Re: Topband: Commond mode choke for Beverage

[Filipe Lopes]

Thanks for this testing suggestiong Eddie, it will sure be a good way to
check if it works or not.

73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M

2015-10-12 20:14 GMT+02:00 Eduardo Araujo :

> >> With these ferrites I ask the same question, should I put the choke
> close
> >> to the 9:1 Balun or near the switching box and how many turns? some bevs
> >> have the feed point at +- 60m away from the switching box.
>
> My two cents..It was interesting during the installation of the last
> beverage, we have only #31 core, so we placed it at the receiver side.
> Disconnecting the coax at the bev feed point and shorting the coax there,
> many AM broadcast stations could be heard and some of them strong,
> indicating that even though one choke was at the receiver side the coax was
> acting like an antenna. The coax was just lying on the ground and is 40/50
> mts long.
> When we got more cores and placed one choke at that place close to the
> short, repeating the test before and after most broadcast vanished and only
> one could be heard very week.
> '73 Eddie, LU2DKT
>
>
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Filipe Lopes]

Thanks JC,

I am reading it right now, very interesting indeed.

73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M

2015-10-12 22:27 GMT+02:00 JC <n...@comcast.net>:

> Hi Felipe
>
>
>
> It works like a voltage divider where the impedance to ground should be
> lower as possible to give you more attenuation  like 1k/500ohms versus 1K/5
> ohms divider. You should use the choke near a good ground before entering
> the station. If you switch box have a good ground it’s a good place to
> install  it.
>
> More turns better, but it is limited by the diameter of the coaxial cable,
> like RG58/RG142 allows 12 to14 turns. RG213  only 8 turns.
>
>
>
> Jim K9YC and a fantastic documentation about chokes. Please read this
> document
>
>
>
> http://audiosystemsgroup.com/RFI-Ham.pdf
>
>
>
> You will be a specialist after reading this guide.
>
>
>
> Regards
>
> JC
>
> N4IS
>
>
>
> *From:* Filipe Lopes [mailto:ct1...@gmail.com]
> *Sent:* Monday, October 12, 2015 9:52 AM
> *To:* JC <n...@comcast.net>
> *Cc:* topBand <topband@contesting.com>
> *Subject:* Re: Topband: Commond mode choke for Beverage
>
>
>
> Hello JC,
>
>
>
> Thanks for your answer.
>
>
>
> I just ordered a few 2631803802 and 5943003801 from mouser.
>
>
>
> With these ferrites I ask the same question, should I put the choke close
> to the 9:1 Balun or near the switching box and how many turns? some bevs
> have the feed point at +- 60m away from the switching box.
>
>
>
>
> 73's Filipe Lopes
>
> CT1ILT - CR6K
>
> F4VPX - TM3M
>
>
>
> 2015-10-12 15:40 GMT+02:00 JC <n...@comcast.net>:
>
> Hi Filipe
>
> Zero , you should use material #31  or #77 , The core you have is not good
> for low bands.
>
> JC
> N4IS
>
> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Filipe
> Lopes
> Sent: Monday, October 12, 2015 8:46 AM
> To: topBand <topband@contesting.com>
> Subject: Topband: Commond mode choke for Beverage
>
> Hi guys,
>
> I am about to add a common mode choke to isolate the antenna from its
> feedline to each of my beverages and I only have FT240-61 ferrites. My
> question is how many turns should I do on the ferrite using RG58 (all my
> bevs are fed with RG58). Also should I put the choke near the 9:1 balun or
> near my bev switching box?
>
> Thanks in advance.
>
> 73's Filipe Lopes
> CT1ILT - CR6K
> F4VPX - TM3M
>
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
>
>
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Filipe Lopes]

Thanks for this grounding tip too Jim.


73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M

2015-10-13 4:03 GMT+02:00 Jim Brown :

> On Mon,10/12/2015 1:27 PM, JC wrote:
>
>> It works like a voltage divider where the impedance to ground should be
>> lower as possible to give you more attenuation  like 1k/500ohms versus 1K/5
>> ohms divider.
>>
>
> Yes.
>
> But to expand on this -- often the interference is coupled into a gain
> stage or RX by a Pin One Problem. ALWAYS make the first connection of any
> cable shield to the shielding enclosure of EVERY active device. Follow this
> rule regardless of the function of the cable -- input, output, control
> line, RF or audio.
>
> It's also good practice to bring RX antennas into the shack via the same
> grounding panel used for TX antennas. And that panel must be tied to local
> ground rods, those rods bonded to all other grounds, to the shack desk, etc.
>
> 73, Jim K9YC
>
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Jim Brown]

On Mon,10/12/2015 6:51 AM, Filipe Lopes wrote:

With these ferrites I ask the same question, should I put the choke close
to the 9:1 Balun or near the switching box and how many turns? some bevs
have the feed point at +- 60m away from the switching box.


Use the #31 material. Wind at least 20 turns of RG58 around it. Place it 
as close to the 9:1 transformer.


73, Jim K9YC
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Jim Brown]

On Mon,10/12/2015 5:45 AM, Filipe Lopes wrote:

I am about to add a common mode choke to isolate the antenna from its
feedline to each of my beverages and I only have FT240-61 ferrites.


#61 is a terrible material for use as a common mode choke below 500 MHz. 
Try to find #31 or #43, and wind LOTS of turns.


73, Jim K9YC
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Commond mode choke for Beverage

[Filipe Lopes]

Hi guys,

I am about to add a common mode choke to isolate the antenna from its
feedline to each of my beverages and I only have FT240-61 ferrites. My
question is how many turns should I do on the ferrite using RG58 (all my
bevs are fed with RG58). Also should I put the choke near the 9:1 balun or
near my bev switching box?

Thanks in advance.

73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[JC]

Hi Filipe

Zero , you should use material #31  or #77 , The core you have is not good
for low bands.

JC
N4IS
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Filipe
Lopes
Sent: Monday, October 12, 2015 8:46 AM
To: topBand <topband@contesting.com>
Subject: Topband: Commond mode choke for Beverage

Hi guys,

I am about to add a common mode choke to isolate the antenna from its
feedline to each of my beverages and I only have FT240-61 ferrites. My
question is how many turns should I do on the ferrite using RG58 (all my
bevs are fed with RG58). Also should I put the choke near the 9:1 balun or
near my bev switching box?

Thanks in advance.

73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M
_
Topband Reflector Archives - http://www.contesting.com/_topband

_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[shristov]

If you must use FT240-61, then in a single layer about 18 turns of RG58 would 
fit,
which should give you ~600 Ohms on 1.8 MHz. That would be very good for a 
dipole,
but for a Beverage a much higher impedance is needed. Try to fit as many turns
as possible, until there is no more room in the center of the core.

Alternatively, use RG174. In a single layer you should be able to put ~32 turns,
which will give you a respectable 2000 Ohms on 1.8 MHz.  But in this case take 
care
to make all coax joints (RG174 to RG58) completely shielded, eg. by using a 
copper foil.

73,

Sinisa  YT1NT, VE3EA



- Originalna poruka -
Pošiljalac: JC <n...@comcast.net>
Datum: Ponedeljak, Oktobar 12, 2015 15:40
Tema: Re: Topband: Commond mode choke for Beverage
Primalac: 'Filipe Lopes' <ct1...@gmail.com>, 'topBand' <topband@contesting.com>

> Hi Filipe
> 
> Zero , you should use material #31  or #77 , The core you 
> have is not good
> for low bands.
> 
> JC
> N4IS
> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf 
> Of Filipe
> Lopes
> Sent: Monday, October 12, 2015 8:46 AM
> To: topBand <topband@contesting.com>
> Subject: Topband: Commond mode choke for Beverage
> 
> Hi guys,
> 
> I am about to add a common mode choke to isolate the antenna 
> from its
> feedline to each of my beverages and I only have FT240-61 
> ferrites. My
> question is how many turns should I do on the ferrite using RG58 
> (all my
> bevs are fed with RG58). Also should I put the choke near the 
> 9:1 balun or
> near my bev switching box?
> 
> Thanks in advance.
> 
> 73's Filipe Lopes
> CT1ILT - CR6K
> F4VPX - TM3M
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
> 
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Filipe Lopes]

Hello JC,

Thanks for your answer.

I just ordered a few 2631803802 and 5943003801 from mouser.

With these ferrites I ask the same question, should I put the choke close
to the 9:1 Balun or near the switching box and how many turns? some bevs
have the feed point at +- 60m away from the switching box.


73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M

2015-10-12 15:40 GMT+02:00 JC <n...@comcast.net>:

> Hi Filipe
>
> Zero , you should use material #31  or #77 , The core you have is not good
> for low bands.
>
> JC
> N4IS
> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Filipe
> Lopes
> Sent: Monday, October 12, 2015 8:46 AM
> To: topBand <topband@contesting.com>
> Subject: Topband: Commond mode choke for Beverage
>
> Hi guys,
>
> I am about to add a common mode choke to isolate the antenna from its
> feedline to each of my beverages and I only have FT240-61 ferrites. My
> question is how many turns should I do on the ferrite using RG58 (all my
> bevs are fed with RG58). Also should I put the choke near the 9:1 balun or
> near my bev switching box?
>
> Thanks in advance.
>
> 73's Filipe Lopes
> CT1ILT - CR6K
> F4VPX - TM3M
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
>
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[shristov]

With 5943003801 and RG58, closely fill-in a single layer,
leaving 10-15 mm on the outside perimeter unused.
That should be ~16 turns, giving you impedance near 4000 Ohm.

Such a choke should be placed close to all points where
the current on the outer surface of the coax shield
can pass to the coax inside space.

This usually means near RX connector, and at the Beverage end of the feeding 
coax.
If the feed line is very long, then a few chokes may be inserted here and there.

But take care to make all coax joints completely shielded,
otherwise chokes may be bypassed.


73,

Sinisa  YT1NT,  VE3EA



- Originalna poruka -
Pošiljalac: Filipe Lopes <ct1...@gmail.com>
Datum: Ponedeljak, Oktobar 12, 2015 15:52
Tema: Re: Topband: Commond mode choke for Beverage
Primalac: JC <n...@comcast.net>
Cc: topBand <topband@contesting.com>

> Hello JC,
> 
> Thanks for your answer.
> 
> I just ordered a few 2631803802 and 5943003801 from mouser.
> 
> With these ferrites I ask the same question, should I put the 
> choke close
> to the 9:1 Balun or near the switching box and how many turns? 
> some bevs
> have the feed point at +- 60m away from the switching box.
> 
> 
> 73's Filipe Lopes
> CT1ILT - CR6K
> F4VPX - TM3M
> 
> 2015-10-12 15:40 GMT+02:00 JC <n...@comcast.net>:
> 
> > Hi Filipe
> >
> > Zero , you should use material #31  or #77 , The core you 
> have is not good
> > for low bands.
> >
> > JC
> > N4IS
> > -Original Message-
> > From: Topband [mailto:topband-boun...@contesting.com] On 
> Behalf Of Filipe
> > Lopes
> > Sent: Monday, October 12, 2015 8:46 AM
> > To: topBand <topband@contesting.com>
> > Subject: Topband: Commond mode choke for Beverage
> >
> > Hi guys,
> >
> > I am about to add a common mode choke to isolate the antenna 
> from its
> > feedline to each of my beverages and I only have FT240-61 
> ferrites. My
> > question is how many turns should I do on the ferrite using 
> RG58 (all my
> > bevs are fed with RG58). Also should I put the choke near the 
> 9:1 balun or
> > near my bev switching box?
> >
> > Thanks in advance.
> >
> > 73's Filipe Lopes
> > CT1ILT - CR6K
> > F4VPX - TM3M
> > _
> > Topband Reflector Archives - http://www.contesting.com/_topband
> >
> >
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Eduardo Araujo via Topband]

>> With these ferrites I ask the same question, should I put the choke close
>> to the 9:1 Balun or near the switching box and how many turns? some bevs
>> have the feed point at +- 60m away from the switching box.

My two cents..It was interesting during the installation of the last 
beverage, we have only #31 core, so we placed it at the receiver side. 
Disconnecting the coax at the bev feed point and shorting the coax there, many 
AM broadcast stations could be heard and some of them strong, indicating that 
even though one choke was at the receiver side the coax was acting like an 
antenna. The coax was just lying on the ground and is 40/50 mts long. 
When we got more cores and placed one choke at that place close to the short, 
repeating the test before and after most broadcast vanished and only one could 
be heard very week.'73 Eddie, LU2DKT 


   
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Filipe Lopes]

Thanks Jim and all for the help.

Mix #31 cores are already ordered in mouser.

73's cu on low bands
Filipe LOPES
CT1ILT CR6K

Sent from my SAMSUNG GALAXY S4
Em 12/10/2015 17:39, "Jim Brown"  escreveu:

> On Mon,10/12/2015 6:51 AM, Filipe Lopes wrote:
>
>> With these ferrites I ask the same question, should I put the choke close
>> to the 9:1 Balun or near the switching box and how many turns? some bevs
>> have the feed point at +- 60m away from the switching box.
>>
>
> Use the #31 material. Wind at least 20 turns of RG58 around it. Place it
> as close to the 9:1 transformer.
>
> 73, Jim K9YC
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[JC]

Hi Felipe

 

It works like a voltage divider where the impedance to ground should be lower 
as possible to give you more attenuation  like 1k/500ohms versus 1K/5 ohms 
divider. You should use the choke near a good ground before entering the 
station. If you switch box have a good ground it’s a good place to install  it.

More turns better, but it is limited by the diameter of the coaxial cable, like 
RG58/RG142 allows 12 to14 turns. RG213  only 8 turns.

 

Jim K9YC and a fantastic documentation about chokes. Please read this document 

 

http://audiosystemsgroup.com/RFI-Ham.pdf

 

You will be a specialist after reading this guide.

 

Regards

JC

N4IS

 

From: Filipe Lopes [mailto:ct1...@gmail.com] 
Sent: Monday, October 12, 2015 9:52 AM
To: JC <n...@comcast.net>
Cc: topBand <topband@contesting.com>
Subject: Re: Topband: Commond mode choke for Beverage

 

Hello JC, 

 

Thanks for your answer.

 

I just ordered a few 2631803802 and 5943003801 from mouser.

 

With these ferrites I ask the same question, should I put the choke close to 
the 9:1 Balun or near the switching box and how many turns? some bevs have the 
feed point at +- 60m away from the switching box.

 




73's Filipe Lopes 

CT1ILT - CR6K

F4VPX - TM3M 

 

2015-10-12 15:40 GMT+02:00 JC <n...@comcast.net <mailto:n...@comcast.net> >:

Hi Filipe

Zero , you should use material #31  or #77 , The core you have is not good
for low bands.

JC
N4IS

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com 
<mailto:topband-boun...@contesting.com> ] On Behalf Of Filipe
Lopes
Sent: Monday, October 12, 2015 8:46 AM
To: topBand <topband@contesting.com <mailto:topband@contesting.com> >
Subject: Topband: Commond mode choke for Beverage

Hi guys,

I am about to add a common mode choke to isolate the antenna from its
feedline to each of my beverages and I only have FT240-61 ferrites. My
question is how many turns should I do on the ferrite using RG58 (all my
bevs are fed with RG58). Also should I put the choke near the 9:1 balun or
near my bev switching box?

Thanks in advance.

73's Filipe Lopes
CT1ILT - CR6K
F4VPX - TM3M

_
Topband Reflector Archives - http://www.contesting.com/_topband

 

_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[shristov]

 Eduardo Araujo via Topband  wrote:

> My two cents..It was interesting during the installation of 
> the last beverage, we have only #31 core, so we placed it at the 
> receiver side. Disconnecting the coax at the bev feed point and 
> shorting the coax there, many AM broadcast stations could be 
> heard and some of them strong, indicating that even though one 
> choke was at the receiver side the coax was acting like an 
> antenna. The coax was just lying on the ground and is 40/50 mts 
> long. 

> When we got more cores and placed one choke at that place close 
> to the short, repeating the test before and after most broadcast 
> vanished and only one could be heard very week.


This is exactly as expected.

In the first case you fed all the RF received by the outer surface of the coax
directly inside the coax, and directly to your RX input.

In the second case, a significant isolating impedance was added
and the said RF was attenuated.

73,

Sinisa  YT1NT, VE3EA
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Commond mode choke for Beverage

[Jim Brown]

On Mon,10/12/2015 1:27 PM, JC wrote:

It works like a voltage divider where the impedance to ground should be lower 
as possible to give you more attenuation  like 1k/500ohms versus 1K/5 ohms 
divider.


Yes.

But to expand on this -- often the interference is coupled into a gain 
stage or RX by a Pin One Problem. ALWAYS make the first connection of 
any cable shield to the shielding enclosure of EVERY active device. 
Follow this rule regardless of the function of the cable -- input, 
output, control line, RF or audio.


It's also good practice to bring RX antennas into the shack via the same 
grounding panel used for TX antennas. And that panel must be tied to 
local ground rods, those rods bonded to all other grounds, to the shack 
desk, etc.


73, Jim K9YC
_
Topband Reflector Archives - http://www.contesting.com/_topband