Re: [Elecraft] RFI in audio chain

[Gene Gabry]

-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Jim
Brown
Sent: Tuesday, December 22, 2015 10:33 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] RFI in audio chain
>Yes. I will again strongly urge Jan to STUDY my tutorial on Power,
Grounding, and Bonding for ham radio. 
> http://k9yc.com/GroundingAndAudio.pdf  If equipment in the shack was
properly bonded, removing that audio cable would not have solved the problem
(and >there would have been no problem).

73, Jim K9YC

Good study material for all to absorb! I would only add one additional
to-do. Check all your bonds, especially outside ground bonds, annually. Even
though you did a good job of bonding connections, oxygen oxidizes, in time.
Speaking from experience :) 

73 Gene, N9TF
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Re: [Elecraft] RFI in audio chain

[Jan Ditzian]

This is a wrap-up post to the discussion about RFI feedback into the 
audio of my K3.


First, I want to thank everyone who offered suggestions, most of which I 
tried to follow up.


After numerous failures, I managed to lure a local guru--a ham who makes 
his living getting RF and audio things to work.  After ten minutes of BS 
in my ham shack, he said to start disconnecting each wire from the back 
of the K3, one-by-one.  Some of you may have told me to do the same 
thing, and I remember approximating that, but somehow I must have messed 
up.  At any rate, as soon as we disconnected the line from my outboard 
USB sound card to the rear input of K3, used for digital work, the audio 
RFI went away.  My friend says he thinks that an isolated line would be 
better, but the fact that I have a stereo output going directly to the 
mono input is probably the real culprit.  At the moment, only hours 
since his discovery, I have successfully worked on 80 and 40 meters with 
the amplifier, but I have not yet fixed up an isolated digital line.


My thanks to the entire K3 community who attacked this problem.

I am now using the original vertical, fed with patched lengths of 
hardline, with a hardline, wound choke at both ends.  Each choke is 
40-50 feet long.


I also discovered that my RF ground point in the shack (back of the 
Ten-Tec KW tuner), shows 30-50 ohms resistance vis-a-vis the electrical 
ground terminals in the shack.  Another rod as part of my RF ground 
system may be forthcoming.


73,

Jan, KX2A

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Re: [Elecraft] RFI in audio chain

[Don Wilhelm]

Jan,

That 30-50 ohms resistance may be a shack safety problem.  Your shack 
ground rod must be connected to the Utility ground rod by a heavy 
conductor (#6 minimum, but #4 preferred).


That ground is only for AC safety and some part of lightning protection.
It does not present an effective RF Ground.  To use an example, consider 
an 8 foot connection to that ground and think of a 10 meter signal.  
That 8 foot connection is about 1/4 wavelength, so while the impedance 
at the ground rod may be low, the impedance to 28 MHz RF at the shack 
end is quite high (due to the properties of antennas and transmission 
lines).  In other words, what you are viewing as an 'RF ground' at 10 
meters is instead exactly the opposite, it is a high impedance to RF at 
10 meters.


The proper place to solve RF problems is in the antenna field, and not 
by attempts (sometimes futile) to bond things to a driven ground stake.


73,
Don W3FPR

On 12/22/2015 8:40 PM, Jan Ditzian wrote:



I also discovered that my RF ground point in the shack (back of the 
Ten-Tec KW tuner), shows 30-50 ohms resistance vis-a-vis the 
electrical ground terminals in the shack.  Another rod as part of my 
RF ground system may be forthcoming.




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Re: [Elecraft] RFI in audio chain

[Jim Brown]

On Tue,12/22/2015 5:57 PM, Don Wilhelm wrote:
That 30-50 ohms resistance may be a shack safety problem.  Your shack 
ground rod must be connected to the Utility ground rod by a heavy 
conductor (#6 minimum, but #4 preferred). 


Yes. I will again strongly urge Jan to STUDY my tutorial on Power, 
Grounding, and Bonding for ham radio. 
http://k9yc.com/GroundingAndAudio.pdf  If equipment in the shack was 
properly bonded, removing that audio cable would not have solved the 
problem (and there would have been no problem).


73, Jim K9YC


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Re: [Elecraft] RFI in audio chain

[Jim Bolit]

Ugly baluns are a P O O R  choice. Don't waste ur time with one.  Use a ferrite
choke with a min of 3k ohms resistive at freq of interest.

Jim
W6AIM

.



 Original message 
From: John Kramer <jkra...@iafrica.com>
Date: 11/22/2015 3:38 PM (GMT-08:00)
To: Jan Ditzian <ditz...@windstream.net>
Cc: Elecraft@mailman.qth.net
Subject: Re: [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 <ditz...@windstream.net> 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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Re: [Elecraft] RFI in audio chain

[Jim Bolit]

Uglies DON'T WORK WELL

Use ferrite

Jim
W6AIM



.



 Original message 
From: Jan Ditzian <ditz...@windstream.net>
Date: 11/22/2015 4:33 PM (GMT-08:00)
To: Elecraft@mailman.qth.net
Subject: Re: [Elecraft] 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 <ditz...@windstream.net> 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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Re: [Elecraft] RFI in audio chain

[Jan Ditzian]

I will continue to try solutions, but they seem to be getting random.

I found my long 50-ohm coax run to the 80-meter vertical.  It ends in a 
DX Engineering 1:1 balun with terminals.  I have tried this before.  I 
connected one of the terminals to the vertical and the other to the 
ground base.  The result was an SWR a little lower than with the 
hardline, patched-together feedline, but RFI when I run power.   I do 
not have a choke or balun on the proximal (shack) end.


It is difficult to assess the radials, but I hope to get some more time 
tomorrow to do this.


73,

Jan, KX2A

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Re: [Elecraft] RFI in audio chain

[Jim Brown]

Gee whiz -- I go into the hospital for a week and thing go WAY off the 
rails!  Thanks to W4TV and W3FPR for intelligently moving the discussion 
back on track.


Questions:

EXACTLY what is the configuration the the "vertical antenna? 
Quarter-wave with radials or half wave without radials?  How many 
radials?  How long?


Where is the antenna feedpoint with respect to the radio?  What coax are 
you feeding it with?  Are you SURE that the connectors at both ends are 
properly installed and gas-pliers tight at both ends?


Is there a short, fat copper bond from chassis to chassis between every 
piece of gear in your shack?  Is there short fat copper from there to 
all the other grounds in your home?


Joe is exactly right -- ANY "balun" that isn't multiple turns of coax 
around a #43 or #31 ferrite core is USELESS at HF.  Those "string of 
beads" "baluns" sold by various vendors are badly misguided copies of 
the W2DU design, which what a very good design that used a LOT of #73 
beads.


Joe is also exactly right -- the ONLY proper connection of a cable 
shield is to the SHIELDING ENCLOSURE of the equipment it feeds. The 
cable shield should ALSO be bonded to the shielding of the microphone.


Some fundamentals:  ANY antenna that "works" will put RF in the shack -- 
it does that by radiating RF. An antenna that lacks an effective common 
mode choke will ALSO put RF onto the feedline.


Summary of suggestions/comments:

Answer the questions I asked above.  They are all important.

Download and STUDY k9yc/com/RFI-Ham.pdfand

http://k9yc.com/GroundingAndAudio.pdf

Follow these instructions carefully.  I suspect that the cause of Jan's 
problem is failure to properly connect cable shields, and/or to bond all 
the gear together.


73, Jim K9YC

On Tue,11/24/2015 6:54 AM, Joe Subich, W4TV wrote:

Not true ... the Icom uses an electret mic, not the dynamic Audio-
Technica.  If the microphone is wired correctly, the issue is in
the antenna system and probably requires improved common mode
decoupling.  Air wound solenoidal chokes are not sufficient in
the most intractable cases *like elevated verticals*.

Replace the elevated vertical with a dummy load.  If the RFI is
eliminated, the problem is in the antenna system.


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Re: [Elecraft] RFI in audio chain

[Joe Subich, W4TV]

You have now eliminated the problem from causes in your station
layout and the antenna/feedline to the K3 - as the complete same
using the 730 works fine. True?


Not true ... the Icom uses an electret mic, not the dynamic Audio-
Technica.  If the microphone is wired correctly, the issue is in
the antenna system and probably requires improved common mode
decoupling.  Air wound solenoidal chokes are not sufficient in
the most intractable cases *like elevated verticals*.

Replace the elevated vertical with a dummy load.  If the RFI is
eliminated, the problem is in the antenna system.

73,

  ... Joe, W4TV


On 11/24/2015 7:00 AM, Bill wrote:

1. I have printed out Joe's directions and placed them in the K3 file -
for future reference.
2. Is you K3's chassis connector OK - loose ground?
3. Have a proper ground from the K3 to your station ground?
4. You are using the same feedline to test the K3 as used to test the
730? If not - do so. Everything needs to be eliminated.

You have now eliminated the problem from causes in  your station layout
and the antenna/feedline to the K3 - as the complete same using the 730
works fine. True? Then the problem is with the K3 or something attached
to it.

5. Disconnect everything from it except power, antenna, and mic. Test
it. All clear - the RF is coming in on something other than the mic
(plugged into the K3). Problem still there?
6. At this point, try an alternate mic and see if it works. If it works
good - the problem is the mic/mic wire/connector. If it does not and you
still have RFI - walk away for a while and cool down.

Just a few simple steps that would apply to any radio in a similar
situation.

Bill W2BLC K-Line



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Re: [Elecraft] RFI in audio chain

[Bill]

1. I have printed out Joe's directions and placed them in the K3 file - 
for future reference.

2. Is you K3's chassis connector OK - loose ground?
3. Have a proper ground from the K3 to your station ground?
4. You are using the same feedline to test the K3 as used to test the 
730? If not - do so. Everything needs to be eliminated.


You have now eliminated the problem from causes in  your station layout 
and the antenna/feedline to the K3 - as the complete same using the 730 
works fine. True? Then the problem is with the K3 or something attached 
to it.


5. Disconnect everything from it except power, antenna, and mic. Test 
it. All clear - the RF is coming in on something other than the mic 
(plugged into the K3). Problem still there?
6. At this point, try an alternate mic and see if it works. If it works 
good - the problem is the mic/mic wire/connector. If it does not and you 
still have RFI - walk away for a while and cool down.


Just a few simple steps that would apply to any radio in a similar 
situation.


Bill W2BLC K-Line



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Re: [Elecraft] RFI in audio chain

[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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Re: [Elecraft] RFI in audio chain

[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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Re: [Elecraft] RFI in audio chain

[Bill]

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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Re: [Elecraft] RFI in audio chain

[Joe Subich, W4TV]

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   1shell shellshellShield
Pin   2  8 11   Mic +
Pin   3  7 77   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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Re: [Elecraft] RFI in audio chain

[John Kramer]

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  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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Re: [Elecraft] RFI in audio chain

[Bob McGraw - K4TAX]

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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Re: [Elecraft] RFI in audio chain

[Joe Subich, W4TV]

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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Re: [Elecraft] RFI in audio chain

[Joe Subich, W4TV]

*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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Re: [Elecraft] RFI in audio chain

[Vic Rosenthal]

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  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  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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>> 
>> 
>> 
>> -
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>> Checked by AVG - www.avg.com
>> Version: 2016.0.7227 / Virus Database: 4460/11045 - Release Date: 11/22/15
> 
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Re: [Elecraft] RFI in audio chain

[Vic Rosenthal]

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  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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Re: [Elecraft] RFI in audio chain

[Jan Ditzian]

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  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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Re: [Elecraft] RFI in audio chain

[Don Wilhelm]

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:
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.




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Re: [Elecraft] RFI in audio chain

[Bob McGraw - K4TAX]

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 


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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Re: [Elecraft] RFI in audio chain

[Bill]

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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[Elecraft] RFI in audio chain

[Jan Ditzian]

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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Re: [Elecraft] RFI in audio chain

[Joe Subich, W4TV]

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


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Re: [Elecraft] RFI in audio chain

[Phil Anderson]

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 
glitchesbut so far very happy.


73 and good luck. Phil Anderson, W0XI, Lawrence, KS
email: aldenmcduf...@sunflower.com




Jan Ditzian 
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



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John Kramer 
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  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 

Re: [Elecraft] RFI in audio chain

[Bob McGraw - K4TAX]

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 
glitchesbut so far very happy.


73 and good luck. Phil Anderson, W0XI, Lawrence, KS 



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Re: [Elecraft] RFI in audio chain

[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:
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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