On Mar 28, 5:26 pm, gccradioscience wrote:
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

Also I used to live in a one floor house with a huge yard to put up
antennas now I have moved to an apartment. My new
longwave antenna is a huge wooden frame wrapped with 5 turns of wire
and I had to modify the longwave coupler with a
extra set of turns of wire to couple the loop to the coupler then the
main wire coupler connects to the radio with a mono
to stereo connector. I will soon share this with others and form a
blog about this apartment LW antenna remedy. I will
also add new pictures of the loop antenna when I get some batteries
for my camera to show this remarkable design. Please
understand that if you have radios with the antenna jack that accepts
50 ohms to 75 ohms impedance some radios with
jacks have connectors that are stereo like (RIGHT) for MW/LW and (LEFT
(SW) you can use a mono to stereo adapter
as well to connect your loop antennas to the radios jack. Catalog
Number 274-374 I did this with the Terk AM Advantage
loop antenna, which helped with interference and not coupling the loop
antenna to the radio. This connector combines the
mono signal and converts it to a stereo signal and reaches the right
connection lug for the MW/LW antenna terminal.










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.

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

"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.


Like I said, it's semantics. The mixer produces two 3rd order products.
One you want and one you call distortion.

Radioguy wrote:
On Mar 27, 9:24 am, dave wrote:
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.- Hide quoted text -

- Show quoted text -

And the owner of that inexpensive radio has a couple of options:

1. Live with the repeats and realize that Radio Havana will likely
not recognize a DX catch on 5100 khz. Owners of most inexpensive
radios just ignore the stuff that doessn't make much sense. My Degen
DE1103 shows repeats of strong stations 900 khz down (2x the IF).

2. Buy a better receiver.

Or an MFJ-956

gccradioscience wrote:
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

MFJ makes a combination active antenna/amplifier/preselector that may be
perfect for you. I forget the model #.

Telamon wrote:


Like I said, it's semantics. The mixer produces two 3rd order products.
One you want and one you call distortion.

Please give an example where you want 3rd order products.


In a mixer

JC wrote:
Telamon wrote:

Like I said, it's semantics. The mixer produces two 3rd order products.
One you want and one you call distortion.

Please give an example where you want 3rd order products.


In a mixer

On my doorstep before I place a fourth order.

--
One meter, to within 0.0125% accuracy (off by just under .005 inches):
Three feet
Three inches
Three eights of an inch

I know what you meain.............gone are the days of tracking front ends,
or tunable preselectors that are integrated within the receiver itself.
I have an old Grundig Satellit 210 and Satellit 3400. Both of those units
use Variometer tracking for the lower single conversion bands, while the
dual conversion SW ranges use a 3-gang tuning capacitor. Even the trimmer
capacitors are high stability ceramic types that you typically see in
Hewlett Packard test equipment. Very good long term stability.
Upconversion types of front ends with input bandpass filters are fine, as
long as PIN diodes or relays are used for input filter
switching.............and as long as the 1st mixer has good multitone
characteristics. It is almost as if somebody forgot how to use good quality
components. With the price of the SD5000 series of Quad FET mixers down to
the under 4 dollar range, there isn't much of an excuse to not be using them
in new designs that are selling for the 200 dollar plus range.
Mini-Circuits even has the LAVI-XXX series of mixers that have an IP3 in the
+40dBm range. I characterized some of these devices when I was working as a
consultant at Motorola a couple of years ago. These things only get better
as time goes on.
Interesting post!

Pete

"gccradioscience" wrote in message
...
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.

I agree with the dual conversion approach. If a high enough 1st I.F. is
used, a 33MHz low-pass filter can eliminate that upper sideband image
response from the 1st mixer.
There is at least one mixer spur program available as a free download from
RF Cafe. It is an older one called RF Workbence.
It is interesting to look at a spur chart, and see how high-side injection
generally has fewer in-band spurs than low-side injection. I
know.............there are some rare exceptions!

Pete

"gccradioscience" wrote in message
...
On Mar 28, 5:26 pm, gccradioscience wrote:
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

Also I used to live in a one floor house with a huge yard to put up
antennas now I have moved to an apartment. My new
longwave antenna is a huge wooden frame wrapped with 5 turns of wire
and I had to modify the longwave coupler with a
extra set of turns of wire to couple the loop to the coupler then the
main wire coupler connects to the radio with a mono
to stereo connector. I will soon share this with others and form a
blog about this apartment LW antenna remedy. I will
also add new pictures of the loop antenna when I get some batteries
for my camera to show this remarkable design. Please
understand that if you have radios with the antenna jack that accepts
50 ohms to 75 ohms impedance some radios with
jacks have connectors that are stereo like (RIGHT) for MW/LW and (LEFT
(SW) you can use a mono to stereo adapter
as well to connect your loop antennas to the radios jack. Catalog
Number 274-374 I did this with the Terk AM Advantage
loop antenna, which helped with interference and not coupling the loop
antenna to the radio. This connector combines the
mono signal and converts it to a stereo signal and reaches the right
connection lug for the MW/LW antenna terminal.










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.

You NEVER choose a 3rd order product as the desired signal. You choose
either the upper sideband or the lower sideband output of the
mixer.........the undesired sideband is commonly called the image. 3rd order
products are a different story......it is not a matter of semantics in this
case.

Pete

"dave" wrote in message
...
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

"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.


Like I said, it's semantics. The mixer produces two 3rd order products.
One you want and one you call distortion.

3rd order products will occur in a mixer, but I haven't ever seen a case
where they would be desirable.

Pete

"JC" wrote in message
...
Telamon wrote:


Like I said, it's semantics. The mixer produces two 3rd order products.
One you want and one you call distortion.

Please give an example where you want 3rd order products.


In a mixer