Whistles on strong MW station
Richard
This problem I think is just with this particular radio I have, because
I've not noticed it with an identical radio.
Coil position on ferrite rod is as original.
I am about 8 miles from Moorside Edge MW station. When I tune into
5Live, I hear a whistle on the signal. No whistles on other local stations.
What could be causing this? Could it be something else other than an
alignment problem?
Ta. Rich
David Woolley
>
> I am about 8 miles from Moorside Edge MW station. When I tune into
> 5Live, I hear a whistle on the signal. No whistles on other local stations.
>
> What could be causing this? Could it be something else other than an
> alignment problem?
Likely to be an image response to the local transmitter.
<http://en.wikipedia.org/wiki/Image_response> Could well be a higher
order (non-linear) spurious signal.
Richard
5Live is on 909Khz. The IF of the RX is 455Khz.
Usually the OSC. is higher than the signal, so OSC will be at 1364 Khz.
So, a signal on 1819Khz would come through, because that's also 455Khz
from 1364Khz, but above, not below.
Second harmonic of 909 Khz, is 1818 Khz.
Aaah, I wonder if that's the problem, a second harmonic at coming out
from the antenna at 1818Khz, and that is not being rejected enough by
the rf stage.
Is that reasonable?
Richard
Well, eebaaagum, I did not think I'd be able the hear the second
harmonic, but on a Roberts RC818, I can hear 5Live on 1818Khz.
Not that strong, but it's there.
I wonder if anyone nearish Moorside Edge can also hear the harmonic and
guagee it's strength. I'm guessing it's strong enough to be causing the
whistles I get on 909Khz.
Ian Jackson
<no...@ntlworld.com> writes
I always thought that the 'traditional' reason for the tuneable whistle
in the middle of the medium waveband (in this case, around 909kHz) was
the second harmonic of the 455kHz IF (=910kHz), generated by the
inherent non-linearity of the mixer stage.
However, the 1818kHz explanation also sounds plausible. But it's more
likely to be that the 1818kHz signal is being produced from the strong
909kHz hitting the mixer. Either way, there's no real cure (unless you
shift the IF slightly).
Of course, at one time, in the UK, our standard IF used to be 465kHz. I
believe that the old allocation of 908kHz for the BBC Brookmans Park
transmitter influenced this choice.
--
Ian
Frank Turner-Smith G3VKI
news:82m78i...@mid.individual.net...
Does the whistle remain even if you turn the radio to reduce the incoming
signal?
--
;-)
.
73 de Frank Turner-Smith G3VKI - mine's a pint.
.
http://turner-smith.co.uk
Richard
My gut reaction is that it's not the second harmonic of 5Live. Even
though there is some RF output on it's 2nd harmonic.
I'de never have thought about it, but from what you said, I bet you are
right. What is happenning is that the 909Khz signal is the offending
signal: I mean if it was not as strong, it beats with the OSC signal and
the mixer ouputs this heterodyne at 455Khz. That's normal operation.
But, it's so strong the second harmonic heterodynes with the OSC signal
and that produes an output at 455 Khz.
It could be that the mixer biasing has gone west, or the mixer
transistor is a but "duff".
Richard
> "Richard" <no...@ntlworld.com> wrote in message
> news:82m78i...@mid.individual.net...
>> I've got an old tranistor radio, 1960's vintage, very good quality.
>>
>> This problem I think is just with this particular radio I have,
>> because I've not noticed it with an identical radio.
>>
>> Coil position on ferrite rod is as original.
>>
>> I am about 8 miles from Moorside Edge MW station. When I tune into
>> 5Live, I hear a whistle on the signal. No whistles on other local
>> stations.
>>
>> What could be causing this? Could it be something else other than an
>> alignment problem?
>>
>> Ta. Rich
>
>
> Does the whistle remain even if you turn the radio to reduce the
> incoming signal?
The signal does not reduce much, and the whistle never goes.
I have another very similar radio, same model number but some differences.
I notice that that too whistles on 909Khz. Several striong MW signals,
but only whistles on 909Khz.
The family had this model of radio in the 1960's and 1970's and it never
whistled. Same Moorside Edge TX as well.
So, that's two sets of this model that whistle on 909Khz. But this model
never used to years back.
Richard
> news:82m78i...@mid.individual.net...
>> I've got an old tranistor radio, 1960's vintage, very good quality.
>>
>> This problem I think is just with this particular radio I have,
>> because I've not noticed it with an identical radio.
>>
>> Coil position on ferrite rod is as original.
>>
>> I am about 8 miles from Moorside Edge MW station. When I tune into
>> 5Live, I hear a whistle on the signal. No whistles on other local
>> stations.
>>
>> What could be causing this? Could it be something else other than an
>> alignment problem?
>>
>> Ta. Rich
>
>
> Does the whistle remain even if you turn the radio to reduce the
> incoming signal?
Actually, by tilting the radio I can reduce 5Live to a weakish signal,
well below say other signals on the band.
And the whistle remains.
I've no idea now what the problem is. Does not seem to be the strength
of the 909Khz signal.
Jim GM4DHJ in the Radio Shack ...
Ian Jackson
No. 909kHz is not the offending signal. From what I've always
understood, it's the second harmonic of the IF (455kHz x 2). [This
effect is more-or-less independent of the strength of a signal on
909kHz.]
--
Ian
Ian Jackson
<no...@ntlworld.com> writes
>So, that's two sets of this model that whistle on 909Khz. But this
>model never used to years back.
Many radios tend to whistle on 909kHz - if they have a 455kHz IF.
--
Ian
Richard
The penny dropped about one minute ago, before I say your post. :c)
I was just about to say, it's nothing to do with the strength of the 909
Khz signal, it's to do with the frequiencies involved.
In the 1960's we listened to Moorside Egge, but not on 909Khz. We
listened on 247 metres.
So, what's going on? I'm not entirely sure how the beat is being
produced, except it's something to do with the second harmonic of the
455Khz IF.
Richard
> Many radios tend to whistle on 909kHz - if they have a 455kHz IF.
Why?
I cannot understand why.
I mean, why my radio is whistling.
All I know, is that it isn't 2nd harmonic radiation from the transmitter.
And it's not down to a strong overloading signal.
It is to do with harmonics or sub harmonics, that are always there
irrespective of strength of signal.
There may be more than one answer I think.
What are the potential answers?
Anybody.
Richard
>
> However, the 1818kHz explanation also sounds plausible. But it's more
> likely to be that the 1818kHz signal is being produced from the strong
> 909kHz hitting the mixer. Either way, there's no real cure (unless you
> shift the IF slightly).
>
Would there be a sufficient signal at 1818 Khz, even when the signal is
weak?
If not, I can eliminate that as the problem.
Ian Jackson
<no...@ntlworld.com> writes
Why are you still expressing such total puzzlement?
I suspect that the reason is exactly the same as I suggested in my first
reply to you.
"I always thought that the 'traditional' reason for the tuneable whistle
in the middle of the medium waveband (in this case, around 909kHz) was
the second harmonic of the 455kHz IF (=910kHz), generated by the
inherent non-linearity of the mixer stage."
--
Ian
Ian Jackson
<g3...@invalid.invalid> writes
>On Wed, 14 Apr 2010 17:49:26 +0100, Richard <no...@ntlworld.com> wrote:
>
>>5Live is on 909Khz. The IF of the RX is 455Khz.
>>
>>Usually the OSC. is higher than the signal, so OSC will be at 1364 Khz.
>>
>>So, a signal on 1819Khz would come through, because that's also 455Khz
>>from 1364Khz, but above, not below.
>>
>>Second harmonic of 909 Khz, is 1818 Khz.
>
>satisfaction. Better still, listen to it on DAB.
>
>Duh!
>
I had actually been thinking along those lines. Could the ability to
receive 5 Live without a whistle be the 'real' reason that DAB is being
thrust on a largely unwilling - and critical - public?
--
Ian
Richard
Okay, my mind just focused on "The second harmonic of the 455 Khz IF"
and then for some reason got to thinking about the IF stage itself, and
"generated by the inherent non linearity of the mixer stage" passed me by.
Frank Turner-Smith G3VKI
news:gY59txGA...@g3ohx.demon.co.uk...
That sounds like the reason to shift the IF from 455 to 465KHz, but why was
455 chosen in the first instance?
Richard
> On Wed, 14 Apr 2010 17:49:26 +0100, Richard<no...@ntlworld.com> wrote:
>
>>
>> Usually the OSC. is higher than the signal, so OSC will be at 1364 Khz.
>>
>> So, a signal on 1819Khz would come through, because that's also 455Khz
>>from 1364Khz, but above, not below.
>>
>> Second harmonic of 909 Khz, is 1818 Khz.
>
> satisfaction. Better still, listen to it on DAB.
>
> Duh!
>
What your comment has to do with a technical enquiry seeking to simply
understand why I'm getting the whistles - well, I just don't know.
Richard
And besides, there might have been a fix.
But, I don't think there is one, because it's not down signal overload.
Brian Gregory [UK]
Can you not tune up or down slightly until the IF signal is at 454.5kHz so
that the second harmonic of the IF is exactly 909kHz.
If tuning up and down the band doesn't change the whistle then it's due to
some other problem.
--
Brian Gregory. (In the UK)
n...@bgdsv.co.uk
To email me remove the letter vee.
Brian Gregory [UK]
news:Jvqxn.149687$Vh1....@newsfe15.ams2...
Probably worked out well somewhere else in the world, perhaps somewhere
where they use 10kHz steps on MW, or perhaps Japan where lots of IF filters
are made.
Ian Jackson
G3VKI <g3...@turner-smith.co.uk> writes
455kHz was the usual American IF, and has become the de facto
international standard for most single-conversion (low end of the
market?) LW/MW/SW radios. However, although the ITU Region 2 MW channel
spacing is 10kHz, they must have the same problem. 2 x 455kHz lands dead
on 910kHz, which is certainly not avoided in the USA.
--
Ian
Richard
Yea, I'd already had that in mind, I forgot when I made the post. :c)
I ought to be able to move the IF a bit. If the IF was say 450 Khz then
the OSC would be on 1359 Khz.
In order for a signal to produce a 450 KHz IF signal the mixer must
produce a signal at 1809 Khz (image freq.).
Of course the harmonic of 909 Khz is 1818 Khz, so that signal would not
come out at 455 Khz. It would be 9 Khz away from 450 Khz, at 459 Khz.
And that woud be a fix, I think.
Don't know if there are better ones.
Brian Gregory [UK]
As far as I can see you totally misunderstood what I said.
Does the radio not have a tuning knob on it?
What happens to the whistle as you tune up and down across Radio 5 Live on
909kHz?
Richard
> As far as I can see you totally misunderstood what I said.
>
> Does the radio not have a tuning knob on it?
>
> What happens to the whistle as you tune up and down across Radio 5 Live on
> 909kHz?
I know what I'm doing. :c)
I just fixed it.
I just tweaked all the IF tranformer cores a turn or so. And the
whistles gone. It needed the IF freq. changing a tad, then problem solved.
Paul Starship
<g3...@invalid.invalid> wrote:
>It was, however, within the "Ship to Shore" Morse code band. This led
>to some listeners in coastal areas experiencing IF breakthrough from
>ships and coast stations.
but all was quiet for 3 minutes
at 00,15,30 and 45 minutes past the hour.
:-)
DieSea
"Walt Davidson" <g3...@invalid.invalid> wrote in message
news:c1hcs51bqukn1t1tp...@4ax.com...
> On Wed, 14 Apr 2010 22:29:14 +0100, Richard <no...@ntlworld.com> wrote:
>
>>> "I always thought that the 'traditional' reason for the tuneable whistle
>>> in the middle of the medium waveband (in this case, around 909kHz) was
>>> the second harmonic of the 455kHz IF (=910kHz), generated by the
>>> inherent non-linearity of the mixer stage."
>>
>>Okay, my mind just focused on "The second harmonic of the 455 Khz IF"
>>and then for some reason got to thinking about the IF stage itself, and
>>"generated by the inherent non linearity of the mixer stage" passed me by.
>
>
> The frequency of the local oscillator in a single conversion superhet
> with a 455 kHz IF will always be 455 kHz below the medium wave
> frequency that you are trying to listen to. There is a potential
> problem when you tune to 909 kHz, because the local oscillator will
> then be on (909 - 455) kHz, i.e. 454 kHz. The second harmonic of the
> local oscillator will therefore be on (2 x 454) kHz, i.e. 908 kHz, and
> this will create a 1 kHz beat note in the receiver.
>
> If you tune a little way either side of the desired station, you will
> hear the beat note rising or falling in pitch, because you are
> effectively moving the frequency of the local oscillator up and down.
> It's like a BFO (beat frequency oscillator).
>
> 73 de G3NYY
>
> --
> Walt Davidson Email: g3nyy @despammed.com
Careful Wlat
You'll be letting the cat out of the bag !!
DieSea
Fuller Fan Club@sgt.co.uk.com Brains of the Outfit
"Walt Davidson" <g3...@invalid.invalid> wrote in message
>
> It was, however, within the "Ship to Shore" Morse code band. This led
> to some listeners in coastal areas experiencing IF breakthrough from
> ships and coast stations.
Music to the ears of Starship and G4SDW ;-)
tox
G4KFK
> On Wed, 14 Apr 2010 22:47:10 GMT, p.blas...@google-nospam-email.com
>
> (Paul Starship ) wrote:
> >>It was, however, within the "Ship to Shore" Morse code band. This led
> >>to some listeners in coastal areas experiencing IF breakthrough from
> >>ships and coast stations.
>
> >but all was quiet for 3 minutes
> >at 00,15,30 and 45 minutes past the hour.
>
> >:-)
>
Only 15 and 45, Shirley?
00 and 30 were the SPs on 2182kHz.
Brian Howie
<g3...@invalid.invalid> writes
>On Wed, 14 Apr 2010 22:31:44 +0100, "Frank Turner-Smith G3VKI"
><g3...@turner-smith.co.uk> wrote:
>
>>That sounds like the reason to shift the IF from 455 to 465KHz, but why was
>>455 chosen in the first instance?
>
>band and the high end of the "Long Wave" band ... and therefore well
>clear of all broadcast stations.
>
>It was, however, within the "Ship to Shore" Morse code band. This led
>to some listeners in coastal areas experiencing IF breakthrough from
>ships and coast stations.
I used to get GPK breaking through on the IF on A2A on the west coast.
Brian
--
Brian Howie
Ian Jackson
<g3...@invalid.invalid> writes
>
>
>The frequency of the local oscillator in a single conversion superhet
>with a 455 kHz IF will always be 455 kHz below the medium wave
>frequency that you are trying to listen to.
No No NO!
Unless it's a very unusual MW receiver indeed, the LO is always on the
high side. That's why you can hear local 160m stations on the MW.
Example:
1900 -(2 x 455) = 990.
In ye olden dayes, that's how many a young lad got started in amateur
radio (by overhearing a local on 160m).
There was a simple mod you could do to a MW radio, by disconnecting the
aerial input ganged tuning (which tracked with the LO) and replacing it
with another, independently-tuned, tuned circuit (ie a pre-selector).
That's how G0HDB get started as an SWL. He lived a few hundred yards
from me, and could my 160m transmissions. At the same time, there was
this article in the SWM about modifying a domestic MW broadcast set for
160, so that's what we did.
--
Ian
Gareth Evans G4SDW
> On Wed, 14 Apr 2010 23:34:10 +0100, Richard <no...@ntlworld.com> wrote:
>>I just tweaked all the IF tranformer cores a turn or so. And the
>>whistles gone. It needed the IF freq. changing a tad, then problem solved.
> broadcast receiver, it won't matter much!
This was the way of doing things for those of us who put together the
"Elegant 7" kit, but without the benefit of any test eqpt.
You tweaked up the IF stages for maximum noise, so that they would
at least be on some approximate but common frequency, and then
padded and trimmed until the dial read correctly.
Paul Rigg
Moorside Edge only transmitted on 909kHz after 1978.
Before that it was
Radio 1 1214kHz
Radio 4 (North Region) 692 kHz.
I can get a mixture of talk sport and 5 live on 180kHz!
That's about 12 miles from Moorside Edge. My Roberts R900 whistes on 5 live
too by my R1155 doesn't (think the IF of that is 560kHz approx)
Gareth Evans G4SDW
news:5LSdnXQ6Cp_xfFvW...@bt.com...
> My Roberts R900 whistles on 5 live
Reminds me of the one about the woman who goes to her GP complaining
that her sexual organ whistles when she walks along.
The GP, unable to reach a diagnosis, makes a tape recording as she
walks across the surgery floor.
At the end of the day, seeking a second opinion, the GP approaches
one of his partners, turns on the tape recorder, and asks
his partner, "What do you make of this?"
"Don't waste my time, Jim, it sounds like some c**t whistling"
G4KFK
> I can get a mixture of talk sport and 5 live on 180kHz!
1089 - 909 = 180
Richard
[...]
> In ye olden dayes, that's how many a young lad got started in amateur
> radio (by overhearing a local on 160m).
>
> There was a simple mod you could do to a MW radio, by disconnecting the
> aerial input ganged tuning (which tracked with the LO) and replacing it
> with another, independently-tuned, tuned circuit (ie a pre-selector).
> That's how G0HDB get started as an SWL. He lived a few hundred yards
> from me, and could my 160m transmissions. At the same time, there was
> this article in the SWM about modifying a domestic MW broadcast set for
> 160, so that's what we did.
My case was different.
With my Philips Electronic Engineer, I made the telephone amplifier, and
heard G8DMK on 2M AM.
Brian Reay
>
> With my Philips Electronic Engineer, I made the telephone amplifier, and
> heard G8DMK on 2M AM.
Ah, the Philips Electronic Engineer!
<old codger mode on>
There don't do toys like that anymore.
<old codger mode off>
Sadly, I can't think of a comparable "toy" these days.
--
73
Brian G8OSN/W8OSN
www.g8osn.net
Paul Rigg
"G4KFK" <mike.ga...@googlemail.com> wrote in message
news:8167f66b-3824-48c6...@z4g2000yqa.googlegroups.com...
Yes I know why. My FT817 gets Absolute Radio on 2430kHz too.
The transmitter power for the old Radio 1 transmitter was only 50kW. The
current Absolute transmitter is shown as 200kW in the WRTH, the most
powerful in the country.
Ian Jackson
<gzer...@tiscali.co.uk> writes
receive the second harmonic of what was then the Northern Ireland Home
Service. During the daytime, it was a consistent S7 to S9+ signal. The
distance must have been at good 300 miles. That was the only BBC MW
harmonic I ever heard, and it certainly was a beauty! I often thought of
letting them know, but never really got a round tuit.
--
Ian
Alf Resko
"Brian Reay" <s...@website.com> wrote in message
news:UzDxn.412930$2R.2...@newsfe11.ams2...
About the same time, I recall playing with a Triang "Trionic" electronics
set. It comprised a selection of components mounted in plastic cases which
plugged into circuit boards to build a series of transistor radios. I have
seen them on Ebay from time to time.
Brian Reay
news:yo0zn.273768$1j3.1...@newsfe10.ams2...
>>
>> Sadly, I can't think of a comparable "toy" these days.
>
> About the same time, I recall playing with a Triang "Trionic" electronics
> set. It comprised a selection of components mounted in plastic cases which
> plugged into circuit boards to build a series of transistor radios. I have
> seen them on Ebay from time to time.
I vaguely recall the Trionic stuff. I've a number of Maxitrionix kits which
I use for some of the IL assessments (eg the ones involving measurements and
transistors) but even these kits seem to be discontinued. I've been looking
for something I can recommend at the TTS courses but, as yet, haven't found
something.
<enter old man mode>
When I was a lad, your everyday geek played with electronic circuits and
radio.
<exit old man mode>
These days the geeks gravitate to computers so there is no demand for the
sort of kits we are discussing.