K3S parasitic oscillation


Paul Bowen <paulbowen@...>
 

Hi

A friend of mine has a K3S he`s 90 years old and does not do the internet so
I have been tasked with helping him find a solution.
I have tried to get support from Elecraft and their just not interested in
helping out the rig has been to the UK dealer at least three times yet still
the problem persists.
They cannot replicate the problem so have washed their hands of it now.

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy
load. When used with the ATU and a power above 10 watts the K3S goes into
parasitic oscillation in bands from 80m and above.
All other HF rigs when used with the same setup are fine including a K3,
Icom IC 7300. The K3S serial number is 11871.

Cheers

Paul

M0pnn


Mike Flowers
 

Hi Paul,

I suspect RF in the shack is causing this. Try only a power supply with very short DC supply leads and a known resonant antenna and see if the problem persists.

-- 73 de Mike Flowers, K6MKF, NCDXC - "It's about DX!"

On Feb 28, 2021, at 6:50 PM, Paul Bowen <paulbowen@pleasemail.me.uk> wrote:

Hi

A friend of mine has a K3S he`s 90 years old and does not do the internet so
I have been tasked with helping him find a solution.
I have tried to get support from Elecraft and their just not interested in
helping out the rig has been to the UK dealer at least three times yet still
the problem persists.
They cannot replicate the problem so have washed their hands of it now.

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy
load. When used with the ATU and a power above 10 watts the K3S goes into
parasitic oscillation in bands from 80m and above.
All other HF rigs when used with the same setup are fine including a K3,
Icom IC 7300. The K3S serial number is 11871.

Cheers

Paul

M0pnn







bill steffey NY9H
 

not to be disrespectful...  maybe you have already dealt with these variables.


always need to ask ....  what is the antenna   ????  ( hope it is not a loop above the shack )...

WHAT IS THE SWR before the tuner?

what is the Atu... IS IT THE INTERNAL ATU ??

stock elecraft microphone  or some assembly of adapters and cables ??? wired boom headset ??  data interface disconnected?

I think that Rf in the shack sounds very plausible.  Especially If it worked at "the shop".


bill




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Michael Kopec
 

Hello Paul. I had a similar problem but only on 160m. Tore my hair out for a while as well as my cables, hi Ended up being the power supply. I bonded the power supply to the K3s and the problem went away. Every thing else in the shack was bonded.

On Sunday, February 28, 2021, 09:50:09 PM EST, Paul Bowen <paulbowen@...> wrote:


Hi

A friend of mine has a K3S he`s 90 years old and does not do the internet so
I have been tasked with helping him find a solution.
I have tried to get support from Elecraft and their just not interested in
helping out the rig has been to the UK dealer at least three times yet still
the problem persists.
They cannot replicate the problem so have washed their hands of it now.

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy
load. When used with the ATU and a power above 10 watts the K3S goes into
parasitic oscillation in bands from 80m and above.
All other HF rigs when used with the same setup are fine including a K3,
Icom IC 7300. The K3S serial number is 11871.

Cheers

Paul

M0pnn








Bob McGraw - K4TAX
 

My K3S had a reported fuzzy sound on SSB.  Turned out to be the KPA3a 100 watt PA.   The issue was not noticed below the power range of 12 watts.  I observed, by spectrum analyzer, the instability.   The end result is that Elecraft replaced the 100 watt PA with "a more stable Rev E unit".

Problem resolved.

73

Bob, K4TAX

On 2/28/2021 11:51 AM, Paul Bowen wrote:
Hi

A friend of mine has a K3S he`s 90 years old and does not do the internet so
I have been tasked with helping him find a solution.
I have tried to get support from Elecraft and their just not interested in
helping out the rig has been to the UK dealer at least three times yet still
the problem persists.
They cannot replicate the problem so have washed their hands of it now.

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy
load. When used with the ATU and a power above 10 watts the K3S goes into
parasitic oscillation in bands from 80m and above.
All other HF rigs when used with the same setup are fine including a K3,
Icom IC 7300. The K3S serial number is 11871.

Cheers

Paul

M0pnn






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Jim Brown
 

Bill and Michael are asking the right questions. End fed wires that end in the shack are a recipe for RF in the shack. To be stable (no RF issues) there MUST be a good counterpoise that approaches resonance on the bands where you want to operate it or lots of on-ground radials that can be of random length.

Second, proper grounding and bonding must be practiced in the shack and throughout the home. Study N0AX's ARRL Book on Grounding and Bonding, to which I contributed) and/or this set of slides for talks I've given at Pacificon, Visalia, and several ham clubs.

http://k9yc.com/GroundingAndAudio.pdf

If any of this is missing, antenna return current will take whatever path that exists by accident, usually through the equipment in your shack to the green wire on the power line outlet in the shack.

73, Jim K9YC

On 2/28/2021 7:15 PM, bill steffey NY9H wrote:
not to be disrespectful...  maybe you have already dealt with these variables.
always need to ask ....  what is the antenna   ????  ( hope it is not a loop above the shack )...
WHAT IS THE SWR before the tuner?
what is the Atu... IS IT THE INTERNAL ATU ??
stock elecraft microphone  or some assembly of adapters and cables ??? wired boom headset ??  data interface disconnected?
I think that Rf in the shack sounds very plausible.  Especially If it worked at "the shop".
bill


Bob McGraw - K4TAX
 

From my experience the ground terminal on the radio  MUST be bonded to the power supply ground.  If nothing else, it reduces the IR drop in the DC cable.   There's other advantages too.

73

Bob, K4TAX


On 2/28/2021 9:24 PM, Michael Kopec via groups.io wrote:
Hello Paul. I had a similar problem but only on 160m. Tore my hair out for a while as well as my cables, hi Ended up being the power supply. I bonded the power supply to the K3s and the problem went away. Every thing else in the shack was bonded.
On Sunday, February 28, 2021, 09:50:09 PM EST, Paul Bowen <paulbowen@...> wrote:


Hi

A friend of mine has a K3S he`s 90 years old and does not do the internet so
I have been tasked with helping him find a solution.
I have tried to get support from Elecraft and their just not interested in
helping out the rig has been to the UK dealer at least three times yet still
the problem persists.
They cannot replicate the problem so have washed their hands of it now.

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy
load. When used with the ATU and a power above 10 watts the K3S goes into
parasitic oscillation in bands from 80m and above.
All other HF rigs when used with the same setup are fine including a K3,
Icom IC 7300. The K3S serial number is 11871.

Cheers

Paul

M0pnn










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Ray Maxfield
 

I would install snap-on ferrite beads on ALL

Wire connected to the K3S………

Ray WA6VAB   K3 # 3824

 

 

 

From: Bob McGraw - K4TAX
Sent: Sunday, February 28, 2021 8:36 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3S parasitic oscillation

 

From my experience the ground terminal on the radio  MUST be bonded to the power supply ground.  If nothing else, it reduces the IR drop in the DC cable.   There's other advantages too.

73

Bob, K4TAX

 

On 2/28/2021 9:24 PM, Michael Kopec via groups.io wrote:

Hello Paul. I had a similar problem but only on 160m. Tore my hair out for a while as well as my cables, hi Ended up being the power supply. I bonded the power supply to the K3s and the problem went away. Every thing else in the shack was bonded.

On Sunday, February 28, 2021, 09:50:09 PM EST, Paul Bowen <paulbowen@...> wrote:

 

 

Hi

 

A friend of mine has a K3S he`s 90 years old and does not do the internet so

I have been tasked with helping him find a solution.

I have tried to get support from Elecraft and their just not interested in

helping out the rig has been to the UK dealer at least three times yet still

the problem persists.

They cannot replicate the problem so have washed their hands of it now.

 

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy

load. When used with the ATU and a power above 10 watts the K3S goes into

parasitic oscillation in bands from 80m and above.

All other HF rigs when used with the same setup are fine including a K3,

Icom IC 7300. The K3S serial number is 11871.

 

Cheers

 

Paul

 

M0pnn

 

 

 

 

 

 

 

 

AVG logo

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Rick NK7I
 

I would submit that if this was required; the station isn't assembled correctly.  While a few interface cables (USB, unfiltered audio) may need added ferrites (a flaw in the computer, not the radio), if the station is built properly (keeping the RF OUTside the shack) very few ferrite are ever needed.

This includes proper grounding, bonding, using a common mode current choke/transformer AT THE ANTENNA FEED POINT and antennas that are correctly installed (not a random end fed, using the coax as the counterpoise).

There should be zero reason to be required to ferrite all the cables.  Something is radically WRONG if that's required.

73,
Rick NK7I


On 3/1/2021 10:42 AM, Ray Maxfield wrote:

I would install snap-on ferrite beads on ALL

Wire connected to the K3S………

Ray WA6VAB   K3 # 3824

 

 

 

From: Bob McGraw - K4TAX
Sent: Sunday, February 28, 2021 8:36 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3S parasitic oscillation

 

From my experience the ground terminal on the radio  MUST be bonded to the power supply ground.  If nothing else, it reduces the IR drop in the DC cable.   There's other advantages too.

73

Bob, K4TAX

 

On 2/28/2021 9:24 PM, Michael Kopec via groups.io wrote:

Hello Paul. I had a similar problem but only on 160m. Tore my hair out for a while as well as my cables, hi Ended up being the power supply. I bonded the power supply to the K3s and the problem went away. Every thing else in the shack was bonded.

On Sunday, February 28, 2021, 09:50:09 PM EST, Paul Bowen <paulbowen@...> wrote:

 

 

Hi

 

A friend of mine has a K3S he`s 90 years old and does not do the internet so

I have been tasked with helping him find a solution.

I have tried to get support from Elecraft and their just not interested in

helping out the rig has been to the UK dealer at least three times yet still

the problem persists.

They cannot replicate the problem so have washed their hands of it now.

 

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy

load. When used with the ATU and a power above 10 watts the K3S goes into

parasitic oscillation in bands from 80m and above.

All other HF rigs when used with the same setup are fine including a K3,

Icom IC 7300. The K3S serial number is 11871.

 

Cheers

 

Paul

 

M0pnn

 

 

 

 

 

 

 

 

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Bob McGraw - K4TAX
 

Agreed!  I've cleaned up my configuration such that no ferrite chokes are required on any inside cables.   I'm using 3 coax fed antennas with ferrite chokes at the feed point and one balanced fed antenna with the balanced line all the way to the balun on top  of the ATU on the desk.  I have no RFI issues at 500 watts, 160M - 6M, any mode. 

73

Bob, K4TAX

On 3/1/2021 12:50 PM, Rick NK7I wrote:

I would submit that if this was required; the station isn't assembled correctly.  While a few interface cables (USB, unfiltered audio) may need added ferrites (a flaw in the computer, not the radio), if the station is built properly (keeping the RF OUTside the shack) very few ferrite are ever needed.

This includes proper grounding, bonding, using a common mode current choke/transformer AT THE ANTENNA FEED POINT and antennas that are correctly installed (not a random end fed, using the coax as the counterpoise).

There should be zero reason to be required to ferrite all the cables.  Something is radically WRONG if that's required.

73,
Rick NK7I


On 3/1/2021 10:42 AM, Ray Maxfield wrote:

I would install snap-on ferrite beads on ALL

Wire connected to the K3S………

Ray WA6VAB   K3 # 3824

 

 

 

From: Bob McGraw - K4TAX
Sent: Sunday, February 28, 2021 8:36 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3S parasitic oscillation

 

From my experience the ground terminal on the radio  MUST be bonded to the power supply ground.  If nothing else, it reduces the IR drop in the DC cable.   There's other advantages too.

73

Bob, K4TAX

 

On 2/28/2021 9:24 PM, Michael Kopec via groups.io wrote:

Hello Paul. I had a similar problem but only on 160m. Tore my hair out for a while as well as my cables, hi Ended up being the power supply. I bonded the power supply to the K3s and the problem went away. Every thing else in the shack was bonded.

On Sunday, February 28, 2021, 09:50:09 PM EST, Paul Bowen <paulbowen@...> wrote:

 

 

Hi

 

A friend of mine has a K3S he`s 90 years old and does not do the internet so

I have been tasked with helping him find a solution.

I have tried to get support from Elecraft and their just not interested in

helping out the rig has been to the UK dealer at least three times yet still

the problem persists.

They cannot replicate the problem so have washed their hands of it now.

 

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy

load. When used with the ATU and a power above 10 watts the K3S goes into

parasitic oscillation in bands from 80m and above.

All other HF rigs when used with the same setup are fine including a K3,

Icom IC 7300. The K3S serial number is 11871.

 

Cheers

 

Paul

 

M0pnn

 

 

 

 

 

 

 

 

AVG logo

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K9MA
 

I think it would take extreme amounts of RF in the shack to require ferrite chokes on any of the K3 cables. My shunt fed tower is only 10 meters from the shack, and I know there's a lot of RF flying around on 160, but the K3 has never missed a beat. The water heater and the wireless weather station on the other hand.....

73,
Scott K9MA

On 3/1/2021 2:17 PM, Bob McGraw - K4TAX wrote:

Agreed!  I've cleaned up my configuration such that no ferrite chokes are required on any inside cables.   I'm using 3 coax fed antennas with ferrite chokes at the feed point and one balanced fed antenna with the balanced line all the way to the balun on top  of the ATU on the desk.  I have no RFI issues at 500 watts, 160M - 6M, any mode. 

73

Bob, K4TAX

On 3/1/2021 12:50 PM, Rick NK7I wrote:

I would submit that if this was required; the station isn't assembled correctly.  While a few interface cables (USB, unfiltered audio) may need added ferrites (a flaw in the computer, not the radio), if the station is built properly (keeping the RF OUTside the shack) very few ferrite are ever needed.

This includes proper grounding, bonding, using a common mode current choke/transformer AT THE ANTENNA FEED POINT and antennas that are correctly installed (not a random end fed, using the coax as the counterpoise).

There should be zero reason to be required to ferrite all the cables.  Something is radically WRONG if that's required.

73,
Rick NK7I


On 3/1/2021 10:42 AM, Ray Maxfield wrote:

I would install snap-on ferrite beads on ALL

Wire connected to the K3S………

Ray WA6VAB   K3 # 3824

 

 

 

From: Bob McGraw - K4TAX
Sent: Sunday, February 28, 2021 8:36 PM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] K3S parasitic oscillation

 

From my experience the ground terminal on the radio  MUST be bonded to the power supply ground.  If nothing else, it reduces the IR drop in the DC cable.   There's other advantages too.

73

Bob, K4TAX

 

On 2/28/2021 9:24 PM, Michael Kopec via groups.io wrote:

Hello Paul. I had a similar problem but only on 160m. Tore my hair out for a while as well as my cables, hi Ended up being the power supply. I bonded the power supply to the K3s and the problem went away. Every thing else in the shack was bonded.

On Sunday, February 28, 2021, 09:50:09 PM EST, Paul Bowen <paulbowen@...> wrote:

 

 

Hi

 

A friend of mine has a K3S he`s 90 years old and does not do the internet so

I have been tasked with helping him find a solution.

I have tried to get support from Elecraft and their just not interested in

helping out the rig has been to the UK dealer at least three times yet still

the problem persists.

They cannot replicate the problem so have washed their hands of it now.

 

The K3S is fine when used with 10 watts and fine with 100 watts into a dummy

load. When used with the ATU and a power above 10 watts the K3S goes into

parasitic oscillation in bands from 80m and above.

All other HF rigs when used with the same setup are fine including a K3,

Icom IC 7300. The K3S serial number is 11871.

 

Cheers

 

Paul

 

M0pnn

 

 

 

 

 

 

 

 

AVG logo

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-- 
Scott  K9MA

k9ma@...


Wes
 

Especially the ground wire.


On 3/1/2021 11:42 AM, Ray Maxfield wrote:

I would install snap-on ferrite beads on ALL

Wire connected to the K3S………

Ray WA6VAB   K3 # 3824

 



Dave (NK7Z)
 

Why the ground wire?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 3/1/21 4:08 PM, Wes wrote:
Especially the ground wire.
On 3/1/2021 11:42 AM, Ray Maxfield wrote:

I would install snap-on ferrite beads on *ALL*

Wire connected to the K3S………

Ray WA6VAB   K3 # 3824


Wes Stewart
 

A little attempt at humor.

The only ferrite in my station is the few molded on pieces in pre-made cables.  I've never understood the need for pounds of ferrite in an amateur radio station, other than feedline chokes at antenna feedpoints.

Wes  N7WS

On Monday, March 1, 2021, 5:28:51 PM MST, Dave Cole <dave@...> wrote:


Why the ground wire?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 3/1/21 4:08 PM, Wes wrote:
> Especially the ground wire.
>
>
> On 3/1/2021 11:42 AM, Ray Maxfield wrote:
>>
>> I would install snap-on ferrite beads on *ALL*
>>
>> Wire connected to the K3S………
>>
>> Ray WA6VAB   K3 # 3824
>>
>
>






K9MA
 

I have plenty of them, but not on the K3. Many of the cables to the desktop computer, for example. However, my antennas aren't far away, and I shunt feed the tower on 80 and 160.

73,
Scott K9MA



On 3/2/2021 7:57 AM, Wes Stewart via groups.io wrote:
A little attempt at humor.

The only ferrite in my station is the few molded on pieces in pre-made cables.  I've never understood the need for pounds of ferrite in an amateur radio station, other than feedline chokes at antenna feedpoints.

Wes  N7WS

On Monday, March 1, 2021, 5:28:51 PM MST, Dave Cole <dave@...> wrote:


Why the ground wire?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 3/1/21 4:08 PM, Wes wrote:
> Especially the ground wire.
>
>
> On 3/1/2021 11:42 AM, Ray Maxfield wrote:
>>
>> I would install snap-on ferrite beads on *ALL*
>>
>> Wire connected to the K3S………
>>
>> Ray WA6VAB   K3 # 3824
>>
>
>






-- 
Scott  K9MA

k9ma@...


Dave (NK7Z)
 

OK, I thought you were serious! :)

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 3/2/21 5:57 AM, Wes Stewart via groups.io wrote:
A little attempt at humor.
The only ferrite in my station is the few molded on pieces in pre-made cables.  I've never understood the need for pounds of ferrite in an amateur radio station, other than feedline chokes at antenna feedpoints.
Wes  N7WS
On Monday, March 1, 2021, 5:28:51 PM MST, Dave Cole <dave@nk7z.net> wrote:
Why the ground wire?
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 3/1/21 4:08 PM, Wes wrote:
> Especially the ground wire.
>
>
> On 3/1/2021 11:42 AM, Ray Maxfield wrote:
>>
>> I would install snap-on ferrite beads on *ALL*
>>
>> Wire connected to the K3S………
>>
>> Ray WA6VAB   K3 # 3824
>>
>
>


 

The ferrite beads on commercially available computer cables are rather ineffective on short wave frequencies. The choking effect occurs above 50 MHz.

73,
Martin, OK1RR

Dne 02. 03. 21 v 15:48 K9MA napsal(a):

I have plenty of them, but not on the K3. Many of the cables to the desktop computer, for example. However, my antennas aren't far away, and I shunt feed the tower on 80 and 160.

73,
Scott K9MA



On 3/2/2021 7:57 AM, Wes Stewart via groups.io wrote:
A little attempt at humor.

The only ferrite in my station is the few molded on pieces in pre-made cables.  I've never understood the need for pounds of ferrite in an amateur radio station, other than feedline chokes at antenna feedpoints.

Wes  N7WS

On Monday, March 1, 2021, 5:28:51 PM MST, Dave Cole <dave@nk7z.net> wrote:


Why the ground wire?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net <https://www.nk7z.net>
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 3/1/21 4:08 PM, Wes wrote:
Especially the ground wire.


On 3/1/2021 11:42 AM, Ray Maxfield wrote:

I would install snap-on ferrite beads on *ALL*

Wire connected to the K3S………

Ray WA6VAB   K3 # 3824





ANDY NEHAN
 

Some antenna systems induce unwanted currents - for me this was true when I used off centre fed dipoles but moving to resonant dipoles the problem disappeared.


Andy G4HUE




------ Original Message ------
From: "K9MA" <K9ma@...>
To: Elecraft-K3@groups.io
Sent: Tuesday, 2 Mar, 2021 At 14:48
Subject: Re: [Elecraft-K3] K3S parasitic oscillation

I have plenty of them, but not on the K3. Many of the cables to the desktop computer, for example. However, my antennas aren't far away, and I shunt feed the tower on 80 and 160.

73,
Scott K9MA



On 3/2/2021 7:57 AM, Wes Stewart via groups.io wrote:
A little attempt at humor.

The only ferrite in my station is the few molded on pieces in pre-made cables. I've never understood the need for pounds of ferrite in an amateur radio station, other than feedline chokes at antenna feedpoints.

Wes N7WS

On Monday, March 1, 2021, 5:28:51 PM MST, Dave Cole <dave@...> wrote:


Why the ground wire?

73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

On 3/1/21 4:08 PM, Wes wrote:
> Especially the ground wire.
>
>
> On 3/1/2021 11:42 AM, Ray Maxfield wrote:
>>
>> I would install snap-on ferrite beads on *ALL*
>>
>> Wire connected to the K3S………
>>
>> Ray WA6VAB K3 # 3824
>>
>
>






-- 
Scott  K9MA

k9ma@...


Bob McGraw - K4TAX
 

Most OCFD antennas require a proper balun at the feed point plus a common mode choke.  I along with others (DJ0IP to mention one) find many commercial baluns do not have proper designs to provide the needed common mode current rejection. 


73

Bob, K4TAX



On 3/2/2021 9:32 AM, ANDY NEHAN via groups.io wrote:
Some antenna systems induce unwanted currents - for me this was true when I used off centre fed dipoles but moving to resonant dipoles the problem disappeared.


Andy G4HUE


------ Original Message ------ From: "K9MA" <K9ma@...> To: Elecraft-K3@groups.io Sent: Tuesday, 2 Mar, 2021 At 14:48 Subject: Re: [Elecraft-K3] K3S parasitic oscillation
I have plenty of them, but not on the K3. Many of the cables to the desktop computer, for example. However, my antennas aren't far away, and I shunt feed the tower on 80 and 160.
73,
Scott K9MA
On 3/2/2021 7:57 AM, Wes Stewart via groups.io wrote:
A little attempt at humor.
The only ferrite in my station is the few molded on pieces in pre-made cables. I've never understood the need for pounds of ferrite in an amateur radio station, other than feedline chokes at antenna feedpoints.
Wes N7WS
On Monday, March 1, 2021, 5:28:51 PM MST, Dave Cole <dave@...> wrote:
Why the ground wire? 73, and thanks, Dave (NK7Z) https://www.nk7z.net ARRL Volunteer Examiner ARRL Technical Specialist, RFI ARRL Asst. Director, NW Division, Technical Resources On 3/1/21 4:08 PM, Wes wrote: > Especially the ground wire. > > > On 3/1/2021 11:42 AM, Ray Maxfield wrote: >> >> I would install snap-on ferrite beads on *ALL* >> >> Wire connected to the K3S……… >> >> Ray WA6VAB K3 # 3824 >> > >

-- 
Scott  K9MA

k9ma@...

Virus-free. www.avg.com


Joe Subich, W4TV
 

On 2021-03-02 11:17 AM, Bob McGraw - K4TAX wrote:
Most OCFD antennas require a proper balun at the feed point plus a
common mode choke.
Correct that to "require an impedance matching transformer (e.g. un-un
or auto transformer) *AND* a proper common mode choke. The device at
the feed point of most OCFDs is not a "BALUN" (balanced to unbalanced
transformer) but an un-un (unbalanced to unbalanced "step up" auto-
transformer).

The antenna builder may use a so called 4:1 "voltage balun" but when
you look at the "voltage balun" there is nothing "balanced" about it
and it is a simple auto-transformer. The auto transformer becomes
even more obvious in OCFDs designed for feed point impedance higher
that 200 Ohms (e.g. antennas designed for operation on other bands
in addition to 80, 40, 20 and 10 meters).

73,

... Joe, W4TV


On 2021-03-02 11:17 AM, Bob McGraw - K4TAX wrote:
Most OCFD antennas require a proper balun at the feed point plus a common mode choke.  I along with others (DJ0IP to mention one) find many commercial baluns do not have proper designs to provide the needed common mode current rejection.
73
Bob, K4TAX
On 3/2/2021 9:32 AM, ANDY NEHAN via groups.io wrote:
Some antenna systems induce unwanted currents - for me this was true when I used off centre fed dipoles but moving to resonant dipoles the problem disappeared.


Andy G4HUE


------ Original Message ------ From: "K9MA" <K9ma@sdellington.us>
To: Elecraft-K3@groups.io Sent: Tuesday, 2 Mar, 2021 At 14:48
Subject: Re: [Elecraft-K3] K3S parasitic oscillation
I have plenty of them, but not on the K3. Many of the cables to
the desktop computer, for example. However, my antennas aren't far
away, and I shunt feed the tower on 80 and 160.
73,
Scott K9MA
On 3/2/2021 7:57 AM, Wes Stewart via groups.io wrote:

A little attempt at humor.
The only ferrite in my station is the few molded on pieces in
pre-made cables. I've never understood the need for pounds of
ferrite in an amateur radio station, other than feedline
chokes at antenna feedpoints.
Wes N7WS
On Monday, March 1, 2021, 5:28:51 PM MST, Dave Cole
<dave@nk7z.net> wrote:
Why the ground wire? 73, and thanks, Dave (NK7Z)
https://www.nk7z.net <https://www.nk7z.net> ARRL Volunteer
Examiner ARRL Technical Specialist, RFI ARRL Asst. Director,
NW Division, Technical Resources On 3/1/21 4:08 PM, Wes wrote:
> Especially the ground wire. > > > On 3/1/2021 11:42 AM, Ray
Maxfield wrote: >> >> I would install snap-on ferrite beads on
*ALL* >> >> Wire connected to the K3S……… >> >> Ray WA6VAB K3 #
3824 >> > >

--
Scott K9MA

k9ma@sdellington.us