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RFI in audio chain

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Jan Ditzian

RFI in audio chain

I have a problem that appears to be changing, but I could use some
help. The problem is RFI in the audio input (microphone input) when I
use my vertical antenna on 40 meters. Here is a rundown of what has
happened:

I have a 67-foot elevated vertical that I can use on 80 and 40, and it
works fine on CW. However, on SSB, both bands, there clearly is
feedback; there is no feedback on the other bands where I use a C3
yagi. Initially, the feedback was so bad that the rig would go into
oscillation, and I had to turn the amp to standby.

I recently purchased the new KSYN3A and decided to install it. I
replaced the K3 with my IC-730 backup, using the hand microphone that
came with the 730. The 730 did not have any RFI. I finished the
modification and returned the K3 as the operating rig. Now, the RFI on
40 seems to have diminished substantially or disappeared, but it still
happens on 75/80. However, it seems to be much less there as well. I
do not suspect that the KSYN3A had anything to do with this, but perhaps
I tightened connections better when I returned the rig to service. I
also redid some ground connections.

The microphone for the K3 is an Audio-Technica that works well
everywhere else. It has a long cord, though. I put a few toroids on
the cord near the microphone connector and that has possibly reduced RFI
a little, but it is still there.

Is there a possibility that a bypass capacitor is bad, or has someone
else had the problem and solved it externally to the K3? For instance,
has anyone found that a long string of ferrite beads has cured this problem?

Despite decades of operating, I am hardly a troubleshooting hotshot, and
I would appreciate guidance.

Thank you,

Jan, KX2A

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Don Wilhelm-4

Re: RFI in audio chain

Jan,

Toroids on the mic cord may help, but the real solution is to eliminate
the RF on the outside of the coax shield in the antenna field.
Refer to the writings of Jim Brown K9YC for effective baluns (he prefers
common mode chokes because balun is not a specific thing - some good,
some bad).
Look at chapters 6 and beyond of
http://audiosystemsgroup.com/RFI-Ham.pdf to eliminate the theory and get
right to the subject of constructing effective common mode chokes for HF.

Keeping RF out of the shack is your first measure of defense. Cure the
antenna field problems and if there are still problems, then try
ferrites on the station equipment lines.

73,
Don W3FPR

On 11/22/2015 6:02 PM, Jan Ditzian wrote:

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John Kramer

Re: RFI in audio chain

In reply to this post by Jan Ditzian

Jan

The easiest, quickest and cheapest method is to wind yourself an “ugly balun” in your coax cable line.
It must be located OUTSIDE your shack to choke the common mode currents from entering the shack.
Wind about 15 - 20 turns of your coax on a 6” PVC pipe. This will give you about 2500 ohms choking
impedance.

If there is still RFI getting in the shack, then purchase a commercial choke either from
http://www.balundesigns.com/model-1115d-max-choking-1-1-balun-1-54-mhz-5kw/
this will provide about 10 - 12 000 ohms of choking impedance, or buy one from

http://myantennas.com/wp/product/cmc-130-3k/
This one will give from 12 000 - 15 000 ohms of choking impedance.

These common mode chokes merely get plugged inline in your coax cable. Always better to locate
them outside the shack

73
John

On 23 Nov 2015, at 1:02 AM, Jan Ditzian <[hidden email]> wrote:

I have a problem that appears to be changing, but I could use some help. The problem is RFI in the audio input (microphone input) when I use my vertical antenna on 40 meters. Here is a rundown of what has happened:

I have a 67-foot elevated vertical that I can use on 80 and 40, and it works fine on CW. However, on SSB, both bands, there clearly is feedback; there is no feedback on the other bands where I use a C3 yagi. Initially, the feedback was so bad that the rig would go into oscillation, and I had to turn the amp to standby.

I recently purchased the new KSYN3A and decided to install it. I replaced the K3 with my IC-730 backup, using the hand microphone that came with the 730. The 730 did not have any RFI. I finished the modification and returned the K3 as the operating rig. Now, the RFI on 40 seems to have diminished substantially or disappeared, but it still happens on 75/80. However, it seems to be much less there as well. I do not suspect that the KSYN3A had anything to do with this, but perhaps I tightened connections better when I returned the rig to service. I also redid some ground connections.

The microphone for the K3 is an Audio-Technica that works well everywhere else. It has a long cord, though. I put a few toroids on the cord near the microphone connector and that has possibly reduced RFI a little, but it is still there.

Is there a possibility that a bypass capacitor is bad, or has someone else had the problem and solved it externally to the K3? For instance, has anyone found that a long string of ferrite beads has cured this problem?

Despite decades of operating, I am hardly a troubleshooting hotshot, and I would appreciate guidance.

Thank you,

Jan, KX2A

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Jan Ditzian

Re: RFI in audio chain

In response to the balun recommendation from several hams, I apologize
for forgetting to mention that the vertical has an "ugly balun" both at
the antenna and near where the feedline enters the house.

Part of the reason I put the question to this group, after first
thinking that the amps group could help, was the fact that the IC-730
shows no RFI, while the K3 shows extreme RFI.

Thanks,

Jan, KX2A

On 11/22/2015 6:36 PM, John Kramer wrote:

> Jan
>
> The easiest, quickest and cheapest method is to wind yourself an “ugly balun” in your coax cable line.
> It must be located OUTSIDE your shack to choke the common mode currents from entering the shack.
> Wind about 15 - 20 turns of your coax on a 6” PVC pipe. This will give you about 2500 ohms choking
> impedance.
>
> If there is still RFI getting in the shack, then purchase a commercial choke either from
> http://www.balundesigns.com/model-1115d-max-choking-1-1-balun-1-54-mhz-5kw/
> this will provide about 10 - 12 000 ohms of choking impedance, or buy one from
>
> http://myantennas.com/wp/product/cmc-130-3k/
> This one will give from 12 000 - 15 000 ohms of choking impedance.
>
> These common mode chokes merely get plugged inline in your coax cable. Always better to locate
> them outside the shack
>
> 73
> John
>
>
>
>
> On 23 Nov 2015, at 1:02 AM, Jan Ditzian <[hidden email]> wrote:
>
> I have a problem that appears to be changing, but I could use some help. The problem is RFI in the audio input (microphone input) when I use my vertical antenna on 40 meters. Here is a rundown of what has happened:
>
> I have a 67-foot elevated vertical that I can use on 80 and 40, and it works fine on CW. However, on SSB, both bands, there clearly is feedback; there is no feedback on the other bands where I use a C3 yagi. Initially, the feedback was so bad that the rig would go into oscillation, and I had to turn the amp to standby.
>
> I recently purchased the new KSYN3A and decided to install it. I replaced the K3 with my IC-730 backup, using the hand microphone that came with the 730. The 730 did not have any RFI. I finished the modification and returned the K3 as the operating rig. Now, the RFI on 40 seems to have diminished substantially or disappeared, but it still happens on 75/80. However, it seems to be much less there as well. I do not suspect that the KSYN3A had anything to do with this, but perhaps I tightened connections better when I returned the rig to service. I also redid some ground connections.
>
> The microphone for the K3 is an Audio-Technica that works well everywhere else. It has a long cord, though. I put a few toroids on the cord near the microphone connector and that has possibly reduced RFI a little, but it is still there.
>
> Is there a possibility that a bypass capacitor is bad, or has someone else had the problem and solved it externally to the K3? For instance, has anyone found that a long string of ferrite beads has cured this problem?
>
> Despite decades of operating, I am hardly a troubleshooting hotshot, and I would appreciate guidance.
>
> Thank you,
>
> Jan, KX2A
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
>
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Joe Subich, W4TV-4

Re: RFI in audio chain

In reply to this post by Jan Ditzian

> I have a 67-foot elevated vertical that I can use on 80 and 40, and
> it works fine on CW. However, on SSB, both bands, there clearly is
> feedback; there is no feedback on the other bands where I use a C3
> yagi.

Elevated verticals will treat the [outside of the] feedline as a
random length radial. The current on the feedline will be proportional
to how close the feedline length is to a quarter (or half) wavelength
depending on whether the chassis of the transceiver/tuner/amplifier is
floating/grounded. It is *imperative* that there be a high quality
common mode choke on the feedline at the feed point of the antenna.
"Ugly balun" or other random solenoid wound chokes are not reliable -
see the work by K9YC, GM3SEK, etc. and select a choke that shows at
least 5 K (preferably 10K) choking impedance on 80 and 40 meters to
disconnect the outside of the coax shield from the antenna.

> The microphone for the K3 is an Audio-Technica that works well
> everywhere else.

Assuming the Audio-Technica has an XLR connector, make *sure* the
shield (pin 1) is *not* connected to the mic return (pin 7, pin 8)
and depending on the age of your K3 make sure there is no RF choke
between pin 7 or pin 8 and the circuit board ground.

73,

... Joe, W4TV

On 11/22/2015 6:02 PM, Jan Ditzian wrote:

> I have a problem that appears to be changing, but I could use some
> help. The problem is RFI in the audio input (microphone input) when I
> use my vertical antenna on 40 meters. Here is a rundown of what has
> happened:
>
> I have a 67-foot elevated vertical that I can use on 80 and 40, and it
> works fine on CW. However, on SSB, both bands, there clearly is
> feedback; there is no feedback on the other bands where I use a C3
> yagi. Initially, the feedback was so bad that the rig would go into
> oscillation, and I had to turn the amp to standby.
>
> I recently purchased the new KSYN3A and decided to install it. I
> replaced the K3 with my IC-730 backup, using the hand microphone that
> came with the 730. The 730 did not have any RFI. I finished the
> modification and returned the K3 as the operating rig. Now, the RFI on
> 40 seems to have diminished substantially or disappeared, but it still
> happens on 75/80. However, it seems to be much less there as well. I
> do not suspect that the KSYN3A had anything to do with this, but perhaps
> I tightened connections better when I returned the rig to service. I
> also redid some ground connections.
>
> The microphone for the K3 is an Audio-Technica that works well
> everywhere else. It has a long cord, though. I put a few toroids on
> the cord near the microphone connector and that has possibly reduced RFI
> a little, but it is still there.
>
> Is there a possibility that a bypass capacitor is bad, or has someone
> else had the problem and solved it externally to the K3? For instance,
> has anyone found that a long string of ferrite beads has cured this
> problem?
>
> Despite decades of operating, I am hardly a troubleshooting hotshot, and
> I would appreciate guidance.
>
> Thank you,
>
> Jan, KX2A
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Bob McGraw - K4TAX

Re: RFI in audio chain

In reply to this post by Jan Ditzian

You more likely need a common mode choke on the feed line close to the
radio. Perhaps where the feed line enters the house. A common mode
choke can be also known as "The Ugly Balun"
http://www.hamuniverse.com/balun.html or can be a series of ferrite
beads on a section of coax.

Also see Model # 8232 found on The Wireman website.
https://thewireman.com/prodpix2.html <https://thewireman.com/prodpix2.html>

73
Bob, K4TAX

On 11/22/2015 5:02 PM, Jan Ditzian wrote:
I have a problem that appears to be changing, but I could use some
help. The problem is RFI in the audio input (microphone input) when I
use my vertical antenna on 40 meters. Here is a rundown of what has
happened:

______________________________________________________________
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Phil Anderson

Re: RFI in audio chain

In reply to this post by Jan Ditzian

Hi Jan,

I'm guessing, as several others have discussed using a balun at the base
of the vertical, that the problem is interference running on the outside
of the coax feed. I'm using a STEPPir vertical for 40 through 10. I
tried several baluns with no satisfying success. I then decided to build
a SPGS (single point grounding system) on the outer wall next to my
shack in the back yard. My SPGS is enclosed by DX Engineering's
"Grounding and Utility Encloser," (DXE-UP-2P) and I installed in that
three ALPHA-DELTA lightning arrest (surge protectors) (for three
different antennas, one being a Beverage), and a CONTROL LINE PROTECTOR,
(DXE-IS-RCT), that protects my Steppir vertical antenna control system.
In addition to that I ran #6 copper to the house utility box ground
(from the antenna ground) AND (perhaps most important) ran three ground
rods spread out (at twice the length of the 8' rods) and connected all
of that to the vertical grounding plate (of the SPGS box) The important
thing is that I did not use #6 wire from the vertical to the SGPS box;
instead, I used 2 inch wide copper strip that is bonded to the rods with
copper plates and connections at each end of the run. The 2 inch copper
strip is then attached to the SPGS 14 x 14 plate (with another ground
rod) just outside the house. THE THEORY IS THAT THE WIDE STRAP PROVIDES
FOR A VERY LOW RF IMPEDANCE AT THE FREQUENCY OF OPERATION. This
substantially shunts off any interference returning on the outside braid
of the coax from the vertical. In addition on the inside (at station) I
ran a strip of the 2 inch copper along the back of the station table and
then smaller braided strap from the copper strip to each major piece of
equipment on the station (a reverse V from the SPGS if you will) : DELL
OPTIPLEX COMPUTER (station computer), two 19 in flat screens, my fully
loaded Elecraft K3 with P3 WinkeyerUSB, and Astron switching supply.

The result was immediately apparent: the spikes I had been receiving
that were spaced up and down the 40 through 20 bands as noted on the P3
panadapter where now completely gone. An added surprise was that the
noise floor even went down a bit (and I live two blocks from a shopping
mall!). Prior to this large station upgrade - inside and outside the
house - I would even see interference on the 19 inch screens - that is
now gone too.

If you like I can send you more detail on what I did, including
pictures. I've only been testing it for a week so may find some
glitches....but so far very happy.

73 and good luck. Phil Anderson, W0XI, Lawrence, KS
email: [hidden email]

> Jan Ditzian <mailto:[hidden email]>
> Sunday, November 22, 2015 6:32 PM
> In response to the balun recommendation from several hams, I apologize
> for forgetting to mention that the vertical has an "ugly balun" both
> at the antenna and near where the feedline enters the house.
>
> Part of the reason I put the question to this group, after first
> thinking that the amps group could help, was the fact that the IC-730
> shows no RFI, while the K3 shows extreme RFI.
>
> Thanks,
>
> Jan, KX2A
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
> John Kramer <mailto:[hidden email]>
> Sunday, November 22, 2015 5:36 PM
> Jan
>
> The easiest, quickest and cheapest method is to wind yourself an "ugly
> balun" in your coax cable line.
> It must be located OUTSIDE your shack to choke the common mode
> currents from entering the shack.
> Wind about 15 - 20 turns of your coax on a 6" PVC pipe. This will give
> you about 2500 ohms choking
> impedance.
>
> If there is still RFI getting in the shack, then purchase a commercial
> choke either from
> http://www.balundesigns.com/model-1115d-max-choking-1-1-balun-1-54-mhz-5kw/
>
> this will provide about 10 - 12 000 ohms of choking impedance, or buy
> one from
>
> http://myantennas.com/wp/product/cmc-130-3k/
> This one will give from 12 000 - 15 000 ohms of choking impedance.
>
> These common mode chokes merely get plugged inline in your coax cable.
> Always better to locate
> them outside the shack
>
> 73
> John
>
>
>
>
> On 23 Nov 2015, at 1:02 AM, Jan Ditzian <[hidden email]> wrote:
>
> I have a problem that appears to be changing, but I could use some
> help. The problem is RFI in the audio input (microphone input) when I
> use my vertical antenna on 40 meters. Here is a rundown of what has
> happened:
>
> I have a 67-foot elevated vertical that I can use on 80 and 40, and it
> works fine on CW. However, on SSB, both bands, there clearly is
> feedback; there is no feedback on the other bands where I use a C3
> yagi. Initially, the feedback was so bad that the rig would go into
> oscillation, and I had to turn the amp to standby.
>
> I recently purchased the new KSYN3A and decided to install it. I
> replaced the K3 with my IC-730 backup, using the hand microphone that
> came with the 730. The 730 did not have any RFI. I finished the
> modification and returned the K3 as the operating rig. Now, the RFI on
> 40 seems to have diminished substantially or disappeared, but it still
> happens on 75/80. However, it seems to be much less there as well. I
> do not suspect that the KSYN3A had anything to do with this, but
> perhaps I tightened connections better when I returned the rig to
> service. I also redid some ground connections.
>
> The microphone for the K3 is an Audio-Technica that works well
> everywhere else. It has a long cord, though. I put a few toroids on
> the cord near the microphone connector and that has possibly reduced
> RFI a little, but it is still there.
>
> Is there a possibility that a bypass capacitor is bad, or has someone
> else had the problem and solved it externally to the K3? For instance,
> has anyone found that a long string of ferrite beads has cured this
> problem?
>
> Despite decades of operating, I am hardly a troubleshooting hotshot,
> and I would appreciate guidance.
>
> Thank you,
>
> Jan, KX2A
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
> Jan Ditzian <mailto:[hidden email]>
> Sunday, November 22, 2015 5:02 PM
> I have a problem that appears to be changing, but I could use some
> help. The problem is RFI in the audio input (microphone input) when I
> use my vertical antenna on 40 meters. Here is a rundown of what has
> happened:
>
> I have a 67-foot elevated vertical that I can use on 80 and 40, and it
> works fine on CW. However, on SSB, both bands, there clearly is
> feedback; there is no feedback on the other bands where I use a C3
> yagi. Initially, the feedback was so bad that the rig would go into
> oscillation, and I had to turn the amp to standby.
>
> I recently purchased the new KSYN3A and decided to install it. I
> replaced the K3 with my IC-730 backup, using the hand microphone that
> came with the 730. The 730 did not have any RFI. I finished the
> modification and returned the K3 as the operating rig. Now, the RFI
> on 40 seems to have diminished substantially or disappeared, but it
> still happens on 75/80. However, it seems to be much less there as
> well. I do not suspect that the KSYN3A had anything to do with this,
> but perhaps I tightened connections better when I returned the rig to
> service. I also redid some ground connections.
>
> The microphone for the K3 is an Audio-Technica that works well
> everywhere else. It has a long cord, though. I put a few toroids on
> the cord near the microphone connector and that has possibly reduced
> RFI a little, but it is still there.
>
> Is there a possibility that a bypass capacitor is bad, or has someone
> else had the problem and solved it externally to the K3? For instance,
> has anyone found that a long string of ferrite beads has cured this
> problem?
>
> Despite decades of operating, I am hardly a troubleshooting hotshot,
> and I would appreciate guidance.
>
> Thank you,
>
> Jan, KX2A
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Phil Anderson

Fwd: Re: RFI in audio chain

CC FYI Bill...........very good results.....

Phil

> *From:* Phil Anderson <[hidden email]>
> *Date:* Sunday, November 22, 2015 7:59 PM
> *To:* Jan Ditzian <[hidden email]>
> *CC:* [hidden email], Phil Anderson
> <[hidden email]>
> *Subject:* [Elecraft] RFI in audio chain
> Hi Jan,
>
> I'm guessing, as several others have discussed using a balun at the
> base of the vertical, that the problem is interference running on the
> outside of the coax feed. I'm using a STEPPir vertical for 40 through
> 10. I tried several baluns with no satisfying success. I then decided
> to build a SPGS (single point grounding system) on the outer wall next
> to my shack in the back yard. My SPGS is enclosed by DX Engineering's
> "Grounding and Utility Encloser," (DXE-UP-2P) and I installed in that
> three ALPHA-DELTA lightning arrest (surge protectors) (for three
> different antennas, one being a Beverage), and a CONTROL LINE
> PROTECTOR, (DXE-IS-RCT), that protects my Steppir vertical antenna
> control system. In addition to that I ran #6 copper to the house
> utility box ground (from the antenna ground) AND (perhaps most
> important) ran three ground rods spread out (at twice the length of
> the 8' rods) and connected all of that to the vertical grounding plate
> (of the SPGS box) The important thing is that I did not use #6 wire
> from the vertical to the SGPS box; instead, I used 2 inch wide copper
> strip that is bonded to the rods with copper plates and connections at
> each end of the run. The 2 inch copper strip is then attached to the
> SPGS 14 x 14 plate (with another ground rod) just outside the house.
> THE THEORY IS THAT THE WIDE STRAP PROVIDES FOR A VERY LOW RF IMPEDANCE
> AT THE FREQUENCY OF OPERATION. This substantially shunts off any
> interference returning on the outside braid of the coax from the
> vertical. In addition on the inside (at station) I ran a strip of the
> 2 inch copper along the back of the station table and then smaller
> braided strap from the copper strip to each major piece of equipment
> on the station (a reverse V from the SPGS if you will) : DELL OPTIPLEX
> COMPUTER (station computer), two 19 in flat screens, my fully loaded
> Elecraft K3 with P3 WinkeyerUSB, and Astron switching supply.
>
> The result was immediately apparent: the spikes I had been receiving
> that were spaced up and down the 40 through 20 bands as noted on the
> P3 panadapter where now completely gone. An added surprise was that
> the noise floor even went down a bit (and I live two blocks from a
> shopping mall!). Prior to this large station upgrade - inside and
> outside the house - I would even see interference on the 19 inch
> screens - that is now gone too.
>
> If you like I can send you more detail on what I did, including
> pictures. I've only been testing it for a week so may find some
> glitches....but so far very happy.
>
> 73 and good luck. Phil Anderson, W0XI, Lawrence, KS
> email: [hidden email]
>
>
>
>
>
> ------------------------------------------------------------------------
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> This email has been checked for viruses by Avast antivirus software.
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>
> *From:* John Kramer <[hidden email]>
> *Date:* Sunday, November 22, 2015 5:36 PM
> *To:* Jan Ditzian <[hidden email]>
> *CC:* [hidden email]
> *Subject:* [Elecraft] RFI in audio chain
> Jan
>
> The easiest, quickest and cheapest method is to wind yourself an "ugly
> balun" in your coax cable line.
> It must be located OUTSIDE your shack to choke the common mode
> currents from entering the shack.
> Wind about 15 - 20 turns of your coax on a 6" PVC pipe. This will give
> you about 2500 ohms choking
> impedance.
>
> If there is still RFI getting in the shack, then purchase a commercial
> choke either from
> http://www.balundesigns.com/model-1115d-max-choking-1-1-balun-1-54-mhz-5kw/
>
> this will provide about 10 - 12 000 ohms of choking impedance, or buy
> one from
>
> http://myantennas.com/wp/product/cmc-130-3k/
> This one will give from 12 000 - 15 000 ohms of choking impedance.
>
> These common mode chokes merely get plugged inline in your coax cable.
> Always better to locate
> them outside the shack
>
> 73
> John
>
>
>
>
> On 23 Nov 2015, at 1:02 AM, Jan Ditzian <[hidden email]> wrote:
>
> I have a problem that appears to be changing, but I could use some
> help. The problem is RFI in the audio input (microphone input) when I
> use my vertical antenna on 40 meters. Here is a rundown of what has
> happened:
>
> I have a 67-foot elevated vertical that I can use on 80 and 40, and it
> works fine on CW. However, on SSB, both bands, there clearly is
> feedback; there is no feedback on the other bands where I use a C3
> yagi. Initially, the feedback was so bad that the rig would go into
> oscillation, and I had to turn the amp to standby.
>
> I recently purchased the new KSYN3A and decided to install it. I
> replaced the K3 with my IC-730 backup, using the hand microphone that
> came with the 730. The 730 did not have any RFI. I finished the
> modification and returned the K3 as the operating rig. Now, the RFI on
> 40 seems to have diminished substantially or disappeared, but it still
> happens on 75/80. However, it seems to be much less there as well. I
> do not suspect that the KSYN3A had anything to do with this, but
> perhaps I tightened connections better when I returned the rig to
> service. I also redid some ground connections.
>
> The microphone for the K3 is an Audio-Technica that works well
> everywhere else. It has a long cord, though. I put a few toroids on
> the cord near the microphone connector and that has possibly reduced
> RFI a little, but it is still there.
>
> Is there a possibility that a bypass capacitor is bad, or has someone
> else had the problem and solved it externally to the K3? For instance,
> has anyone found that a long string of ferrite beads has cured this
> problem?
>
> Despite decades of operating, I am hardly a troubleshooting hotshot,
> and I would appreciate guidance.
>
> Thank you,
>
> Jan, KX2A
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
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Bill-3

Re: RFI in audio chain

In reply to this post by Phil Anderson

I may be way off on this, but I would be into that mic and the connector
before I got involved with baluns, ground straps, and all the
complicated stuff.

Make sure your mic wire's shield is properly grounded (both ends) -
remember, XLR was not designed for RF use.

Bill W2BLC K-Line

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Bob McGraw - K4TAX

Re: RFI in audio chain

In reply to this post by Phil Anderson

There is nothing better than "doing it right"! Great job Phil.

73 Bob, K4TAX

On 11/22/2015 7:59 PM, Phil Anderson wrote:

> Hi Jan,
>
> I'm guessing, as several others have discussed using a balun at the
> base of the vertical, that the problem is interference running on the
> outside of the coax feed. I'm using a STEPPir vertical for 40 through
> 10. I tried several baluns with no satisfying success. I then decided
> to build a SPGS (single point grounding system) on the outer wall next
> to my shack in the back yard. My SPGS is enclosed by DX Engineering's
> "Grounding and Utility Encloser," (DXE-UP-2P) and I installed in that
> three ALPHA-DELTA lightning arrest (surge protectors) (for three
> different antennas, one being a Beverage), and a CONTROL LINE
> PROTECTOR, (DXE-IS-RCT), that protects my Steppir vertical antenna
> control system. In addition to that I ran #6 copper to the house
> utility box ground (from the antenna ground) AND (perhaps most
> important) ran three ground rods spread out (at twice the length of
> the 8' rods) and connected all of that to the vertical grounding plate
> (of the SPGS box) The important thing is that I did not use #6 wire
> from the vertical to the SGPS box; instead, I used 2 inch wide copper
> strip that is bonded to the rods with copper plates and connections at
> each end of the run. The 2 inch copper strip is then attached to the
> SPGS 14 x 14 plate (with another ground rod) just outside the house.
> THE THEORY IS THAT THE WIDE STRAP PROVIDES FOR A VERY LOW RF IMPEDANCE
> AT THE FREQUENCY OF OPERATION. This substantially shunts off any
> interference returning on the outside braid of the coax from the
> vertical. In addition on the inside (at station) I ran a strip of the
> 2 inch copper along the back of the station table and then smaller
> braided strap from the copper strip to each major piece of equipment
> on the station (a reverse V from the SPGS if you will) : DELL OPTIPLEX
> COMPUTER (station computer), two 19 in flat screens, my fully loaded
> Elecraft K3 with P3 WinkeyerUSB, and Astron switching supply.
>
> The result was immediately apparent: the spikes I had been receiving
> that were spaced up and down the 40 through 20 bands as noted on the
> P3 panadapter where now completely gone. An added surprise was that
> the noise floor even went down a bit (and I live two blocks from a
> shopping mall!). Prior to this large station upgrade - inside and
> outside the house - I would even see interference on the 19 inch
> screens - that is now gone too.
>
> If you like I can send you more detail on what I did, including
> pictures. I've only been testing it for a week so may find some
> glitches....but so far very happy.
>
> 73 and good luck. Phil Anderson, W0XI, Lawrence, KS

Bob McGraw - K4TAX

Re: RFI in audio chain

In reply to this post by Bill-3

Oh but it is. There is pin #1, pin #2 and pin #3 plus a ground
terminal. The cable between the mike and radio should be 3 conductor
shielded. Thus - Red, Black, White and shield. And the shield should
be connected at one end only, preferably the signal receiving end or
mike connector at the radio. That way, there is no current flowing on
the shield.

73
Bob, K4TAX

On 11/22/2015 8:07 PM, Bill wrote:
> Make sure your mic wire's shield is properly grounded (both ends) -
> remember, XLR was not designed for RF use.

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Joe Subich, W4TV-4

Re: RFI in audio chain

> And the shield should be connected at one end only, preferably the
> signal receiving end or mike connector at the radio. That way, there
> is no current flowing on the shield.

*Except* with a transmitter. Connecting the shield to one side of the
mic element provides a path for any common mode current reaching the
rig directly *into* the mic circuits! *NEVER* connect the shield of
any mic cable to the mic return - it only makes any "pin 1 problem"
much worse.

73,

... Joe, W4TV

On 11/22/2015 9:20 PM, Bob McGraw - K4TAX wrote:

> Oh but it is. There is pin #1, pin #2 and pin #3 plus a ground
> terminal. The cable between the mike and radio should be 3 conductor
> shielded. Thus - Red, Black, White and shield. And the shield should
> be connected at one end only, preferably the signal receiving end or
> mike connector at the radio. That way, there is no current flowing on
> the shield.
>
> 73
> Bob, K4TAX
>
> On 11/22/2015 8:07 PM, Bill wrote:
>> Make sure your mic wire's shield is properly grounded (both ends) -
>> remember, XLR was not designed for RF use.
>
>
> ______________________________________________________________
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>

Bob McGraw - K4TAX

Re: RFI in audio chain

In reply to this post by Bob McGraw - K4TAX

And if you happen to have the connector(s) that do not have a dedicated
ground terminal, then connect the shield and white wire to pin #1, at
the radio end of the cable and leave the shield floating or not
connected at the mike end.

73
Bob, K4TAX

On 11/22/2015 8:20 PM, Bob McGraw - K4TAX wrote:

Joe Subich, W4TV-4

Re: RFI in audio chain

*NO!* Do not connect the shield to *either* pin 1 (mic hot) or pin 7
(mic return) of the Foster connector. If you must connect the shield,
connect it to the *shell* of the Foster connector (chassis). Chassis
*with no intervening component/impedance* is the only appropriate
connection for a shield.

73,

... Joe, W4TV

On 11/22/2015 9:28 PM, Bob McGraw - K4TAX wrote:

> And if you happen to have the connector(s) that do not have a dedicated
> ground terminal, then connect the shield and white wire to pin #1, at
> the radio end of the cable and leave the shield floating or not
> connected at the mike end.
>
> 73
> Bob, K4TAX
>
> On 11/22/2015 8:20 PM, Bob McGraw - K4TAX wrote:
>> Oh but it is. There is pin #1, pin #2 and pin #3 plus a ground
>> terminal. The cable between the mike and radio should be 3 conductor
>> shielded. Thus - Red, Black, White and shield. And the shield
>> should be connected at one end only, preferably the signal receiving
>> end or mike connector at the radio. That way, there is no current
>> flowing on the shield.
>>
>> 73
>> Bob, K4TAX
>>
>> On 11/22/2015 8:07 PM, Bill wrote:
>>> Make sure your mic wire's shield is properly grounded (both ends) -
>>> remember, XLR was not designed for RF use.
>
>
> ______________________________________________________________
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>

Vic Rosenthal

Re: RFI in audio chain

In reply to this post by Jan Ditzian

A vertical should have an RF choke at the feed point. This is sometimes called a 'balun', but in this application it is common mode choke.

To reduce RF pickup with ferrite beads or toroids at HF, especially on the lower bands, you need to wind multiple turns around the ferrites. Also they should be the appropriate type of ferrite material. 31 mix is good for 160-40 meters.

Vic 4X6GP/K2VCO

> On 23 Nov 2015, at 1:02 AM, Jan Ditzian <[hidden email]> wrote:
>
> I have a problem that appears to be changing, but I could use some help. The problem is RFI in the audio input (microphone input) when I use my vertical antenna on 40 meters. Here is a rundown of what has happened:
>
> I have a 67-foot elevated vertical that I can use on 80 and 40, and it works fine on CW. However, on SSB, both bands, there clearly is feedback; there is no feedback on the other bands where I use a C3 yagi. Initially, the feedback was so bad that the rig would go into oscillation, and I had to turn the amp to standby.
>
> I recently purchased the new KSYN3A and decided to install it. I replaced the K3 with my IC-730 backup, using the hand microphone that came with the 730. The 730 did not have any RFI. I finished the modification and returned the K3 as the operating rig. Now, the RFI on 40 seems to have diminished substantially or disappeared, but it still happens on 75/80. However, it seems to be much less there as well. I do not suspect that the KSYN3A had anything to do with this, but perhaps I tightened connections better when I returned the rig to service. I also redid some ground connections.
>
> The microphone for the K3 is an Audio-Technica that works well everywhere else. It has a long cord, though. I put a few toroids on the cord near the microphone connector and that has possibly reduced RFI a little, but it is still there.
>
> Is there a possibility that a bypass capacitor is bad, or has someone else had the problem and solved it externally to the K3? For instance, has anyone found that a long string of ferrite beads has cured this problem?
>
> Despite decades of operating, I am hardly a troubleshooting hotshot, and I would appreciate guidance.
>
> Thank you,
>
> Jan, KX2A
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Message delivered to [hidden email]

Vic Rosenthal

Re: RFI in audio chain

In reply to this post by Jan Ditzian

I don't like 'ugly baluns', especially for the lower bands. If you do use one, you should wind the coax as a single layer solenoid, not a "hank" of coax. Also, as someone else suggested, you need a large number of turns for it to be effective on 80 m.

Vic 4X6GP/K2VCO

> On 23 Nov 2015, at 2:32 AM, Jan Ditzian <[hidden email]> wrote:
>
> In response to the balun recommendation from several hams, I apologize for forgetting to mention that the vertical has an "ugly balun" both at the antenna and near where the feedline enters the house.
>
> Part of the reason I put the question to this group, after first thinking that the amps group could help, was the fact that the IC-730 shows no RFI, while the K3 shows extreme RFI.
>
> Thanks,
>
> Jan, KX2A
>
>> On 11/22/2015 6:36 PM, John Kramer wrote:
>> Jan
>>
>> The easiest, quickest and cheapest method is to wind yourself an “ugly balun” in your coax cable line.
>> It must be located OUTSIDE your shack to choke the common mode currents from entering the shack.
>> Wind about 15 - 20 turns of your coax on a 6” PVC pipe. This will give you about 2500 ohms choking
>> impedance.
>>
>> If there is still RFI getting in the shack, then purchase a commercial choke either from
>> http://www.balundesigns.com/model-1115d-max-choking-1-1-balun-1-54-mhz-5kw/
>> this will provide about 10 - 12 000 ohms of choking impedance, or buy one from
>>
>> http://myantennas.com/wp/product/cmc-130-3k/
>> This one will give from 12 000 - 15 000 ohms of choking impedance.
>>
>> These common mode chokes merely get plugged inline in your coax cable. Always better to locate
>> them outside the shack
>>
>> 73
>> John
>>
>>
>>
>>
>> On 23 Nov 2015, at 1:02 AM, Jan Ditzian <[hidden email]> wrote:
>>
>> I have a problem that appears to be changing, but I could use some help. The problem is RFI in the audio input (microphone input) when I use my vertical antenna on 40 meters. Here is a rundown of what has happened:
>>
>> I have a 67-foot elevated vertical that I can use on 80 and 40, and it works fine on CW. However, on SSB, both bands, there clearly is feedback; there is no feedback on the other bands where I use a C3 yagi. Initially, the feedback was so bad that the rig would go into oscillation, and I had to turn the amp to standby.
>>
>> I recently purchased the new KSYN3A and decided to install it. I replaced the K3 with my IC-730 backup, using the hand microphone that came with the 730. The 730 did not have any RFI. I finished the modification and returned the K3 as the operating rig. Now, the RFI on 40 seems to have diminished substantially or disappeared, but it still happens on 75/80. However, it seems to be much less there as well. I do not suspect that the KSYN3A had anything to do with this, but perhaps I tightened connections better when I returned the rig to service. I also redid some ground connections.
>>
>> The microphone for the K3 is an Audio-Technica that works well everywhere else. It has a long cord, though. I put a few toroids on the cord near the microphone connector and that has possibly reduced RFI a little, but it is still there.
>>
>> Is there a possibility that a bypass capacitor is bad, or has someone else had the problem and solved it externally to the K3? For instance, has anyone found that a long string of ferrite beads has cured this problem?
>>
>> Despite decades of operating, I am hardly a troubleshooting hotshot, and I would appreciate guidance.
>>
>> Thank you,
>>
>> Jan, KX2A
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
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>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>>
>>
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Bill-3

Re: RFI in audio chain

In reply to this post by Joe Subich, W4TV-4

Joe,

Thanks for straightening that out. I did not recall which pins and lugs
to tell him to use.

Bill W2BLC - K-Line

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Jan Ditzian

Re: RFI in audio chain

In reply to this post by Jan Ditzian

Joe and Bob,

I decided to chop things up to see what was inside. I found a
surprising result:

The microphone wire is a two-conductor wire, consisting of a single
insulated conductor and a shield. At the microphone XLR end the single
wire is connected to pin 2. At the rig end, this same wire is connected
to pin 1 of the eight pin connector. At the XLR end, the shield is
connected to pin3 and pin 1, while at the rig end, this shield goes to
pin 8. I know that audio gets to the rig with this setup, but it
clearly is not what you guys are talking about.

I see several alternatives:

1. Remove the shield connection to pin 3 at the XLR; leave pin 2 connected.
2. Remove the shield connection to pin 1 at the XLR; leave pin 2 connected.
3. Get a new cable with two or three conductors inside a shield and
still use only pins 1 and 2 at the XLR, using only conductors, not
shield.
4. Get a new cable with two or three conductors inside a shield and
still use only pins 3 and 2 at the XLR, using only conductors, not
shield.

Alternatives 3 and 4 leave me the choice of connecting the shield only
at the microphone end, or not, depending upon what works best at
reducing RFI.

I think that this exhausts the alternatives, so if one or both of you
can give me a shove in a single direction, I may be able to row out the
rest of the way by myself.

I gently patched things back together so I can meet my 2000Z sched, but
I await further instructions, O Masters of the Universe.

Your obdt. svt,
Jan, KX2A

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Joe Subich, W4TV-4

Re: RFI in audio chain

Jan,

On an XLR pin 1 is shield/ground, pin 2 is mic hot, pin 3 is mic
return. The proper connections (as I described in another forum
a couple days ago) are:

> For *any* microphone with a 3pin XLR one needs a cable with XLR
> on one end (for the "professional" mic) and a Foster plug for
> the rig. Connections are:
>
> MIC (XLR) Radio (Foster) signal
> Yaesu Kenwood/Elecraft Icom
> Pin 1 shell shell shell Shield
> Pin 2 8 1 1 Mic +
> Pin 3 7 7 7 Mic -
>
> Note: Install a 10 uF capacitor between pin 2 of the XLR and
> pin 1 of the Foster for use with Icom (+ to the Foster) to
> block DC on the mic line.
>
> Note 2: *NEVER* connect the shield (Pin 1 of the XLR) to the
> Mic - or "mic ground" and *never* connect "mic ground" to the
> PTT Ground/shell or chassis of the transceiver.

As pointed out in private e-mail, professional installations have
migrated to *three wire* plus shield cables with pin 1 connected
to circuit return (PTT ground in the case of amateur transceivers)
and shield connected to the shell of the connector (chassis) on
both ends. However, most analog work still uses two wire plus
shield with an XLR plug that ties pin1 to the shell internally.

> I see several alternatives:
>
> 1. Remove the shield connection to pin 3 at the XLR; leave pin 2
> connected.

If your cable is a "coaxial" one - a single wire with shield, the best
short term "fix" is to connect the center wire from pin 2 of the XLR
to pin 1 of the Kenwood/Elecraft Foster plug and connect the shield
from pin 3 of the XLR to pin 7 of the Kenwood/Elecraft Foster plug
*with no connection to pin 1 of the XLR plug*. In this case the cable
is acting as a simple two wire cable.

> 4. Get a new cable with two or three conductors inside a shield and
> still use only pins 3 and 2 at the XLR, using only conductors, not
> shield.

If I were using two conductor with shield, I would wire pins 2 and 3 as
above and connect the shield between pin 1 on the XLR and the *shell*
of the Foster plug. If the transceiver properly bonds the Foster jack
to a metallic chassis, the shield is properly terminated on the chassis
as it should be. If the transceiver mounts the mic jack to a circuit
board on an insulated panel, the shield is floating (isolated) where it
should cause no problem. *Under no circumstances* would I connect the
shell of the Foster plug to either the mic return (e.g. Pin 7 as done
by Heil) or the PTT ground (e.g. Pin 8) as that "circuit' can wind its
way many places in the transceiver before it is bonded to the actual
chassis (and power supply) return.

If replacing the cable, look for shielded, *twisted pair* cable. The
twisted pair will help balance out any common mode RF and hum resulting
in lower noise even when the shield is floating on one end.

73,

... Joe, W4TV

On 11/23/2015 2:20 PM, Jan Ditzian wrote:

> Joe and Bob,
>
> I decided to chop things up to see what was inside. I found a
> surprising result:
>
> The microphone wire is a two-conductor wire, consisting of a single
> insulated conductor and a shield. At the microphone XLR end the single
> wire is connected to pin 2. At the rig end, this same wire is connected
> to pin 1 of the eight pin connector. At the XLR end, the shield is
> connected to pin3 and pin 1, while at the rig end, this shield goes to
> pin 8. I know that audio gets to the rig with this setup, but it
> clearly is not what you guys are talking about.
>
> I see several alternatives:
>
> 1. Remove the shield connection to pin 3 at the XLR; leave pin 2 connected.
> 2. Remove the shield connection to pin 1 at the XLR; leave pin 2 connected.
> 3. Get a new cable with two or three conductors inside a shield and
> still use only pins 1 and 2 at the XLR, using only conductors, not
> shield.
> 4. Get a new cable with two or three conductors inside a shield and
> still use only pins 3 and 2 at the XLR, using only conductors, not
> shield.
>
> Alternatives 3 and 4 leave me the choice of connecting the shield only
> at the microphone end, or not, depending upon what works best at
> reducing RFI.
>
> I think that this exhausts the alternatives, so if one or both of you
> can give me a shove in a single direction, I may be able to row out the
> rest of the way by myself.
>
> I gently patched things back together so I can meet my 2000Z sched, but
> I await further instructions, O Masters of the Universe.
>
> Your obdt. svt,
> Jan, KX2A
>
>
> ______________________________________________________________
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> Message delivered to [hidden email]
>

Jan Ditzian

Re: RFI in audio chain

In reply to this post by Jan Ditzian

I have followed Joe's directions: I found a two-conductor-plus-shield
cable in the junk box (aka hamshack) and wired it as he instructed. It
works properly as a microphone, but still has extreme RFI on 75 phone.
I rechecked my other microphone, a Ten Tec Model 705 with a home made
adapter from 4 to 8 pins. That microphone shows the same RFI. I know
that my IC-730, tested last week, did not have any RFI on 75 meters, so
I am still stuck as to why this is happening.

Both the "ugly" baluns (coiled hardline chokes) in this feedline are
about 50 feet in length, and both are spiral-wound, not scramble-wound.
I will try to do a radial survey on Sunday. I believe that I already
tried removing all other feedlines from the antenna tuner, but I will
assess that again on Sunday.

A field-strength meter in my shack shows RF on 80 when I transmit, but
there is some RF on 20 meters as well; there is less RF on 20, but there
is absolutely no sign of audio problems.

73,

Jan, KX2A

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