"R.F. Collins" wrote in message
...
This is a common problem with single conversion. If your front end is
too sensitive as on some Grundigs, you can overload the IF and get a
mixing product generated at 2 x IF frequency (455kHz) = 910 kHz. This
gives you the image at 910kHz above and below the actual frequency.
This is why more expensive radios are dual and triple conversion.

Jim



Images have nothing to do with overloading.

I read the linked web page and it says:

"Earlier in the year 2003, we made the mistake of taking seriously some
very enthusiastic posts on rec.radio.shortwave -- "the trailer-park
shortwave newsgroup" according to one of our acquaintances -- by
dim-wits who were overjoyed with a ten-dollar multiband radio with the
unexpected brand name "Bell & Howell""

"dim-wits"? "the trailer-park shortwave newsgroup" ?

As far as images go, there's only one. The signal mixes with the local
oscillator. Either the sum or difference signal is the desired signal.
The other signal is the image.

There may be other false signals from oscillator harmonics. But these
will be totally out of band, even VHF signals.

The page's insults and cheap shots on cheap radios continue:

http://www.home.earthlink.net/~srw-s...rundig-100.htm

It's just one crackpot's opinion, but I find insult humor unimaginative.

There's is a another image at the bottom of the page:

"by Steve Waldee, retired broadcast consultant, AM-FM transmitter
engineer, and audio specialist;"

If the original poster is still reading this, I'll suggest the problem
with FM DXing has little to do with PLLs and more to do with stereo. It
takes a lot more signal to get adaquate quieting with FM stereo.

I used to receive a Green Bay public radio station from Chicago with a
DX-440 on a semiregular basis. No more, the local stations around 88 -
89 Mhz are broadcasting almost full time now.

All the radios on the webpage, aside from the old Grundig, were bottom
end in both price and performance. There might be a pattern there.

Frank "trailer park" Dresser

"Richard" wrote in message ...
"Ian Smith" wrote in message
...
"Richard" wrote in message
...
http://www.home.earthlink.net/%7Esrw...rundig-100.htm

"FM? Whazzat?


snipped

I found FM performance to be excellent from my old Grundig
Satellit 1400 (c.1983). Got many a continental European from up here
in Scotland, during Sporadic 'E' lifts in the summer.

--
Ian Smith, Renfrew, Scotland. 55.868733°N 4.399517°W, 7m asl

Yep.

Reading some comments about the Sony ICFM33RDS, and the bit I text I quoted
to start the thread, I've somehow got the impression that many modern
portable PL sets are "rap" with a capital "C"on FM. Radio Shack DX-397 and
the Sony 7600GR quoted as not being that good. Not sure how expensive these
radios are, but, the ICFM33RDS is only£35, so maybe poorish FM performance
is to be expected for this set. If I pay say £80 or £100 for a PLL radio,
maybe FM performance would get to as good as the old Grundig. I don't want
the RX to be deaf on FM, or have images from localstations all over the
band.

You've made a classic mistake, that because shortwave receivers carry
relatively high price tags, that they then offer superior FM broadcast
reception.

In the first place, a higher price tag may reflect the limited interest
in shortwave. If you have to design something out of the ordinary,
it will cost more than an average design. And if fewer people are
interested, then you have to recoup the cost by a higher price.

But more important, any design concerns will be put into what
the radio is intended for, ie shortwave. And for anyone
who understands radio design, there is virtually no overlap
between what's good for an FM broadcast receiver in the 88 to 108MHz
range, and a shortwave receiver. One is for FM reception, the other
is for AM reception. One is for wideband signals relative far
apart in a part of the spectrum that is at least three times the
upper frequency of the other, while the other is for narrow signals
with narrow spacing between channels and still at a relatively low
frequency. Shortwave and the FM broadcast band are not close
together. All of this means that there is very little where
the designs overlap. What you are buying is a shortwave radio
(and maybe/likely that circuitry is used to tune the AM broadcast
band since the frequencies are adjacent and the mode and signal
bandwidth would be the same) and an FM broadcast radio in
the same box. Traditionally, shortwave radios did not include
an FM band, with a few exceptions; it changed as small shortwave
receivers from Asian companies became the norm. In other words,
the FM BCB section is thrown in as a marketing matter.

Since that FM section does nothing for the main selling point
of the radio, that shortwave reception, then any money put
into that section will take away from the design of the
shortwave section. So realistically, one might as well
put in as cheap an FM section as possible, since it's just
added circuitry, and one can so very easily pick the
same sort of circuit that is in any average FM radio.

Buying a shortwave radio will not automatically give better
FM reception, and depending on specific design, it may be
inferior to what you could find elsewhere.

Car radios are often good, because they require sensitivity yet
also the ability to withstand strong signals. FM reception is
a key part of the design, so it gets the attention. I have various
digitally tuned Delco car radios around the house, and they are
the best FM radios I've ever had. I have no idea of the absolute
performance, just that in my passing contact with relatively low
end receivers the FM section is great. On FM, the PLL is well
designed so I don't get spurious responses. The sensitivity seems
good, yet it doesn't overload. It is rare to find a station where
it doesn't belong. Selectivity is pretty good. The other day,
conditions were great and a non-local station was booming in.
It's adjacent to another non-local station but which comes in
regular (though it's strength varies). There was no problem
that day from adjacent channel interference.

FM broadcast receivers intended for good performance will also
be good contenders. Note that you have to go for something
with a beyond average design. Just as in those shortwave radios,
FM (and AM even moreso) are considered not so important in a "hifi"
situation, so they put little money into the tuner section. You would
have lousy FM radios in consumer equipment twenty and thirty years
ago, and you have it today, whether they are digitally tuned or
not. Such receivers are intended for local reception (who would
be interested in that noisy signal from a bit further out, especially
since the ads and traffic reports aren't local?) so weak signal
reception is not a concern in the design. And as with a lot of
FM receivers, they tend to be too sensitive, but that never becomes
useful for weak signal reception because that sensitivity also
means a tendency to overload on the local and strong signals.

Michael

In article , Richard says...

http://www.home.earthlink.net/%7Esrw...rundig-100.htm

"FM? Whazzat?

After 25+ years in that business, we no longer listen to any FM
broadcasting. Why; when we have 9,000 classical CDs, an eight-foot grand
piano, a Yamaha Clavinova, and a harpsichord?! In order to be useful to
readers who might, however, want to know about the FM performance, we did
tune to the band and TRY to pick up a station. Surely the only one we would
ever want to hear, from our home in San Jose, would be classical KDFC,
102.1, in San Francisco. It was absolutely unreceivable. Ditto via the Radio
Shack DX-397; and there is almost no trace of it either using the Sony
7600GR.

But a late-60's Grundig Music-Boy germanium transistor radio (original
manual at left) picks it up quite clearly! This shows the sad deterioration
of FM radio design over the decades; the old discrete-component radio, with
excellent selectivity, could pull KDFC out of the hiss and mush; the new
ones, with their short whip aerials and IC cookbook designs, just did not
have the power and discrimination."

Apparently, there are several kinds of FM signals being used. Vertical,
horizontal, and circular polarized signals. Don't ask my for a technical
explanation. I'm wondering if an FM stations signal type can affect how well
you can get the station with a generic FM radio.




I'm wanting a pockety sized PLL radio that will, on FM performance, actually
equal, at least an, old Grundig radio for sensitivity, cross-modulation and
image rejection!


I have the same 'want' as you....pocket sized PLL FM that's designed from the
get-go as a good FM receiver. I just prefer FM to AM and don't consider myself
a DX'er in the traditional sense. I have a Sony ICF 2010, 7600GR, RS DX-396,
DX-402, Panasonic RF B300. They all PALE in comparison to my Superadio II for
FM performance. Not digital, no PLL, no memory presets but it brings in FM
stations that the others can't hear.

I guess when all is said and done, a "good" analog radio is hard to beat,
especially when it's an older model. Amazingly enough, my BEST FM receiver is
an AM/FM/stereo amplifier from Radio Shack that was made in 1985. It picks up
the hard to get FM stations WITHOUT AN ANTENNA. Zero...nada...zippo connected
to the FM antenna lugs. Before I got my Superadio, I stopped BARELY receiving
my favorite FM stations on my 2010. I actually thought the station had gone off
the air (I even sent an email to the station asking when they'd return to normal
broadcasting...never got a reply). I finally turned on that old Radioshack amp,
and the station came in like it was next door.

I've taken out of the attic an old car AM/FM/FM stereo cassette digital radio
from Panasonic that's at least 25 years old. My plan is to put it on batteries
to see how well it works as a desktop. Unfortunately, at 5 pounds (without
batteries and speaker), it won't be 'pocket sized'.

elfa

BTW, I'm also bay area....30 miles north of SF. Just tried your KDFC and got it
fairly good on the Sony 2010. Tried it on the Superadio and it boomed right in,
crystal clear. Try my favorite SF FM station....KKSF...103.7....light jazz.

"elfa" wrote in message
...

Apparently, there are several kinds of FM signals being used. Vertical,
horizontal, and circular polarized signals. Don't ask my for a technical
explanation. I'm wondering if an FM stations signal type can affect how
well
you can get the station with a generic FM radio.


Nearly all FM's now use circular polarization for their main antennas.
Circular polarization is less efficient, power wise, than a simple dipole,
but they do tend to penetrate better into crowded urban areas than either
horizontal or vertical polarization.

In article , Brenda Ann says...


"elfa" wrote in message
...

Apparently, there are several kinds of FM signals being used. Vertical,
horizontal, and circular polarized signals. Don't ask my for a technical
explanation. I'm wondering if an FM stations signal type can affect how
well
you can get the station with a generic FM radio.


Nearly all FM's now use circular polarization for their main antennas.
Circular polarization is less efficient, power wise, than a simple dipole,
but they do tend to penetrate better into crowded urban areas than either
horizontal or vertical polarization.



Thanks Brenda Ann....

I know I can rely on you to come up with an explanation that makes sense.

elfa

Michael Black wrote:

You've made a classic mistake, that because shortwave receivers carry
relatively high price tags, that they then offer superior FM broadcast
reception.

In the first place, a higher price tag may reflect the limited interest
in shortwave. If you have to design something out of the ordinary,
it will cost more than an average design. And if fewer people are
interested, then you have to recoup the cost by a higher price.

But more important, any design concerns will be put into what
the radio is intended for, ie shortwave. And for anyone
who understands radio design, there is virtually no overlap
between what's good for an FM broadcast receiver in the 88 to 108MHz
range, and a shortwave receiver. One is for FM reception, the other
is for AM reception. One is for wideband signals relative far
apart in a part of the spectrum that is at least three times the
upper frequency of the other, while the other is for narrow signals
with narrow spacing between channels and still at a relatively low
frequency. Shortwave and the FM broadcast band are not close
together. All of this means that there is very little where
the designs overlap. What you are buying is a shortwave radio
(and maybe/likely that circuitry is used to tune the AM broadcast
band since the frequencies are adjacent and the mode and signal
bandwidth would be the same) and an FM broadcast radio in
the same box. Traditionally, shortwave radios did not include
an FM band, with a few exceptions; it changed as small shortwave
receivers from Asian companies became the norm. In other words,
the FM BCB section is thrown in as a marketing matter.

Since that FM section does nothing for the main selling point
of the radio, that shortwave reception, then any money put
into that section will take away from the design of the
shortwave section. So realistically, one might as well
put in as cheap an FM section as possible, since it's just
added circuitry, and one can so very easily pick the
same sort of circuit that is in any average FM radio.

Buying a shortwave radio will not automatically give better
FM reception, and depending on specific design, it may be
inferior to what you could find elsewhere.

Car radios are often good, because they require sensitivity yet
also the ability to withstand strong signals. FM reception is
a key part of the design, so it gets the attention. I have various
digitally tuned Delco car radios around the house, and they are
the best FM radios I've ever had. I have no idea of the absolute
performance, just that in my passing contact with relatively low
end receivers the FM section is great. On FM, the PLL is well
designed so I don't get spurious responses. The sensitivity seems
good, yet it doesn't overload. It is rare to find a station where
it doesn't belong. Selectivity is pretty good. The other day,
conditions were great and a non-local station was booming in.
It's adjacent to another non-local station but which comes in
regular (though it's strength varies). There was no problem
that day from adjacent channel interference.

FM broadcast receivers intended for good performance will also
be good contenders. Note that you have to go for something
with a beyond average design. Just as in those shortwave radios,
FM (and AM even moreso) are considered not so important in a "hifi"
situation, so they put little money into the tuner section. You would
have lousy FM radios in consumer equipment twenty and thirty years
ago, and you have it today, whether they are digitally tuned or
not. Such receivers are intended for local reception (who would
be interested in that noisy signal from a bit further out, especially
since the ads and traffic reports aren't local?) so weak signal
reception is not a concern in the design. And as with a lot of
FM receivers, they tend to be too sensitive, but that never becomes
useful for weak signal reception because that sensitivity also
means a tendency to overload on the local and strong signals.

Michael

Points:

I think some of the the points you raise are probably applicable to any
radio that is not FM only.

I do not think I can buy a PLL FM only RX, and besides I'd want AM broadcast
band at least, in addition.

One would imagine a portable that was just FM and broadcast band (no
shortwave) the money would be spent on better FM performance. But, I
suspect that in many cases that might not be the case.

Not sure whether poor FM perfornance is related to PLL. Maybe not, but
generally to use of IC's.

Maybe biggest reason that the the ICFM33RDS FM performance at FM might not
be that good is because it's an inexpensive set. Maybe.

Maybe no modern worldband RX will be that good on FM. Then again maybe some
are at least as good as (say) an old Grundig. Perhaps the likely candidates
would be FM/Broadcast band ony RX. Or the more expensive worldband. As
usual, you get what you pay for.

Bottom line for me I guess is that I'd like to feel that if I went ahead an
spent say £80 to £100 on a PLL radio, that FM performance would be as good
as an old Grundig. Worldband RX or no. Or is it the case that I could
spend much more than this and still not get the old Grundig performance. If
that was the case, surely that would say something about modern FM design?

I could end up with two radios, a FM/Broadcast band RX. Plus a worldband
set.

That article really does scathe rec.radio,shortwave"!! Ha!! That was just
unfortunate, I was not concentrating on that part of the article. Just came
with the bit I was interested in.:c)

"Richard" wrote in message ...
http://www.home.earthlink.net/%7Esrw...rundig-100.htm

"FM? Whazzat?

After 25+ years in that business, we no longer listen to any FM
broadcasting. Why; when we have 9,000 classical CDs, an eight-foot grand
piano, a Yamaha Clavinova, and a harpsichord?! In order to be useful to
readers who might, however, want to know about the FM performance, we did
tune to the band and TRY to pick up a station. Surely the only one we would
ever want to hear, from our home in San Jose, would be classical KDFC,
102.1, in San Francisco. It was absolutely unreceivable. Ditto via the Radio
Shack DX-397; and there is almost no trace of it either using the Sony
7600GR.

But a late-60's Grundig Music-Boy germanium transistor radio (original
manual at left) picks it up quite clearly! This shows the sad deterioration
of FM radio design over the decades; the old discrete-component radio, with
excellent selectivity, could pull KDFC out of the hiss and mush; the new
ones, with their short whip aerials and IC cookbook designs, just did not
have the power and discrimination."


I'm wanting a pockety sized PLL radio that will, on FM performance, actually
equal, at least an, old Grundig radio for sensitivity, cross-modulation and
image rejection!

While it is certainly unfortunate that KDFC is the only classical
station left in the SF Bay Area, you overlook (perhaps deliberately?)
a few of the root causes of this problem: More stations jammed onto
the band as close together as permitted, most of them using higher
power than the good old days, and the fact that stereo requires a
better signal to get through.

You really cannot blame the receivers for this mess.

In article ,=20
says...
Michael Black wrote:
=20
You've made a classic mistake, that because shortwave receivers carry
relatively high price tags, that they then offer superior FM broadcast
reception.

In the first place, a higher price tag may reflect the limited interest
in shortwave. If you have to design something out of the ordinary,
it will cost more than an average design. And if fewer people are
interested, then you have to recoup the cost by a higher price.

But more important, any design concerns will be put into what
the radio is intended for, ie shortwave. And for anyone
who understands radio design, there is virtually no overlap
between what's good for an FM broadcast receiver in the 88 to 108MHz
range, and a shortwave receiver. One is for FM reception, the other
is for AM reception. One is for wideband signals relative far
apart in a part of the spectrum that is at least three times the
upper frequency of the other, while the other is for narrow signals
with narrow spacing between channels and still at a relatively low
frequency. Shortwave and the FM broadcast band are not close
together. All of this means that there is very little where
the designs overlap. What you are buying is a shortwave radio
(and maybe/likely that circuitry is used to tune the AM broadcast
band since the frequencies are adjacent and the mode and signal
bandwidth would be the same) and an FM broadcast radio in
the same box. Traditionally, shortwave radios did not include
an FM band, with a few exceptions; it changed as small shortwave
receivers from Asian companies became the norm. In other words,
the FM BCB section is thrown in as a marketing matter.

Since that FM section does nothing for the main selling point
of the radio, that shortwave reception, then any money put
into that section will take away from the design of the
shortwave section. So realistically, one might as well
put in as cheap an FM section as possible, since it's just
added circuitry, and one can so very easily pick the
same sort of circuit that is in any average FM radio.

Buying a shortwave radio will not automatically give better
FM reception, and depending on specific design, it may be
inferior to what you could find elsewhere.

Car radios are often good, because they require sensitivity yet
also the ability to withstand strong signals. FM reception is
a key part of the design, so it gets the attention. I have various
digitally tuned Delco car radios around the house, and they are
the best FM radios I've ever had. I have no idea of the absolute
performance, just that in my passing contact with relatively low
end receivers the FM section is great. On FM, the PLL is well
designed so I don't get spurious responses. The sensitivity seems
good, yet it doesn't overload. It is rare to find a station where
it doesn't belong. Selectivity is pretty good. The other day,
conditions were great and a non-local station was booming in.
It's adjacent to another non-local station but which comes in
regular (though it's strength varies). There was no problem
that day from adjacent channel interference.

FM broadcast receivers intended for good performance will also
be good contenders. Note that you have to go for something
with a beyond average design. Just as in those shortwave radios,
FM (and AM even moreso) are considered not so important in a "hifi"
situation, so they put little money into the tuner section. You would
have lousy FM radios in consumer equipment twenty and thirty years
ago, and you have it today, whether they are digitally tuned or
not. Such receivers are intended for local reception (who would
be interested in that noisy signal from a bit further out, especially
since the ads and traffic reports aren't local?) so weak signal
reception is not a concern in the design. And as with a lot of
FM receivers, they tend to be too sensitive, but that never becomes
useful for weak signal reception because that sensitivity also
means a tendency to overload on the local and strong signals.

Michael
=20
Points:
=20
I think some of the the points you raise are probably applicable to any
radio that is not FM only.
=20
I do not think I can buy a PLL FM only RX, and besides I'd want AM broadc=
ast
band at least, in addition.
=20
One would imagine a portable that was just FM and broadcast band (no
shortwave) the money would be spent on better FM performance. But, I
suspect that in many cases that might not be the case.
=20
Not sure whether poor FM perfornance is related to PLL. Maybe not, but
generally to use of IC's.
=20
Maybe biggest reason that the the ICFM33RDS FM performance at FM might no=
t
be that good is because it's an inexpensive set. Maybe.
=20
Maybe no modern worldband RX will be that good on FM. Then again maybe so=
me
are at least as good as (say) an old Grundig. Perhaps the likely candida=
tes
would be FM/Broadcast band ony RX. Or the more expensive worldband. As
usual, you get what you pay for.
=20
Bottom line for me I guess is that I'd like to feel that if I went ahead=
an
spent say =A380 to =A3100 on a PLL radio, that FM performance would be as=
good
as an old Grundig. Worldband RX or no. Or is it the case that I could
spend much more than this and still not get the old Grundig performance. =
If
that was the case, surely that would say something about modern FM design=
?
=20
I could end up with two radios, a FM/Broadcast band RX. Plus a worldband
set.
=20
That article really does scathe rec.radio,shortwave"!! Ha!! That was jus=
t
unfortunate, I was not concentrating on that part of the article. Just ca=
me
with the bit I was interested in.:c)
=20
=20
=20

My Panasonic RF-2200 was fantastic on FM, I could hear stations 50+=20
miles away on it, and it actually sounded good too. The next best one I=20
ever had was an old Delco car radio, with the "wonderbar" seek deal that=20
I bought at a garage sale for 10 bucks. I ran it off a 12V power supply.

I had it for about 20 years, then it suddenly died without warning. It=20
was playing away, I went to get something to snack on, and when I came=20
back it was sizzling away. It really smoked itself. I ended up tossing=20
it out in the yard so it wouldn't stink the place up.=20

I miss that thing.

BDK

Another effect is from the quality and expertise of the broadcast engineers
for various radio stations.

A free-lance radio engineer named Fulgham used to tweak several of the
stations in the Jackson, Mississippi area (could be he still does -- I've
lost track of him).

He was the best I've ever seen. Driving up from the New Orleans area, the
difference in audio quality of some the Jackson stations was noticably
several notches above the stations I listened to in New Orleans. It would
have you thinking "I didn't know my car stereo could sound that good."

-- Stinger

"elfa" wrote in message
...
In article , Brenda Ann says...


"elfa" wrote in message
...

Apparently, there are several kinds of FM signals being used.
Vertical,
horizontal, and circular polarized signals. Don't ask my for a
technical
explanation. I'm wondering if an FM stations signal type can affect
how
well
you can get the station with a generic FM radio.


Nearly all FM's now use circular polarization for their main antennas.
Circular polarization is less efficient, power wise, than a simple
dipole,
but they do tend to penetrate better into crowded urban areas than either
horizontal or vertical polarization.



Thanks Brenda Ann....

I know I can rely on you to come up with an explanation that makes sense.

elfa

"Richard" wrote in message
...


Yep.

Reading some comments about the Sony ICFM33RDS, and the bit I text I
quoted
to start the thread, I've somehow got the impression that many modern
portable PL sets are "rap" with a capital "C"on FM. Radio Shack DX-397
and
the Sony 7600GR quoted as not being that good. Not sure how expensive
these
radios are, but, the ICFM33RDS is only£35, so maybe poorish FM
performance
is to be expected for this set. If I pay say £80 or £100 for a PLL
radio,
maybe FM performance would get to as good as the old Grundig. I don't
want
the RX to be deaf on FM, or have images from localstations all over
the
band.

My DX 440 is a PLL portable and it's a good FM DXer, although I rarely
get to FM DX due to the crowed frequencies here. I was picking up a
small station, maybe 5kW or less, almost 200 miles away when conditions
were good.

Shirt pocket portables have some problems the larger portables don't.
Most small portables use the headphone cord as an antenna. The antenna
may be off it's ideal length. Stretching the cord out straight makes it
a better antenna and a poorer headphone cord.

Small portables have to use small batteries, so power consumption
becomes an important issue. It's a bit of an oversimplification, but a
RF stage which operates a high power is less prone to overloading than a
RF stage which operates on minimal power. The power consumption issue
becomes more important on radios which use power hungry PLL circuits.
So I suppose small PLL radios might starve the RF amp to preserve the
batteries. But that's just speculation.

I wonder then if I need double conversion on FM.I bet ICFM33RDS is not
double. Thats actually just a two band RX. I probably should spend a
bit
more and go for worldband. I vacillate between worldband and not
worldband.
:c)


The normal 10.7 Mhz IF is OK. You'll get an extra set of images with
each conversion. A poorly done double conversion radio is worse than a
single conversion radio.

You might want to consider radios larger than shirt pocket size. In my
expirence, the larger portables are the better performers.





Frank Dresser