Elecraft › [HAM]

Re: Update on my progress - Now General RF Issue WAS 160m loop experiment a big failure

Classic

List

Threaded

6 messages Options

KD8NNU

Re: Update on my progress - Now General RF Issue WAS 160m loop experiment a big failure

First, let me say thank you to everyone on the list who has replied via
the list or directly. The help has been fantastic and has increased my
general knowledge as well as helping me with the problem.

Althought I have pointed to the start of the problem with the
installation of the Loop and the install of the propane tank and
possible crushed coax, I now believe that I have always had some RF
issues but it was brought to my attention by the Loop being real bad and
then I was highly sensitive to the whole system.

First I had made a significant error in the basic grounding of my shack.
This error I will call the green wire mistake. What I had done was add
the chassis ground of all my 12v devices and tuner to the green wire
ground of the house electrical system. This is in fact a signficant
error and has been corrected. What I have learned that there is a
difference for a saftey ground for lightening protection and so on and
it has nothing to do with an RF ground. So green wire error fixed, long
term a total revamp of the system for a safety ground.

Second I did a lot of checking of the coax yesterday. Checked it with
nothing attached, checked it with a dummy load, used functions of my MFJ
259b that I did not even know existed. Basically the coax checks out
fine, but I still have RF. The coax at this point in time is no longer
buried, I completely unearthed it.

At this point in time I put a choke at the antenna feed up in the air
with 31 mix ferrites and no improvement. So if the problem is at the
antenna feed this should have fixed it. I remove my lightening arrestor
from the system just to check it out no change. So I pull the choke
down.

Next I put a choke right at the antenna out the same choke that I had
put on the antenna feed point. Wow big improvement plus I added more
snap on 31 ferrites directly on the coax. So I have a choke in the
shack and now I can go full power. So having the choke at the feed
into the antenna tuner has a dramatic effect.

Now I am thinking ok I will burry the coax again, easy to do in the soft
grass plus I want to see if the problem turns on again as I have changed
the system with the coax laying on the ground and the outside is dry not
directly coupled to the set ground. After the burry RF is bad real bad.
So coax is now on laying on the ground again unearthed and the system
again functions, points again to bad coax.

I am now convenced that this is it so I turn on the shack PC to get some
more information and so on. Plus I am talking to some other hams on
what I have found. As the PC boots up the RF is back and it is strong.
Holy Sxxt Batman, now what. So I ponder this for a moment, since I
removed my geen wire error the PC is no longer connected to the K3 than
thru the rs232 so I am assuming Pin1 problem. I make a ground wire from
the chassis of the PC to the center of the grounding point (grounding
star as it is referred to) and fixed. So I take a critical look at the
PC installation and the coax runs right next to the PC. So I disconnect
everything and move the PC to the other side of the desk to get it as
far away from the coax as I can plus this eleminates short jumper cables
for the mouse and so on. So other than a brief instant when the PC
boots up and it is a very specfic part of the boot cycle there is no RF.

So in a nutshell

1) fixed green wire problem
2) unearthed coax and it is laying on the ground on the top of the grass
3) build choke with 31 mix at antenna out on the tuner
4) moved PC

I am on the air.

To do when the order shows up from UPS.

Install new coax, I assume the one I have is not happy anymore and test
the system to see if I can remove the choke at the tuner.

From my perspective I am on the air, but I do not have a robust
installation being on the 2nd floor. I probally can survive this winter
this way with the simple antenna shield grounding outside as I did last
winter as there is no lightning normally. However, I have to determine
the best way to redo the installation and am considering moving the
shack to the basement where then it will be signficantly eaiser to have
the shack properly grounded for safety and then bonded.

Again thanks for the help, as I am on the air but not convinced that I
have it fully cured. So there may be more questions in the future when
I find stuff starts to not work again.

~73
Don
KD8NNU

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Ken Alexander-2

Re: Update on my progress - Now General RF Issue WAS 160m loop experiment a big failure

Thanks Don, and all who contributed to help him.

Yours has been an interesting story and it was educational to watch it
unfold here. I bet the CQ or QST would eat up a story like that if it
was well documented and turned out as well as yours.

Regards,

Ken Alexander
VE3HLS

On 23/10/2011 9:13 AM, [hidden email] wrote:

> First, let me say thank you to everyone on the list who has replied via
> the list or directly. The help has been fantastic and has increased my
> general knowledge as well as helping me with the problem.
>
> Althought I have pointed to the start of the problem with the
> installation of the Loop and the install of the propane tank and
> possible crushed coax, I now believe that I have always had some RF
> issues but it was brought to my attention by the Loop being real bad and
> then I was highly sensitive to the whole system.
>
> First I had made a significant error in the basic grounding of my shack.
> This error I will call the green wire mistake. What I had done was add
> the chassis ground of all my 12v devices and tuner to the green wire
> ground of the house electrical system. This is in fact a signficant
> error and has been corrected. What I have learned that there is a
> difference for a saftey ground for lightening protection and so on and
> it has nothing to do with an RF ground. So green wire error fixed, long
> term a total revamp of the system for a safety ground.
>
> Second I did a lot of checking of the coax yesterday. Checked it with
> nothing attached, checked it with a dummy load, used functions of my MFJ
> 259b that I did not even know existed. Basically the coax checks out
> fine, but I still have RF. The coax at this point in time is no longer
> buried, I completely unearthed it.
>
> At this point in time I put a choke at the antenna feed up in the air
> with 31 mix ferrites and no improvement. So if the problem is at the
> antenna feed this should have fixed it. I remove my lightening arrestor
> from the system just to check it out no change. So I pull the choke
> down.
>
> Next I put a choke right at the antenna out the same choke that I had
> put on the antenna feed point. Wow big improvement plus I added more
> snap on 31 ferrites directly on the coax. So I have a choke in the
> shack and now I can go full power. So having the choke at the feed
> into the antenna tuner has a dramatic effect.
>
> Now I am thinking ok I will burry the coax again, easy to do in the soft
> grass plus I want to see if the problem turns on again as I have changed
> the system with the coax laying on the ground and the outside is dry not
> directly coupled to the set ground. After the burry RF is bad real bad.
> So coax is now on laying on the ground again unearthed and the system
> again functions, points again to bad coax.
>
> I am now convenced that this is it so I turn on the shack PC to get some
> more information and so on. Plus I am talking to some other hams on
> what I have found. As the PC boots up the RF is back and it is strong.
> Holy Sxxt Batman, now what. So I ponder this for a moment, since I
> removed my geen wire error the PC is no longer connected to the K3 than
> thru the rs232 so I am assuming Pin1 problem. I make a ground wire from
> the chassis of the PC to the center of the grounding point (grounding
> star as it is referred to) and fixed. So I take a critical look at the
> PC installation and the coax runs right next to the PC. So I disconnect
> everything and move the PC to the other side of the desk to get it as
> far away from the coax as I can plus this eleminates short jumper cables
> for the mouse and so on. So other than a brief instant when the PC
> boots up and it is a very specfic part of the boot cycle there is no RF.
>
> So in a nutshell
>
> 1) fixed green wire problem
> 2) unearthed coax and it is laying on the ground on the top of the grass
> 3) build choke with 31 mix at antenna out on the tuner
> 4) moved PC
>
> I am on the air.
>
> To do when the order shows up from UPS.
>
> Install new coax, I assume the one I have is not happy anymore and test
> the system to see if I can remove the choke at the tuner.
>
> From my perspective I am on the air, but I do not have a robust
> installation being on the 2nd floor. I probally can survive this winter
> this way with the simple antenna shield grounding outside as I did last
> winter as there is no lightning normally. However, I have to determine
> the best way to redo the installation and am considering moving the
> shack to the basement where then it will be signficantly eaiser to have
> the shack properly grounded for safety and then bonded.
>
> Again thanks for the help, as I am on the air but not convinced that I
> have it fully cured. So there may be more questions in the future when
> I find stuff starts to not work again.
>
> ~73
> Don
> KD8NNU
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

Re: Update on my progress - Now General RF Issue

In reply to this post by KD8NNU

Don,

Your "green wire mistake" was not a mistake at all. Everything in the
shack should have its chassis bonded together - by a connection to a
"single point ground" - that includes computers, power supplies, and
yes, the chassis of your 12 volt equipment too. That "single point
ground" should be bonded to the green wire ground too.

If you have a heavy wire to an earth driven ground rod from that single
point ground, all the better, BUT that driven ground rod must be also
connected to the Utility Entrance Ground - preferably by a wire outside
the house. See the Safety chapter in a 2010 or newer ARRL Handbook for
more information.

You should not rely entirely on the internal "green wire" at your shack
receptacles - it wanders about in your house wiring, and the only
requirement for AC safety is that it be all connected together - and it
sometimes fails. An annual check with one of the inexpensive testers is
a good thing.

You are quite correct that the above grounding schemes are for safety
ground and for protection from surges from nearby lightning. To survive
a direct strike, something much more extensive is required.
Those grounds are in no way an RF ground point and are not intended to
be. Other means will be required to establish an RF ground (actually a
low impedance point for RF).

One way to establish that low impedance point for RF in a 2nd floor
environment with 1/4 wave wires for all bands that you intend to
operate, and it may be the only practical way if you cannot keep common
mode RF off your antenna feedlines.

73,
Don W3FPR

On 10/23/2011 9:13 AM, [hidden email] wrote:

> First I had made a significant error in the basic grounding of my shack.
> This error I will call the green wire mistake. What I had done was add
> the chassis ground of all my 12v devices and tuner to the green wire
> ground of the house electrical system. This is in fact a signficant
> error and has been corrected. What I have learned that there is a
> difference for a saftey ground for lightening protection and so on and
> it has nothing to do with an RF ground. So green wire error fixed, long
> term a total revamp of the system for a safety ground.
>
>

gm3sek

Re: Update on my progress - Now General RF Issue WAS 160m loop experiment a big failure

In reply to this post by KD8NNU

Don wrote:

...]

>
>1) fixed green wire problem
>2) unearthed coax and it is laying on the ground on the top of the
>grass
>3) build choke with 31 mix at antenna out on the tuner
>4) moved PC
>
>I am on the air.
>
>To do when the order shows up from UPS.
>
>Install new coax, I assume the one I have is not happy anymore and test
>the system to see if I can remove the choke at the tuner.
>
> From my perspective I am on the air, but I do not have a robust
>installation being on the 2nd floor. I probally can survive this
>winter this way with the simple antenna shield grounding outside as I
>did last winter as there is no lightning normally. However, I have to
>determine the best way to redo the installation and am considering
>moving the shack to the basement where then it will be signficantly
>eaiser to have the shack properly grounded for safety and then bonded.
>
>Again thanks for the help, as I am on the air but not convinced that I
>have it fully cured. So there may be more questions in the future when
>I find stuff starts to not work again.

Well done - you made some real progress.

While you're waiting for the brown van, how about building a simple
clamp-on RF current meter? It is the most useful tool for this kind of
RFI investigation, because it lets you *see* where the stray currents
are. Once you've tried one, you'll wonder how you ever managed without
it.

The simplest 'Mousetrap' version only takes a half-hour to build:
<http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm>

In a review of commercial meters for 'Radcom' (RSGB), the MFJ-854
performed well but I found the MFJ-805 very poor:
<www.ifwtech.co.uk/g3sek/clamp-on/mfj-reviews.pdf>

--

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Guy, K2AV

Re: Update on my progress - Now General RF Issue WAS 160m loop experiment a big failure

In reply to this post by KD8NNU

I have been watching this thread out of the corner of my eye, but not
reading it real close. This post caught my attention.

I'm thinking you may actually have a break in the shield at a
connector point on the coax. That would cause heavy RF on the coax
shield coming back at the shack, and would STILL accept power from
your transmitter. Putting the coax on the ground may relieve stress on
the joint and allow the shield to make contact again.

Sometimes folks forget to solder the shield to PL259 as just one way
this can happen, or the shield internally isn't trimmed right for the
connector, etc, etc, ad naseum.

Another way that kind of break can happen is a lightning strike that
evaporated the connection at the connector, or at a strike point.

But to my mind, anyway, the coax shield and/or connections are
completely suspect for shield continuity. What you have described are
what would cause me to completely replace the coax and connectors.

We spend so much money on rigs and amps and then go cheep cheap on
feedline and connectors. Consider small hardline and connectors made
for that hardline, and some kinds of troubles will just go away.

73, Guy.

On Sun, Oct 23, 2011 at 9:13 AM, <[hidden email]> wrote:

Tony Estep

Re: Update on my progress - Now General RF Issue

In reply to this post by Don Wilhelm-4

On Sun, Oct 23, 2011 at 9:10 AM, Don Wilhelm <[hidden email]> wrote:

> ...One way to establish that low impedance point for RF in a 2nd floor
> environment with 1/4 wave wires for all bands that you intend to
> operate, and it may be the only practical way if you cannot keep common
> mode RF off your antenna feedlines...
>
> ===============
This is spot on. If you can get a good counterpoise scheme worked out,
there's no need to move the shack downstairs. Your symptoms indicate that
the trouble is stemming from common mode currents on the outside of your
coax. Once these are cured, there may be no need to hang ferrites on the
connecting wires in the shack. It sounds as if you're on the right track,
but you can do more to choke off the common mode currents and divert them so
they won't travel on the coax.

73, Tony KT0NY

--
http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html