Date   

Re: IC700 and PRO7 IC headset RFI on my rig

Robert Farey <robert.farey@...>
 

HI guys 
we here in the uk have even bigger issues with earthing with respect to house wiring. Not only are modern houses not fed by Copper water main pipes or lead as was the case back in he 1950. 
today many houses and residences are fed by plastic water pipe. 
then we have the other issue since about 1970's we have also issues around earthing as the P.M.E. mains supplies where three Phase is fed into a housing estate. this leads to a potential hazard with respect to 440volts being present between adjacent properties. so the whole subject of earthing needs reference back to the local electricity supply company.
                                                       Best Regards Robert G6LLP  ex british telecom engineer. 


Re: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

cpcohen1945@...
 

These "long-wire tuners" are very flexible beasts.

There's not much info in the AH-4 user manual, but SGC has a whole line of them, and there is _extensive_ information on the SGC website:


http://www.sgcworld.com

One of the things that SGC recommends them for, is delta-loop antennas.

I had an SG-230 on my boat, feeding an insulated backstay against two long wires forming a "ground plane". It worked very well. But -- with the boat's interior in the "near field" of the antenna -- I used _lots_ of ferrites!

So, having a delta loop right over the rig might lead to trouble, no matter what tuner is used. The problem may not be _conducted_ RFI, brought in through feedline, but _radiated_ RFI from the antenna.

. CHarles VA7CPC


Re: IC700 and PRO7 IC headset RFI on my rig

Steve W3AHL
 

I would start with adding a common-mode choke on the output of the AH-4 instead of at the feed point.  A coiled coax (solenoid) choke provides minimal CM attenutation across the bands due to capacitive coupling between the turns.  Eight turns of RG-8X wound as a single layer on 6" PVC pipe (best case for your situation probably) results in about 760 ohms at 7 MHz, peaking at 15,000 ohms at 12 MHz and back 2800 at 14 MHz, 860 at 21 MHz and 360 at 28 MHz.  The capacitance results in self-resonance that causes actual performance to vary greatly with minor changes in construction details.

The goal should be 3,000-5,000 ohms across all bands.  This is achievable using 5 turns of RG-8X through 5 type 31 2.4" ferrite cores (Fair-Rite part # 2631803802, about $6 USD each ), taking care to splay the turns of coax out to minimize capacitive coupling.  This provides 4,500 ohms at 7 MHz, peaking at 5,500 at 14 MHz and down to 3,000 at 28 MHz.  Performance is much less affected by minor variations in construction, as long as the turns for coax are spread out and secured so they stay that way.

For good practical info on RFI backed up by measurements and lots of experience see:
http://audiosystemsgroup.com/RFI-Ham.pdf   K9YC has many other good articles on his web site.

Steve, W3AHL
 
---In ic7000@..., <colin.christie34@...> wrote :

Hi Steve,

 the test of the headset/microphone was done at my friends place. It worked fine with the IC7000.

 I doubt my radio has any problems. 
Going to relocate the AH4 outside the shack and connect up again to see if RFI is still present.

My other thought is to make a coax choke of 8 turns and placed it under the balun before the coax transmission line and see what happens.

73
Colin
 


Re: IC700 and PRO7 IC headset RFI on my rig

Colin Christie
 

David, it is copper pipe.
No doubt at all.

thanks
73
Colin


Re: IC700 and PRO7 IC headset RFI on my rig

Colin Christie
 

Hi Steve,

 the test of the headset/microphone was done at my friends place. It worked fine with the IC7000.

 I doubt my radio has any problems. 
Going to relocate the AH4 outside the shack and connect up again to see if RFI is still present.

My other thought is to make a coax choke of 8 turns and placed it under the balun before the coax transmission line and see what happens.

73
Colin


Re: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

r norris
 


On Nov 26, 2016, at 20:08, Colin Christie colin.christie34@... [ic7000] <ic7000@...> wrote:


Charles,

 The base of the 40m Delta loop is directly over the top of my shack.

The AH 4 is in the shack so my next experiment is to relocate it outside the window of the house.

 I tried a coax "choke" on the coax line about half way along the transmission coax but did not fix the problem.

73
Colin 



As someone else mentioned, the AH-4 is NOT designed to be in the shack or connected to a resonant antenna.

It was designed for a singe wire or mobile whip, and not one that is a half or full wave.

In the holiday spirit, stop trying to make a chicken into a turkey.

I got one from an estate, who must have tried to use it, as you are doing.

He had it full of ferrite beads and donuts.

I yanked all the junk out, mounted it on a 4x4, post 30 feet from the shack, and feed a 48 foot single wire.

There are two ground rods, at the base.

It is not as good as dipoles or dedicated verticals, but it plays on all the bands, when I want quick switching, more for receive.

Stop messing and go for a MFJ or such tuner if you have to have one.

I don’t own one, or need one. All my antennas are resonant for the bands of interest.





Re: [IC-7000] Re: IC700 and PRO7 IC headset RFI on my rig

Colin Christie
 

Charles,

 The base of the 40m Delta loop is directly over the top of my shack.

The AH 4 is in the shack so my next experiment is to relocate it outside the window of the house.

 I tried a coax "choke" on the coax line about half way along the transmission coax but did not fix the problem.

73
Colin 



From: "w3ahl@... [ic7000]" To: ic7000@...
Sent: Friday, 25 November 2016, 6:31
Subject: [IC-7000] Re: IC700 and PRO7 IC headset RFI on my rig

 
The AH-4 has a control cable to the radio, so mounting at the feed point of distant antenna is not recommended.  Wherever it is mounted the common-mode choke should be place on the coax to the radio AT the tuner.  The AH-4 input and output is inherently unbalanced for any type of antenna, so a VERY GOOD common mode choke is needed.

Using the AH-4 inside the shack is probably a bad idea, since I don't believe it has any l shielding in the case.    It is similar to the SGC SG-237 I use for portable operation at the feed point.  The SG-237 doesn't use any control cable and the DC is usually supplied over the coax using a DC injector box on each end.

One big issue with any tuner is making sure the antenna doesn't exceed the tuner's ratings, which are often poorly specified, if at all.  That shouldn't be an issue with a 40M delta loop.  It would be for long-wires or dipoles that are operated at frequencies where the antenna presents a very high impedance (multiples of 0.5 WL's for long wire or 1 WL for dipoles).  This is covered in the AH-4 manual.

Steve, W3AHL

---In ic7000@..., wrote :

FWIW --

My memory could be wrong, but I think the AH-4 is a "long-wire" tuner, designed to be mounted at the antenna feedpoint.

I think the AH-4 ATU should be mounted at the feedpoint of the Delta Loop, and _directly connected_ to it.  The "hot" terminal to one end of the loop, and the "ground" terminal to the other.

Run coax from the rig to the AH-4.  No 4:1 balun needed.  You might need a "choke balun" on the coax, at the IC-7000's output.

Another question:

. . . How close is your antenna, to your rig?

Sometimes, if they're close together, the problem is direct radiation from the antenna, not grounding, or feedling common-mode current.

.    Charles VA7CPC



Re: [IC-7000] Re: IC700 and PRO7 IC headset RFI on my rig

Colin Christie
 

Noted chuck.
Thank you
73
Colin



From: "Charles Scott cscott@... [ic7000]"
To: ic7000@...
Sent: Friday, 25 November 2016, 7:15
Subject: Re: [IC-7000] Re: IC700 and PRO7 IC headset RFI on my rig

 
Just to clarify, the common-mode choke needs to be on both the coax and the control cable to the tuner. The situation with respect to common-mode currents is the same for both cables and there should either be good common-mode chokes on each or together into one common-mode choke. Also, distance for the control cable isn't a problem if reasonable gauge is used and there's proper attention to lightning/impulse protection.
Chuck - N8DNX

On 11/24/2016 2:31 PM, w3ahl@... [ic7000] wrote:
The AH-4 has a control cable to the radio, so mounting at the feed point of distant antenna is not recommended.  Wherever it is mounted the common-mode choke should be place on the coax to the radio AT the tuner.  The AH-4 input and output is inherently unbalanced for any type of antenna, so a VERY GOOD common mode choke is needed
.....
Steve, W3AHL




Re: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

Colin Christie
 

Perry, the head is not remote. Operated As a base station.
73 Colin



From: "'Perry Ogletree K4PWO' k4pwo@... [ic7000]"
To: ic7000@...
Sent: Friday, 25 November 2016, 8:46
Subject: RE: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

 
If you have the head remoted be sure you have the small screw that attaches the control cable to the main unit in place! Loss of that ground point will cause lots of RFI issues.

Perry K4PWO

From: ic7000@... [mailto:ic7000@...]
Sent: Thursday, November 24, 2016 12:32 AM
To: yahoogroups
Subject: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

Hi,

I have RFI on my rig screen when I transmit using the Heil PRO7 IC Headset and Microphone.

However, when I tried the headset/microphone on my mates IC7000 rig no such problem exists.

Using a ICOM AH4 ATU , antenna is delta loop cut for 40m , coax feed and 4.1 balun at the apex fed point of the delta.

No separation cable in use as it is a operated as a base station.

Grounding to water pipe system of house.

I tried a loop of coax with ferrite on the rear of the rig.

I have tried ferrites on the leads of the headset.

Grounded to rear of rig and AH4 ATU.

I would love to hear from you with any solutions how to stop the RFI in my IC7000 rig

73 Colin VK2JCC

[Non-text portions of this message have been removed]




Re: [IC-7000] Very low receive audio

Ronald Baran
 

How bout dat?  Both ATT and MN!  Thanks Robie. Now those East Coast stations are rattling my malleus, incus and stapes once again.  It hurts so good.


73


Ron
W9XS





From: ic7000@... on behalf of Robie Elms ruler552003@... [ic7000]
Sent: Saturday, November 26, 2016 11:08 AM
To: ic7000@...
Subject: Re: [IC-7000] Very low receive audio
 
 

Could you have accidentally turned on the ATT (attenuators)?

Robie - AJ4F

On Nov 26, 2016, at 10:54, Ron Baran ronbaran@... [ic7000] <ic7000@...> wrote:

 

Started searching for new countries during CQWW and found that my receive audio was very low.  Cranked the AF gain all the way up and could barely make out the East coast stations on 20 meters from 9 land.  Low audio both on speaker and earphones.  Usually the audio blows my sox off.  Suggestions? 


Ron  W9XS


Re: [IC-7000] Very low receive audio

R Elms
 

Could you have accidentally turned on the ATT (attenuators)?

Robie - AJ4F

On Nov 26, 2016, at 10:54, Ron Baran ronbaran@... [ic7000] <ic7000@...> wrote:

 

Started searching for new countries during CQWW and found that my receive audio was very low.  Cranked the AF gain all the way up and could barely make out the East coast stations on 20 meters from 9 land.  Low audio both on speaker and earphones.  Usually the audio blows my sox off.  Suggestions? 


Ron  W9XS


Very low receive audio

Ronald Baran
 

Started searching for new countries during CQWW and found that my receive audio was very low.  Cranked the AF gain all the way up and could barely make out the East coast stations on 20 meters from 9 land.  Low audio both on speaker and earphones.  Usually the audio blows my sox off.  Suggestions? 


Ron  W9XS


Re: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

Colin Christie
 

No thats not the case.

On Fri, 25 Nov, 2016 at 8:46, 'Perry Ogletree K4PWO' k4pwo@... [ic7000]
wrote:
 

If you have the head remoted be sure you have the small screw that attaches the control cable to the main unit in place! Loss of that ground point will cause lots of RFI issues.

Perry K4PWO

From: ic7000@... [mailto:ic7000@...]
Sent: Thursday, November 24, 2016 12:32 AM
To: yahoogroups
Subject: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

Hi,

I have RFI on my rig screen when I transmit using the Heil PRO7 IC Headset and Microphone.

However, when I tried the headset/microphone on my mates IC7000 rig no such problem exists.

Using a ICOM AH4 ATU , antenna is delta loop cut for 40m , coax feed and 4.1 balun at the apex fed point of the delta.

No separation cable in use as it is a operated as a base station.

Grounding to water pipe system of house.

I tried a loop of coax with ferrite on the rear of the rig.

I have tried ferrites on the leads of the headset.

Grounded to rear of rig and AH4 ATU.

I would love to hear from you with any solutions how to stop the RFI in my IC7000 rig

73 Colin VK2JCC

[Non-text portions of this message have been removed]


Re: [IC-7000] IC700 and PRO7 IC headset RFI on my rig

Perry Ogletree K4PWO <k4pwo@...>
 

If you have the head remoted be sure you have the small screw that attaches the control cable to the main unit in place! Loss of that ground point will cause lots of RFI issues.



Perry K4PWO



From: ic7000@... [mailto:ic7000@...]
Sent: Thursday, November 24, 2016 12:32 AM
To: yahoogroups <ic7000@...>
Subject: [IC-7000] IC700 and PRO7 IC headset RFI on my rig








Hi,



I have RFI on my rig screen when I transmit using the Heil PRO7 IC Headset and Microphone.



However, when I tried the headset/microphone on my mates IC7000 rig no such problem exists.



Using a ICOM AH4 ATU , antenna is delta loop cut for 40m , coax feed and 4.1 balun at the apex fed point of the delta.



No separation cable in use as it is a operated as a base station.



Grounding to water pipe system of house.



I tried a loop of coax with ferrite on the rear of the rig.



I have tried ferrites on the leads of the headset.



Grounded to rear of rig and AH4 ATU.



I would love to hear from you with any solutions how to stop the RFI in my IC7000 rig







73 Colin VK2JCC


Re: [IC-7000] Re: IC700 and PRO7 IC headset RFI on my rig

Charles Scott <cscott@...>
 

Just to clarify, the common-mode choke needs to be on both the coax and the control cable to the tuner. The situation with respect to common-mode currents is the same for both cables and there should either be good common-mode chokes on each or together into one common-mode choke. Also, distance for the control cable isn't a problem if reasonable gauge is used and there's proper attention to lightning/impulse protection.

Chuck - N8DNX


On 11/24/2016 2:31 PM, w3ahl@... [ic7000] wrote:
The AH-4 has a control cable to the radio, so mounting at the feed point of distant antenna is not recommended.  Wherever it is mounted the common-mode choke should be place on the coax to the radio AT the tuner.  The AH-4 input and output is inherently unbalanced for any type of antenna, so a VERY GOOD common mode choke is needed
.....
Steve, W3AHL


Re: IC700 and PRO7 IC headset RFI on my rig

Steve W3AHL
 

The AH-4 has a control cable to the radio, so mounting at the feed point of distant antenna is not recommended.  Wherever it is mounted the common-mode choke should be place on the coax to the radio AT the tuner.  The AH-4 input and output is inherently unbalanced for any type of antenna, so a VERY GOOD common mode choke is needed.

Using the AH-4 inside the shack is probably a bad idea, since I don't believe it has any l shielding in the case.    It is similar to the SGC SG-237 I use for portable operation at the feed point.  The SG-237 doesn't use any control cable and the DC is usually supplied over the coax using a DC injector box on each end.

One big issue with any tuner is making sure the antenna doesn't exceed the tuner's ratings, which are often poorly specified, if at all.  That shouldn't be an issue with a 40M delta loop.  It would be for long-wires or dipoles that are operated at frequencies where the antenna presents a very high impedance (multiples of 0.5 WL's for long wire or 1 WL for dipoles).  This is covered in the AH-4 manual.

Steve, W3AHL

---In ic7000@..., <cpcohen1945@...> wrote :

FWIW --

My memory could be wrong, but I think the AH-4 is a "long-wire" tuner, designed to be mounted at the antenna feedpoint.

I think the AH-4 ATU should be mounted at the feedpoint of the Delta Loop, and _directly connected_ to it.  The "hot" terminal to one end of the loop, and the "ground" terminal to the other.

Run coax from the rig to the AH-4.  No 4:1 balun needed.  You might need a "choke balun" on the coax, at the IC-7000's output.

Another question:

. . . How close is your antenna, to your rig?

Sometimes, if they're close together, the problem is direct radiation from the antenna, not grounding, or feedling common-mode current.

.    Charles VA7CPC


Re: IC700 and PRO7 IC headset RFI on my rig

cpcohen1945@...
 

FWIW --

My memory could be wrong, but I think the AH-4 is a "long-wire" tuner, designed to be mounted at the antenna feedpoint.

I think the AH-4 ATU should be mounted at the feedpoint of the Delta Loop, and _directly connected_ to it.  The "hot" terminal to one end of the loop, and the "ground" terminal to the other.

Run coax from the rig to the AH-4.  No 4:1 balun needed.  You might need a "choke balun" on the coax, at the IC-7000's output.

Another question:

. . . How close is your antenna, to your rig?

Sometimes, if they're close together, the problem is direct radiation from the antenna, not grounding, or feedling common-mode current.

.    Charles VA7CPC


Re: [IC-7000] Re: IC700 and PRO7 IC headset RFI on my rig

Charles Scott <cscott@...>
 

Graham:

That's certainly the primary way those currents end up on the transmission line and into your shack, and for some antennas a "common-mode" choke or balun is a requirement or your transmission line becomes part of your antenna.

Near-field coupling to transmission lines, interconnection cables, power, etc are also a possibility. If the antenna is close to the house, or the transmission line at any point is in an orientation that can result in power being coupled onto it, other things may need to be done to suppress the problem.

Chuck - N8DNX


On 11/24/2016 4:01 AM, Graham Shaw muzzo@... [ic7000] wrote:
Hi - put your coax choke at the antenna as this is how to remove common mode currents traveling on the outside of the coax and back into your shack.

73 de Graham
ZL3TV
 


Re: IC700 and PRO7 IC headset RFI on my rig

Steve W3AHL
 

Colin,  
When you tested with your friend's radio, was it at your location using your antenna?  If so and you didn't see the problem, then the problem would seem to be in your radio.  If not then the problem could still be RFI in the shack.

If the problem seems to be in the radio, does it change when the mic is plugged into the rear MIC jack instead of the display head MIC jack.  Does unplugging only the headphone jack make a significant difference?  Does unplugging all other non-essential cables from the radio make a difference (to eliminate ground loops and RF from other devices' cables)?  Previously you said the standard HM-151 mic also caused display noise.  Is that still the case?

What year did you buy your 7K?  How many hours per week do you estimate it has been powered on?  Has it ever been repaired?  Depending on your answers to the above I might have some suggestion on what to check next.
 
If the problem could still be outside the radio:

Water pipes are usually a poor RF ground.  Previously you said you had an outside ground.  If you are using both, they should be bonded together near the rig and that point should be your radio system ground point for radios, tuner, computers, etc.   But for RFI in the shack problems, the most important thing is to ground the coax shield to the EXTERNAL earth ground before it enters the  building, typically using a lightning suppressor.  Common-mode RF flows on the outside of the shield, so if the RF ground has a low inductance (short, fat wire to ground rod) this will reduce RF inside the building.  But a GOOD common-mode choke near the feed point is still the best RFI fix in most cases.   Sometimes a second CM choke near the entry point is needed also.

All ferrites cores used on cables inside/outside the shack must be made from a material that is designed for the frequencies being used.  Fair-Rite brand type 31 is best for 3-30 MHz; type 43 from 10-50 MHz roughly.  It usually takes a large ferrite with multiple turns of the cable through the core to be effective at HF.  The goal is to get about 5,000 ohms of series resistive impedance across the problem frequency range.  Many ferrites bought  by hams are designed for VHF+ and are useless at HF.  They aren't marked, so either you have to have the equipment to test them or only buy from reputable distributors.

Sorry for all the questions and details but it is hard recommend next steps without seeing and measuring things at the site!

Steve, W3AHL

---In ic7000@..., <colin.christie34@...> wrote :

Hi,

I have RFI on my rig screen when I transmit using the Heil PRO7 IC  Headset and Microphone.

However, when I tried the headset/microphone on my mates  IC7000 rig no such problem exists.

Using a ICOM AH4  ATU , antenna is delta loop cut for 40m ,  coax feed and 4.1 balun at the apex fed point of the delta.

No separation cable in use as it is a operated as a base station.

Grounding  to water pipe system of house.

I tried a loop of coax with ferrite on the rear of the rig.

I have tried ferrites on the leads of the headset.

Grounded to rear of rig and AH4 ATU.

I would love to hear from you with any solutions how to stop the RFI in my IC7000 rig



73 Colin VK2JCC


Re: IC700 and PRO7 IC headset RFI on my rig

Graham Shaw <muzzo@...>
 

Hi - put your coax choke at the antenna as this is how to remove common mode currents traveling on the outside of the coax and back into your shack.

73 de Graham
ZL3TV

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