For the last month or so, whilst driving around town listening to Radio
4 on FM, I've been getting short bursts (3 - 4 seconds) of interference
in the form of loud music; garage, hip hop, indie or whatever it is -
not something any sane person would listen to.

Not connected with any specific area or vehicle that I can see.

Is this some form of pirate radio station?



--
Dave - The Medway Handyman www.medwayhandyman.co.uk

Is this some form of pirate radio station?

I get it in E London if I have RDS traffic announcements enabled. One
or more pirates seem to trigger them - on purpose (though why given it's
just a second or 2?) or through incompetence. If you have TA on you
could try turning them off and see if the interruptions go.

Mind you, don't blame me if Sod's law then means you get stuck in a jam
for 2 hours for lack of the news
--
Robin
reply to address is (meant to be) valid

Quite probably, they abound everywhere these days. Havyou been in
hibernation? Most are supported by drug money and bricked in at the top of
tower blockes operated remotely via uhf/vhf and even microwave feeds from
other locations, enabling quick switching if the fuzz find the installation.

You say that no sane person would listen to it, but its not meant to be
listened to, its mostly trance dance stuff as often heard in what we used to
call raves, where the dealers make their sales.
Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"The Medway Handyman" wrote in message
...
For the last month or so, whilst driving around town listening to Radio 4
on FM, I've been getting short bursts (3 - 4 seconds) of interference in
the form of loud music; garage, hip hop, indie or whatever it is - not
something any sane person would listen to.

Not connected with any specific area or vehicle that I can see.

Is this some form of pirate radio station?



--
Dave - The Medway Handyman www.medwayhandyman.co.uk

The Medway Handyman wrote:
For the last month or so, whilst driving around town listening to Radio
4 on FM, I've been getting short bursts (3 - 4 seconds) of interference
in the form of loud music; garage, hip hop, indie or whatever it is -
not something any sane person would listen to.

Not connected with any specific area or vehicle that I can see.

Is this some form of pirate radio station?

1. Could be one of those gadgets that send the output of a music-playing
device to the radio via RF. The radiation from them can pass to other
vehicles.

2. When it happens, try to remember the music and then tune through the
band to see if you can find a continuous transmission.

3. Could be triggered by RDS.

Bill

In article ,
The Medway Handyman wrote:
For the last month or so, whilst driving around town listening to Radio
4 on FM, I've been getting short bursts (3 - 4 seconds) of interference
in the form of loud music; garage, hip hop, indie or whatever it is -
not something any sane person would listen to.

Not connected with any specific area or vehicle that I can see.

Is this some form of pirate radio station?

Almost certainly.

One reason DAB is so good in the car. No pirates and excellent reception
round London. Much better reception on R4 than FM.

--
*Don't worry; it only seems kinky the first time.*

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 03 Jan 2015 15:58:25 +0000, The Medway Handyman wrote:

For the last month or so, whilst driving around town listening to Radio
4 on FM, I've been getting short bursts (3 - 4 seconds) of interference
in the form of loud music; garage, hip hop, indie or whatever it is -
not something any sane person would listen to.

Not connected with any specific area or vehicle that I can see.

Is this some form of pirate radio station?


I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones. They allow you to play the music
from your phone through any FM radio receiver, in a car or at home,
without having to bother about a lead or a special stand. The car
versions plug into the lighter socket to keep the iPhone charged. There
are millions in use.

/I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones. They allow you to play the music
from your phone through any FM radio receiver, in a car or at home,
without having to bother about a lead or a special stand. The car
versions plug into the lighter socket to keep the iPhone charged. There
are millions in use. /q

All with very short ranges...?

Jim K

"mick" wrote in message
eb.com...
On Sat, 03 Jan 2015 15:58:25 +0000, The Medway Handyman wrote:

For the last month or so, whilst driving around town listening to Radio
4 on FM, I've been getting short bursts (3 - 4 seconds) of interference
in the form of loud music; garage, hip hop, indie or whatever it is -
not something any sane person would listen to.

Not connected with any specific area or vehicle that I can see.

Is this some form of pirate radio station?


I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones. They allow you to play the music
from your phone through any FM radio receiver, in a car or at home,
without having to bother about a lead or a special stand. The car
versions plug into the lighter socket to keep the iPhone charged. There
are millions in use.

Yeah, bet thats it. I have one myself to play
the iphone thru the sound system in the car.

On 2015-01-03 16:56:00 +0000, Brian Gaff said:

You say that no sane person would listen to it, but its not meant to be
listened to, its mostly trance dance stuff as often heard in what we
used to call raves, where the dealers make their sales.

A lot of pirate stations are just community stations carrying ads for
services and playing music mainstream stations rarely play, such as
soul and reggae. I often listen to those local to me, especially
reggae, of which I'm a fan.

E.

On Sat, 3 Jan 2015 13:47:41 -0800 (PST), JimK
wrote:

/I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones. They allow you to play the music
from your phone through any FM radio receiver, in a car or at home,
without having to bother about a lead or a special stand. The car
versions plug into the lighter socket to keep the iPhone charged. There
are millions in use. /q

All with very short ranges...?

Jim K

What's the typical separation of two vehicles passing each other on a
narrow road. A couple of meters maybe?

I was very surprised when these Band II transmitters were legalised.

Having said that I don't think I have ever had my listening interfered
with by one.

Years ago you used to be able to hear carriers at around 100Mhz as you
drove along residential streets, some had speech and music faintly
audible. These were the local oscillators of radios tuned to Radio 2
10.7Mhz lower down the band. The signal strength was much higher than
these legal FM transmitters.

I don't seem to hear them now, partly I think because there are so
many stations above 100MHz these days, and also it is quite possible
these were valve radios emitting fairly high levels of RF.




--

Graham.

%Profound_observation%

eastender wrote:


I often listen to those local to me, especially reggae, of
which I'm a fan.

I suppose it is one duty of society to cater for those of limited
intelligence.

Bill

Rod Speed wrote:

I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones. They allow you to play the music
from your phone through any FM radio receiver, in a car or at home,
without having to bother about a lead or a special stand. The car
versions plug into the lighter socket to keep the iPhone charged. There
are millions in use.

Yeah, bet thats it. I have one myself to play
the iphone thru the sound system in the car.

As I said a long time earlier in this thread:

1. Could be one of those gadgets that send the output of a music-playing
device to the radio via RF. The radiation from them can pass to other
vehicles.

Does no ****er listen to them that knows?

Bill

On Sun, 04 Jan 2015 04:53:07 +0000, Bill Wright wrote:

1. Could be one of those gadgets that send the output of a music-playing
device to the radio via RF. The radiation from them can pass to other
vehicles.

Does no ****er listen to them that knows?

Legal Band II (87.5 to 108 MHz) FM senders have a power limit of 50
nW ERP. (yes, nano Watts, 50 millionths of a milli Watt).

I doubt that gets out of the steel box of a car with sufficient level
to capture the receiver in an adjacent car tuned to a broadcast
station near to the senders frequency. The one I have tunes in 100
kHz steps, 100 kHz is the next channel so, theoretically, shouldn't
cause interference with adjacent channels even at much higher ERPs.
If the sender was on the same frequency it would suffer interference
from the broadcast station.

The OPs "problem" is far more likely to be much higher power and
"dirty" signals from pirate station(s) deliberately tuned to be close
to the local legitimate stations.

--
Cheers
Dave.

In article o.uk, Dave
Liquorice scribeth thus
On Sun, 04 Jan 2015 04:53:07 +0000, Bill Wright wrote:

1. Could be one of those gadgets that send the output of a music-playing
device to the radio via RF. The radiation from them can pass to other
vehicles.

Does no ****er listen to them that knows?

Legal Band II (87.5 to 108 MHz) FM senders have a power limit of 50
nW ERP. (yes, nano Watts, 50 millionths of a milli Watt).

I doubt that gets out of the steel box of a car with sufficient level
to capture the receiver in an adjacent car tuned to a broadcast
station near to the senders frequency. The one I have tunes in 100
kHz steps, 100 kHz is the next channel so, theoretically, shouldn't
cause interference with adjacent channels even at much higher ERPs.
If the sender was on the same frequency it would suffer interference
from the broadcast station.



The OPs "problem" is far more likely to be much higher power and
"dirty" signals from pirate station(s) deliberately tuned to be close
to the local legitimate stations.


Indeed. Can try a complaint to Ofcom but it's more of less out of
control in London and has been so for quite some time now.

They also occupy sections of the old TV Band 1 40 to 68 odd MHz to link
sites together but I believe current practice is to use Internet dongles
nowadays to supply signals to their transmitters, makes finding them
harder and they can just switch another transmitter on as easy as they
can switch any of the ones they might be using off...

They haven't got around to using DAB as yet but it can be done its not
that difficult, but there are still far more FM receivers around..

Still as they often nick the transmitters other pirates use I rather
doubt they'll be doing that for sometime to come ..
--
Tony Sayer

In article om,
lid says...

I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones.

No. RDS, as others have said - but not Traffic Announcements.

Data is transmitted which tells the radio the frequency of adjacent
transmitters carrying the same programme. If the signal level/quality drops,
the radio looks for a strong transmission on one of them and then switches to
it.

In London there are relays of the main transmitter (Wrotham) at Crystal
Palace and my car radio will switch seamlessly back and forth between the two
as I drive around. Unless I look to see which of the two frequencies it is
tuned to, I won't even know it has happened in the majority of cases.

However, if a pirate uses one of the stored frequencies, the radio will
switch to that but will find the data stream doesn't match and promptly
switch back again.

In this neck of the woods, I find that pirates camping out on Classic FM
alternative frequencies are the worst problem.

Traffic Announcements rely on the receiver being instructed via the data
stream that a Traffic Announcement is being currently carried on another
frequency - to which the radio briefly switches. If the signal is there, the
radio switches to it but if it is not, because the distance to the local
radio station is too great, for example, it switches back. This causes a
brief gap of silence during the process.

--

Terry

In article ,
Terry Casey scribeth thus
In article om,
says...

I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones.

No. RDS, as others have said - but not Traffic Announcements.

Data is transmitted which tells the radio the frequency of adjacent
transmitters carrying the same programme. If the signal level/quality drops,
the radio looks for a strong transmission on one of them and then switches to
it.

In London there are relays of the main transmitter (Wrotham) at Crystal
Palace and my car radio will switch seamlessly back and forth between the two
as I drive around. Unless I look to see which of the two frequencies it is
tuned to, I won't even know it has happened in the majority of cases.

However, if a pirate uses one of the stored frequencies, the radio will
switch to that but will find the data stream doesn't match and promptly
switch back again.

In this neck of the woods, I find that pirates camping out on Classic FM
alternative frequencies are the worst problem.



Traffic Announcements rely on the receiver being instructed via the data
stream that a Traffic Announcement is being currently carried on another
frequency - to which the radio briefly switches. If the signal is there, the
radio switches to it but if it is not, because the distance to the local
radio station is too great, for example, it switches back. This causes a
brief gap of silence during the process.


What some pirates do is to transmit the "Traffic Flag" or TA all the
time this causes your radio to lock onto their transmission.

Expressly prohibited on the Ofcom regs but as there're Pirates;!...
--
Tony Sayer

In article , says...

In article ,
Terry Casey scribeth thus
In article om,
says...

I suspect that it's the result of the little low-power FM transmitters
that you can get to plug into iPhones.

No. RDS, as others have said - but not Traffic Announcements.

Data is transmitted which tells the radio the frequency of adjacent
transmitters carrying the same programme. If the signal level/quality drops,
the radio looks for a strong transmission on one of them and then switches to
it.

In London there are relays of the main transmitter (Wrotham) at Crystal
Palace and my car radio will switch seamlessly back and forth between the two
as I drive around. Unless I look to see which of the two frequencies it is
tuned to, I won't even know it has happened in the majority of cases.

However, if a pirate uses one of the stored frequencies, the radio will
switch to that but will find the data stream doesn't match and promptly
switch back again.

In this neck of the woods, I find that pirates camping out on Classic FM
alternative frequencies are the worst problem.



Traffic Announcements rely on the receiver being instructed via the data
stream that a Traffic Announcement is being currently carried on another
frequency - to which the radio briefly switches. If the signal is there, the
radio switches to it but if it is not, because the distance to the local
radio station is too great, for example, it switches back. This causes a
brief gap of silence during the process.


What some pirates do is to transmit the "Traffic Flag" or TA all the
time this causes your radio to lock onto their transmission.

Expressly prohibited on the Ofcom regs but as there're Pirates;!...

Yes, Tony, but your radio won't be monitoring every transmission in Band II
to see if any have raised the flag!

Your radio will only know that a TA is available because of data received
with the transmission it is tuned to at the time. When it switches to the TA
it uses the other station's flag - or rather the loss of it - to signal that
it is time to return to the previous transmission ...

--

Terry

That could well explain why I still get some interruptions with TA
disabled. But I get more with TA enabled. So - perhaps unsurprisingly -
the pirates* could be causing maximum bother.


*I make no apologies for causing them pirates rather than "community
channels". They do cause harm - eg when I miss a bit of the afternoon
drama And if the name of the game is anarchy then can I join in by
taking a stick to the next sodcaster who shares rap - or reggae - with
me?

--
Robin
reply to address is (meant to be) valid

On 03/01/2015 17:13, Dave Plowman (News) wrote:
In article ,
The Medway Handyman wrote:
For the last month or so, whilst driving around town listening to Radio
4 on FM, I've been getting short bursts (3 - 4 seconds) of interference
in the form of loud music; garage, hip hop, indie or whatever it is -
not something any sane person would listen to.

Not connected with any specific area or vehicle that I can see.

Is this some form of pirate radio station?

Almost certainly.

Or bad taxi service breakthrough at close range. Also these dongles that
rebroadcast iPads on close range FM in passing vehicles.

One reason DAB is so good in the car. No pirates and excellent reception
round London. Much better reception on R4 than FM.

That isn't much use to the majority of us who do not live in London.

Last night DAB radio in parts of North Yorkshire was decoding as
"service unavailable" an error I have never previously seen before.

--
Regards,
Martin Brown

Traffic Announcements rely on the receiver being instructed via the data
stream that a Traffic Announcement is being currently carried on another
frequency - to which the radio briefly switches. If the signal is there, the
radio switches to it but if it is not, because the distance to the local
radio station is too great, for example, it switches back. This causes a
brief gap of silence during the process.


What some pirates do is to transmit the "Traffic Flag" or TA all the
time this causes your radio to lock onto their transmission.

Expressly prohibited on the Ofcom regs but as there're Pirates;!...

Yes, Tony, but your radio won't be monitoring every transmission in Band II
to see if any have raised the flag!

No course not, but I haven't seen it myself but these buggers have got
some way to trigger off in some radios a "scan" and then once on that
frequency it stays there...

--
Tony Sayer

On Mon, 05 Jan 2015 08:50:54 +0000, Martin Brown wrote:

Last night DAB radio in parts of North Yorkshire was decoding as
"service unavailable" an error I have never previously seen before.

Pushes "auto tune" on DAB set twiddles thumbs "NO SERV"

--
Cheers
Dave.

In article ,
Martin Brown wrote:
One reason DAB is so good in the car. No pirates and excellent
reception round London. Much better reception on R4 than FM.

That isn't much use to the majority of us who do not live in London.

Then you're not so likely to suffer interference on FM from pirates.

--
*If at first you don't succeed, then skydiving definitely isn't for you *

Dave Plowman London SW
To e-mail, change noise into sound.

In article o.uk,
Dave Liquorice wrote:
On Mon, 05 Jan 2015 08:50:54 +0000, Martin Brown wrote:

Last night DAB radio in parts of North Yorkshire was decoding as
"service unavailable" an error I have never previously seen before.

Pushes "auto tune" on DAB set twiddles thumbs "NO SERV"

Wonder how good your aerial is? My aftermarket DAB car radio was useless
with the original car aerial. The expensive one I bought has a built in
head amp for DAB. Despite being a 1/4 wave for that frequency.

--
*Why is the third hand on the watch called a second hand?

Dave Plowman London SW
To e-mail, change noise into sound.

On Monday, 5 January 2015 11:31:07 UTC, Dave Plowman (News) wrote:
In article o.uk,
Dave Liquorice wrote:
On Mon, 05 Jan 2015 08:50:54 +0000, Martin Brown wrote:

Last night DAB radio in parts of North Yorkshire was decoding as
"service unavailable" an error I have never previously seen before.

Pushes "auto tune" on DAB set twiddles thumbs "NO SERV"

Wonder how good your aerial is? My aftermarket DAB car radio was useless
with the original car aerial. The expensive one I bought has a built in
head amp for DAB. Despite being a 1/4 wave for that frequency.

--
*Why is the third hand on the watch called a second hand?

Dave Plowman London SW
To e-mail, change noise into sound.

To go off at a slight tangent, for which apologies ...
I know a bit about antenna theory in general, but next to nothing about
commercial (FM/AM) car radio antennae. I have a Aldidl Car Radio and a
nondescript roof-mounted antenna, and experience fairly poor reception and
frequent fading etc. Would it be worth my while upgrading to a better aerial,
and if so can anyone suggest something 'cheap-ish' (say £20) to try? Or is
the problem likely to be due to poor intrinsic sensitivity of the radio?

Sorry for the vagueness of this...

Cheers
Jon N

In article ,
jkn wrote:
I know a bit about antenna theory in general, but next to nothing about
commercial (FM/AM) car radio antennae. I have a Aldidl Car Radio and a
nondescript roof-mounted antenna, and experience fairly poor reception
and frequent fading etc. Would it be worth my while upgrading to a
better aerial, and if so can anyone suggest something 'cheap-ish' (say
£20) to try? Or is the problem likely to be due to poor intrinsic
sensitivity of the radio?

I'd say most modern car radios will be (near) state of the art as regards
sensitivity, since they'll likely use a 'chip' front end.

Is the roof aerial a factory fit 'bee sting' one? Many of those are also
active - have a head amp inside them. Is that powered if you've changed
the head unit?

A basic simple rod aerial for FM should be 1 metre long.

--
*Your kid may be an honours student, but you're still an idiot.

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 05 Jan 2015 11:27:25 +0000 (GMT), Dave Plowman (News) wrote:

Pushes "auto tune" on DAB set twiddles thumbs "NO SERV"

Wonder how good your aerial is?

Aerial is as supplied by the maker (Sony), about 6' of plain wire and
connects to the set via a small plastic molex style connector. The
instructions make no mention of using anything other than the
supplied bit of wire. As that is what the maker supplies and they
don't suggest any alternatives I expect it to work...

One day I might get around to putting an aerial in one of the lofts
and bodging up some form of coax to "molex" connector but the average
punter wouldn't be able to do that nor should they be expected to be
able either.

--
Cheers
Dave.

In article o.uk,
Dave Liquorice wrote:
On Mon, 05 Jan 2015 11:27:25 +0000 (GMT), Dave Plowman (News) wrote:

Pushes "auto tune" on DAB set twiddles thumbs "NO SERV"

Wonder how good your aerial is?

Aerial is as supplied by the maker (Sony), about 6' of plain wire and
connects to the set via a small plastic molex style connector. The
instructions make no mention of using anything other than the
supplied bit of wire. As that is what the maker supplies and they
don't suggest any alternatives I expect it to work...

One day I might get around to putting an aerial in one of the lofts
and bodging up some form of coax to "molex" connector but the average
punter wouldn't be able to do that nor should they be expected to be
able either.

I'd hope a maker might just supply any radio with a standard UK external
aerial connector. Or an adaptor for one.

An FM portable radio doesn't work well indoors in this part of London.

--
*The best cure for sea sickness, is to sit under a tree.

Dave Plowman London SW
To e-mail, change noise into sound.

"tony sayer" wrote in message
...
Traffic Announcements rely on the receiver being instructed via the
data
stream that a Traffic Announcement is being currently carried on
another
frequency - to which the radio briefly switches. If the signal is
there, the
radio switches to it but if it is not, because the distance to the
local
radio station is too great, for example, it switches back. This causes
a
brief gap of silence during the process.


What some pirates do is to transmit the "Traffic Flag" or TA all the
time this causes your radio to lock onto their transmission.

Expressly prohibited on the Ofcom regs but as there're Pirates;!...

Yes, Tony, but your radio won't be monitoring every transmission in Band
II
to see if any have raised the flag!

No course not, but I haven't seen it myself but these buggers have got
some way to trigger off in some radios a "scan" and then once on that
frequency it stays there...

It can't be that because the OP says that it only switches away temporarily
so there is only a burst of the 'music' he doesn’t like.

Hi Dave, thanks for the posting:

On Monday, 5 January 2015 12:53:55 UTC, Dave Plowman (News) wrote:
In article ,
jkn wrote:
I know a bit about antenna theory in general, but next to nothing about
commercial (FM/AM) car radio antennae. I have a Aldidl Car Radio and a
nondescript roof-mounted antenna, and experience fairly poor reception
and frequent fading etc. Would it be worth my while upgrading to a
better aerial, and if so can anyone suggest something 'cheap-ish' (say
£20) to try? Or is the problem likely to be due to poor intrinsic
sensitivity of the radio?

I'd say most modern car radios will be (near) state of the art as regards
sensitivity, since they'll likely use a 'chip' front end.

OK, good to know. I did a quick google about the Aldilidl radios with no sign
of sensitivity problems.

Is the roof aerial a factory fit 'bee sting' one? Many of those are also
active - have a head amp inside them. Is that powered if you've changed
the head unit?

I hadn't come across the term before ... it used to be a simple (I thought)
half-metre or so aerial a bit like:

http://www.rockshore.uk.com/universa...ase-1911-p.asp

The roof fitting degraded and I replaced it with something similar-ish from
eBay, but kept the coax. But there was some swapping of head units between cars
at the time so it's hard to be sure. We have spotty reception round here anyway,
I'm not expecting 100% ... but it's hard to receive R4 on a good day at the
moment.

I see that (eg.) from the website above you can get amplifed (head amp) roof
mounted aerials for not much more than a tenner - maybe I'll get one of those
and bite the bullet about changing the cable.


A basic simple rod aerial for FM should be 1 metre long.


Thanks
J^n

In article , says...

A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be 750mm.

The centre of Band II is slightly below this (longer wavelength) but is close
enough.

Mount in the CENTRE of the roof so that the roof becomes an earth plane and
gives omni-directional performance.

If you make a simple base for starters with a rubber covering on the bottom
and a couple of suitable neodymium magnets to ensure it doesn't move you will
end up with a suitable basic aerial to experiment with.

You might want to contrive a flexible joint at the base to allow for places
with restricted headroom in the permanent design!

--

Terry

On Mon, 05 Jan 2015 17:38:25 +0000 (GMT), Dave Plowman (News) wrote:

I'd hope a maker might just supply any radio with a standard UK external
aerial connector. Or an adaptor for one.

So would I but not on/with this Sony "micro HiFi".

The best I've managed to get out of it from DAB was a test upstairs,
on the right side of the house, by a window. All that gave was
"boiling mud" but you could tell the difference between music and
speech. Speech had gaps in the boiling mud noise. B-)

--
Cheers
Dave.

On Mon, 5 Jan 2015 21:25:36 -0000, Terry Casey wrote:

A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be 750mm.

You've forgotten the velocity factor... B-)

--
Cheers
Dave.

On 05/01/15 21:33, Dave Liquorice wrote:
On Mon, 5 Jan 2015 21:25:36 -0000, Terry Casey wrote:

A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be 750mm.

You've forgotten the velocity factor... B-)

oh well 749.99957mm


--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll

On Mon, 05 Jan 2015 22:28:56 +0000, The Natural Philosopher wrote:

A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be
750mm.

You've forgotten the velocity factor... B-)

oh well 749.99957mm

A rod is considered to be around 96% IIRC so more like 720 mm.

--
Cheers
Dave.

In article ,
Terry Casey wrote:
A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be 750mm.

Right - I was merely quoting the recommendation from the car radio
handbook. Perhaps 1 metre is their best compromise for FM and AM including
SW.

--
*I don't have a license to kill, but I do have a learner's permit.

Dave Plowman London SW
To e-mail, change noise into sound.

In article o.uk,
says...

On Mon, 5 Jan 2015 21:25:36 -0000, Terry Casey wrote:

A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be 750mm.

You've forgotten the velocity factor... B-)

No I didn't! I did consider it: (~95%) which reduces the rod length but when
you add in the +2% difference for the true centre of the band, this reduces
to 97%, so the precise length of the whip isn't really that important.

750mm is a lot closer to the centre of Band II than the 1000mm originally
proposed!

--

Terry

In article o.uk, Dave
Liquorice scribeth thus
On Mon, 05 Jan 2015 22:28:56 +0000, The Natural Philosopher wrote:

A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be
750mm.

You've forgotten the velocity factor... B-)

oh well 749.99957mm

A rod is considered to be around 96% IIRC so more like 720 mm.


Depends on the metal;!.

It is true, there are differing coefficients for differing metals and
alloys thereof for use in aerial design programs..

For most s/steel whips .9 is near enough but its a bit academic anyway
with regard to the needed 20 MHz band coverage. If you are going to use
one then best cut for the lower end of the band, seems work better
overall..
--
Tony Sayer

In article ,
Terry Casey scribeth thus
In article , says...

A basic simple rod aerial for FM should be 1 metre long.

100MHz is a wavelength of 3 metres so a 1/4 wave whip would be 750mm.

The centre of Band II is slightly below this (longer wavelength) but is close
enough.

Mount in the CENTRE of the roof so that the roof becomes an earth plane and
gives omni-directional performance.

Now your asking!. Thats where peeps don't want them which is a shame as
I normally have a 1/4 wave for VHF Hi-band on the rear of an estate car
and thats connected to the FM radio thru a diplexer unit but when the
full length FM aerial is on a mag-mount in the middle of the roof the FM
band just comes alive..


--
Tony Sayer

In article o.uk, Dave
Liquorice scribeth thus
On Mon, 05 Jan 2015 17:38:25 +0000 (GMT), Dave Plowman (News) wrote:

I'd hope a maker might just supply any radio with a standard UK external
aerial connector. Or an adaptor for one.

So would I but not on/with this Sony "micro HiFi".

The best I've managed to get out of it from DAB was a test upstairs,
on the right side of the house, by a window. All that gave was
"boiling mud" but you could tell the difference between music and
speech. Speech had gaps in the boiling mud noise. B-)


The overall sound quality on DAB these days Dave low bitrates and mainly
Mono isn't worth bothering with, stay with FM and the better online
stations for decent reception;!..
--
Tony Sayer

On 06/01/15 12:53, tony sayer wrote:
In article o.uk, Dave
Liquorice scribeth thus
On Mon, 05 Jan 2015 17:38:25 +0000 (GMT), Dave Plowman (News) wrote:

I'd hope a maker might just supply any radio with a standard UK external
aerial connector. Or an adaptor for one.

So would I but not on/with this Sony "micro HiFi".

The best I've managed to get out of it from DAB was a test upstairs,
on the right side of the house, by a window. All that gave was
"boiling mud" but you could tell the difference between music and
speech. Speech had gaps in the boiling mud noise. B-)


The overall sound quality on DAB these days Dave low bitrates and mainly
Mono isn't worth bothering with, stay with FM and the better online
stations for decent reception;!..

Frankly at home most of what I listen to is on the interwebby thing anyway.

Or on digital TV MUXES


Not up to FM, but better than DAB!

Frankly I think DAB will disappear and be replaced domestically with
internet and as far as cars go...well the tendency there is MP3 - you
only need a radio for traffic, and thats being replaced by smart satnav.



--
Everything you read in newspapers is absolutely true, except for the
rare story of which you happen to have first-hand knowledge. €“ Erwin Knoll