Topics

low-band filter


doug
 

I wonder if there is available from some source a simple filter that would attenuate the broadcast band
to a sufficient extent as to not create harmonics or overload the input of simple sdr devices, or the tinySA
spectrum analyzer. I am interested in tracking down the source of some broad-band noise in the lower
frequency range from about 3 to 15 MHz.
--doug, WA2SAY


jdow
 

https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html

That has some interesting observations and well down the page some interesting schematics.

It appears he revisited the filter a couple more times if you dig a little.

{^_^}

On 20201112 18:01:07, doug wrote:
I wonder if there is available from some source a simple filter that would attenuate the broadcast band
to a sufficient extent as to not create harmonics or overload the input of simple sdr devices, or the tinySA
spectrum analyzer. I am interested in tracking down the source of some broad-band noise in the lower
frequency range from about 3 to 15 MHz.
--doug, WA2SAY






Kriss Kliegle KA1GJU
 

I built the W1VLF AM BC filter to tame the SDR Play I have on my server network.
Works  as published!
I used axial inductors in mine, very compact, and stuffed into a diy copper box for shielding.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DvI6N_uVErKA&ved=2ahUKEwjV4sy4vv_sAhVjoFkKHST6BOEQwqsBMAB6BAgBEAM&usg=AOvVaw1dvKEeaIGUkpFQLCmCueUx


Kjell-Goran SM4GRP
 

Hello,
Heros Technology provides RF filters.
https://www.herostechnology.co.uk/pages/RF_Filters.html

73/Kjell-Goran SM4GRP


doug
 

On 11/13/20 2:40 AM, jdow wrote:
https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html <https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html>

That has some interesting observations and well down the page some interesting schematics.

It appears he revisited the filter a couple more times if you dig a little.

{^_^}

On 20201112 18:01:07, doug wrote:
I wonder if there is available from some source a simple filter that would attenuate the broadcast band
to a sufficient extent as to not create harmonics or overload the input of simple sdr devices, or the tinySA
spectrum analyzer. I am interested in tracking down the source of some broad-band noise in the lower
frequency range from about 3 to 15 MHz.
--doug, WA2SAY

Thanx, JoAnne--It's obvious that the writer has done his homework. I have already investigated some
filter designs but my problem is that I'm no longer working in this field--I've been retired for 18 years--
and have no access to the components any more. I am hoping that someone, somewhere, who does
have access has designed and built a filter for the purpose, and is now selling copies of it for some
reasonable price--say $15 or so? (I'll put it in a shielded box, if it doesn't come with one.)
--doug, WA2SAY


Tracey Gardner
 

Hello Doug

How about this ready made filter from SV1AFN for approx. $43

https://www.sv1afn.com/en/product-category-4/1-8-mhz-high-pass-filter-for-receivers-only-or-qrp-radios-10-w-max.html

73s Tracey G5VU

----- Original Message -----
From: doug <dmcgarrett@...>
Reply-To: <main@SDR-Radio.groups.io>
To: <main@SDR-Radio.groups.io>
Sent: 13/11/2020 17:52:34
Subject: Re: [SDR-Radio] low-band filter
________________________________________________________________________________



Thanx, JoAnne--It's obvious that the writer has done his homework. I
have already investigated some
filter designs but my problem is that I'm no longer working in this
field--I've been retired for 18 years--
and have no access to the components any more. I am hoping that someone,
somewhere, who does
have access has designed and built a filter for the purpose, and is now
selling copies of it for some
reasonable price--say $15 or so? (I'll put it in a shielded box, if it
doesn't come with one.)
--doug, WA2SAY


Tom Seeger
 

Or you can buy a BCB filter.
https://www.amazon.ca/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V/ref=sr_1_5?dchild=1&keywords=am+filter&qid=1605286620&sr=8-5


doug
 

On 11/13/20 12:00 PM, Tom Seeger wrote:
Or you can buy a BCB filter.
https://www.amazon.ca/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V/ref=sr_1_5?dchild=1&keywords=am+filter&qid=1605286620&sr=8-5
_._,_._,_
This is exactly what I want, except amazon.ca says it can't ship it to my Long Island New York USA address. It apparently
is made by Nooelec which is surely Chinese, and seems to be actually shipping from Canada. Since when can't I buy
something from Canada?

Anyway, I will see if the US Amazon operation can come by this unit.
Thanx for the information.

--doug


doug
 

On 11/13/20 12:52 PM, doug wrote:


On 11/13/20 2:40 AM, jdow wrote:
https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html <https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html>

That has some interesting observations and well down the page some interesting schematics.

It appears he revisited the filter a couple more times if you dig a little.

{^_^}

On 20201112 18:01:07, doug wrote:
I wonder if there is available from some source a simple filter that would attenuate the broadcast band
to a sufficient extent as to not create harmonics or overload the input of simple sdr devices, or the tinySA
spectrum analyzer. I am interested in tracking down the source of some broad-band noise in the lower
frequency range from about 3 to 15 MHz.
--doug, WA2SAY

Thanx, JoAnne--It's obvious that the writer has done his homework. I have already investigated some
filter designs but my problem is that I'm no longer working in this field--I've been retired for 18 years--
and have no access to the components any more. I am hoping that someone, somewhere, who does
have access has designed and built a filter for the purpose, and is now selling copies of it for some
reasonable price--say $15 or so? (I'll put it in a shielded box, if it doesn't come with one.)
--doug, WA2SAY

It turns out that there are some ready-to-use hp filters. On source was Canadian Amazon, and they can't ship to US,
apparently. (Tried to buy but was was advised I can't.) But US Amazon has a couple of filters, a bit cheaper, AAMOF,
and I ordered one. About $16. I suppose it has about $1.00 worth of parts in it, but worth the no-hassle!
Thanx to all. I didn't know that Amazon would have such a thing, but I should have known better--they have
everything!
--doug, WA2SAY


doug
 

On 11/13/20 1:01 PM, Tracey Gardner via groups.io wrote:
Hello Doug

How about this ready made filter from SV1AFN for approx. $43

https://www.sv1afn.com/en/product-category-4/1-8-mhz-high-pass-filter-for-receivers-only-or-qrp-radios-10-w-max.html

73s Tracey G5VU
Thanx, Tracy. Ordered a much cheaper unit from Amazon (US division.) Should be enough for my purposes.
--doug


----- Original Message -----
From: doug <dmcgarrett@...>
Reply-To: <main@SDR-Radio.groups.io>
To: <main@SDR-Radio.groups.io>
Sent: 13/11/2020 17:52:34
Subject: Re: [SDR-Radio] low-band filter
________________________________________________________________________________



Thanx, JoAnne--It's obvious that the writer has done his homework. I
have already investigated some
filter designs but my problem is that I'm no longer working in this
field--I've been retired for 18 years--
and have no access to the components any more. I am hoping that someone,
somewhere, who does
have access has designed and built a filter for the purpose, and is now
selling copies of it for some
reasonable price--say $15 or so? (I'll put it in a shielded box, if it
doesn't come with one.)
--doug, WA2SAY




doug
 

On 11/13/20 2:02 PM, doug wrote:


On 11/13/20 12:00 PM, Tom Seeger wrote:
Or you can buy a BCB filter.
https://www.amazon.ca/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V/ref=sr_1_5?dchild=1&keywords=am+filter&qid=1605286620&sr=8-5

_._,_._,_
This is exactly what I want, except amazon.ca says it can't ship it to
my Long Island New York USA address. It apparently
is made by Nooelec which is surely Chinese, and seems to be actually
shipping from Canada. Since when can't I buy
something from Canada?

Anyway, I will see if the US Amazon operation can come by this unit.
Thanx for the information.

--doug
Done!  Thanx for your interest.  --doug, WA2SAY


jdow
 



On 20201113 09:52:34, doug wrote:


On 11/13/20 2:40 AM, jdow wrote:
https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html <https://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html>

That has some interesting observations and well down the page some interesting schematics.

It appears he revisited the filter a couple more times if you dig a little.

{^_^}

On 20201112 18:01:07, doug wrote:
I wonder if there is available from some source a simple filter that would attenuate the broadcast band
to a sufficient extent as to not create harmonics or overload the input of simple sdr devices, or the tinySA
spectrum analyzer. I am interested in tracking down the source of some broad-band noise in the lower
frequency range from about 3 to 15 MHz.
--doug, WA2SAY


Thanx, JoAnne--It's obvious that the writer has done his homework. I have already investigated some
filter designs but my problem is that I'm no longer working in this field--I've been retired for 18 years--
and have no access to the components any more. I am hoping that someone, somewhere, who does
have access has designed and built a filter for the purpose, and is now selling copies of it for some
reasonable price--say $15 or so? (I'll put it in a shielded box, if it doesn't come with one.)
--doug, WA2SAY
DigiKey. Mouser, and Newark (perhaps others) are your friends.

{^_^}


jdow
 

They are a US company. Some years ago I did some business with them and they treated me right with good working product.

https://www.nooelec.com/store/

The filter appears to be here.
https://www.nooelec.com/store/sdr/flamingo-am.html

{^_^}

On 20201113 11:02:22, doug wrote:


On 11/13/20 12:00 PM, Tom Seeger wrote:
Or you can buy a BCB filter.
https://www.amazon.ca/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V/ref=sr_1_5?dchild=1&keywords=am+filter&qid=1605286620&sr=8-5
_._,_._,_
This is exactly what I want, except amazon.ca says it can't ship it to my Long Island New York USA address. It apparently
is made by Nooelec which is surely Chinese, and seems to be actually shipping from Canada. Since when can't I buy
something from Canada?

Anyway, I will see if the US Amazon operation can come by this unit.
Thanx for the information.

--doug






Dennis Matzen
 

Looks like US Amazon does have this filter:

https://www.amazon.com/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V

--
Dennis
KA6FUB


doug
 

On 11/14/20 5:18 AM, jdow wrote:
They are a US company. Some years ago I did some business with them and they treated me right with good working product.

https://www.nooelec.com/store/

The filter appears to be here.
https://www.nooelec.com/store/sdr/flamingo-am.html

{^_^}

On 20201113 11:02:22, doug wrote:
Thanx, JoAnne. I have ordered a filter from US Amazon. It should come in a day or two.
--doug


Lawrence Stoskopf
 

OT. A couple of days ago Amazon popped up in French. I shut everything down, run Defender which found a couple of things. Rebooted and it came up in US English. Gremlins somewhere as always. N0UU

On Nov 13, 2020, at 13:38, doug <dmcgarrett@...> wrote:



On 11/13/20 2:02 PM, doug wrote:


On 11/13/20 12:00 PM, Tom Seeger wrote:
Or you can buy a BCB filter.
https://www.amazon.ca/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V/ref=sr_1_5?dchild=1&keywords=am+filter&qid=1605286620&sr=8-5

_._,_._,_
This is exactly what I want, except amazon.ca says it can't ship it to
my Long Island New York USA address. It apparently
is made by Nooelec which is surely Chinese, and seems to be actually
shipping from Canada. Since when can't I buy
something from Canada?

Anyway, I will see if the US Amazon operation can come by this unit.
Thanx for the information.

--doug
Done! Thanx for your interest. --doug, WA2SAY





jdow
 

Be VERY paranoid about when you open mail or unknown pages. Loren and I have had one infection each in 35 years online mostly by being cautious. (And he still uses XP for some of his work and for email.)

{^_-}

On 20201115 07:49:49, Lawrence Stoskopf via groups.io wrote:
OT. A couple of days ago Amazon popped up in French.  I shut everything down, run Defender which found a couple of things. Rebooted and it came up in US English. Gremlins somewhere as always.  N0UU
On Nov 13, 2020, at 13:38, doug <dmcgarrett@...> wrote:



On 11/13/20 2:02 PM, doug wrote:


On 11/13/20 12:00 PM, Tom Seeger wrote:
Or you can buy a BCB filter.
https://www.amazon.ca/Flamingo-AM-Broadcast-Bandstop-Applications/dp/B079CMB44V/ref=sr_1_5?dchild=1&keywords=am+filter&qid=1605286620&sr=8-5

_._,_._,_
This is exactly what I want, except amazon.ca says it can't ship it to
my Long Island New York USA address. It apparently
is made by Nooelec which is surely Chinese, and seems to be actually
shipping from Canada. Since when can't I buy
something from Canada?

Anyway, I will see if the US Amazon operation can come by this unit.
Thanx for the information.

--doug

Done!  Thanx for your interest.  --doug, WA2SAY