North London and clashing signals
 

We live in North London (Mill Hill) and we pick up Gold Radio Station on the
medium wave on a small pocket radio.

However the World Service is interfering with the Gold signal. This occurs
on our analogue radios and digital tuner radios. Since we use pocket size
radios, these AM radios are better for us than using a DAB radio.

Is there any advice you can offer on solving this clashing signal problem?
Especially annoying as the world service and Gold are the two stations most
listened to. Who should we best complain to about this, if you think that
might do any good?

Grateful for any advice. Thanks.

North London and clashing signals
 

In article , john hamiliton
wrote:

We live in North London (Mill Hill) and we pick up Gold Radio Station on
the medium wave on a small pocket radio.

However the World Service is interfering with the Gold signal. This
occurs on our analogue radios and digital tuner radios. Since we use
pocket size radios, these AM radios are better for us than using a DAB
radio.

Is there any advice you can offer on solving this clashing signal
problem? Especially annoying as the world service and Gold are the two
stations most listened to. Who should we best complain to about this, if
you think that might do any good?

Grateful for any advice. Thanks.

you need to buy a better quality radio - it's a design fault causing the
problem.

--
From KT24

Using a RISC OS computer running v5.16

North London and clashing signals
 

"john hamiliton" wrote in message
...

We live in North London (Mill Hill) and we pick up Gold Radio Station on
the medium wave on a small pocket radio.

However the World Service is interfering with the Gold signal. This
occurs on our analogue radios and digital tuner radios. Since we use
pocket size radios, these AM radios are better for us than using a DAB
radio.

Is there any advice you can offer on solving this clashing signal problem?
Especially annoying as the world service and Gold are the two stations
most listened to. Who should we best complain to about this, if you think
that might do any good?

Grateful for any advice. Thanks.

Gold is on 1548kHz in London, right?

There's no BBC world service anywhere near that as far as I know.

Can you shed any light on what frequency might be interfering with Gold?

--

Brian Gregory. (In the UK)

To email me remove the letter vee.

North London and clashing signals
 

On 08/06/2010 23:19, Brian Gregory [UK] wrote:
"john wrote in message


Gold is on 1548kHz in London, right?

There's no BBC world service anywhere near that as far as I know.

Capital Gold 1548 kHz

BBC World Service 648 kHz

1548-648= 900kHz

900/2= 455 kHz

455 kHz the local oscillator frequency for many MW radios.

Therefore BBC World is appearing 'on top of' Capital Gold as a 2xIF image.

As Charles says, crap receiver design/quality.


--
Mark
Please replace invalid and invalid with gmx and net to reply.

http://www.paras.org.uk/

North London and clashing signals
 

"Mark Carver" wrote in message
...
On 08/06/2010 23:19, Brian Gregory [UK] wrote:
"john wrote in message


Gold is on 1548kHz in London, right?

There's no BBC world service anywhere near that as far as I know.

Capital Gold 1548 kHz

BBC World Service 648 kHz

1548-648= 900kHz

900/2= 455 kHz

455 kHz the local oscillator frequency for many MW radios.

Therefore BBC World is appearing 'on top of' Capital Gold as a 2xIF image.

As Charles says, crap receiver design/quality.



Even Sony = 'made in China'?

North London and clashing signals
 

The message
from Mark Carver contains these words:

On 08/06/2010 23:19, Brian Gregory [UK] wrote:
"john wrote in message


Gold is on 1548kHz in London, right?

There's no BBC world service anywhere near that as far as I know.

Capital Gold 1548 kHz

BBC World Service 648 kHz

1548-648= 900kHz

900/2= 455 kHz

455 kHz the local oscillator frequency for many MW radios.

Therefore BBC World is appearing 'on top of' Capital Gold as a 2xIF image.

As Charles says, crap receiver design/quality.

John's reply regarding the frequency was slightly ambiguous. I thought
he was referring to Gold's frequency being 648KHz (with BBC WS on
1548KHz). It would have to be this way round for the IF image mechanism
to be responsible for the interference from BBC WS on Gold since it has
been standard practice for the LO to be tuned above the incoming MW
signal[1].

A definitive indicator for image frequency interference is the classic
rapid pitch change of the beat frequency as you slowly tune across the
channel occupied by the wanted broadcast.

A better design of radio, in this context, would either be a double
conversion type or an extra tuned circuit (amplified or not) on the
input stage to the mixer requiring a three gang tuning capacitor. These
are features that simply don't appear on cheap LW/MW radios (not even if
the have a VHF tuner).

One "Quick Fix" in this particular case, would be to retune the IF
stages up or down by 4 or 5KHz if the radio is a basic analogue tuned
design (a 5KHz shift would displace the unwanted image by 10KHz). Such
tuning is well within the adjustment range of the IF coils but you might
upset any 'stagger tuning' used to approximate a flat bandpass filter
effect.

[1] The MW broadcast band covers a frequency ratio range of 3 to 1 which
is just tunable with a vaned variable tuning capacitor (air spaced or
polyethylene dielectric type) with a min to max ratio of 10 to 1 which
is typically reduced to about 9 to 1 due to the trimming caps.

To run the LO below the wanted frequency in a single sweep would
require an impossible to achieve 100KHz to 2MHz frequency ratio (20 to 1
f ratio requiring a C ratio of 400 to 1) whereas running the LO in the
range 1MHz to 2.6MHz would only require a C ratio of about 7 to 1,
easily achieved on a twin gang tuning capacitor with a series padding
cap in the LO circuit.

North London and clashing signals
 

On 09/06/2010 00:37, Ivan wrote:

"Mark Carver" wrote in message

Even Sony = 'made in China'?

Well, I've got the reasonably 'up market' and 20 year old, made in
Japan, ICF-SW7600. That performs very well on the MF and HF bands, but
the FM section (that tunes from 76.0 MHz to 108.0), is easily
overloaded, and nasty IF images pop up from stations that have
relatively moderate RF levels. Someone told me, the FM section is just
'chucked in' afterthought. A shame because it lets the receiver down.


--
Mark
Please replace invalid and invalid with gmx and net to reply.

http://www.paras.org.uk/

North London and clashing signals
 

In article ,
Johnny B Good wrote:
The message
from Mark Carver contains these words:

On 08/06/2010 23:19, Brian Gregory [UK] wrote:
"john wrote in message


Gold is on 1548kHz in London, right?

There's no BBC world service anywhere near that as far as I know.

Capital Gold 1548 kHz

BBC World Service 648 kHz

1548-648= 900kHz

900/2= 455 kHz

455 kHz the local oscillator frequency for many MW radios.

Therefore BBC World is appearing 'on top of' Capital Gold as a 2xIF
image.

As Charles says, crap receiver design/quality.

John's reply regarding the frequency was slightly ambiguous. I thought
he was referring to Gold's frequency being 648KHz (with BBC WS on
1548KHz). It would have to be this way round for the IF image mechanism
to be responsible for the interference from BBC WS on Gold since it has
been standard practice for the LO to be tuned above the incoming MW
signal[1].

It was "Mark's" reply not "John's".

Try wanted frequency 1548, LO frequency + 1548 + 450 =1998.

1998 - (3 x 450) = 648.

So it's a 3rd harmonic problem.

Once upon a time mf radios had a choice of if depending on which country it
was to be used in. 455 (or 450) is not too good in the UK since 910 is one
of our main frequencies.

--
From KT24

Using a RISC OS computer running v5.16

North London and clashing signals
 

Mark Carver wrote:
On 08/06/2010 23:19, Brian Gregory [UK] wrote:
"john wrote in message


Gold is on 1548kHz in London, right?

There's no BBC world service anywhere near that as far as I know.

Capital Gold 1548 kHz

BBC World Service 648 kHz

1548-648= 900kHz

900/2= 455 kHz

Er, ... is it really?

Have they changed the rules?

North London and clashing signals
 

On 09/06/2010 09:10, Norman Wells wrote:


900/2= 455 kHz

Er, ... is it really?

Have they changed the rules?

No, it's just that I can't do simple division, after I've been out and
had one too many beers.

I'll get me coat. . .



--
Mark
Please replace invalid and invalid with gmx and net to reply.

http://www.paras.org.uk/