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Old 22-02-2014, 12:11   #16
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Re: Issue with Icom M802 Installation

Terry,

I am using a 23' antenna, not the back stay. The antenna was mounted in a vertical position per icom instructions. It is located at the aft of the vessel about 30 feet away from the nav station below.

I only question the use of ferrites at this point because of the large amount of RFI experienced. When I transmit on high power, I can hear my voice coming out of the VHF radio speaker that is turned off.

I could somewhat understand the need for ferrites regarding the GPS and AIS as the antennas are located in the same proximity as the SSB antenna.

When you installed ferrites as part of your previous trouble shooting, what was the most effective location you found for effectiveness? The location nearest the the antenna (stern - outside) or the location nearest the device (nav station - inside)?
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Old 22-02-2014, 14:00   #17
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Re: Issue with Icom M802 Installation

Very interesting Mark,

I have not seen to many issues with a vertical. However it is very possible depending on the relationship to the other wires. Since it is vertical, how does it relate to the wires effected. Are they running vertically at any point in your boat?

However, I still think ferrite cores on the effected equipments wiring is still the best tack for solving the problem. It might be worth your while to try it on at east one piece of effected equipment.

Regards
Terry
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Quote:
Originally Posted by mcerdos View Post
Terry,

I am using a 23' antenna, not the back stay. The antenna was mounted in a vertical position per icom instructions. It is located at the aft of the vessel about 30 feet away from the nav station below.

I only question the use of ferrites at this point because of the large amount of RFI experienced. When I transmit on high power, I can hear my voice coming out of the VHF radio speaker that is turned off.

I could somewhat understand the need for ferrites regarding the GPS and AIS as the antennas are located in the same proximity as the SSB antenna.

When you installed ferrites as part of your previous trouble shooting, what was the most effective location you found for effectiveness? The location nearest the the antenna (stern - outside) or the location nearest the device (nav station - inside)?
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Old 22-02-2014, 16:49   #18
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Re: Issue with Icom M802 Installation

My tuner had an issue. The RF cable was installed so that there was a strain on the connection which actually caused a bit inside the tuner to come off the PCB. can't recall exactly what, been a couple of years now. Anyway, I soldered it up and all went back to normal.
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Old 23-02-2014, 09:14   #19
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Re: Issue with Icom M802 Installation

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Originally Posted by TLSparks View Post
Very interesting Mark,

I have not seen to many issues with a vertical. However it is very possible depending on the relationship to the other wires. Since it is vertical, how does it relate to the wires effected. Are they running vertically at any point in your boat?

However, I still think ferrite cores on the effected equipments wiring is still the best tack for solving the problem. It might be worth your while to try it on at east one piece of effected equipment.

Regards
Terry
AD7XL


Hi Terry,

All other wire is horizontal with the exception of antenna coax for the AIS/GPS and WI-FI booster that are located on a cross bar between the back stay spreaders. There have about 6 feet of vertical before going horizontal.

When you installed ferrites as part of your previous trouble shooting, what was the most effective location you found for effectiveness? The location nearest the the antenna (stern - outside) or the location nearest the device (nav station - inside) Or, both ends?
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Old 23-02-2014, 09:26   #20
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Re: Issue with Icom M802 Installation

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Originally Posted by mcerdos View Post
Hi Terry,

All other wire is horizontal with the exception of antenna coax for the AIS/GPS and WI-FI booster that are located on a cross bar between the back stay spreaders. There have about 6 feet of vertical before going horizontal.

When you installed ferrites as part of your previous trouble shooting, what was the most effective location you found for effectiveness? The location nearest the the antenna (stern - outside) or the location nearest the device (nav station - inside) Or, both ends?
Hi Mark,
The snap on Ferrite cores are best installed as close to the equipment and at both ends of a cable going between equipment. They form what is called an RF Choke for the cable.

The RF will continue to come into the cable as you can not stop that from happening without extensive shielding.

The cores will stop the RF from continuing into the equipment.
Again, adding 2 cores doubles the strength, looping through a core twice quadruples the strength. This is because the equation for a coil is proportional to the square of the number of turns.

They make cores for all sizes of cable. I like to use the RG8/RG213 cores as they have approximately a 1/4 inch hole and I can get more than one turn through the core.

Regards
Terry
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Old 23-02-2014, 14:47   #21
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Re: Issue with Icom M802 Installation

RF "looks" for a return path (a counterpoise, radial, or ground) to the transmitter. The better the counterpoise, the less RF current will return via other wiring. Even adding a KISS, which I think little of, to your existing RF ground or counterpoise system may help. If you are sure you have a good RF ground system then the ferrites are a good step. Others have made good suggestions on implementing a good RF ground. Use as many of them as you can.
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Old 24-02-2014, 08:24   #22
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Re: Issue with Icom M802 Installation

Quote:
Originally Posted by SoonerSailor View Post
RF "looks" for a return path (a counterpoise, radial, or ground) to the transmitter. The better the counterpoise, the less RF current will return via other wiring. Even adding a KISS, which I think little of, to your existing RF ground or counterpoise system may help. If you are sure you have a good RF ground system then the ferrites are a good step. Others have made good suggestions on implementing a good RF ground. Use as many of them as you can.
I would have to disagree. Each ground has its own way of working. What ever RF ground you decide to use you should make it the best you can, but don't mix types of grounds. e.g. KISS is a radial ground if mixed with copper capacitive grounds it typically results in high SWR bands and lower antenna current. One cruiser I repaired had a Dyna plate and also tied to his rudder post and motor. No one could hear him. He had poor SWR, poor Antenna current, and when he transmitted a pump turned on. Just using the Dynaplate he went from the poorest signal in Mexico to one of the loudest and the pump no longer runs when he hits the PTT.

By the way the KISS and Backstay tests almost as good as a Dynaplate for antenna current and there is no maintenance with a KISS. Fo non radio people, and that may be the majority of cruisers, I highly recommend KISS as even the best RF ground (a Dynaplate) the connection will corrode over time and then not work as well as a KISS. The best I have seen for overall performance here in Mexico and down to the South Pacific is a capacitive ground where massive copper was laid into the fiberglass, but the connection still corrodes and needs some maintenance.

Regards
Terry
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Old 24-02-2014, 09:52   #23
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Re: Issue with Icom M802 Installation

I would have to diasagree. The KISS is not equivalent to a tuned elevated radial, electrically it is simply a fat wire laid against the ground (seawater on the other side of the hull), and it IS capacitively coupled to that seawater ground. Maybe a wire or two laid in the bilge, like the KISS, gets you to 90% radiation efficiency in the special case of seawater. Maybe it doesn't. If one is looking to get the best from their radio installation and what one has now isn't working well, its worth trying some different ideas. If the KISS seems to satisfy ones needs for $160, then great. If one doesn't want to drink the Kool-Aid many alternatives will work as well or better and often at lesser expense. Please note I am not saying the KISS does not work. It just doesn't work the way the ad copy claims it does, and its results can be easily duplicated with a little bit of wire.
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Old 24-02-2014, 12:55   #24
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Re: Issue with Icom M802 Installation

Mark,
I'm sorry I'm coming in here two weeks late!!!

1) First off, you've gotten some good advice here (esp. from Bill, Chip, etc.)
And, getting of RFI can be a pain....but, if you follow the proper steps, it is usually a one-afternoon project costing about $100 or less...(see below for details..)


2) But, nobody has hit hard on an important issues yet...
When you wrote:
Quote:
Originally Posted by mcerdos View Post
I have a bronze plate on the rudder.
My "internal alarm" went off!!!
As, I've never seen an RF ground plate on a rudder provide an adequate RF ground / antenna ground...

Some of the functions of the RF Grond / Antenna Ground are:
a -- reduce/eliminate feedline radiation...(thereby reducing/eliminating RFI to other systems on-board)
b -- on some freqs / bands, they provide "the other half of the antenna"....provide a low-loss path for antenna-return currents...
c -- shunt "un-radiated" RF to ground (thereby further reducing RFI, etc.).....
d -- assist an antenna couple (auto-tuner) in making an adequate match..

One of the ways that a direct sea water connection RF ground works well, is when there is a low-inductance ("low RF loss") connection to the sea water....
But, trying to connect a plate on the rudder to the antenna tuner "ground lug", in a low-inductance way is problematic....
I.E. How is this "bronze plate" connected to the remote tuner's ground lug???
There cannot be a copper strap running from its mounting bolts, inside the rudder, up to the tuner ground lug!!! So, is this bronze plate bolted to the rudder structure (usually steel) and then a flexible wire (or worse a copper braid) attached to the upper rudder post, and that is run to the tuner???

Please note that a copper braid, even a "tinned copper braid" can have many 100's or 1000's of small connections/disconnections and even "semi-conductors" with RF flowing on it, that can cause serious RFI issues....especially in a salty marine environment!!
Quote:
Originally Posted by mcerdos View Post
Also, instead of running a wire from the antenna tuner to the grounding counterpoise copper strip, I added a piece of flat copper webbing from the tuner to copper counterpoise stripe. I read this in an iCom publication.
And as such I NEVER recommend an open copper braid be used for any RF connection....even though this is used as the shield of most coaxial cables, there it is tight woven and wrapped tightly by an outer jacket....
Have a look at any HF hi-power RF tank circuit, you'll find solid copper wire, copper strap, and sometimes even copper tubing....but NEVER braid!!!
It just is NOT done in the RF (HF world)....
(for a flexible "dc ground" strap, tinned braid is fine...but not for RF!!)

(I might be mistaken here, but I believe Amel's factory HF set-up uses this unusual approach of placing the direct sea water connection plate for the RF antenna ground on the rudder???
And, some of my experience talking with Amel owners/captains at sea, is that they never have very good results/signals....even a few years ago, an Amel with a NEW 250-watt Furuno, installed a month earlier in Gibraltar, sailing just miles from me repeated had significantly worse signal reports than I did....and many times could not even be heard/understood, while I was "loud 'n clear" to/from the same station....)

I'm not saying that I am 100% correct that this is the only cause of you troubles, but I suspect that it is one of the primary causes....
So, in that vein, you may need to do more than the average sailor to reduce/eliminate on-board RFI issues...(or consider a different approach for an RF Antenna Ground....)




3) Anytime I read/hear of HF radio RFI issues on-board, my three very first thoughts are:
a) Did they read and follow Sailmail's recommendations in the Sailmail Primer???
SailMail Primer

b) Do they have a low-inductance connection (short, wide, copper strap), from the tuner ground lug to a direct sea water contact???
GEORGIA COPPER - Copper ground strap
GEORGIA COPPER - Copper ground strap
GEORGIA COPPER - Comparison of Braid, Strap, Wire

c) Do they have a "line isolator" that provides a few thousand ohms of reactance on the outside of the coax, versus a few "clip-on" ferrites that provide a few hundred at best...
http://www.dxengineering.com/parts/dxe-fcc050-h05-a
T-4
Line Isolator System


http://www.dxengineering.com/search/...-ferrite-beads
http://www.dxengineering.com/parts/dxe-csb-combo
http://www.dxengineering.com/parts/dxe-csb-525p


Please note that part of the proper installation procedure (in addition to the use of a "line isolator" on the coax, AT the tuner end) is to NOT connect any "rf ground" strap between the tuner and the transceiver (main unit) chassis, nor any "rf ground" strap at all to the transceiver main unit!!!
Yes, this contrary to the Icom manual, but the manual was written by BOTH land-based design engineers in Japan (few of whom have any real-world HF installation experience), AND by lawyers/risk-management assessment teams trying to comply with various "grounding" / "safety" / RF-exposure rules world wide....
So, PLEASE understand that what "Icom recommends" in some of these matters is VERY WRONG!!!
And, to provide sufficient RF isolation of the tuner power/control wires, by using a few ferrites on these control/power wires (AT the tuner end)....




4) FYI, while proximity of the coax (running between the transceiver unit and the remote tuner) to the other wiring on-board CAN have an effect on your RFI issues...the farther away, the better...
Quote:
Originally Posted by mcerdos View Post
I am experiencing interference problems. The coax cable from the base unit to the AT 140 antenna tuner runs to the aft locker via a conduit that houses AIS/GPS cables and a couple of Ethernet cables for the computer network. When I transmit on the SSB, the AIS crashes and the computer network is having problems (the router will reset).
If proper installation methods (adequate RF antenna ground) and equipment (line isolator on the coax, AT the remote tuner end), you CAN have the coax running near other equipment wiring WITHOUT issue!!!
But, putting them through the SAME hole/wiring chase seems like a BAD idea...and I'm with Bill on this one, why not just drill (and seal up) another hole a few feet away???

{As example, on my current boat I have my coax (RG-213) running within 8" of my autopilot corepak / computer and its wiring....and only a few feet away from most other instrument / electronics wiring...(this is just the way it is on many boats these days, lots of wiring/electronics, so everything ends up in "close proximity")
And, heck my GTO-15 wire from the tuner up to the backstay runs only a couple feet away from some of my GPS wiring...
And, I have NO on-board transmit RFI issues at all!!!}




5) Scrap the RG-8x coax....not because it is "too small", etc. (as the loss on HF is insignificant), but because "RG-8x" is not a any kind of "standard" and as such anybody anywhere can make and market coax as RG-8x, and you have NO idea the quality of the cable!!!
Not to mention many will use poor/inferior connectors with this cable...
Although I recommend RG-213/u or the double-shielded RG-214/u (both "mil-spec" type cable), even a good quality (Belden or Times) RG-58/u or LMR-240, etc. would be a better choice that they typical RG-8x!!!
Quote:
Originally Posted by mcerdos View Post
There are common connections to these devises. I used RG8X from recommended by my West Marine and crimp on PL259 connectors for this run.
And, certainly scrap the "crimp-on" connectors, from West Marine!!!
These connectors alone may in fact be the primary cause of your troubles!!!
I didn't actually see this last part until I'd already written all the above, but absolutely get rid of those connectors (and cable)!!!
And, please not that if you cannot install the proper connectors, such as the solder-type or professional crimp-type (requires a professional tool), do NOT attempt to install these connectors....either buy pre-made (and tested/guaranteed) cable assemblies, or hire a professional to do it for you!!! (as doing a poor job of soldering the connectors will be no better than the horrible "west marine" crimp-types!!!)
Understand that testing connectors with an ohm-meter might show DC-continuity, BUT....
But, will NOT show the RF issues present in a bad connector!!!

--- SCRAP those connectors (and cable) and buy a tested/guaranteed cable assembly!!
--- Drill another hole through the water-tight bulkhead (as far away from the other wires as possible) and run the new cable through there..
--- Install a "line isolator" (at the tuner end of the coax), and a few clip-on ferrite beads on the tuner control/power wires...
--- Install clip-on ferrites on ALL electronics wiring (AIS wiring, instrument wiring, etc.)

Doing the first 3 things (above in red) will cost you about $150....and just might solve your problem...adding the ferrites to all the other electronics wiring will cost a bit more (< $100) and take a bit of effort...but this all should solve all or most of your RFI troubles!!
If not, then we'll need to discuss improving your RF Ground system...

If you desire a good quality cable assembly, with professionally installed and tested/guaranteed connectors, have a look at Davis RF, DX Engineering, or Texas Towers....I've done business with all of them for years, and they will all take good care of you!!!
http://www.dxengineering.com/search/...ble-assemblies

Texas Towers, Coax Jumpers Page

Texas Towers, Coax Jumpers Page

Texas Towers, Coax Jumpers Page

Davis RF Co. - The Price Leader in Times LMR, Andrews Heliax and other cables

http://www.dxengineering.com/search/...-ferrite-beads
http://www.dxengineering.com/parts/dxe-csb-combo
http://www.dxengineering.com/parts/dxe-csb-525p


6) Mark, understand that what some refer to as an "RF Choke" by winding the coax into a tight coil, does NOT provide much in the way of "rf choking" on the middle and lower ends of the HF spectrum....and certainly NOT even 10% of the choking inductance of a good quality line isolator!!!
And, I've seen many hams try to "homebrew" something from old torroids and/or TV flyback transformer cores (which are iron-powder NOT ferrite) and have NO difference vs. just a wrapped coil of coax....

So, my advice here is to spend the $50 to $80 on a real line isolator (and good quality coax / connectors) and solve your issues easily and reliably!!!



7) Terry make a point about RF radiated by your antenna being a possible cause of your troubles....
And, although this is a rare occurrence, it is possible....
And, this is where clip-on ferrites (at BOTH ends) on all your
electronics/instrument wiring (just prior to it entering the equipment and/or making connection with another piece of equipment) will make a big difference!!!
(see above for sources...)



8) At this point, you've been pointed in many directions by many well-intentioned folks...
But, my BEST advice is to take a 5 minute break, read what I wrote, read the links, etc...and understand that most times you need to take a "systems approach", and not a "hit 'n miss" approach...
What I mean is this:
a) Give us more/better info and we can give more/better answers...
and
b) Don't believe everything you read!!!



9) Oh, and while I don't recommend the "KISS" (see other threads), I'm not going to debate that here.....primarily as it has no bearing on this discussion!!



I know I'm coming in here late (sorry about that), but if you read what I wrote and give us a better understanding of WHERE and HOW all your SSB wiring and other electronics wiring is run...
AND ESPECIALLY how your "factory" RF grounding is done (if possible), then we can give you a much better idea of how-to solve your troubles!!!

Fair winds..

John
s/v Annie Laurie
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Old 24-02-2014, 15:26   #25
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Re: Issue with Icom M802 Installation

Quote:
Originally Posted by SoonerSailor View Post
I would have to diasagree. The KISS is not equivalent to a tuned elevated radial, electrically it is simply a fat wire laid against the ground (seawater on the other side of the hull), and it IS capacitively coupled to that seawater ground. Maybe a wire or two laid in the bilge, like the KISS, gets you to 90% radiation efficiency in the special case of seawater. Maybe it doesn't. If one is looking to get the best from their radio installation and what one has now isn't working well, its worth trying some different ideas. If the KISS seems to satisfy ones needs for $160, then great. If one doesn't want to drink the Kool-Aid many alternatives will work as well or better and often at lesser expense. Please note I am not saying the KISS does not work. It just doesn't work the way the ad copy claims it does, and its results can be easily duplicated with a little bit of wire.
SoonerSailor
I do not want to start the old HAM perception of KISS argument so I will not address your concept of KISS.

I have tested and/or repaired well over 250 boats coming to the West Coast of Mexico over the last 4 years. Given the average cruiser is not a radio engineer and do not want to work on radio equipment, I have begain to think simple is better. Most cruisers are successful bankers, lawyers, and business owners. Not that they are not smart, but in most cases they are not interested in becoming radio engineers.

I have also found that several "Professional" installers have no clue how to install a HF SSB radio. I was just aboard a boat that bought the equipment from a well known San Diego seller and installer. Fortunately the boat had a built in copper ground as that was the only thing right about the install. e.g Transceiver in a sealed very small locker with no air, powered from the breaker panel (Only provided 10.5 VDC at full power of 100W), broken control cable, and the best was the hose clamps holding the GTO wire to the back stay that had already left rust deposits on the GTO. My gut feeling is they never actually tested the radio as it did not work.

So I am beginning to thinking a radio with a KISS and and even a GAM antenna that works at 90% of maximum capability all the time is better than a radio that should work at 100% and does not because of lack of maintenance or, what seems typical down here, poor "Professional" installation.

If you install radios, I hope you do it all at the 100% level and are able to train the bankers and lawyers how to keep the radio running well when they are far far away where there are no Icom dealers or support. If not, keep sending them down and I will continue to get them working.

This has been my experience with cruisers in Mexico.

Kind Regards
Terry
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Old 24-02-2014, 15:42   #26
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Re: Issue with Icom M802 Installation

Oh, for goodness sakes.....
If you wish to argue about the "KISS", PLEASE PLEASE PLEASE do so, on the "KISS" discussion (something I gave up on last year)!!
And, let Mark get the information he needs to solve his troubles!!


The "KISS" system has NOTHING to do with Mark's issues and nothing to do with this discussion/thread!!

(I know sometimes threads drift around, and it is nobody's fault....but please understand when there is such a detailed, and recently active, thread already dedicated to a subject, there is no reason to drift another thread in that direction....especial here, as Mark doesn't have a "KISS" and his troubles have nothing to do with it...)



Thank you all very much!

Fair winds to all!!

John
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Old 24-02-2014, 16:55   #27
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Re: Issue with Icom M802 Installation

John you may not have seen the part where Mark thought he should also tie in a KISS to solve the problem. Totally agree that would not help. That is how Kiss got into the conversation.

Terry

Quote:
Originally Posted by ka4wja View Post
Oh, for goodness sakes.....
If you wish to argue about the "KISS", PLEASE PLEASE PLEASE do so, on the "KISS" discussion (something I gave up on last year)!!
And, let Mark get the information he needs to solve his troubles!!


The "KISS" system has NOTHING to do with Mark's issues and nothing to do with this discussion/thread!!

(I know sometimes threads drift around, and it is nobody's fault....but please understand when there is such a detailed, and recently active, thread already dedicated to a subject, there is no reason to drift another thread in that direction....especial here, as Mark doesn't have a "KISS" and his troubles have nothing to do with it...)



Thank you all very much!

Fair winds to all!!

John
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Old 24-02-2014, 20:42   #28
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Re: Issue with Icom M802 Installation

Mark,
I kinda glossed over this, as I didn't want to impugn the reputation of a guy I've never met, your "ham friend"....
Quote:
Originally Posted by mcerdos View Post
I have a HAM friend that is helping me now. He believes the RG8X coax I used for the 40' run from the navigation station to the lazarette should be ample and not radiate enough RFI to impact other electronics. Next week he is giving me a crash course on a BIRD meter and some steps to narrow down the problem. I will also install a RF choke and ferrites. Although, I wish to minimize the RFI as much as possible prior to the installation filters.
-- But, if you don't mind my bluntness, unless he has experience with (or has read a lot about) multi-band, end-fed, "Marconi-type" vertical antennas, especially on boats, he may end up unintentionally leading you astray from the crux of the problem / finding a solution....

-- RG-8x coax works fine for most HF ham applications, but it is not a "standard", meaning that there is NO spec that the cable is made to, and you are at the mercy of whoever manufactured that specific run of cable....

-- "west marine" crimp-on connectors are crap!!!

-- I current only own two Birds, one for 40 years now....they great meters, but they're only as good as the last calibration of the particular slug you're using....not to mention I can't fathom how a wattmeter can be of much help tracking down an RFI issue....
(yeah, you can check the cable's loss, and the VSWR provided to the radio by the tuner.....but not much else...)

-- I hope by "rf choke" you mean a line isolator and not simply a coil of coax....as a I wrote in detail about the effectiveness / use of each in my earlier posting...

-- Your desire to "minimize the RFI as much as possible prior to the installation filters", is a GREAT approach to take!!!
In that vein, scrap the RG-8x, and crappy connectors....and install better coax/connectors (see earlier posting) in a newly drilled and sealed hole a couple feet away from your other wiring....






Do the above, before speculating on what changes you may never need to make to your RF Ground system....
Quote:
Originally Posted by mcerdos View Post
At this point, I think what we expect to find is a) a problem with the iCom AT140 Antenna Tuner or b) that the manufacturer pre-installed counterpoise is insufficient. If B is the issue, the next step will be to install the KISS SSB Grounding System.
But, whatever we find, adding a "KISS" isn't going to be off help....




Good luck and Fair winds...

John
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Old 28-02-2014, 11:46   #29
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Re: Issue with Icom M802 Installation

Mark,
I assume that you've been busy working on your boat, as you've not been around since last Sunday....I hope the guys arguing about the "KISS" didn't put you off..

In any case, I think my detailed post from Monday should have well on your way to figuring out what's up with your system...



And, for those of you who are interested in seeing the common mode choking capabilities of various "chokes", ferrites, etc. and why a "line isolator" is so often recommended..
Quote:
Originally Posted by ka4wja View Post
c) Do they have a "line isolator" that provides a few thousand ohms of reactance on the outside of the coax, versus a few "clip-on" ferrites that provide a few hundred at best...
http://www.dxengineering.com/parts/dxe-fcc050-h05-a
T-4
Line Isolator System


http://www.dxengineering.com/search/...-ferrite-beads
http://www.dxengineering.com/parts/dxe-csb-combo
http://www.dxengineering.com/parts/dxe-csb-525p
Have a look at this site, where you can compare various approaches...
Common-mode chokes

You can quickly see how a few turns of coax in the air, might clean up the pattern of a tri-band yagi (14mhz - 28mhz), but have little common mode choking capability (where more than 2000ohms is desired)...and certainly none of any use on the lower HF frequencies...
And, with 4mhz - 8mhz being the most oft used for cruiser's nets, etc. and 4mhz thru 14mhz, being most oft used for all HF comms at sea (long-range or regional), it makes sense that coiling up the coax a few turns has no effect on-board....and this is why ferrites (mix 31 or 43) work so well....and why "line isolator" (usually a few turns of coax around a few cores...or a bifilar winding) works so well!!




Fair winds..

John
s/v Annie Laurie
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Old 04-03-2014, 11:27   #30
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Join Date: Jan 2011
Location: Full time cruiser
Boat: Amel Super Maramu 53
Posts: 187
Re: Issue with Icom M802 Installation

Hi Guys,

Thank you for the support and help. I am heading out to the boat this week with a multi-step plan.

Step 1 - Using the Bird meter (and radio in cw mode) check the cable for forward power and reverse power while AT140 is connected.

Disconnect the AT140 and place a dummy load on the end of the RC8X cable at the AT140 end and check forward power and reverse power. This should tell me if the current cable is bad. If the cable is good and the readings are within spec, at least I can eliminate everything pre AT140.

Step 2 – (Probably) replace RG8Xcable anyway with a length of RG213 and check to see if RFI is lower. Prior to changing the cable, run the cable over the deck and check to see if RFI is gone. If RFI is still present, this will be confirmation I am getting it post AT140. Please note here – I am somewhat forced to run the cable through the same conduit as other cables as this passes through two watertight bulkheads. Running the cable outside of the conduit will require an awful lot of work. This can be done, but only as a last resort.

Step 3 – Replace wire connecting AT140 to antenna with high voltage wire and ensure crimps are secure and watertight.

Step 4 – Connect AT140 to manufacturer installed counterpoise using pure copper strip (not wire). I have ruled out the KISS grounding system option.

Again check for RFI

Step 5 – install ferrites with at least 2 wraps on all cabling running through the conduit AND on all cabling near the antenna.

If this all works and I have no RFI, I will know my basic installation is good. I will pull the cable back through the conduit. If I am still getting RFI while in the conduit, I know at that point I will have to run the cable through a separate channel. Like I said, this is a last resort.

I haven’t decided yet on a line isolator. I have one from my HAM friend to try out.

More to come soon.

Thanks for all the ideas and thoughts.
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