900 kHz Image Problem with the Longwave Bands even on a Grundig G5receiver
 

If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz (1050 kHz to 1419 kHz) the 900 kHz carrier image. Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is


150 kHz = 1050 kHz WVXX -AM
210 kHz = 1110 kHz WYRM-AM
330 kHz = 1230 kHz WJOI -AM
410 kHz = 1310 kHz WGH-AM
450 kHz = 1350 kHz WGPL -AM
500 kHz = 1400 kHz WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

900 kHz Image Problem with the Longwave Bands even on a GrundigG5 receiver
 

On Mar 26, 1:56*pm, gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz * (1050 kHz to 1419 kHz) *the 900 kHz carrier image. * Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. * The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . * * * I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is

150 kHz = 1050 kHz *WVXX -AM
210 kHz = 1110 kHz *WYRM-AM
330 kHz = 1230 kHz *WJOI -AM
410 kHz = 1310 kHz *WGH-AM
450 kHz = 1350 kHz *WGPL -AM
500 kHz = 1400 kHz *WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

You are seeing a problem that is common to many inexpensive radios.
If you tune down 900khz from a strong nighttime station on the 6mhz
band you will hear image signals too. The solution is to pay more for
a better designed radio.

900 kHz Image Problem with the Longwave Bands even on a Grundig G5 receiver
 

What you are seeing are 3rd order intermodulation products that are being
generated in your 1st mixer. If you will notice, the frequencies that you
are hearing the stations on are mathematically related to the station minus
900kHz.
The way that you can eliminate them is to use a low-pass filter that cuts
off at 500kHz at the antenna input of your receiver. Some of today's
receivers use a 1MHz low-pass filter as the first preselector range. Not a
good idea, since in the Chicago area, you can get 3rd order mixing products
from WGN 720 mixing with WBBM 780, with a resultant on 60kHz.
Another example would be WGN 720 mixing with WIND 560. The resultant product
would be 720 - 560, or 220kHz. Please note that the 3rd order IMD products
are not only difference frequencies, but you can also have the sum of the
two frequencies showing up as an upper sideband in addition to the lower
sideband that manifests itself in the LW band.
That other fellow's post about the (2 X 450kHz) image was a good suggestion,
but in this case, you are encountering 3rd order mixing products.
Two solutions...............use band limit filters ahead of the receiver's
front end, or use a mixer that requires a much higher LO injection level. A
diode ring mixer or some kind of FET switching mixer will fill the bill
here. The key is having a high enough LO injection level in this case, so
that the LO is actually turning on and switching the devices in the mixer
instead of the signal that appears at the RF port of the mixer.
This is one of the things that you pay for when you purchase a more
expensive communications receiver. In the old days, this problem wasn't
really an issue, since receivers of that time either used a tracking front
end that had a multiple gang tuning capacitor that would tune the input
circuits as you varied the frequency...........or, they had a separate
preselector control that you would peak to the desired frequency.
I hope this helps.

Pete

"gccradioscience" wrote in message
...

If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz (1050 kHz to 1419 kHz) the 900 kHz carrier image. Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is


150 kHz = 1050 kHz WVXX -AM
210 kHz = 1110 kHz WYRM-AM
330 kHz = 1230 kHz WJOI -AM
410 kHz = 1310 kHz WGH-AM
450 kHz = 1350 kHz WGPL -AM
500 kHz = 1400 kHz WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

900 kHz Image Problem with the Longwave Bands even on a Grundig G5 receiver
 

Radioguy wrote:

On Mar 26, 1:56Â*pm, gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz Â* (1050 kHz to 1419 kHz) Â*the 900 kHz carrier image. Â* Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. Â* The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . Â* Â* Â* I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is

150 kHz = 1050 kHz Â*WVXX -AM
210 kHz = 1110 kHz Â*WYRM-AM
330 kHz = 1230 kHz Â*WJOI -AM
410 kHz = 1310 kHz Â*WGH-AM
450 kHz = 1350 kHz Â*WGPL -AM
500 kHz = 1400 kHz Â*WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

You are seeing a problem that is common to many inexpensive radios.
If you tune down 900khz from a strong nighttime station on the 6mhz
band you will hear image signals too. The solution is to pay more for
a better designed radio.


Problems like this come from two problems. On some radios, the ferrite
antenna used for AM and longwave is not tuned and therefore provides no
selectivity that can provide image rejection. This is combined with first
IF filters that do not have high ultimate rejection.

If ultimate rejection of the first IF is only 30-40 dB, then that is all the
image rejection you will see. (What matters here is the rejection of
signals 900 kHz away from the center of the filter's passband.

900 kHz Image Problem with the Longwave Bands even on a GrundigG5 receiver
 

gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz (1050 kHz to 1419 kHz) the 900 kHz carrier image. Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is


150 kHz = 1050 kHz WVXX -AM
210 kHz = 1110 kHz WYRM-AM
330 kHz = 1230 kHz WJOI -AM
410 kHz = 1310 kHz WGH-AM
450 kHz = 1350 kHz WGPL -AM
500 kHz = 1400 kHz WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.






It's a single-conversion phenomenom usually. Two times the IF, + or -
the FOI.

900 kHz Image Problem with the Longwave Bands even on a GrundigG5 receiver
 

Radioguy wrote:
On Mar 26, 1:56 pm, gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz (1050 kHz to 1419 kHz) the 900 kHz carrier image. Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is

150 kHz = 1050 kHz WVXX -AM
210 kHz = 1110 kHz WYRM-AM
330 kHz = 1230 kHz WJOI -AM
410 kHz = 1310 kHz WGH-AM
450 kHz = 1350 kHz WGPL -AM
500 kHz = 1400 kHz WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

You are seeing a problem that is common to many inexpensive radios.
If you tune down 900khz from a strong nighttime station on the 6mhz
band you will hear image signals too. The solution is to pay more for
a better designed radio.

Or build a preselector for $20

900 kHz Image Problem with the Longwave Bands even on a GrundigG5 receiver
 

On Mar 27, 6:26*am, dave wrote:
Radioguy wrote:
On Mar 26, 1:56 pm, gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz * (1050 kHz to 1419 kHz) *the 900 kHz carrier image. * Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. * The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . * * * I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is

150 kHz = 1050 kHz *WVXX -AM
210 kHz = 1110 kHz *WYRM-AM
330 kHz = 1230 kHz *WJOI -AM
410 kHz = 1310 kHz *WGH-AM
450 kHz = 1350 kHz *WGPL -AM
500 kHz = 1400 kHz *WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

You are seeing a problem that is common to many inexpensive radios.
If you tune down 900khz from a strong nighttime station on the 6mhz
band you will hear image signals too. The solution is to pay more for
a better designed radio.
-
- Or build a preselector for $20
-

GCCRS,

Or simply Buy a Ready-Made one and use it with a
35~60 Foot long Random Wire {Longwire} Antenna

MFJ-956 : Long Wave, AM/BCB Medium Wave and
Shortwave Bands Pre-Selector : 150 kHz ~ 30 MHz
http://www.universal-radio.com/catal...amps/2964.html
http://www.universal-radio.com/catal...s/2964band.jpg

idtars ~ RHF

900 kHz Image Problem with the Longwave Bands even on a GrundigG5 receiver
 

Pete KE9OA wrote:
This can also occur in multiple conversion receivers, depending on the
ultimate rejection of the roofing filters.
In this case, image rejection has nothing to do with it. What is being
experienced are 3rd order IMD products. Do a Google search on 3rd order IMD
products in mixers, and it will become very clear.............

Pete

"dave" wrote in message
...
gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz (1050 kHz to 1419 kHz) the 900 kHz carrier image. Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is


150 kHz = 1050 kHz WVXX -AM
210 kHz = 1110 kHz WYRM-AM
330 kHz = 1230 kHz WJOI -AM
410 kHz = 1310 kHz WGH-AM
450 kHz = 1350 kHz WGPL -AM
500 kHz = 1400 kHz WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.






It's a single-conversion phenomenom usually. Two times the IF, + or - the
FOI.


Sir, I am a professional frequency coordinator and need no schooling on
3rd order IMD.

My trusty Philips AE-3805 (Sangean innards) has a big gap in coverage
(7300 kHz-9.500 kHz) that can largely be overcome by tuning 900 kHz
either side of the frequency of interest. 900 kHz is twice the IF.
This is the exact mathematical relationship described in the original
post. I suspect we are arguing over word usage, not the science.

A mixer simply produces a desired intermod product.

One of the few positives of a dual-conversion receiver is their ability
to keep the first image out of the downstream bandpass.

900 kHz Image Problem with the Longwave Bands even on a GrundigG5 receiver
 

On Mar 28, 10:12 am, "Pete KE9OA" wrote:
I have been an RF Engineer, specializing in low level RF design since 1992.
Why are we having this conversation in the first place? The reason for my
post was to clarify which mechanism was responsible for the manifestation
that the original poster was experiencing.
To glibly state that this was an image problem is clearly misinformation.
Too much of that going around these days. Mini-Circuits has a very good
tutorial on this subject on their website.
Now, what does being a professional frequency coordinator have to do with RF
engineering principles, specifically, small signal RF design? I have no
doubt that you have experience in this area, and the 900kHz frequency that
the original poster mentioned can confuse the issue if is is assumed that
the receiver has a 450kHz I.F. which it may or may not have..........many
receivers over the years used a 455kHz I.F. which would place the primary
image 910kHz below the actual frequency. A simple analysis of this problem
clearly shows that it is a 3rd order IMD problem.
For other folks out there that may be interested, 3rd order intermodulation
products don't exclusively occur only in mixers.......they can occur in any
nonlinear system, such as oxidized electrical connectors, saturated ferrite
cores in front ends of receivers, bandpass filter switching diodes, crystal
filters, and AGC diodes. It can also occur in rusty rain gutters, or
anywhere else that galvanic corrosion can occur.
I am sorry if you took offense at my post, but next to doing everything to
preserving life, truth is the most important thing in this world.........
thus, the reason for my reply to the original poster.

Pete

It was something that I needed to address that I have been
experiencing in most of my radio receivers that engineers in China
have
trouble fixing. You see, I have a shortwave radio receiver that has
the long wave bands that cover 144 kHz to 353 kHz without no
problems. When I received the G5, this was something that I thought
would replace the Yacht Boy 400 Pro Edition, but it did not
make no improvement for me the LW DXer. I have owned previously
the Sangean (Radio Shack) DX 380, 392, and 390 and since
you mentioned you've been an RF engineer since 1992, well I have owned
the DX-380 since 1992. I have dealt with this problem
even when I used a longwire antenna. I thought hey its just another
radio station on 150 kHz thats rebroadcasting a signal, but
now since I have owned the YB-400 PE radio the station does not appear
on the YB-400PE. It seems that the YB-400PE
has its own LW tuned circuit seperate from the others like AM and SW.
I see why the radio was set at 144 kHz to 353 kHz
They could of extended the coverage to 519 kHz and keep the same tuned
circuit.

You see, if you lived in Europe and you have received stations on LW
from the AM broadcasters you probably have lots of
overloading along with LW and MW radio stations cause of the 900 kHz
signal being such a pain to get rid of. Here do
the math

Above all, this problem has been an issue not just on LW but on AM (MW
as well trying to receive a station on 550 kHz
when you got another station from the 1450 kHz - 900 kHz = 550 kHz
being a problem. This is one reason I had to
one day take some radios apart and get them aligned the best as I can,
good and some bad. I feel that we need to
get this problem fixed on new radios. And about mini circuits
Grundig does not use those parts anymore. So yes I
may have to buy another receiver since Grundig is cheap garbage and
lost its German quality.

Anyways, I got myself a loop antenna and coupler built to reject the
intermod garbage and the signal from 1050 kHz
is gone from 150 kHz. So everything is fine as long as you use a
preselector or a 500 kHz low pass filter. Still I
do appreciate spending $149.99 on something thats suppose to be crap
on LW and gold on AM and SW. Engineers,
give LW a chance for NDB DXers and Transalantic LW DXers. One day
I am going to be releasing information about
transatlantic DXing and form a forum about this subject. This
spring LW transatlantic DX is possible and I have the
cassette tapes to prove and the minidiscs. Thank you very much.


49N4AE and gccengineering





"dave" wrote in message

...

Pete KE9OA wrote:
This can also occur in multiple conversion receivers, depending on the
ultimate rejection of the roofing filters.
In this case, image rejection has nothing to do with it. What is being
experienced are 3rd order IMD products. Do a Google search on 3rd order
IMD products in mixers, and it will become very clear.............

Pete

"dave" wrote in message
...
gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz (1050 kHz to 1419 kHz) the 900 kHz carrier image. Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is

150 kHz = 1050 kHz WVXX -AM
210 kHz = 1110 kHz WYRM-AM
330 kHz = 1230 kHz WJOI -AM
410 kHz = 1310 kHz WGH-AM
450 kHz = 1350 kHz WGPL -AM
500 kHz = 1400 kHz WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

It's a single-conversion phenomenom usually. Two times the IF, + or -
the FOI.

Sir, I am a professional frequency coordinator and need no schooling on
3rd order IMD.

My trusty Philips AE-3805 (Sangean innards) has a big gap in coverage
(7300 kHz-9.500 kHz) that can largely be overcome by tuning 900 kHz either
side of the frequency of interest. 900 kHz is twice the IF. This is the
exact mathematical relationship described in the original post. I suspect
we are arguing over word usage, not the science.

A mixer simply produces a desired intermod product.

One of the few positives of a dual-conversion receiver is their ability to
keep the first image out of the downstream bandpass.

900 kHz Image Problem with the Longwave Bands even on a GrundigG5 receiver
 

On Mar 28, 7:04 am, RHF wrote:
On Mar 27, 6:26 am, dave wrote:

Radioguy wrote:
On Mar 26, 1:56 pm, gccradioscience wrote:
If you live in a city area or some rural area with a real strong AM
station its likely it will be found on the longwave bands from 150 to
519 kHz (1050 kHz to 1419 kHz) the 900 kHz carrier image. Please
understand that this station is not a real longwave radio station.
Its a image from the broadcast station when the station is strong
enough to bleed on other longwave frequencies. The radios that I
have is the DX-380, DX-390, DX-392 and the yes the new Grundig G5.
It has do something with the dual conversion circuitry . I am
hoping that manufactuers, hobbyists, and technicians will use the 900
kHz formula to see other image stations to show that these AM stations
should not be on the LW bands.

Desired AM Station (kHz) - 900 kHz = Image Station

The images I am getting here locally in Virginia Beach, VA on LW is

150 kHz = 1050 kHz WVXX -AM
210 kHz = 1110 kHz WYRM-AM
330 kHz = 1230 kHz WJOI -AM
410 kHz = 1310 kHz WGH-AM
450 kHz = 1350 kHz WGPL -AM
500 kHz = 1400 kHz WPCE-AM

AM Band Images that are annoying

550 kHz = 1450 kHz
650 kHz = 1550 kHz

Adam E.

You are seeing a problem that is common to many inexpensive radios.
If you tune down 900khz from a strong nighttime station on the 6mhz
band you will hear image signals too. The solution is to pay more for
a better designed radio.

-
- Or build a preselector for $20
-

GCCRS,

Or simply Buy a Ready-Made one and use it with a
35~60 Foot long Random Wire {Longwire} Antenna

MFJ-956 : Long Wave, AM/BCB Medium Wave and
Shortwave Bands Pre-Selector : 150 kHz ~ 30 MHzhttp://www.universal-radio.com/catalog/preamps/2964.htmlhttp://www.universal-radio.com/catalog/preamps/2964band.jpg

idtars ~ RHF
.

Why should I buy something that cost $60.00 for longwire I cannot not
even put up in an apartment????? RHF, I live in a apartment
for now best thing I was going to do with the preselector is use it
with a KA-35 antenna to eliminate images. I don't have no
way for a good alternative to an RF ground. Plus I am not on the
second floor elevation for to use outdoor active antennas. If
placed outdoor antennas they would be vandalized.

gccengineering