Sorry to burden you all with a very thick radio question.....
PPRuNe Engineering Dept Apprentice
Thread Starter
Join Date: Mar 2001
Location: Deep in the boglands of Western Ireland
Posts: 295
Likes: 0
Received 0 Likes
on
0 Posts
Sorry to burden you all with a very thick radio question.....
...but I had to ask, the idea's been chewing on my head for weeks! Is it possible (in theory or otherwise) to open up a normal FM radio (one that goes up to 108.0) and fiddle with it to get it to crank the freq up above that (to, say, 121.5)? Probably illegal 'n all, but no harm in asking, I hope..... . 
Join Date: Feb 2001
Location: LISBO/DUFFY-ish
Age: 73
Posts: 70
Likes: 0
Received 0 Likes
on
0 Posts
Hi NIG,
As you know nothing is ever simple. Basically the answer to your question is yes - BUT!
I have a thirty year old ITT FM broadcast band (89 - 108 Mhz) tranny which I tweaked to listen to my local App/radar freq. An FM set will "hear" AM transmissions. Inside are some adjustable capacitors on the tuning condenser. Twiddling these allowed me to listen to all sorts of 'stuff' in the seventies.
That's the good news.
The bad news is that, like most things in life, they don't build them like that any more. The chances are that the radio in your car is full of chips and uses PLL circuitry to generate its frequencies. This precludes the simply twiddling option.
Unless, of course, somebody out ther knows better.
(I think that hearing the tower tranmission when close by means that the signal is coming in through the IF stage in your car radio receiver. But that's harmonics theory and way, way beyond me.)
As you know nothing is ever simple. Basically the answer to your question is yes - BUT!
I have a thirty year old ITT FM broadcast band (89 - 108 Mhz) tranny which I tweaked to listen to my local App/radar freq. An FM set will "hear" AM transmissions. Inside are some adjustable capacitors on the tuning condenser. Twiddling these allowed me to listen to all sorts of 'stuff' in the seventies.
That's the good news.
The bad news is that, like most things in life, they don't build them like that any more. The chances are that the radio in your car is full of chips and uses PLL circuitry to generate its frequencies. This precludes the simply twiddling option.
Unless, of course, somebody out ther knows better.
(I think that hearing the tower tranmission when close by means that the signal is coming in through the IF stage in your car radio receiver. But that's harmonics theory and way, way beyond me.)
PPRuNe Engineering Dept Apprentice
Thread Starter
Join Date: Mar 2001
Location: Deep in the boglands of Western Ireland
Posts: 295
Likes: 0
Received 0 Likes
on
0 Posts
Don't worry, they still make the dirt cheap analog ones! As long as China and Taiwan and street markets are around...
But one thing, is there any way they can tell you're using a receiver?
[ 26 January 2002: Message edited by: Nose Indiana Groond ]</p>
But one thing, is there any way they can tell you're using a receiver?
[ 26 January 2002: Message edited by: Nose Indiana Groond ]</p>
Regarding 'legality', if you have an FRTO licence and wish to listen to the 'licensed broadcasts' being made 'for navigation' by other 'licensed radio operators'........?? All a bit 'big brother-ish' - and the Enforcement branch would be better employed rounding up pirate broadcasters and illegal transmitter operators than bothering a few innocent spotters.
When I was on my Hunter course some years ago, one of the blokes had a cheap and nasty 'multi band' radio receiver - one of those things you'd see advertised in the weekend papers. One day it fell onto the crewroom floor and this must have done something weird to its IF cans because it started picking up all manner of transmissions! Instead of air band VHF it would pick up Westward TV sound on Band 3 (around 206 MHz), so we stuck a picture of the Wetstward TV test card onto its speaker grille - but we also found that it would now tune up into the UHF military air band! So effective was it that my boss was having a cup of coffee in the crewroom one day when he heard a Hunter pilot (me) telling his leader that he'd got a suspected engine snag, was jettisoning his drop tanks and coming home! The boss was on to ATC in a flash - they had no knowledge of the problem until the leader came up and told them a few minutes later! They never did discover how he'd found out!
[ 27 January 2002: Message edited by: BEagle ]</p>
When I was on my Hunter course some years ago, one of the blokes had a cheap and nasty 'multi band' radio receiver - one of those things you'd see advertised in the weekend papers. One day it fell onto the crewroom floor and this must have done something weird to its IF cans because it started picking up all manner of transmissions! Instead of air band VHF it would pick up Westward TV sound on Band 3 (around 206 MHz), so we stuck a picture of the Wetstward TV test card onto its speaker grille - but we also found that it would now tune up into the UHF military air band! So effective was it that my boss was having a cup of coffee in the crewroom one day when he heard a Hunter pilot (me) telling his leader that he'd got a suspected engine snag, was jettisoning his drop tanks and coming home! The boss was on to ATC in a flash - they had no knowledge of the problem until the leader came up and told them a few minutes later! They never did discover how he'd found out!
[ 27 January 2002: Message edited by: BEagle ]</p>
None but a blockhead
Join Date: Nov 1999
Location: London, UK
Posts: 535
Likes: 0
Received 0 Likes
on
0 Posts
The Innovations catalogue -- of all things -- has a £35 digital airband radio, with 25 memories. No idea how well it works, and I'd be surprised if it had squelch or anything like sensible image rejection and overload, but it's the cheapest I've seen. And I think that's a first for that particular source...
R
<a href="http://www.innovations.co.uk/gus/product.asp?brand=newInnovations&cat%5Fid=0&prod%5Fid=52390& offer%5Fid=52390R&link%5Fid=&search%5Fcriteria=ML7314&price% 5Funder=10000&search%5Fcolour=&search%5Fsize=&match%5Fmethod =AND&extra=&mscs_sid=DPHPBVNB2KS92MRH0G05L0" target="_blank">http://www.innovations.co.uk/gus/product.asp?brand=newInnovations&cat%5Fid=0&prod%5Fid=52390& offer%5Fid=52390R&link%5Fid=&search%5Fcriteria=ML7314&price% 5Funder=10000&search%5Fcolour=&search%5Fsize=&match%5Fmethod =AND&extra=&mscs_sid=DPHPBVNB2KS92MRH0G05L0</a> X3U9H22M1A is the link. Ouch.
R
<a href="http://www.innovations.co.uk/gus/product.asp?brand=newInnovations&cat%5Fid=0&prod%5Fid=52390& offer%5Fid=52390R&link%5Fid=&search%5Fcriteria=ML7314&price% 5Funder=10000&search%5Fcolour=&search%5Fsize=&match%5Fmethod =AND&extra=&mscs_sid=DPHPBVNB2KS92MRH0G05L0" target="_blank">http://www.innovations.co.uk/gus/product.asp?brand=newInnovations&cat%5Fid=0&prod%5Fid=52390& offer%5Fid=52390R&link%5Fid=&search%5Fcriteria=ML7314&price% 5Funder=10000&search%5Fcolour=&search%5Fsize=&match%5Fmethod =AND&extra=&mscs_sid=DPHPBVNB2KS92MRH0G05L0</a> X3U9H22M1A is the link. Ouch.
Join Date: May 2001
Location: Frankfurt, Germany
Posts: 143
Likes: 0
Received 0 Likes
on
0 Posts
Nose Indiana Groond
Your question has already been answered more than effectively by others. However, if you are still keen to modify an ordinary portable radio then I have got a magazine article laying around that will help you to do it.
You would probably be better off getting hold of a cheapish scanner as this would do a better job, but if you want a copy of the article then drop me an e-mail. It is a scanned copy, so will be easy to send.
[ 28 January 2002: Message edited by: ramsrc ]</p>
Your question has already been answered more than effectively by others. However, if you are still keen to modify an ordinary portable radio then I have got a magazine article laying around that will help you to do it.
You would probably be better off getting hold of a cheapish scanner as this would do a better job, but if you want a copy of the article then drop me an e-mail. It is a scanned copy, so will be easy to send.
[ 28 January 2002: Message edited by: ramsrc ]</p>
Join Date: Jan 2002
Location: Paros, Greece
Posts: 768
Likes: 0
Received 0 Likes
on
0 Posts
On the question of legality, in the UK...
I'm setting off for a mornings flying at the airfield and want to be up to date on the Wx. At what point am I OK to tune into the ATIS or air/ground? In the car on the way there? Once I have arrived on the field? Once I climb into the a/c? In other words, what exactly is 'permission' to tune in? Probably a pointless question as I can't forsee ever being challenged, but would be interested to know. Surely as a pilot, I could justify listening into to any normal (civil) ATC as 'training'. Exactly what permission would I need? Daft, realy, isn't it?
And in the US...
I've heard somewhere (ages ago, can't remember) that each state has different laws on using airband receivers. Some or OK with it, in some it's illegal but they don't mind, in others it's taken more seriously. Any idea where I could find out? (I ALWAYS have my scanner on when driving around on hols. out there - again I see this as 'training'). Would be nice not to get arrested, especially in the current security climate.
I'm setting off for a mornings flying at the airfield and want to be up to date on the Wx. At what point am I OK to tune into the ATIS or air/ground? In the car on the way there? Once I have arrived on the field? Once I climb into the a/c? In other words, what exactly is 'permission' to tune in? Probably a pointless question as I can't forsee ever being challenged, but would be interested to know. Surely as a pilot, I could justify listening into to any normal (civil) ATC as 'training'. Exactly what permission would I need? Daft, realy, isn't it?
And in the US...
I've heard somewhere (ages ago, can't remember) that each state has different laws on using airband receivers. Some or OK with it, in some it's illegal but they don't mind, in others it's taken more seriously. Any idea where I could find out? (I ALWAYS have my scanner on when driving around on hols. out there - again I see this as 'training'). Would be nice not to get arrested, especially in the current security climate.
Join Date: Oct 2000
Location: London
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Diver,
The question of legality has come up again and again on these forums.
The link below clearly shows that it is illegal to listen to anything other than transmissions meant for general reception (whether or not you intend to pass on the information obtained). It is illegal to listen to the airband frequencies in the UK.
<a href="http://www.radio.gov.uk/publication/ra_info/ra169.htm" target="_blank">www.radio.gov.uk/publication/ra_info/ra16 9.htm</a>
The link goes on to say that it is illegal unless you are a licensed user of the frequencies.. .Therefore it is completely legal for pilots / ATCOs to listen to the airband frequencies on their own receivers / scanners whilst away from work.
Although quite why they'd want to, I don't know!
AI
[ 14 February 2002: Message edited by: Aluminium Importer ]
[ 14 February 2002: Message edited by: Aluminium Importer ]</p>
The question of legality has come up again and again on these forums.
The link below clearly shows that it is illegal to listen to anything other than transmissions meant for general reception (whether or not you intend to pass on the information obtained). It is illegal to listen to the airband frequencies in the UK.
<a href="http://www.radio.gov.uk/publication/ra_info/ra169.htm" target="_blank">www.radio.gov.uk/publication/ra_info/ra16 9.htm</a>
The link goes on to say that it is illegal unless you are a licensed user of the frequencies.. .Therefore it is completely legal for pilots / ATCOs to listen to the airband frequencies on their own receivers / scanners whilst away from work.
Although quite why they'd want to, I don't know!
AI
[ 14 February 2002: Message edited by: Aluminium Importer ]
[ 14 February 2002: Message edited by: Aluminium Importer ]</p>
AI - one reason to listen in to airband frequencies whilst 'away' from work is to keep an ear on students on cross-country flights, for example.
But it can be fun 'listening in' to studes. We used to have an approved RT scanner in the office at work and I heard 2 students being told to 'hold off' clear of the aerodrome as the circuit was too busy. Now, both were returning from GH and aeros trips, both were quite spirited characters and both were 'holding' more or less at the same place. Another mate and I looked at eachother and I said "What do you think they'll be up to?". "Dog fighting, perhaps?", he replied. So when they landed we just said "OK - who started it?" - and they fell for it. "It wasn't my fault, he turned towards me and I had to get out of the way" said one...."I suddenly saw another aircraft near me and took avoiding action" said the other. Talk about digging themselves a hole......!! Unfortunately they'd been seen by the visiting trappers who had no choice but to comment (albeit with 'knowing expressions') - and the misery of a Boss wanted to throw them out. We said that they were both very good pilots and had the right streak of tempered aggresion for military aviators - and if he threw them out then he could throw us out as well please. He didn't much like that and asked how we would punish them. Easy - make them sweat for a couple of days, give them a rollicking and then forget it. Which he did!
So now and again I still keep an ear on students who I've authorised....on an approved radio installation, of course!
But it can be fun 'listening in' to studes. We used to have an approved RT scanner in the office at work and I heard 2 students being told to 'hold off' clear of the aerodrome as the circuit was too busy. Now, both were returning from GH and aeros trips, both were quite spirited characters and both were 'holding' more or less at the same place. Another mate and I looked at eachother and I said "What do you think they'll be up to?". "Dog fighting, perhaps?", he replied. So when they landed we just said "OK - who started it?" - and they fell for it. "It wasn't my fault, he turned towards me and I had to get out of the way" said one...."I suddenly saw another aircraft near me and took avoiding action" said the other. Talk about digging themselves a hole......!! Unfortunately they'd been seen by the visiting trappers who had no choice but to comment (albeit with 'knowing expressions') - and the misery of a Boss wanted to throw them out. We said that they were both very good pilots and had the right streak of tempered aggresion for military aviators - and if he threw them out then he could throw us out as well please. He didn't much like that and asked how we would punish them. Easy - make them sweat for a couple of days, give them a rollicking and then forget it. Which he did!
So now and again I still keep an ear on students who I've authorised....on an approved radio installation, of course!
