem.

In an Urban area, whilst there might be no interference to other legal users close to the receive end, you might cause a great deal of interference in the near locality of the transmitter.
 
R

rigidigital

Senior Member
I am in awe of the concerns and also surprised and pretty happy. I have used a few rf units, nothing more than twenty dollars. Some ten dollars. I never got a good signal over around 100 feet ! Ok, maybe my rf chips were not too good(obviously) but it seems for " A Few Dollars More" (yep im a Clint fan :) Its possible to get some real transmissions happening. BTW if this begings to look like it's irresponsible in anyway, it will be canned pronto !
 
R

rigidigital

Senior Member
eclectic said:
geoff7 has already given you some excellent advice.

And from me
"what about it ?"

Do you KNOW the legalities?
And moralities?

e
Click to expand...
As far as moralites I know that you should never let the public know who is on air without the persons consent. I think australian radio has recently had a big wake up call in that regard. I think you all know what I'm refering to.
 
techElder

techElder

Well-known member
Nothing like raising the next generation to respect the law of the land. Why not get him/her/them involved in organized amateur radio? It's a hobby that he/she/them can practice through old age.

Oh well, your choice.
 
N

nick12ab

Senior Member
Dippy said:
When I fiddled with radio bugs as a boy (when I was Nick's age) I had one that had terrible harmonics all over the shop which could have upset neighbours, so I gave it away (to someone who lived miles away!) . Even now it makes me cringe when people obsess with cheapness over quality with RF.
Click to expand...
Dippy makes a good point there. I got my FM transmitter thing out and it too has terrible harmonics. Two could be found just by tuning the receiving radio into different frequencies, but when I connected a composite video signal to the input there were loads that could be seen on a TV in the VHF and UHF bands. Unfortunately it didn't produce a watchable picture when the TV was tuned into the correct frequency - presumably for the same reason that the sound distorts if the volume on the source of the sound to be transmitted is turned up to maximum.

I took the thing apart but couldn't find any sort of antenna inside. Maybe that would mean that if someone could find the right spot a proper antenna could actually give very good range. Could a bandpass filter be used to filter out the unwanted harmonics?
 
M

manuka

Senior Member
I got my FM transmitter thing out ... a composite video signal to the input ...
Click to expand...
Any chance of a SCHEMATIC so we can better relate to your circuitry? Your approach seems akin to throwing a bomb into a phone exchange to see what happens!

But i say that out of what little commonsense I possess, not knowing anything about regulations.
Click to expand...
Ignorance is not an excuse with illegal transmitters,especially as regulations are readily available online. Ethical issues associated with snooping can be very emotive -about 30 years back I recall a student using an FM bug to eavesdrop on his older brother's "courting", with considerable fireworks erupting when it was discovered...
 
S

SAborn

Senior Member
Ignorance is not an excuse with illegal transmitters
Click to expand...
Hmmm i think you can park your bike back in the shed on this one, the kits i linked to and the OP has purchased including the book of designs has been around for more than 20 years as a kit form, and from a dedicated purpose behind the designer to educate any who was interested to learn about FM transmitters.

The designs target the 80-100mhz range where very little traffic is on that FM band range.

The designer of the circuits wrote books on FM transmitters over 20 years ago, and has supported development ever since.

Im sure he has crossed his Tee's and dotted his I's over time to comply with regulations.

The moral use, aspect is only one of parent installed understanding, not law.
 
M

manuka

Senior Member
The moral use, aspect is only one of parent installed understanding, not law. The designs target the 80-100mhz range where very little traffic is on that FM band range
Click to expand...
SAborn: Sorry mate but these statements don't make much sense-even for a "speaka da lingo" Kiwi ! In urban regions the regular 88-108 MHz band is now almost wall to wall with powerful signals. Flea power FM bugs are usually so trivial in such a busy spectrum slot that they may well be ignored.

Colin Mitchell of "Talking Electronics" fame is indeed a guru, & his circuitry lucidly explained.
 
S

srnet

Senior Member
manuka said:
the regular 88-108 MHz band is now almost wall to wall with powerful signals.
Click to expand...
I was wondering if it was an Australia specific thing, in the UK, the 88Mhz to 108M is well full of broadcast signals.

Off course that you have to choose a frequency that is free of local FM radio stations don't you.
 
S

SAborn

Senior Member
Part of the educational information to adjusting the bug frequency, is to select a dead spot on the band range.

Most bugs target the lower 88+/-mhz range, and the author even goes into detail of detuming a FM radio to detect frequencies down to 80mhz, being outside the average FM receiver range.

The moral use, aspect is only one of parent installed understanding, not law.
Click to expand...
This is not too far different than giving your son a gun, its not the Gun thats the problem, but the education of the gun use that makes it a weapon or not.

I had my first rifle at the age of 15, and learnt to respect the use of it, to date never harmed anyone with a firearm....waitimg ... waitimg...... joking!
 
T

TheChief

Senior Member
When I fiddled with radio bugs as a boy (when I was Nick's age) I had one that had terrible harmonics all over the shop which could have upset neighbours, so I gave it away (to someone who lived miles away!) . Even now it makes me cringe when people obsess with cheapness over quality with RF.
Click to expand...
I remember building a kit when I was a young lad also. I did a bit of follow up research a few years ago. I bought the kit from an ad in the magazine Practical Electronics. I believe the kit was dubbed "Pantek" design and from what I remember and follow up reading it was an oscillating heap of junk. The harmonics were a big problem and would cause interference with TV channels. A few years ago I bought a 50W rig of eBay and a 5/8 tuned antenna from Aareff/Veronica.
I haven't had the balls to fire it up except testing it with a dummy load and SWR meter, it throws out 50 of the best alright.
I'd be interest to see a project of someone using a PICAXE to generate RDS encoding, again I bought and build a kit for this a few years back, must dig it out and see what's inboard.
 
N

nick12ab

Senior Member
manuka said:
Any chance of a SCHEMATIC so we can better relate to your circuitry? Your approach seems akin to throwing a bomb into a phone exchange to see what happens!
Click to expand...
I just used a phono-to-3.5mm adaptor to directly connect the video signal to the transmitter. The transmitter is similar to the one I posted earlier.
 
I

IronJungle

Senior Member
If the goal is to learn about RF transmission, etc., then build a transmitter.

If the goal is to broadcast audio to students to convey a message, then create a Podcast.

A quick check around tells me the young ones aren't really into terrestrial radio.
 
M

MPep

Senior Member
IronJungle said:
A quick check around tells me the young ones aren't really into terrestrial radio.
Click to expand...
"Duuhhhhh what's a tuning dial Grandad??"
You can just see these types of statements/questions abound now, can't you? :)

The designs target the 80-100mhz range where very little traffic is on that FM band range.
Click to expand...
Not correct in lil' ol' NZ, whereby commercial Broadcast Stations are numerous between 88 - 108 MHz.
 
G

Grogster

Senior Member
I've done a lot of pirate radio.

I stopped when I got busted for running 15 watts when I was supposed to be only 500mW. ;)

...someone spash some water on manuka at this point...

Seriously, the signal was fine, clean, and it took more then a year at that power before I was busted, and they ONLY busted me on the illegal power output, as the radio inspector came out and checked the gear, and it was all technically compliant, as I was using compressor/limiters and 15kHz brickwall-filters, PLL frequency control, out-of-lock power-down, multi-pole RF output filters and cavity filters along with correctly matched aerial.

So, no license cost me $250 fine, but I deserved it - I was breaking the law, technically, and that slap on the hand has made me remain compliant since then. :D

One of these 100mW units would be compliant, plugs right into a computer, has it's own USB soundcard onboard, and you're up and running in no time.

http://www.vastelec.com/index.php?main_page=product_info&cPath=68&products_id=220

I have these in stock at the moment, and they are good for about 250 meters "Thru walls" - more with a correctly matched aerial and coax.

Powered from the USB port, compressor/limiter RDS...

PM me if you are interested.

EDIT: ...or you can also buy direct from their ebay shop at this link:
http://www.ebay.com/itm/RDS-HiFi-FM-Transmitter-HiFi-FMT-VASTINT-V-FMT212R-Digital-FM-Transmitter-/261126499246?pt=US_Ham_Radio_Transmitters&hash=item3ccc5a2bae
 
Last edited:
You must log in or register to reply here.
Top