Predicting MW Intermod/Bleedthrough


m_a_schuster
 

I'm posting this to a couple of radio-related groups in order to get a wider audience of collective wisdom. I live in an area of northern New Jersey that I've come to refer to as RF Alley because of the concentration of powerful transmitter towers situated in wetlands a few miles away. The most annoying result of this proximity is rampant MW intermod and bleed-through on some, but not all portable radios which can make for frustrating bandscanning; especially on the upper end of the band.


Like many in these forums I've bought many portables over the years; held on to many and sold or returned others because of poor performance otherwise, or sometimes just because of the MW intermod issue alone. I'm getting tired of playing Russian Roulette with online purchases, and was wondering how I might predict this propensity ahead of time - but in spite of reading numerous online reviews before purchase I often fail because others' experiences doe not match mine. Can anyone see a predictive design/architecture pattern here?


SUFFER FROM SEVERE MW INTERMOD:

  • Tescun Mid-Full Size PLL: PLL660, 800
  • Degen Mid-Size PLL: DE-1102, Grundig/Eton G5/E5
  • Tecsun Ultralight PLL: PL-210
  • Redsun Ultralight PLL: CCrane SWP


DO NOT SUFFER FROM SEVERE MW INTERMOD

  • Sangean Pocket AM/FM PLL: DT 200, 220, 400; ?Ccrane AM/FM Pocket
  • Sangean Mid-Full Size PLL: ATS-505, 606
  • Tecsun Ultralight Analog: R-9702
  • Tecsun Ultralight PLL: PL-200
  • Redsun Ultralight PLL: Digitech AR1733 (and so probably the upcoming CCrane AM/FM/SW/Air)
  • Sony 1-chip analog ultralight: SRF-59, etc
  • Tecsun Ultralight/Medium DSP: PL-300, 310, 380, 390, 505, 606


Even the "immune" radios are not totally immune; for instance a local blowtorch at 1010 KHz appears at 1090 on every single radio of every brand, size, vintage, or design over the years; but I've learned to live with that.




Russ Edmunds <wb2bjh@...>
 

I lived in Kinnelon and Parsippany for a total of about 13 years, and in Glen Rock for about 6 months, so
I know what you're running into. There are just too many high power stations crammed into too small of
a geographic area, and withhigh ground conducivity coupled with marshland just to make things worse.

Some of what you're experiencing is likely externally generated. Mixing spurs can develop with the audio
from multiple stations showing up on a different frequency. No radio is immune to those since they act
like their own separate transmitters.

Overload on channel or on adjacent channels is a problem with portables because while the smaller
radios seem immune, that may be simply because they have too small a ferrite antenna to be
sensitive enough ( which means they aren't really good AM DX receivers in the first place ).

At the time I lived there ( 1969-82 ) the small portables of the day were largely inferior to the current DSP
chip designs, and the larger portables had decent nulling capability which could be used.

Bottom line, this is going to be an ongoing issue with portables.


Russ Edmunds
15 mi NNW of Philadelphia
Grid FN20id
<wb2bjh@yahoo.com>

AM:  Modified Sony ICF 2010's barefoot
FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder;
Onkyo T-450RDS; Tecsun PL-310 ( 2);
modified Sony ICF2010 w/APS9B @ 15';
Grundig G8 w/whip; modified Sony ICF2010 w/whip

--------------------------------------------

On Mon, 9/1/14, schuster@panix.com [ultralightdx] <ultralightdx@yahoogroups.com> wrote:

Subject: [ultralightdx] Predicting MW Intermod/Bleedthrough
To: ultralightdx@yahoogroups.com
Date: Monday, September 1, 2014, 9:15 AM


 









I'm posting this to a couple of
radio-related groups in order to get a wider audience of
collective wisdom. I live in an area of northern New Jersey
that I've come to refer to as RF Alley because of the
concentration of powerful transmitter towers situated in
wetlands a few miles away. The most annoying result of this
proximity is rampant MW intermod and bleed-through on some,
but not all portable radios which can make for frustrating
bandscanning; especially on the upper end of the
band.
Like
many in these forums I've bought many portables over the
years; held on to many and sold or returned others because
of poor performance otherwise, or sometimes just because of
the MW intermod issue alone. I'm getting tired of
playing Russian Roulette with online purchases, and was
wondering how I might predict this propensity ahead of time
- but in spite of reading numerous online reviews before
purchase I often fail because others' experiences doe
not match mine. Can anyone see a predictive
design/architecture pattern here?
SUFFER FROM SEVERE MW
INTERMOD:Tescun Mid-Full Size PLL:
PLL660, 800
Degen Mid-Size PLL: DE-1102,
Grundig/Eton G5/E5
Tecsun Ultralight PLL:
PL-210
Redsun Ultralight PLL: CCrane
SWP
DO NOT
SUFFER FROM SEVERE MW INTERMODSangean Pocket AM/FM PLL: DT
200, 220, 400; ?Ccrane AM/FM Pocket
Sangean Mid-Full Size PLL:
ATS-505, 606
Tecsun Ultralight Analog:
R-9702
Tecsun Ultralight PLL:
PL-200
Redsun Ultralight PLL: Digitech
AR1733 (and so probably the upcoming CCrane
AM/FM/SW/Air)
Sony 1-chip analog ultralight:
SRF-59, etc
Tecsun Ultralight/Medium DSP:
PL-300, 310, 380, 390, 505, 606

Even the "immune" radios are
not totally immune; for instance a local blowtorch at 1010
KHz appears at 1090 on every single radio of every brand,
size, vintage, or design over the years; but I've
learned to live with that.











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m_a_schuster
 

Thanks for the sympathetic response.

If one eliminates modern DSP designs though, the age of the receiver isn't necessarily the determining factor. If you look at the list - for instance, my decades-old ATS-606 does not suffer from significant MW interference issues, but the brand-spanking-new Tecsun PL-880 does.


Russ Edmunds <wb2bjh@...>
 

Agreed - the DSP largely works against adjacent channel interference, improving selectivity.

The other part of the equation has to do with the overall quality ( or lack thereof ) in the Chinese-made radios
of today vs those from the 1970's. And with the former, there are also unit-to-unit quality and performance variations.
That is one contributing factor.

Where I am located now, I have a concentration of transmitters as well - fewer of them and not as many at 50 kw, but
there are still issues. I mostly use the 2010's for AM DX, but I still get some external mixing products. Those I can
usually null but that does limit where the peaks are.


Russ Edmunds
15 mi NNW of Philadelphia
Grid FN20id
<wb2bjh@yahoo.com>

AM:  Modified Sony ICF 2010's barefoot
FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder;
Onkyo T-450RDS; Tecsun PL-310 ( 2);
modified Sony ICF2010 w/APS9B @ 15';
Grundig G8 w/whip; modified Sony ICF2010 w/whip

--------------------------------------------

On Mon, 9/1/14, schuster@panix.com [ultralightdx] <ultralightdx@yahoogroups.com> wrote:

Subject: Re: [ultralightdx] Predicting MW Intermod/Bleedthrough
To: ultralightdx@yahoogroups.com
Date: Monday, September 1, 2014, 10:19 AM


 









Thanks for the sympathetic response.
If one eliminates modern DSP designs
though, the age of the receiver isn't necessarily the
determining factor. If you look at the list - for instance,
my decades-old ATS-606 does not suffer from significant MW
interference issues, but the brand-spanking-new Tecsun
PL-880 does.










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m_a_schuster
 

From a response given to me elsewhere, and one that makes sense, the front-end design might be the critical variable. Radios that use a broad and front-end without frequency tracking are more likely to experience this issue. If only it were possible to know that while shopping :-)

Also my 1010 - on 1090 issue is likely coming from the transmitter site as it appears on all types of radios regardless of architecture.



Russ Edmunds <wb2bjh@...>
 

Likely an external mixing product. 1050 - 1010 = 40. 1050 + 40 = 1090. A 'standard' "sum-and/or-difference" spur.
Those are generated by something metallic out in or near the transmitter swamp picking up both signals and then
mixing and retransmitting them. You might have it on 970 except that you already have a local there. There were
lots of those up there when I was there and that's only one. All it takes is two powerful transmitters which are both
close in frequency and in geography.

Russ Edmunds
15 mi NNW of Philadelphia
Grid FN20id
<wb2bjh@yahoo.com>

AM:  Modified Sony ICF 2010's barefoot
FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder;
Onkyo T-450RDS; Tecsun PL-310 ( 2);
modified Sony ICF2010 w/APS9B @ 15';
Grundig G8 w/whip; modified Sony ICF2010 w/whip

--------------------------------------------

On Mon, 9/1/14, schuster@panix.com [ultralightdx] <ultralightdx@yahoogroups.com> wrote:

Subject: Re: [ultralightdx] Predicting MW Intermod/Bleedthrough
To: ultralightdx@yahoogroups.com
Date: Monday, September 1, 2014, 10:42 AM


 









From a response given to me elsewhere, and one that
makes sense, the front-end design might be the critical
variable. Radios that use a broad and front-end without
frequency tracking are more likely to experience this issue.
If only it were possible to know that while shopping
:-)
Also my 1010 - on
1090 issue is likely coming from the transmitter site as it
appears on all types of radios regardless of
architecture.












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mediumwavedx
 

I find that the weak point of the newer DSP radios seems to be desense more than anything else. I think it comes from an inadequate front end. It does little to have a 1 KHz filter further downline in the receiver chain if the front end is desensitized by strong local signals. The filter (and radio) works great out in the boondocks, but bring it to the city near several 5 KW - 50 KW stations and the desense is apparent for +/- 50 KHz sometimes. Couple that with the soft-mute irritant and you are basically blanked out for a width of 100 KHz.

I am sandwiched between two 5 KW stations (both at 1.2 miles), and a 1 KW station at 2 miles. About 250 KHz of bandwidth is unusable due to desense. Not so on my double conversion, non-DSP Tecsun PL-600. Even the single conversion analogs are better and some of the single conversion PLL units.

I am not sold on the DSP radios. I have been burned on two out of three. I own a PL-380 which I like (except for the desense problem in the city). It is a great little radio which works well in the boondocks when I travel across country. It has average sensitivity. The Tecsun R2010D and Kaito KA321 DSP radios I bought were, in my opinion, engineering disasters. They attempted to mimic analog tuning through software and it didn't work. The Kaito 321 was virtually impossible to tune and land on a weak station. In the Tecsun 2010D they decided, I don't know why, to smooth the tuning across a station by locking the adjacent channels (in frequency) to the center channel, thus eliminating any possibility to receive a weaker channel 10 KHz from a stronger channel.

I do not own a Tecsun PL-880, the new flagship radio. I refuse to pay $150 for overpriced DSP technology.

By the way, all of the above comments are concerning mediumwave performance of these radios.

Bill
RADIO-TIMETRAVELLER
http://radio-timetraveller.blogspot.com


Michael <michael.setaazul@...>
 

----- Original Message ----- From: mediumwavedx

I find that the weak point of the newer DSP radios seems to be desense
more than anything else. I think it comes from an inadequate front end.
It does little to have a 1 KHz filter further downline in the receiver chain
if the front end is desensitized by strong local signals. The filter (and radio)
works great out in the boondocks, but bring it to the city near several
5 KW - 50 KW stations and the desense is apparent for +/- 50 KHz sometimes.
Couple that with the soft-mute irritant and you are basically blanked out for a width of 100 KHz.

________________________________________________

Spot-on! Many receivers, including high-spec amateur radio transceivers,
incorporate a barn-door front-end for design and production convenience.
This allows everything with a few uV to surge in and infect even sophisticated
signal processing further down the chain.

If we buy into this market, we must expect to be duped. But we can up-front
the front-end with vicious selectivity - sigh...

PS : If you have local AM power-houses, be grateful. In the Old World, our
medium-wave transmitters are being culled at an alarming rate.

Michael


Bruce Conti
 

If the problem is a wide-as-a-barndoor receiver front end, then maybe you should invest in one of those monster DeBock FSL antennas.  This type of tuned antenna will knock down much of the interference while peaking the desired frequency, except anything from an external source like the 1010/1050 product.  To further narrow the bandpass would require the external antenna connected to a positive feedback RF amp like the Connelly MWT-3.

--
Bruce Conti
B.A.Conti Photography www.baconti.com
¡BAMLog! www.bamlog.com


Michael <michael.setaazul@...>
 

Yep, I dream of a proper FSL....

But almost any front-end selection will help significantly.
A well-built tunable loop inductively coupled to even a lowly
radio will work wonders by dint of its notch-like tuning, directivity
and gain.

Michael

----- Original Message ----- From: Bruce Conti


If the problem is a wide-as-a-barndoor receiver front end, then maybe
you should invest in one of those monster DeBock FSL antennas.
This type of tuned antenna will knock down much of the interference
while peaking the desired frequency, except anything from an external source
like the 1010/1050 product. To further narrow the bandpass would require
the external antenna connected to a positive feedback RF amp like the Connelly MWT-3.


Guy Atkins
 
Edited

I don't know if this will be of interest, but I've used this web page before to predict true intermod frequencies (3rd order, 5th order, etc.):

http://www.arcticpeak.com/radiopages/intermodulationproducts.htm

73,

Guy Atkins
Puyallup, WA


Russ Edmunds
 

Interesting. I created a couple of these in Excel many years ago only including frequencies of locals ( and I have enough of those ) - one for AM and another for FM.
Never knew someone had put up a site.


Russ Edmunds

<wb2bjh@...>




On Mon, Jan 14, 2019 at 8:24 PM Guy Atkins <dx@...> wrote:
I don't if this will be of interest, but I've used this web page before to predict true intermod frequencies (3rd order, 5th order, etc.):

http://www.arcticpeak.com/radiopages/intermodulationproducts.htm

73,

Guy Atkins
Puyallup, WA


Rik
 

Another factor is the raw sensitivity of the radio. That and a number of other things going on inside the radio circuit make predictions guesses at best. Interesting you hear WINS on top of  WBAL. I don't understand all the things occurring inside a radio, and I doubt even some one familiar with each and every set you mention could predict which would be best at your difficult location for certain. A directional antenna might help, especially a unidirectional antenna. I found my PL-600 to be among the portables with the narrowest MW pick up patterns. Seldom do air core loops have sharp patterns. Do narrower band width selections available on some radios help? I have a couple of sharply directional MW antennas which can be coupled to the  portables you mention. But then your radio is not so portable and they are not inexpensive. -FARMERIK


Russ Edmunds
 

Another factor in the mix is that some mixing products originate outside of the receive and away from the receiving location. These may be caused by two signals mixing at some other point - usually close to one or both transmitters. These then behave like and are received ( in terms of antenna bearing ) like separate transmitters. Wet or frozen ground can also enhance these.




Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Rik <farmerik@...>
Sent: Tuesday, January 15, 2019 10:22:40 AM
To: main@UltralightDX.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
Another factor is the raw sensitivity of the radio. That and a number of other things going on inside the radio circuit make predictions guesses at best. Interesting you hear WINS on top of  WBAL. I don't understand all the things occurring inside a radio, and I doubt even some one familiar with each and every set you mention could predict which would be best at your difficult location for certain. A directional antenna might help, especially a unidirectional antenna. I found my PL-600 to be among the portables with the narrowest MW pick up patterns. Seldom do air core loops have sharp patterns. Do narrower band width selections available on some radios help? I have a couple of sharply directional MW antennas which can be coupled to the  portables you mention. But then your radio is not so portable and they are not inexpensive. -FARMERIK


Paul Blundell
 

I have this issue with my "local" station on 1008kHz which knocks out stations a few steps on either side.


On Wed, Jan 16, 2019 at 2:37 AM Russ Edmunds <wb2bjh@...> wrote:

Another factor in the mix is that some mixing products originate outside of the receive and away from the receiving location. These may be caused by two signals mixing at some other point - usually close to one or both transmitters. These then behave like and are received ( in terms of antenna bearing ) like separate transmitters. Wet or frozen ground can also enhance these.




Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Rik <farmerik@...>
Sent: Tuesday, January 15, 2019 10:22:40 AM
To: main@UltralightDX.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
Another factor is the raw sensitivity of the radio. That and a number of other things going on inside the radio circuit make predictions guesses at best. Interesting you hear WINS on top of  WBAL. I don't understand all the things occurring inside a radio, and I doubt even some one familiar with each and every set you mention could predict which would be best at your difficult location for certain. A directional antenna might help, especially a unidirectional antenna. I found my PL-600 to be among the portables with the narrowest MW pick up patterns. Seldom do air core loops have sharp patterns. Do narrower band width selections available on some radios help? I have a couple of sharply directional MW antennas which can be coupled to the  portables you mention. But then your radio is not so portable and they are not inexpensive. -FARMERIK



--
Paul


--
Paul - Moderator
UltralightDX


Russ Edmunds
 

I think that is a different problem. I was referring to mixinig products from two powerful stations located near to each other.


Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Paul Blundell <tanger32au@...>
Sent: Tuesday, January 15, 2019 5:18:24 PM
To: main@ultralightdx.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
I have this issue with my "local" station on 1008kHz which knocks out stations a few steps on either side.

On Wed, Jan 16, 2019 at 2:37 AM Russ Edmunds <wb2bjh@...> wrote:

Another factor in the mix is that some mixing products originate outside of the receive and away from the receiving location. These may be caused by two signals mixing at some other point - usually close to one or both transmitters. These then behave like and are received ( in terms of antenna bearing ) like separate transmitters. Wet or frozen ground can also enhance these.




Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Rik <farmerik@...>
Sent: Tuesday, January 15, 2019 10:22:40 AM
To: main@UltralightDX.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
Another factor is the raw sensitivity of the radio. That and a number of other things going on inside the radio circuit make predictions guesses at best. Interesting you hear WINS on top of  WBAL. I don't understand all the things occurring inside a radio, and I doubt even some one familiar with each and every set you mention could predict which would be best at your difficult location for certain. A directional antenna might help, especially a unidirectional antenna. I found my PL-600 to be among the portables with the narrowest MW pick up patterns. Seldom do air core loops have sharp patterns. Do narrower band width selections available on some radios help? I have a couple of sharply directional MW antennas which can be coupled to the  portables you mention. But then your radio is not so portable and they are not inexpensive. -FARMERIK



--
Paul


--
Paul - Moderator
UltralightDX


Paul Blundell
 

Sorry, I read the post wrong. I understand what you mean now.


On Wed, Jan 16, 2019 at 9:29 AM Russ Edmunds <wb2bjh@...> wrote:

I think that is a different problem. I was referring to mixinig products from two powerful stations located near to each other.


Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Paul Blundell <tanger32au@...>
Sent: Tuesday, January 15, 2019 5:18:24 PM
To: main@ultralightdx.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
I have this issue with my "local" station on 1008kHz which knocks out stations a few steps on either side.

On Wed, Jan 16, 2019 at 2:37 AM Russ Edmunds <wb2bjh@...> wrote:

Another factor in the mix is that some mixing products originate outside of the receive and away from the receiving location. These may be caused by two signals mixing at some other point - usually close to one or both transmitters. These then behave like and are received ( in terms of antenna bearing ) like separate transmitters. Wet or frozen ground can also enhance these.




Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Rik <farmerik@...>
Sent: Tuesday, January 15, 2019 10:22:40 AM
To: main@UltralightDX.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
Another factor is the raw sensitivity of the radio. That and a number of other things going on inside the radio circuit make predictions guesses at best. Interesting you hear WINS on top of  WBAL. I don't understand all the things occurring inside a radio, and I doubt even some one familiar with each and every set you mention could predict which would be best at your difficult location for certain. A directional antenna might help, especially a unidirectional antenna. I found my PL-600 to be among the portables with the narrowest MW pick up patterns. Seldom do air core loops have sharp patterns. Do narrower band width selections available on some radios help? I have a couple of sharply directional MW antennas which can be coupled to the  portables you mention. But then your radio is not so portable and they are not inexpensive. -FARMERIK



--
Paul


--
Paul - Moderator
UltralightDX



--
Paul


--
Paul - Moderator
UltralightDX


Will <will_k53@...>
 

There also used to be the Radio Luxembourg effect.  It cross modulated its long wave signal onto other transmitters by heating  the ionosphere.

Cheers,
Will

On 16/01/19 11:29 AM, Russ Edmunds wrote:

I think that is a different problem. I was referring to mixinig products from two powerful stations located near to each other.


Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Paul Blundell <tanger32au@...>
Sent: Tuesday, January 15, 2019 5:18:24 PM
To: main@ultralightdx.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
I have this issue with my "local" station on 1008kHz which knocks out stations a few steps on either side.

On Wed, Jan 16, 2019 at 2:37 AM Russ Edmunds <wb2bjh@...> wrote:

Another factor in the mix is that some mixing products originate outside of the receive and away from the receiving location. These may be caused by two signals mixing at some other point - usually close to one or both transmitters. These then behave like and are received ( in terms of antenna bearing ) like separate transmitters. Wet or frozen ground can also enhance these.




Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Rik <farmerik@...>
Sent: Tuesday, January 15, 2019 10:22:40 AM
To: main@UltralightDX.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
Another factor is the raw sensitivity of the radio. That and a number of other things going on inside the radio circuit make predictions guesses at best. Interesting you hear WINS on top of  WBAL. I don't understand all the things occurring inside a radio, and I doubt even some one familiar with each and every set you mention could predict which would be best at your difficult location for certain. A directional antenna might help, especially a unidirectional antenna. I found my PL-600 to be among the portables with the narrowest MW pick up patterns. Seldom do air core loops have sharp patterns. Do narrower band width selections available on some radios help? I have a couple of sharply directional MW antennas which can be coupled to the  portables you mention. But then your radio is not so portable and they are not inexpensive. -FARMERIK


--
Paul


--
Paul - Moderator
UltralightDX


Russ Edmunds
 

Luxembourg effect is observed when you have multiple close locals and you are able to null one of them down and end up hearing the signal from another local on the nulled frequency -- not its own frequency.


Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Will <will_k53@...>
Sent: Tuesday, January 15, 2019 9:40:01 PM
To: main@UltralightDX.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
There also used to be the Radio Luxembourg effect.  It cross modulated its long wave signal onto other transmitters by heating  the ionosphere.

Cheers,
Will

On 16/01/19 11:29 AM, Russ Edmunds wrote:

I think that is a different problem. I was referring to mixinig products from two powerful stations located near to each other.


Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Paul Blundell <tanger32au@...>
Sent: Tuesday, January 15, 2019 5:18:24 PM
To: main@ultralightdx.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
I have this issue with my "local" station on 1008kHz which knocks out stations a few steps on either side.

On Wed, Jan 16, 2019 at 2:37 AM Russ Edmunds <wb2bjh@...> wrote:

Another factor in the mix is that some mixing products originate outside of the receive and away from the receiving location. These may be caused by two signals mixing at some other point - usually close to one or both transmitters. These then behave like and are received ( in terms of antenna bearing ) like separate transmitters. Wet or frozen ground can also enhance these.




Russ Edmunds

WB2BJH

Blue Bell, PA

Grid FN20id


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Rik <farmerik@...>
Sent: Tuesday, January 15, 2019 10:22:40 AM
To: main@UltralightDX.groups.io
Subject: Re: [UltralightDX] Predicting MW Intermod/Bleedthrough
 
Another factor is the raw sensitivity of the radio. That and a number of other things going on inside the radio circuit make predictions guesses at best. Interesting you hear WINS on top of  WBAL. I don't understand all the things occurring inside a radio, and I doubt even some one familiar with each and every set you mention could predict which would be best at your difficult location for certain. A directional antenna might help, especially a unidirectional antenna. I found my PL-600 to be among the portables with the narrowest MW pick up patterns. Seldom do air core loops have sharp patterns. Do narrower band width selections available on some radios help? I have a couple of sharply directional MW antennas which can be coupled to the  portables you mention. But then your radio is not so portable and they are not inexpensive. -FARMERIK


--
Paul


--
Paul - Moderator
UltralightDX