Topics

Band pass filter

Preston
 

I am in a condo in Scottsdale, and have tried my new Ubitx on a MFJ 1622 apartment antenna and on a 40 meter half wave center fed dipole.  All I am getting is static on every band with some periodic continuous tones, although it worked in Wisconsin with a dipole.  The ARRL video on Youtube about the Ubitx says at the end, that there is an AM station within a mile that causes problems with the receiver.  They say to buy or build a band pass filter.  I am wondering if this is my problem.  Has anyone run into this?  If so, is there a brand and model that has worked for you?

 

Preston,

 If it is indeed from a AM station I sell a BCI filter kit with instructions to install in the uBitx/Bitx40 radios for 5$

https://shop.kit-projects.com/index.php?route=product/product&path=59&product_id=118

73


--
David

 N8DAH
Kit-Projects.com

Shop is open!

iz oos
 

Indeed, if the AM station is on mediumwave a BCI filter (just a highpass filter) is the solution. I have had a similar issue with a religious FM channel I heard spread over the 144mhz band. A highpass filter was enough. I hope you can solve it equally well. It also depends on how clean is their TX. But they might be legally compliant (-43db? from the fundamental) but not enough for you.


Il 14/nov/2019 05:29, "Preston" <preston.azcpapro@...> ha scritto:
I am in a condo in Scottsdale, and have tried my new Ubitx on a MFJ 1622 apartment antenna and on a 40 meter half wave center fed dipole.  All I am getting is static on every band with some periodic continuous tones, although it worked in Wisconsin with a dipole.  The ARRL video on Youtube about the Ubitx says at the end, that there is an AM station within a mile that causes problems with the receiver.  They say to buy or build a band pass filter.  I am wondering if this is my problem.  Has anyone run into this?  If so, is there a brand and model that has worked for you?

Jack, W8TEE
 

Preston:

There's an article (A Cheap and Easy BCI Filter”, CQ Magazine, August, 2016) that describes such a filter. I built a QRP version for my 49-er that works quite well. It cost be about $0.80 to build the QRP version (perf board works fine, of course):

Inline image

Inline image

Inline image


As you can see, the insertion loss is very small, but it knocks the slats out of any BCI interference.

Jack, W8TEE


On Wednesday, November 13, 2019, 11:29:00 PM EST, Preston <preston.azcpapro@...> wrote:


I am in a condo in Scottsdale, and have tried my new Ubitx on a MFJ 1622 apartment antenna and on a 40 meter half wave center fed dipole.  All I am getting is static on every band with some periodic continuous tones, although it worked in Wisconsin with a dipole.  The ARRL video on Youtube about the Ubitx says at the end, that there is an AM station within a mile that causes problems with the receiver.  They say to buy or build a band pass filter.  I am wondering if this is my problem.  Has anyone run into this?  If so, is there a brand and model that has worked for you?

--
Jack, W8TEE

Martin Potter
 

Preston wrote :
"I am in a condo ... static ... periodic continuous tones"

It could also be RFI from a local source. If you can power the rig (receiver only) from a battery, put a whip antenna on it (or several feet of wire) and check the level of interference in your condo. Then go up to the roof and check, and out to the parking lot, and finally to the big park down the road. If there is much difference in the noise level between those different places ...
73,
... Martin VE3OAT

Ken Held KF7DUR
 

The only AM broadcast transmitter in Scottsdale is located @ 64th st. & Thomas rd.
KAZG 1440AM 5,000 W day, 52 W night
Are you close to that location?

David Forrest
 

Can you tune in the AM station (with either your MFJ1622 or a length of wire) to test the rest of the system?

Doug W
 

On Thu, Nov 14, 2019 at 08:15 AM, Jack, W8TEE wrote:
I built a QRP version for my 49-er that works quite well.
At QRP levels is there an advantage or disadvantage to using wound toriods versus radial inductors (or even SMD), especially on the receive side?
 
--
www.bitxmap.com

iz oos
 

For TX I would only use toroids or air wound coils. For RX you could use radial or SMD. The Q might be better with toroids, although.


Il 14/nov/2019 16:39, "Doug W" <dougwilner@...> ha scritto:
On Thu, Nov 14, 2019 at 08:15 AM, Jack, W8TEE wrote:
I built a QRP version for my 49-er that works quite well.
At QRP levels is there an advantage or disadvantage to using wound toriods versus radial inductors (or even SMD), especially on the receive side?
 
--
www.bitxmap.com

Jack, W8TEE
 

I'm a software guy, so probably shouldn't answer that. My gut says wound toroids are always better, but the axials worked fine for me. Some EE-type can give a better answer.

Jack, W8TEE

On Thursday, November 14, 2019, 10:39:43 AM EST, Doug W <dougwilner@...> wrote:


On Thu, Nov 14, 2019 at 08:15 AM, Jack, W8TEE wrote:
I built a QRP version for my 49-er that works quite well.
At QRP levels is there an advantage or disadvantage to using wound toriods versus radial inductors (or even SMD), especially on the receive side?
 
--
www.bitxmap.com

--
Jack, W8TEE

Preston
 

I am about 14 miles away.  I am in a densely populated area with a large apartment group next to our condo community, so I suspect there is probably a huge number of different electronic devices and there could be spurious emissions from them.

Preston

G. Preston Parker

5704 E Aire Libre Ave Unit 1025

Scottsdale, AZ 85254

preston.azcpapro@...

480 499-5427  866 459-5242

480 499-5761 Fax

http://azcpapro.com

Help us improve by taking a short survey http://www.azcpapro.com/client-survey.aspx



On Thu, Nov 14, 2019 at 7:44 AM Ken Held KF7DUR via Groups.Io <kf7dur=aol.com@groups.io> wrote:
The only AM broadcast transmitter in Scottsdale is located @ 64th st. & Thomas rd.
KAZG 1440AM 5,000 W day, 52 W night
Are you close to that location?

MadRadioModder
 

You might do a little investigating to see if there really is a loud station blocking your receiver before you invest in something you may not need.  The first thing I would try is just receiving off a long wire stuffed into the antenna port (NO TRANSMITTING!).  You’ll get a better understanding if the receiver is the problem that way.

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Preston
Sent: Thursday, November 14, 2019 10:22 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Band pass filter

 

I am about 14 miles away.  I am in a densely populated area with a large apartment group next to our condo community, so I suspect there is probably a huge number of different electronic devices and there could be spurious emissions from them.

Preston

G. Preston Parker

5704 E Aire Libre Ave Unit 1025

Scottsdale, AZ 85254

preston.azcpapro@...

480 499-5427  866 459-5242

480 499-5761 Fax

http://azcpapro.com

Help us improve by taking a short survey http://www.azcpapro.com/client-survey.aspx

 

 

On Thu, Nov 14, 2019 at 7:44 AM Ken Held KF7DUR via Groups.Io <kf7dur=aol.com@groups.io> wrote:

The only AM broadcast transmitter in Scottsdale is located @ 64th st. & Thomas rd.
KAZG 1440AM 5,000 W day, 52 W night
Are you close to that location?


--

…_. _._

Dave New
 

Toroids are self-shielding.

Axials need to be mounted at right angles to minimize coupling between them.  If you have three, you can mount them in the x, y, and z planes.

At this point, most folks just give up and use toroids. Laughing

73,

-- Dave, N8SBE

-------- Original Message --------
Subject: Re: [BITX20] Band pass filter
From: "Jack, W8TEE via Groups.Io" <jjpurdum@...>
Date: Thu, November 14, 2019 11:07 am
To: <BITX20@groups.io>

I'm a software guy, so probably shouldn't answer that. My gut says wound toroids are always better, but the axials worked fine for me. Some EE-type can give a better answer.

Jack, W8TEE

On Thursday, November 14, 2019, 10:39:43 AM EST, Doug W <dougwilner@...> wrote:


On Thu, Nov 14, 2019 at 08:15 AM, Jack, W8TEE wrote:
I built a QRP version for my 49-er that works quite well.
At QRP levels is there an advantage or disadvantage to using wound toriods versus radial inductors (or even SMD), especially on the receive side?
 
--
www.bitxmap.com

--
Jack, W8TEE

Preston
 

I tried tuning 1440 and don't hear much, but 1510 KFNN is really, really loud.  They show their address at 8145 E Evans Rd Scottsdale, 85260 which would be very close if the antenna is at that location.

Preston
 

According to Wikipedia KFNN broadcasts from 8145 E Evans Rd in Scottsdale which is 4.5 miles away.  Wattage is 22,000.

Adrian Chadd
 

you'll probably want the BCB filter /and/ a notch filter for that
specific AM transmitter.



-adrian
(about 8mi from a 50KW AM transmitter, and 10mi from another..)

On Thu, 14 Nov 2019 at 16:40, Preston <@Preston2> wrote:

According to Wikipedia KFNN broadcasts from 8145 E Evans Rd in Scottsdale which is 4.5 miles away. Wattage is 22,000.

Miguel Angelo Bartie
 

A simple way to kill BC AM signals is using a 1µH or less in pararllel with antenna input....
Try ... 

73 from py2ohh miguel

MVS Sarma
 

Great. Simpler idea. Elektor sdr design by Burkhard Kainka  had 2.2mH inductor across antenna


On Fri, 15 Nov 2019, 11:25 pm Miguel Angelo Bartie via Groups.Io, <py2ohh=yahoo.com.br@groups.io> wrote:
A simple way to kill BC AM signals is using a 1µH or less in pararllel with antenna input....
Try ... 

73 from py2ohh miguel

Curt
 

Lots of data here already. An AM station antenna is actually the very tall tower itself,  should be easy to see where it is. But you might have other interference sources there. If you can take your ubitx to a park with a battery and many feet of wire, see if it receives better there. Some have to enjoy their ham radio away from home because of interference. Do see if the bad interference at home is on every ham band.

Curt

iz oos
 

2.2mH is a large value. I guess its purpose be protection against statics. 1uH has is a low impedance at MW providing some highpass but maybe not enough in presence of a nearby station. Try it in any case.


Il 16/nov/2019 04:15, "MVS Sarma" <mvssarma@...> ha scritto:
Great. Simpler idea. Elektor sdr design by Burkhard Kainka  had 2.2mH inductor across antenna

On Fri, 15 Nov 2019, 11:25 pm Miguel Angelo Bartie via Groups.Io, <py2ohh=yahoo.com.br@groups.io> wrote:
A simple way to kill BC AM signals is using a 1µH or less in pararllel with antenna input....
Try ... 

73 from py2ohh miguel