Topics

How to get rid of Local FM broadcast stations #ubitx

Gavin
 

I just wired up my v5 uBitx and have it on the table and have have an EFHW antenna plugged in. I am picking up two different loud FM stations, one is 97.7 and the other is around 104. When I unplug the antenna I can’t hear them. How is this solved? Or what might be causing this? I am new to both HF and kit radios. Thanks. 

Adrian Chadd
 

hi! There are AM and FM filter kits you can place in the receive path.
(I'm hoping that the bitx v6 will have some jumpers on the rx path to
insert extra filtering..)

Are those stations super close to you?


-adrian

On Sun, 1 Dec 2019 at 15:05, <gdesplin@...> wrote:

I just wired up my v5 uBitx and have it on the table and have have an EFHW antenna plugged in. I am picking up two different loud FM stations, one is 97.7 and the other is around 104. When I unplug the antenna I can’t hear them. How is this solved? Or what might be causing this? I am new to both HF and kit radios. Thanks.

Curt
 

Most unusual.  are these stations coming in at a particular setting of the radio tuning, or all the time regardless of where it is tuned? If the latter, then these stations could he overwhelming the audio section.

I would check to insure you have a ground path connection from the board to the antenna connector. If this is an open circuit ehen checked with a dvm, it may he involved.

Curt

Vince Vielhaber
 

The first thing to figure out is where it's REALLY coming from. Are the stations' transmitters really close to you? Do you hear them on any other receiver tuned to the same freq(s)? Are they coming in on the same freq? What freq(s) are you hearing them on?

Vince - K8ZW.

On 12/01/2019 06:05 PM, gdesplin@... wrote:
I just wired up my v5 uBitx and have it on the table and have have an
EFHW antenna plugged in. I am picking up two different loud FM stations,
one is 97.7 and the other is around 104. When I unplug the antenna I
can’t hear them. How is this solved? Or what might be causing this? I am
new to both HF and kit radios. Thanks.

Gavin
 

The FM stations are about or at least 5 1/2 miles away from me. I hear them no matter where I tune too, both of them. And yes I can tune to them with a regular fm receiver. They are at 97.7 and around 104. 

I did solder the ground to the antenna connector, but I can double check that. 

Gavin
 

Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Adrian Chadd
 

well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:

Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Gavin
 

Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ?  Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.


On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:
well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:

Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Ashhar Farhan
 

If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?

- f

On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:
Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ?  Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.

On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:
well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:

Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Gavin
 

I tried taking it of the metal chassis and now the broadcast stations were quiet compared to a loud hum. The hum got more intense if I put my fingers close it the volume control wires. Also if things got moved around a bit it the broadcast stations would get loud and then stop when things moved back around again.

On Mon, Dec 2, 2019 at 06:10 PM, Ashhar Farhan wrote:

If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?
 
- f

On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:
Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ?  Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.

On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:
well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:

Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Adrian Chadd
 

hi,

post a photo of the wiring. you may need to shorten some wires and do
some RF bypassing?



-adrian

On Mon, 2 Dec 2019 at 19:33, <gdesplin@...> wrote:

I tried taking it of the metal chassis and now the broadcast stations were quiet compared to a loud hum. The hum got more intense if I put my fingers close it the volume control wires. Also if things got moved around a bit it the broadcast stations would get loud and then stop when things moved back around again.

On Mon, Dec 2, 2019 at 06:10 PM, Ashhar Farhan wrote:

If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?

- f

On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:

Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ? Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.

On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:

well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:


Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Ashhar Farhan
 

Look carefully at your ground wire. it maybe floating.

- f

On Tue, Dec 3, 2019 at 9:33 AM Adrian Chadd <adrian.chadd@...> wrote:
hi,

post a photo of the wiring. you may need to shorten some wires and do
some RF bypassing?



-adrian

On Mon, 2 Dec 2019 at 19:33, <gdesplin@...> wrote:
>
> I tried taking it of the metal chassis and now the broadcast stations were quiet compared to a loud hum. The hum got more intense if I put my fingers close it the volume control wires. Also if things got moved around a bit it the broadcast stations would get loud and then stop when things moved back around again.
>
> On Mon, Dec 2, 2019 at 06:10 PM, Ashhar Farhan wrote:
>
> If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?
>
> - f
>
> On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:
>>
>> Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ?  Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.
>>
>> On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:
>>
>> well, yeah. If you have AM stations close by then they can definitely
>> overwhelm your frontend.
>>
>> Get one of the bitx AM broadcast filters; they're high-pass filters
>> that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
>> that's ok right?
>>
>>
>> -adrian
>>
>> On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:
>>
>>
>> Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?
>
>



Gavin
 

Sorry I'm pretty new at these things. The ground wire connecting to the volume control, or to the DC connector? They look fine, what would be a way to test to make sure? Or anything to look out for?

Thanks!
- Gavin


On Mon, Dec 2, 2019 at 10:06 PM, Ashhar Farhan wrote:
Look carefully at your ground wire. it maybe floating.
 
- f

On Tue, Dec 3, 2019 at 9:33 AM Adrian Chadd <adrian.chadd@...> wrote:
hi,

post a photo of the wiring. you may need to shorten some wires and do
some RF bypassing?



-adrian

On Mon, 2 Dec 2019 at 19:33, <gdesplin@...> wrote:
>
> I tried taking it of the metal chassis and now the broadcast stations were quiet compared to a loud hum. The hum got more intense if I put my fingers close it the volume control wires. Also if things got moved around a bit it the broadcast stations would get loud and then stop when things moved back around again.
>
> On Mon, Dec 2, 2019 at 06:10 PM, Ashhar Farhan wrote:
>
> If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?
>
> - f
>
> On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:
>>
>> Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ?  Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.
>>
>> On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:
>>
>> well, yeah. If you have AM stations close by then they can definitely
>> overwhelm your frontend.
>>
>> Get one of the bitx AM broadcast filters; they're high-pass filters
>> that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
>> that's ok right?
>>
>>
>> -adrian
>>
>> On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:
>>
>>
>> Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?
>
>



Gavin
 

I have my radio in the chassis now, no more humming, but the radio stations are back. I can’t see any wires touching the chassis and the stations were there without the lid. And they are persistent no matter my tuning. Here are some pictures:

On Mon, Dec 2, 2019 at 08:03 PM, Adrian Chadd wrote:

hi,

post a photo of the wiring. you may need to shorten some wires and do
some RF bypassing?



-adrian

On Mon, 2 Dec 2019 at 19:33, <gdesplin@...> wrote:

I tried taking it of the metal chassis and now the broadcast stations were quiet compared to a loud hum. The hum got more intense if I put my fingers close it the volume control wires. Also if things got moved around a bit it the broadcast stations would get loud and then stop when things moved back around again.

On Mon, Dec 2, 2019 at 06:10 PM, Ashhar Farhan wrote:

If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?

- f

On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:

Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ? Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.

On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:

well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:


Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

MVS Sarma
 

Use a 2wire + shield cable between audio 8 pin plug and the volume control. The ground pin of VC can return  back on the shield wire to the connector. But not to be grounded there at VC.
Hope this method helps.

Sarma vu3zmv

On Sat, 7 Dec 2019, 9:24 pm Gavin, <gdesplin@...> wrote:

I have my radio in the chassis now, no more humming, but the radio stations are back. I can’t see any wires touching the chassis and the stations were there without the lid. And they are persistent no matter my tuning. Here are some pictures:

On Mon, Dec 2, 2019 at 08:03 PM, Adrian Chadd wrote:

hi,

post a photo of the wiring. you may need to shorten some wires and do
some RF bypassing?



-adrian

On Mon, 2 Dec 2019 at 19:33, <gdesplin@...> wrote:

I tried taking it of the metal chassis and now the broadcast stations were quiet compared to a loud hum. The hum got more intense if I put my fingers close it the volume control wires. Also if things got moved around a bit it the broadcast stations would get loud and then stop when things moved back around again.

On Mon, Dec 2, 2019 at 06:10 PM, Ashhar Farhan wrote:

If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?

- f

On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:

Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ? Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.

On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:

well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:


Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Mike Short
 

Did you remove the paint from all of the holes to insure good contact?  Antenna jack, power, board mounting holes, jacks, case screws,etc. Twist your audio wiring together more as well. 

On Sat, Dec 7, 2019 at 10:43 MVS Sarma <mvssarma@...> wrote:
Use a 2wire + shield cable between audio 8 pin plug and the volume control. The ground pin of VC can return  back on the shield wire to the connector. But not to be grounded there at VC.
Hope this method helps.

Sarma vu3zmv

On Sat, 7 Dec 2019, 9:24 pm Gavin, <gdesplin@...> wrote:

I have my radio in the chassis now, no more humming, but the radio stations are back. I can’t see any wires touching the chassis and the stations were there without the lid. And they are persistent no matter my tuning. Here are some pictures:

On Mon, Dec 2, 2019 at 08:03 PM, Adrian Chadd wrote:

hi,

post a photo of the wiring. you may need to shorten some wires and do
some RF bypassing?



-adrian

On Mon, 2 Dec 2019 at 19:33, <gdesplin@...> wrote:

I tried taking it of the metal chassis and now the broadcast stations were quiet compared to a loud hum. The hum got more intense if I put my fingers close it the volume control wires. Also if things got moved around a bit it the broadcast stations would get loud and then stop when things moved back around again.

On Mon, Dec 2, 2019 at 06:10 PM, Ashhar Farhan wrote:

If the stations are heard regardless of your tuning, it is probable that they are being picked up by the audio system. Can you double check that the volume control and the speaker wires don't touch the chassis anywhere?

- f

On Tue 3 Dec, 2019, 1:36 AM , <gdesplin@...> wrote:

Ok, so are you talking about getting this http://qrpme.com/?p=product&id=BCI like suggested at http://ubitx.net/fix-bci-filter/ or another one of their suggestions? Or maybe something like in this youtube video https://www.youtube.com/watch?v=fgQenFJOjr4 ? Or did you have something else in mind? I'm all for whichever is simplest/easiest as I am a beginner.

On Mon, Dec 2, 2019 at 10:20 AM, Adrian Chadd wrote:

well, yeah. If you have AM stations close by then they can definitely
overwhelm your frontend.

Get one of the bitx AM broadcast filters; they're high-pass filters
that drop-off around 3MHz. So yeah, you won't be receiving 160m, but
that's ok right?


-adrian

On Mon, 2 Dec 2019 at 09:17, <gdesplin@...> wrote:


Ah, it looks like both these stations also have AM counterparts, at 1490 kHz and 1210 kHz. Does that change things?

Gary Anderson
 

Hi Gavin.
I don't see a RF ground. The (-)DC voltage is not a ground.  On most power supplies it is a common.  If connected to ground at the supply, it is connected to mains electrical system ground, not a good RF ground.
Since you are in a metal chassis, remove the paint to have a good connection between the chassis and all the connectors including the 4 PCB stand-offs. Then bond the chassis to your RF ground.
Also make sure you have a proper size fuse inline between your power source and your uBITX.

The green/yellow/orange bundle to your volume control: Move that forward and down close to the chassis to minimize coupling from the encoder and USB

Rgds,
Gary

Curt
 

Yes sometimes seeing can be the issue! 

Better to use an ohmmeter (DVM or other type) to see if there is continuity from 'ground connections on the board - any, they are all connected within the board) to the OUTER conductor of the coax connector.  if this is an open circuit, you aren't properly connected.  (you might be connected to the board but maybe not the case - see note about scraping paint if you case has paint). 

building RF stuff requires some investigation - use a meter always, don't trust your eyes.  don't ask about my own misadvertures!

73 Curt

David Wilcox <Djwilcox01@...>
 

And don’t forget the microscope we all have in our smart phones.  Take a photo and blow it up on your computer...... shows all my sins usually.  An ohm meter and a smart phone are the start of anyones build or repair kit.  In fact I bought a USB electronic microscope a few years ago at Dayton but have never had to use it... my smart phone does all I have needed so far.

Dave K8WPE   

David J. Wilcox K8WPE’s iPad

On Dec 8, 2019, at 1:16 PM, Curt via Groups.Io <wb8yyy@...> wrote:

Yes sometimes seeing can be the issue! 

Better to use an ohmmeter (DVM or other type) to see if there is continuity from 'ground connections on the board - any, they are all connected within the board) to the OUTER conductor of the coax connector.  if this is an open circuit, you aren't properly connected.  (you might be connected to the board but maybe not the case - see note about scraping paint if you case has paint). 

building RF stuff requires some investigation - use a meter always, don't trust your eyes.  don't ask about my own misadvertures!

73 Curt

Gavin
 

I stripped all the paint from the connections to the chassis, and twisted the wires up a bit more. There is continuity between the coax ground and the other grounds. Any other ideas why its picking up these local stations?