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I am getting am broadcast stations on my bitx 40 at night time I am not seeing these stations in the day any help in stopping this from happing is anyone else ?in euro land seeing this ?I posted this last night but it never got on the group thanks for any tips
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I get them around 7.210?
It is sw radio. I get them also on my not home made rigs...?
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no sup price ! there have been a explanation for it somewhere ..... short version is.. something with BFO and VFO frequency !
you can change from LSB to USB on BFO and change VFO from 5 MHz to 19MHz and you will not hear the Broadcast stations
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OK is it if brake through from 12mhz could I add a 12 mhz trap on the rx fount end there is broadcast station at 12,0020mhz am I found on my ICOM think its Russian?
On 3 Jul 2017 12:45, "OZ9AEW" < madsen1960@...> wrote: no sup price ! there have been a explanation for it somewhere ..... short version is.. something with BFO and VFO frequency !
you can change from LSB to USB on BFO and change VFO from 5 MHz to 19MHz and you will not hear the Broadcast stations
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These are images resulting from the 4th harmonic of the VFO mixing with SW broadcast stations higher up in the band (above 7200kHz). There has been an extensive discussion about this: /g/BITX20/message/21511One solution is to move the VFO to the high side of the IF, but then you must also shift the BFO down by some kHz for LSB operation. 73 Allard PE1NWL
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On Mon, July 3, 2017 13:54, chris gress wrote: OK is it if brake through from 12mhz could I add a 12 mhz trap on the rx
fount end there is broadcast station at 12,0020mhz am I found on my ICOM
think its Russian No, that won't help, see my earlier mail 73 Allard PE1NWL
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OK I got it as soon as I see the first post it all adds up same places I get the am I think I can live with it not planing on been out portable with it at night?
On 3 Jul 2017 13:02, "Allard PE1NWL" < pe1nwl@...> wrote: On Mon, July 3, 2017 13:54, chris gress wrote:
> OK is it if brake through from 12mhz could I add a 12 mhz trap on the rx
> fount end there is broadcast station at 12,0020mhz am I found on my ICOM
> think its Russian
No, that won't help, see my earlier mail
73 Allard PE1NWL
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I have local strong? am broadcast station near by. I had to used flexiable 50 ohm coax? inside cabinet due to my ant is front to back. Sheild speaker wired will help eliminate? am broadcast. The more expose wiring acts like antenna for am broadcast. Cabinet metal over plastic make? a better? protection for RF and better ground.
Lady Francesca W7ltg
--
Sent from Hotmail Email App for Android
Monday, 03 July 2017, 05:07AM -07:00 from chris gress Chrisg0wfh@...:
OK I got it as soon as I see the first post it all adds up same places I get the am I think I can live with it not planing on been out portable with it at night? On 3 Jul 2017 13:02, "Allard PE1NWL" < pe1nwl@...> wrote: On Mon, July 3, 2017 13:54, chris gress wrote:
> OK is it if brake through from 12mhz could I add a 12 mhz trap on the rx
> fount end there is broadcast station at 12,0020mhz am I found on my ICOM
> think its Russian
No, that won't help, see my earlier mail
73 Allard PE1NWL
--
I have ?bitx40 ?and completely wired up. get nice hiss when the volume up. display lights up only showing Raduino V1.01. ?frequency never shown, anyone have that problem? ?i think the software is not in the chip.
Francesca W7LTG ? NV?
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I had that problem with the Forty-9er and added a 7-pole BCI?filter. I used molded inductors and regular caps because it is a QRP rig. It totally knocked out the AM stations. Insertion loss was 0.04dB.
 The cost was $0.37 as I had most of the stuff on hand. The filter is symmetric, so it doesn't matter which end is input/output.
 Jack, W8TEE
From: Francesca Wine via Groups.Io <francescawine@...>
To: [email protected]
Sent: Monday, July 3, 2017 8:46 AM
Subject: Re: [BITX20] Am radio stations
I have local strong? am broadcast station near by. I had to used flexiable 50 ohm coax? inside cabinet due to my ant is front to back. Sheild speaker wired will help eliminate? am broadcast. The more expose wiring acts like antenna for am broadcast. Cabinet metal over plastic make? a better? protection for RF and better ground.
Lady Francesca W7ltg
--
Sent from Hotmail Email App for Android
Monday, 03 July 2017, 05:07AM -07:00 from chris gress Chrisg0wfh@...:
OK I got it as soon as I see the first post it all adds up same places I get the am I think I can live with it not planing on been out portable with it at night? On 3 Jul 2017 13:02, "Allard PE1NWL" < pe1nwl@...> wrote: On Mon, July 3, 2017 13:54, chris gress wrote:
> OK is it if brake through from 12mhz could I add a 12 mhz trap on the rx
> fount end there is broadcast station at 12,0020mhz am I found on my ICOM
> think its Russian
No, that won't help, see my earlier mail
73 Allard PE1NWL
--
I have ?bitx40 ?and completely wired up. get nice hiss when the volume up. display lights up only showing Raduino V1.01. ?frequency never shown, anyone have that problem? ?i think the software is not in the chip.
Francesca W7LTG ? NV?
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The world above 7.2 is commercial in most places. When propagation if good you will hear them.
I don't hear much between 7 and 7.2Mhz
Raj, vu2zap
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At 03-07-2017, you wrote: I am getting am broadcast stations on my bitx 40 at night time I am not seeing these stations in the day any help in stopping this from happing is anyone else in euro land seeing this I posted this last night but it never got on the group thanks for any tips
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True. As I said, this is a BCI filter which serves me well, as I have a 50KW AM station just down the road and the Forty-9er has almost zero protection in its design. The filter would not help with foreign BC stations.
Jack, W8TEE
From: Raj vu2zap <rajendrakumargg@...>
To: [email protected]
Sent: Monday, July 3, 2017 9:51 AM
Subject: Re: [BITX20] Am radio stations
The world above 7.2 is commercial in most places. When propagation if good you will hear them.
I don't hear much between 7 and 7.2Mhz
Raj, vu2zap
At 03-07-2017, you wrote:
>I am getting am broadcast stations on my bitx 40 at night time I am not seeing these stations in the day any help in stopping this from happing is anyone else? in euro land seeing this? I posted this last night but it never got on the group thanks for any tips
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I think that Raj is correct.? If the unwanted broadcast stations are commercial stations operating
just above 7.0 MHz they will be heard on any good 40 Meter receiver or transceiver that is tuned
to their frequency.? No amount of AM BCB filtering for? 500 KHz to 1.8 MHz will help in this case.
The original post claims that these stations are not present during the day and are present during
night time.? That further strengthens the case for them to be actual broadcasting stations in the
7.1+ frequency range.?
A rotatable antenna system might help if it can null-out signals from a particular direction.? While
a rotatable dipole on 40 meters may not be feasible, it is possible to enhance or null signals with
a 40M loop antenna that is installed on a rotator.
There is also the possibility of IF frequency feed-through.? This was a problem with the original
BITX design which used 10.0 MHz IF crystals and allowed strong WWVB or WWV time-and-frequency
signals to bleed through for hams who were located very close to those transmitters.? Subsequent
moving of the IF to 11 or 12 MHz solved that problem.? The IF frequency is not critical, except that
what frequency you use should be evaluated to insure that you are not inserting harmonic related
spurious signals and that you are not using a frequency that is close to that of any very strong local
radio transmitters.
Moving the IF to 19 MHz also works, except that the existing crystal filter is optimized for LSB and
usually has a broader skirt section on the opposite sideband.? Moving the IF to 19 MHz does put
your LSB signal on the side of the crystal filter that usually has a gentler slope factor.? This can be
fixed but it does involve adding another crystal as a series-tuned attenuation section to make
the gentler sloping skirt into a steeper one.?
It might be possible to make a very selective front-end attenuator if you have a crystal that is on
the same frequency as the offending 7 MHz commercial broadcast station, but this will also block
any ham signals that fall within the range of that suck-out filter.? Such a filter would also have to
be broad enough to fully block both carrier and modulation component (sidebands) of the
offending signal.
Arv? K7HKL
_._
On Mon, Jul 3, 2017 at 7:55 AM, Jack Purdum via Groups.Io <econjack@...> wrote: True. As I said, this is a BCI filter which serves me well, as I have a 50KW AM station just down the road and the Forty-9er has almost zero protection in its design. The filter would not help with foreign BC stations.
Jack, W8TEE
The world above 7.2 is commercial in most places. When propagation if good you will hear them.
I don't hear much between 7 and 7.2Mhz
Raj, vu2zap
At 03-07-2017, you wrote:
>I am getting am broadcast stations on my bitx 40 at night time I am not seeing these stations in the day any help in stopping this from happing is anyone else? in euro land seeing this? I posted this last night but it never got on the group thanks for any tips
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Yes same here in US. ?Shortwave radio stations either Asian or Spanish language speaking a.m. stations show up here at night due to propagation.?
Best,
Joe KD2NFC
Sent from my iPhone
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On Jul 3, 2017, at 6:33 AM, chris gress < Chrisg0wfh@...> wrote: I am getting am broadcast stations on my bitx 40 at night time I am not seeing these stations in the day any help in stopping this from happing is anyone else ?in euro land seeing this ?I posted this last night but it never got on the group thanks for any tips
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Allred I see these signals on my SDR's and even my Yaesu HF rig. Are you sure these are images?
Sent from my iPhone
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On Jul 3, 2017, at 7:59 AM, Allard PE1NWL <pe1nwl@...> wrote:
These are images resulting from the 4th harmonic of the VFO mixing with SW
broadcast stations higher up in the band (above 7200kHz).
There has been an extensive discussion about this:
/g/BITX20/message/21511
One solution is to move the VFO to the high side of the IF, but then you
must also shift the BFO down by some kHz for LSB operation.
73 Allard PE1NWL
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In ITU regions 1 and 3, the section above 7200 is allocated to SW broadcast.
Only in Region 2 (Americas) the section 7200-7300 is allocated to amateur
radio.
So if you're sometimes receiving SW broadcast stations ABOVE 7200, then
that is quite possible due to propagation.
But if you hear broadcast signals BELOW 7200, then these are probably
images from SW stations just ABOVE 7200 (due to mixing with the 4th
harmonic of the VFO).
This is probably not a severe problem when you are in America, but in
Europe and Asia the images can be really annoying, especially in the
evenings.
73 Allard PE1NWL
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On Mon, July 3, 2017 18:18, Joe Puma wrote: Yes same here in US. Shortwave radio stations either Asian or Spanish
language speaking a.m. stations show up here at night due to propagation.
Best,
Joe
KD2NFC
Sent from my iPhone
On Jul 3, 2017, at 6:33 AM, chris gress <Chrisg0wfh@...> wrote:
I am getting am broadcast stations on my bitx 40 at night time I am not
seeing these stations in the day any help in stopping this from happing
is anyone else in euro land seeing this I posted this last night but
it never got on the group thanks for any tips
|
Hi I am talking broadcast stations in the? 7,100 to 7,200 mhz part of the band I have put in rg174 between dds and vfo input on bitx also used some for my rf gain control r13 to 1k pot?
On 3 Jul 2017 17:35, "Allard PE1NWL" < pe1nwl@...> wrote: In ITU regions 1 and 3, the section above 7200 is allocated to SW broadcast.
Only in Region 2 (Americas) the section 7200-7300 is allocated to amateur
radio.
So if you're sometimes receiving SW broadcast stations ABOVE 7200, then
that is quite possible due to propagation.
But if you hear broadcast signals BELOW 7200, then these are probably
images from SW stations just ABOVE 7200 (due to mixing with the 4th
harmonic of the VFO).
This is probably not a severe problem when you are in America, but in
Europe and Asia the images can be really annoying, especially in the
evenings.
73 Allard PE1NWL
On Mon, July 3, 2017 18:18, Joe Puma wrote:
> Yes same here in US.? Shortwave radio stations either Asian or Spanish
> language speaking a.m. stations show up here at night due to propagation.
>
>
> Best,
>
> Joe
> KD2NFC
>
> Sent from my iPhone
>
>> On Jul 3, 2017, at 6:33 AM, chris gress <Chrisg0wfh@...> wrote:
>>
>> I am getting am broadcast stations on my bitx 40 at night time I am not
>> seeing these stations in the day any help in stopping this from happing
>> is anyone else? in euro land seeing this? I posted this last night but
>> it never got on the group thanks for any tips
>>
>
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Yes, exactly same here in The Netherlands.
As there are no broadcast stations in that part of the band, then these
MUST be images.
These images are simply inherent to the BitX design.
One way to prove this is: When you switch mode to USB then you don't here
them anymore as the VFO is then set to the high side of the IF (19 MHz
instead of 5MHz).
73 Allard PE1NWL
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On Mon, July 3, 2017 18:59, chris gress wrote: Hi I am talking broadcast stations in the
7,100 to 7,200 mhz part of the band I have put in rg174 between dds and
vfo
input on bitx also used some for my rf gain control r13 to 1k pot
On 3 Jul 2017 17:35, "Allard PE1NWL" <pe1nwl@...> wrote:
In ITU regions 1 and 3, the section above 7200 is allocated to SW
broadcast.
Only in Region 2 (Americas) the section 7200-7300 is allocated to
amateur
radio.
So if you're sometimes receiving SW broadcast stations ABOVE 7200, then
that is quite possible due to propagation.
But if you hear broadcast signals BELOW 7200, then these are probably
images from SW stations just ABOVE 7200 (due to mixing with the 4th
harmonic of the VFO).
This is probably not a severe problem when you are in America, but in
Europe and Asia the images can be really annoying, especially in the
evenings.
73 Allard PE1NWL
On Mon, July 3, 2017 18:18, Joe Puma wrote:
Yes same here in US. Shortwave radio stations either Asian or Spanish
language speaking a.m. stations show up here at night due to propagation.
Best,
Joe
KD2NFC
Sent from my iPhone
On Jul 3, 2017, at 6:33 AM, chris gress <Chrisg0wfh@...> wrote:
I am getting am broadcast stations on my bitx 40 at night time I am
not
seeing these stations in the day any help in stopping this from
happing
is anyone else in euro land seeing this I posted this last night
but
it never got on the group thanks for any tips
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Radio Havana broadcasts a monstrously powerful, ridiculously wide bandwidth signal out Cuba on 6.0 MHZ. The 2nd harmonic of that frequency is 12 MHZ, which is the same frequency as the IF stage. I've picked them up at 7.035, which is supposed to be a QRP calling frequency. If there is any other carrier at or near that frequency, it knocks Radio Havana out. I also find that when I orient my antenna East to West, but turn slightly south of west (heading 260), Radio Havana falls into one of my antenna's null zones.?
Although, listening to socialist propaganda on the CRI re-broadcasts is always amusing....
On Mon, Jul 3, 2017 at 12:59 PM, chris gress <Chrisg0wfh@...> wrote: Hi I am talking broadcast stations in the? 7,100 to 7,200 mhz part of the band I have put in rg174 between dds and vfo input on bitx also used some for my rf gain control r13 to 1k pot?
--
Andrew KrauseGeneral Class Amateur Radio License: KM4ZJO
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Hi to all.
I'm in a kind of similar situation here and this is my experience
about it:
I live in Cuba, yes, THAT island in the Caribbean sea, any in the
SWL community knows what that means: Cuba has a military program
to interfere radio signals in the SW bands from USA.
What ever you tune to a frequency of "Radio Mart¨ª" or some times
"VOA" you may heard a "wrack, wrack, wrack, wrack... " signals on
top of it, that's what I'm taking about.
But happens that I live near (~120 meters) from one of that
little interfering stations, (infamously) knows by the Cuba ham's
community as "las sombrillitas" (the "little" umbrellas), I can't
talk about the transmit station but yes about the antennas, the
name came from the discone antennas they use to broadcast, as per
my calcs tuned as low as 4 Mhz... hence the "little" nickname.
Why I tell you this?
Because every day at 6:00 pm local time they switch from a ~12-13
Mhz frequency (ruining 20m) to a 7 Mhz one, exactly on 7.435 kc
most of the time.
Now imagine with me a powerful (don't know how exactly how much,
but I would say about more than 100W) at 120 meters from your
antenna and just ~300 Kc away, in the "pass" part of your passband
filter.
Tip: around the end of 2015 they changed/perfected the
transmitter technology. Before that, they transmitted a very broad
signal of about 100 to 200 Khz one (at least on my reception point
and looking it with a SDR) and now is just about 15 Khz. Before
2015 I have to turn my rig off and do anything else then they came
to 40m...
Even my older FT-747GX has troubles with that, mind the little
bitx40...
My task was research, experiment and test; and the result is
this:
- Don't use a COAXIAL to feed your antenna, the external part of
it is a third wire and will act as a marconi antenna, at that
power levels any fraction of RF will ruin your reception.
(Having a heart connection just will worst the problem, current
balums over the coaxial helps but not as much as the following
item)
- Use a twisted open wire line, and a balanced tuner if
possible, if not, don't even try any type of voltage balums
(Rutherfort, the kind almost any manual tuner has) use the
current type of balums (Guanella) at least in my case they are
more efficient fighting that interference.?
- Put your antenna in the line formed by your position and the
position of the emitter (whit the tip facing the transmitter,
hence the null, not the lobe)
This kind of things will help to minimize the impact, not eliminate
it, just the first two items will bring the interference a few S
units down, the third will lower it a bit more but may ruin your DX
as you may need to point your antenna to an ocean and not a
continent as in my case...
Just a few cents of my experience.
73 de Pavel CO7WT.
?
El 03/07/17 a las 06:33, chris gress
escribi¨®:
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I am getting am
broadcast stations on my bitx 40 at night time I am not seeing
these stations in the day any help in stopping this from happing
is anyone else ?in euro land seeing this ?I posted this last night
but it never got on the group thanks for any tips
|
Allard PE1NWL
Raj vu2zap