On Sat, 20 Mar 2010 16:42:29 +1100, "Phil Allison"
wrote:

** Hearing the same FM station at more than one spot is still possible even

in a very crappy receiver. It has already been said.

Not the usual quality one expects from Sony, but Mike's testimony
suggests otherwise hence we cannot discount a comb generator having
been dropped into the LO chip's place. Pity that, it must have been a
bad year.

73's
Richard Clark, KB7QHC

"Phil Allison" wrote
...

"Richard Clark"

Now, as to your experience of receiving signals on the wrong
frequency, that is a classic situation of image rejection being poor
due to the lack of a tuned front-end (something that dissappeared with
the dinosaurs). If I were to guess on the basis of 40 year old
experience fixing these suckers, your off-frequency signals are
probably shifted by twice the IF frequency of your receiver. The
classical FM IF frequency of 10.7 MHz might apply, but time has
marched on and designers may select their own. This old standard
would argue that you shouldn't experience images except where they
would be out-of-band (the 88-107 band with this IF would force that).


** Hearing the same FM station at more than one spot is still possible
even with a 10.7 MHz IF frequency - if the signal is very strong. The
reason is harmonics of the incoming carrier generated in the RF stage
interacting with harmonics of the local oscillator in the mixer.

It sound like the "Luxemburg Effect". The signal was from the dipole
antenna.
Are now the FM stations which use the dipoles?

Eg:

A 100MHz FM carrier generates a harmonic at 200MHz in the receiver.

When the local oscillator is adjusted to 94.65 MHz, its second harmonic is
189.3 MHz.

The difference frequency is then 10.7 MHz - so goes through to the FM
detector.

In this situation, the FM deviation is doubled so the recovered audio will
be distorted on loud passages.
S*

The usual solution on boats: Use a decent car radio.. Well shielded,
expects outdoor antenna. Runs on 12Volts... Can be had with CD player,
separate input for your Ipod etc.., good audio power to speakers
etc.... And designed to work inside a metal vehicle....

"Richard Clark"
"Phil Allison"


** Hearing the same FM station at more than one spot is still possible
even

in a very crappy receiver.

** Not by any method you alluded to - ****wit.


It has already been said.

** But not in any detail - ****wit.

No surprise a radio ham ****head like YOU deleted all the facts.

Pure embarrassment to a know nothing turds like radio hams.




..... Phil

"Joerg" wrote in message
...
amdx wrote:
"Richard Clark" wrote in message
...
On Fri, 19 Mar 2010 15:22:42 -0500, "amdx" wrote:

So I installed the antenna on the outside of the boat and the radio
inside,
now one station I listen to is weak, but if I unplug the antenna and
let the
center pin touch ground of the connector on the radio it comes in
great.
Just curious why it is working this way.
Hi Mike,

You moved the antenna.

Most loss of signal as you describe comes from not being a weak
signal, but the mixture of signals that combine negatively at some
spot due to multiple reflections. When you replaced the line cord as
antenna for this better implementation, you also found that "sour (not
sweet) spot." This can occur for any frequency with the equal
likelihood of reflections combining negatively. Move your antenna a
quarter wave and see what happens.

Your description of your having an aluminum boat almost guarantees a
multitude of RF-bright reflections. At short wavelengths, this also
guarantees many, many regions that will exhibit destructive (as well
as constructive) combinations of those reflections.

Put your antenna as far away from the superstructure or hull as
possible. This will reduce the reflection path differences.

BTW, the mod did cure the computer hash.
Mike
FM has what is called a "full quieting" effect. It would suggest that
your first signal levels were just barely above the level of full
quiet (and perhaps not even that good).

73's
Richard Clark, KB7QHC
Richard, after I read your letter I did a little better checking and
found
my signal is not weak it is to strong, I'm getting interference from
other frequencies.
Also I get stations on the wrong frequency.
I went out and collapsed the antenna to minimum about 1/3 of what it
was and
my problem station is perfect and the other station I listen to is still
good. The local
NPR station isn't good though. But I can download the podcast of Science
Friday :-)
Thanks, Mike

The usual, lousy FM tuner. They don't make'em like they used to. It's the
same with television sets, one large signal and they fall off the rocker.

If you have a radio with a signal strength meter you could notch out a
strong station. But that only works it it's just one and far away from the
NPR frequency. The only other options are to get a better radio, a
directional antenna, or just live with it and use the podcast.

--
Regards, Joerg
This morning I got on the boat and the signal that was improved to good by
shortening the antenna is now bad. 94.5 has interference from 101.1.
Oh well!
Mike

amdx wrote:
"Joerg" wrote in message
...
amdx wrote:
"Richard Clark" wrote in message
...
On Fri, 19 Mar 2010 15:22:42 -0500, "amdx" wrote:

So I installed the antenna on the outside of the boat and the radio
inside,
now one station I listen to is weak, but if I unplug the antenna and
let the
center pin touch ground of the connector on the radio it comes in
great.
Just curious why it is working this way.
Hi Mike,

You moved the antenna.

Most loss of signal as you describe comes from not being a weak
signal, but the mixture of signals that combine negatively at some
spot due to multiple reflections. When you replaced the line cord as
antenna for this better implementation, you also found that "sour (not
sweet) spot." This can occur for any frequency with the equal
likelihood of reflections combining negatively. Move your antenna a
quarter wave and see what happens.

Your description of your having an aluminum boat almost guarantees a
multitude of RF-bright reflections. At short wavelengths, this also
guarantees many, many regions that will exhibit destructive (as well
as constructive) combinations of those reflections.

Put your antenna as far away from the superstructure or hull as
possible. This will reduce the reflection path differences.

BTW, the mod did cure the computer hash.
Mike
FM has what is called a "full quieting" effect. It would suggest that
your first signal levels were just barely above the level of full
quiet (and perhaps not even that good).

73's
Richard Clark, KB7QHC
Richard, after I read your letter I did a little better checking and
found
my signal is not weak it is to strong, I'm getting interference from
other frequencies.
Also I get stations on the wrong frequency.
I went out and collapsed the antenna to minimum about 1/3 of what it
was and
my problem station is perfect and the other station I listen to is still
good. The local
NPR station isn't good though. But I can download the podcast of Science
Friday :-)
Thanks, Mike
The usual, lousy FM tuner. They don't make'em like they used to. It's the
same with television sets, one large signal and they fall off the rocker.

If you have a radio with a signal strength meter you could notch out a
strong station. But that only works it it's just one and far away from the
NPR frequency. The only other options are to get a better radio, a
directional antenna, or just live with it and use the podcast.

--
Regards, Joerg
This morning I got on the boat and the signal that was improved to good by
shortening the antenna is now bad. 94.5 has interference from 101.1.
Oh well!


You really need a better quality radio and with radios and a lot of
other stuff older = better :-)

I mean, considering what the boat must have cost ...

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

amdx wrote:
"Richard Clark" wrote in message
...
On Fri, 19 Mar 2010 17:42:15 -0500, "amdx" wrote:

Richard, after I read your letter I did a little better checking and
found
my signal is not weak it is to strong, I'm getting interference from other
frequencies.
Also I get stations on the wrong frequency.
I went out and collapsed the antenna to minimum about 1/3 of what it was
and
my problem station is perfect and the other station I listen to is still
good. The local
NPR station isn't good though. But I can download the podcast of Science
Friday :-)
Thanks, Mike
Hi Mike,

Normally, a too strong signal is not a problem with FM as FM literally
locks onto the strongest signal and rejects the competitors. This is
not a characteristic of the RF wave, but rather the modulation
employed.

Collapsing your antenna is the same thing as moving it.

Now, as to your experience of receiving signals on the wrong
frequency, that is a classic situation of image rejection being poor
due to the lack of a tuned front-end (something that dissappeared with
the dinosaurs). If I were to guess on the basis of 40 year old
experience fixing these suckers, your off-frequency signals are
probably shifted by twice the IF frequency of your receiver. The
classical FM IF frequency of 10.7 MHz might apply, but time has
marched on and designers may select their own. This old standard
would argue that you shouldn't experience images except where they
would be out-of-band (the 88-107 band with this IF would force that).
A simple test is to tune into at least two of these off-frequency
stations, note what frequency they should be and subtract the
frequency where they appear. If you are having image issues (no, this
is not a self-help hint), the two or more stations should come up with
the same differences.

If you come up with the same number, AND you have trouble with
interference from adjacent stations (there are guard bands to prevent
this), THEN you have one crappy receiver.

73's
Richard Clark, KB7QHC

The receiver is an undercounter mounting Sony AM/FM, radio with CD.
Nothing great, but Sony ususally does a fair job.
Mike


I have learned not to trust any radio that's newer than 30 years,
whether name-brand or not. And that's from experience. Unless it is from
companies like Icom.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

TerryKing wrote:
The usual solution on boats: Use a decent car radio.. Well shielded,
expects outdoor antenna. Runs on 12Volts... Can be had with CD player,
separate input for your Ipod etc.., good audio power to speakers
etc.... And designed to work inside a metal vehicle....


Best of all, it can be bolted down. That's really important on a boat.
However, many newer car radios (newer as in "last 20-30 years") don't
have very good tuners. Best to get one from the era of Ge-transistors,
those radios were usually good.

Better yet, get an Icom, Yeasu or whatever comms receiver. Most have a
WFM setting. Ok, no stereo sound but one can easily listen to NOAA
radio, ship-to-shore channels and so on.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Joerg wrote:

amdx wrote:
"Joerg" wrote in message
...
amdx wrote:
"Richard Clark" wrote in message
...
On Fri, 19 Mar 2010 15:22:42 -0500, "amdx" wrote:

So I installed the antenna on the outside of the boat and the radio
inside,
now one station I listen to is weak, but if I unplug the antenna and
let the
center pin touch ground of the connector on the radio it comes in
great.
Just curious why it is working this way.
Hi Mike,

You moved the antenna.

Most loss of signal as you describe comes from not being a weak
signal, but the mixture of signals that combine negatively at some
spot due to multiple reflections. When you replaced the line cord as
antenna for this better implementation, you also found that "sour (not
sweet) spot." This can occur for any frequency with the equal
likelihood of reflections combining negatively. Move your antenna a
quarter wave and see what happens.

Your description of your having an aluminum boat almost guarantees a
multitude of RF-bright reflections. At short wavelengths, this also
guarantees many, many regions that will exhibit destructive (as well
as constructive) combinations of those reflections.

Put your antenna as far away from the superstructure or hull as
possible. This will reduce the reflection path differences.

BTW, the mod did cure the computer hash.
Mike
FM has what is called a "full quieting" effect. It would suggest that
your first signal levels were just barely above the level of full
quiet (and perhaps not even that good).

73's
Richard Clark, KB7QHC
Richard, after I read your letter I did a little better checking and
found
my signal is not weak it is to strong, I'm getting interference from
other frequencies.
Also I get stations on the wrong frequency.
I went out and collapsed the antenna to minimum about 1/3 of what it
was and
my problem station is perfect and the other station I listen to is still
good. The local
NPR station isn't good though. But I can download the podcast of Science
Friday :-)
Thanks, Mike
The usual, lousy FM tuner. They don't make'em like they used to. It's the
same with television sets, one large signal and they fall off the rocker.

If you have a radio with a signal strength meter you could notch out a
strong station. But that only works it it's just one and far away from the
NPR frequency. The only other options are to get a better radio, a
directional antenna, or just live with it and use the podcast.

--
Regards, Joerg
This morning I got on the boat and the signal that was improved to good by
shortening the antenna is now bad. 94.5 has interference from 101.1.
Oh well!

You really need a better quality radio and with radios and a lot of
other stuff older = better :-)

I mean, considering what the boat must have cost ...


Or a tuned trap to reduce the signal from that one station.


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

On Mar 20, 8:26*am, Szczepan Bia³ek wrote:
*"Phil Allison" ...





"Richard Clark"

Now, as to your experience of receiving signals on the wrong
frequency, that is a classic situation of image rejection being poor
due to the lack of a tuned front-end (something that dissappeared with
the dinosaurs). *If I were to guess on the basis of 40 year old
experience fixing these suckers, your off-frequency signals are
probably shifted by twice the IF frequency of your receiver. *The
classical FM IF frequency of 10.7 MHz might apply, but time has
marched on and designers may select their own. *This old standard
would argue that you shouldn't experience images except where they
would be out-of-band (the 88-107 band with this IF would force that).

** *Hearing the same FM station at more than one spot is still possible
even with a 10.7 MHz IF frequency - *if the signal is very strong. * The
reason is harmonics of the incoming carrier generated in the RF stage
interacting with harmonics of the local oscillator in the mixer.

It sound like the "Luxemburg Effect". The signal was from the dipole
antenna.
Are now the FM stations which use the dipoles?

Eg:

A 100MHz FM carrier generates a harmonic at 200MHz in the receiver.

When the local oscillator is adjusted to 94.65 MHz, its second harmonic is
189.3 MHz.

The difference frequency is then 10.7 MHz *- *so goes through to the FM
detector.

In this situation, the FM deviation is doubled so the recovered audio will
be distorted on loud passages.

S*

all antennas are dipoles, you just can't always see the other half.
and Luxembourg has nothing to do with it, your silly frequency
doubling notions should be packaged up in art's box and never see the
light of day.