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K3/100 -Second floor- no RF ground ??

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callen1155

K3/100 -Second floor- no RF ground ??

Hello guys,

I'm planning on purchasing a K3/100 but am concerned about my second floor shack and RF problems.

First of all:
1) I don't have an RF ground (don't really want to drill thru the house and siding for the ground strap) and

2) my antenna is a semi-indoor/attic dipole (HOA).
I'm running a coax from the second floor radio to the attic where i attach to a dipole (no balun) and the dipole runs the length of the house each way and out the eaves where both wires run out about 35 yards to the trees.

I'm using my K2/15 and don't have problems but previously with my old Knwd TS 830 at about 100 watts the vibroplex bug would 'bite' me. I'd also get some RFI on the TV (didn't try any filters to prevent it).

I know both of the above arrangements are potential sources for RF problems. What I don't know is whether RF problems (both the 'burn' and RFI) are radio related; i.e. are some radios more prone cause issues and how is the K3/100 in this regard as compared to the TS 830? (this may be a non-question-- i just don't have enough experience with different radios to know).

So I'm wonder if any of you operate a K3/100 from a second floor shack, with no RF ground, (guess it's too much to ask about a semi-indoor antenna) and if you're experiencing RF problems?

Also, if I experience RF problems with the K3 do any you have any experience with an "Artificial RF Ground" such as the MFJ-931?

Sorry about being long winded.

Hope I'm not 'destined' to order a K3/10 instead.

thanks again.
chuck
af4xk

David Herring-2

Re: K3/100 -Second floor- no RF ground ??

Hi Chuck

I have no experience with artificial grounds, but I can tell you that
a balun will quite likely put an end to your RF burn problem.

Regarding RF ground, most hams don't have one. It's rarely needed (I'm
talking about rig RF ground, not, say for antennas, which is a whole
other thing). And it's hard to really make one that really works, due
to impedance issues. Being on the second floor, it would just be an
antenna anyway, making your problems with TVI just that much worse.

Go get a good 1:1 current balun (or make one) and start from there. It
should improve or eliminate both you TVI and your RF at the operating
position problem. If it doesn't, there are other steps to be taken,
but this is your best starting point.

Good luck

73,
David K6DCH

Sent from my iPhone

On Feb 24, 2010, at 12:18 PM, callen1155 <[hidden email]> wrote:

>
>
> Hello guys,
>
> I'm planning on purchasing a K3/100 but am concerned about my second
> floor
> shack and RF problems.
>
> First of all:
> 1) I don't have an RF ground (don't really want to drill thru the
> house and
> siding for the ground strap) and
>
> 2) my antenna is a semi-indoor/attic dipole (HOA).
> I'm running a coax from the second floor radio to the attic where i
> attach
> to a dipole (no balun) and the dipole runs the length of the house
> each way
> and out the eaves where both wires run out about 35 yards to the
> trees.
>
> I'm using my K2/15 and don't have problems but previously with my
> old Knwd
> TS 830 at about 100 watts the vibroplex bug would 'bite' me. I'd
> also get
> some RFI on the TV (didn't try any filters to prevent it).
>
> I know both of the above arrangements are potential sources for RF
> problems.
> What I don't know is whether RF problems (both the 'burn' and RFI)
> are radio
> related; i.e. are some radios more prone cause issues and how is the
> K3/100
> in this regard as compared to the TS 830? (this may be a non-
> question-- i
> just don't have enough experience with different radios to know).
>
> So I'm wonder if any of you operate a K3/100 from a second floor
> shack, with
> no RF ground, (guess it's too much to ask about a semi-indoor
> antenna) and
> if you're experiencing RF problems?
>
> Also, if I experience RF problems with the K3 do any you have any
> experience
> with an "Artificial RF Ground" such as the MFJ-931?
>
> Sorry about being long winded.
>
> Hope I'm not 'destined' to order a K3/10 instead.
>
> thanks again.
> chuck
> af4xk
> --
> View this message in context: http://n2.nabble.com/K3-100-Second-floor-no-RF-ground-tp4628979p4628979.html
> Sent from the [K3] mailing list archive at Nabble.com.
> ______________________________________________________________
> 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

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Don Wilhelm-4

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by callen1155

Chuck,

RF-in-the-shack is always antenna related and not transceiver related.
Unless the transceiver is having some kind of strong parasitic
oscillation, and that would show up in other ways as well.

You may not notice the RF at low power levels, but when you get up to
the 30 watt and above level, it is likely to begin to be troublesome.

A ground to Mother Earth is not likely to help - the wire down to the
ground will have some length to it and where it is near a quarter
wavelength long, it will present a high RF impedance in the shack,
exactly opposite of what you are trying to accomplish.

Given your difficult situation, I would suggest that quarter wavelength
counterpoise wires will be your best choice for creating an RF Ground in
the shack. Cut one for each band you will operate - treat the far ends
just like the end of an antenna, insulate it and keep it out of reach
for humans and pets. The far end will be hot with RF when you operate.
Yes, it may radiate, for it will become a part of your antenna system.
If you have multiple wires, then try to separate the ends as much as
possible, they will interact and de-tune each other. If you can get
them outside, do so, but they will work run out on the floor of the
shack if necessary - if you have to do that, I would suggest keeping the
power low for safety - I would think 50 watts is a practical upper
limit, but your choice may be otherwise.
Don't forget about the RF at the far end - at higher power levels, it
can start fires if near or in contact with combustible materials.

An Artificial Ground such as the one from MFJ is nothing more than a
series tuned circuit with a single wire running from it - it behaves
just like my suggested counterpoise wires - but it must be tuned to
resonate with the wire. If you are planning rapid and easy band changes
with the K3 tuner, then forget it because you would have to tune the
artificial ground too.

Your physical constraints will likely dictate the solution that is
"best" for you. We all do not enjoy ideal antenna systems.

73,
Don W3FPR

callen1155 wrote:

> Hello guys,
>
> I'm planning on purchasing a K3/100 but am concerned about my second floor
> shack and RF problems.
>
> First of all:
> 1) I don't have an RF ground (don't really want to drill thru the house and
> siding for the ground strap) and
>
> 2) my antenna is a semi-indoor/attic dipole (HOA).
> I'm running a coax from the second floor radio to the attic where i attach
> to a dipole (no balun) and the dipole runs the length of the house each way
> and out the eaves where both wires run out about 35 yards to the trees.
>
> I'm using my K2/15 and don't have problems but previously with my old Knwd
> TS 830 at about 100 watts the vibroplex bug would 'bite' me. I'd also get
> some RFI on the TV (didn't try any filters to prevent it).
>
> I know both of the above arrangements are potential sources for RF problems.
> What I don't know is whether RF problems (both the 'burn' and RFI) are radio
> related; i.e. are some radios more prone cause issues and how is the K3/100
> in this regard as compared to the TS 830? (this may be a non-question-- i
> just don't have enough experience with different radios to know).
>
> So I'm wonder if any of you operate a K3/100 from a second floor shack, with
> no RF ground, (guess it's too much to ask about a semi-indoor antenna) and
> if you're experiencing RF problems?
>
> Also, if I experience RF problems with the K3 do any you have any experience
> with an "Artificial RF Ground" such as the MFJ-931?
>
>

Merv Schweigert

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by callen1155

I operated inside a condo on the beach for several years with a 44 foot
wire center fed
with ladder line antenna, fed with a Johnson matchbox, I had some RF
on some bands, so I
strung a wire around the edge of the room on the floor cut for the band
that had the
worst RF. Connected it to the ground on the tuner, all was cured.
I tried the MFJ ground box and found no use for it with the wire cut for
the band in
question. If you have RF on more than one band a piece of multi strand
wire cut for
different bands works well.
Merv KH7C

> So I'm wonder if any of you operate a K3/100 from a second floor shack, with
> no RF ground, (guess it's too much to ask about a semi-indoor antenna) and
> if you're experiencing RF problems?
>
> Also, if I experience RF problems with the K3 do any you have any experience
> with an "Artificial RF Ground" such as the MFJ-931?
>
> Sorry about being long winded.
>
> Hope I'm not 'destined' to order a K3/10 instead.
>
> thanks again.
> chuck
> af4xk
>

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by callen1155

Chuck, I had a second floor shack in a beach house. The first antenna that I had was a Butternut vertical mounted on a tripod on the roof. It had four 32 foot radials that ran just over the roof to some 20 foot poles attached to my fence. It worked very well, but the RF was another thing. The shack was hotter than a pistol when I ran my amplifier with about 600 watts out. I bought a MFJ artificial ground and could not find a way to make it help. I had a #6 wire running through the floor to a triad of ground rods in a 10 ft triangle which did very little for the RF but did ground my AC service very well since they were driven into salt water. I don't think the brand or model of transceiver will make a lot of difference since the RF will be coming from the antenna just a few feet over your head. The best cure is to get the antenna higher and farther away, but of course you will incur the wrath of the HOA and possibly the XYL or some
other three or four letter acronym. You might not like my final cure, MOVE, but it did help when I put up a 60 ft tower with a beam. The Butternut was pretty good, but the Cushcraft was much better!
Willis 'Cookie' Cooke
K5EWJ

________________________________
From: callen1155 <[hidden email]>
To: [hidden email]
Sent: Wed, February 24, 2010 4:18:50 PM
Subject: [Elecraft] K3/100 -Second floor- no RF ground ??

Hello guys,

I'm planning on purchasing a K3/100 but am concerned about my second floor
shack and RF problems.

First of all:
1) I don't have an RF ground (don't really want to drill thru the house and
siding for the ground strap) and

2) my antenna is a semi-indoor/attic dipole (HOA).
I'm running a coax from the second floor radio to the attic where i attach
to a dipole (no balun) and the dipole runs the length of the house each way
and out the eaves where both wires run out about 35 yards to the trees.

I'm using my K2/15 and don't have problems but previously with my old Knwd
TS 830 at about 100 watts the vibroplex bug would 'bite' me. I'd also get
some RFI on the TV (didn't try any filters to prevent it).

I know both of the above arrangements are potential sources for RF problems.
What I don't know is whether RF problems (both the 'burn' and RFI) are radio
related; i.e. are some radios more prone cause issues and how is the K3/100
in this regard as compared to the TS 830? (this may be a non-question-- i
just don't have enough experience with different radios to know).

So I'm wonder if any of you operate a K3/100 from a second floor shack, with
no RF ground, (guess it's too much to ask about a semi-indoor antenna) and
if you're experiencing RF problems?

Also, if I experience RF problems with the K3 do any you have any experience
with an "Artificial RF Ground" such as the MFJ-931?

Sorry about being long winded.

Hope I'm not 'destined' to order a K3/10 instead.

thanks again.
chuck
af4xk
--
View this message in context: http://n2.nabble.com/K3-100-Second-floor-no-RF-ground-tp4628979p4628979.html
Sent from the [K3] mailing list archive at Nabble.com.
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Jim Brown-10

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by callen1155

On Wed, 24 Feb 2010 14:18:50 -0800 (PST), callen1155 wrote:

>I'm planning on purchasing a K3/100 but am concerned about my second floor
>shack and RF problems.

The most important thing to understand is that a connection to EARTH has NOTHING
to do with RFI, or RF feedback, or any of the problems you are describing.

The word "ground" in this context really means "signal common" and "shielding."
I ran 1.5kW from a second floor shack in my wood frame house in Chicago. I used
mostly dipole antennas that were no more than 40 ft off the ground, so only
about 20 ft above my operating desk. There was direct radiation of RF from those
antennas into wiring in my shack and in my home, but the only problems came from
improper connection of cable shields in equipment.

I also ran 1.5kW on 160M and 80 into a long wire antenna that ended in my shack.
As a counterpoise for that antenna, I used a large wrought iron fence that ran
around the front of my city lot, roughly 150 linear feet, 6 ft high, plus some
wire radials. That antenna had a very strong current peak at the transmitter, so
there was a very strong magnetic field sounding it. The only problem I had with
that antenna was with the stock control cable for my K2/100, which was parallel
wires in a foil shield. I replaced that cable with twisted pairs, with one side
of each pair serving as signal return and connected to the chassis of the
computer and the chassis of the K2. That solved that problem.

A radio does not need ANY connection to the EARTH. If you doubt that, think
about how radios in aircraft work! Didja ever see a 747 taking off trailing a
ground wire?

What I strongly recommend for your new QTH is resonant antennas fed with coax.
Keep them as far away from your home electronics and from your shack. Use good
coaxial ferrite chokes on all the feedlines. Study

http://audiosystemsgroup.com/RFI-Ham.pdf

73,

Jim Brown K9YC

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N4CW

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by callen1155

IMHO, the real problem is the location of the r.f. and not the ground. My
shack is also on the second floor and I NEVER have problems with r.f. in the
shack, even with high power.

I've also done attic and gutter/eaves antennas, and they've ALWAYS managed
to couple into house AC and telephone wiring. If you have absolutely no
choice but to keep the antennas hidden (in or on the house), then
you MUST decouple the antenna from your feedline. You can use lots of
ferrite beads on the existing feedline, close to the antenna. If you have a
current balun, use that in place of the center insulator.

But if at all possible, go outside the house...preferably, away from it!

Good luck,
Bert, N4CW
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Alan Bloom

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by Jim Brown-10

On Wed, 2010-02-24 at 18:16 -0800, Jim Brown wrote:
> On Wed, 24 Feb 2010 14:18:50 -0800 (PST), callen1155 wrote:
>
> >I'm planning on purchasing a K3/100 but am concerned about my second floor
> >shack and RF problems.
>
> The most important thing to understand is that a connection to EARTH has NOTHING
> to do with RFI, or RF feedback, or any of the problems you are describing.

It's amazing how widely the concept of ground is misunderstood. For
years the ARRL Handbook repeated the myth that you need a good earth
ground to prevent TVI. I think we finally got that straightened out.

People say that your low-pass filter won't work without a ground because
the shunt capacitors need to be "grounded" but then they are at a loss
to explain how low-pass filters work in satellites.

I think the fundamental problem is that people don't understand (or
forget) that "voltage" means "potential difference", the difference in
electrical potential between two points. It makes no sense to speak of
the voltage "at" a particular circuit point unless you define the
reference point -- the place the other lead of your voltmeter or
oscilloscope is connected to.

There can be 1000V difference in potential between earth and the chassis
of your radio and the radio will continue to work perfectly normally as
long as it is completely isolated from earth. What matters is the
potential difference between the circuit nodes inside the radio, not the
voltage with respect to earth.

Al N1AL

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Don Wilhelm-4

Re: K3/100 -Second floor- no RF ground ??

Thanks for that Alan,

I have been saying the same thing for years. Earth grounds are for AC
safety and Lightning safety. They have nothing to do with RF Ground
reference. Yes, RF "Ground" is nothing but a reference point for the RF
voltage (or current).

For our purposes, think of it only as a low impedance (ideally zero, but
normally higher) for RF at the frequency of operation. A truly balanced
antenna will have that point halfway between the feedline conductors at
the feedpoint. While that may be 'stretching science' a small amount,
it is the closest I can get with a visual example.
When the currents (and voltages) are equal and opposite, RF "Ground"
will be the value midway between those voltages (or currents).
Since a balanced feedline should have equal and opposite (differential)
currents on the two conductors (that is the definition of balanced), if
the antenna is balanced and the feedline does not pick up radiation from
the antenna, that RF Gound reference point will be conducted into the
shack by the feedline.

The problem is that the feedline does pick up radiation from the antenna
- and that is carried by the feedline into the shack as well - that is
called common mode current. If that common mode current exists, it will
bring RF into the shack and must be dealt with by either bleeding it off
into a low impedance for RF (the counterpoise wires mentioned earlier of
an artificial RF Ground), or eliminating it at the source by proper
feedline placement if the feedline is balanced.

Coax fed antennas are a bit different than those fed with balanced
feedlines. Due to skin effects, a coax feedline has 3 effective
conductors - the center conductor, the inside of the shield and the
outside of the shield. The currents inside the coax are actually
balanced - they must be equal and opposite. When the end of a coax
feedline is connected to two wires of equal length, the center conductor
sees only the antenna half for the current to flow onto, but the side
connected to the shield sees two conductors - one is the antenna half
and the other is the outside of the coax shield. If current does flow
onto the outside of the coax shield, it is common mode current when it
arrives at the shack end. The cure is to use a current balun at the
antenna feedpoint, and run the feedline at right angles away from the
radiating elements for as great a distance as possible so the coax does
not pick up radiation from the antenna.

A choke balun is nothing more than an RF Choke - it can be formed with
ferrite beads over the coax, or by coiling the coax into an inductor.
The reactance of the inductor thus formed should be greater than 5 times
the antenna feedpoint impedance (note that this may or may not be not be
the characteristic impedance of the coax feedline). The required
impedance is determined by the antenna, and not by the feedline. I know
there have been a lot of things published about "forcing balance" by
using a balun - I just do not buy that concept. My education in
antennas is much more simplistic and clear (to me), and it is based on
one principle - the current at the end of an antenna *must* be zero.
Think about that for a while and you may change your thinking about
anteennas - one does not "force" an antenna to be balanced, that is
determined by the relationship between the feedpoint and the ends of the
antenna. The radiating portion of the antenna sets the "rules" - any
differences are dissipated as heat.

73,
Don W3FPR

73,
Don W3FPR

Alan Bloom wrote:

> On Wed, 2010-02-24 at 18:16 -0800, Jim Brown wrote:
>
>> On Wed, 24 Feb 2010 14:18:50 -0800 (PST), callen1155 wrote:
>>
>>
>>> I'm planning on purchasing a K3/100 but am concerned about my second floor
>>> shack and RF problems.
>>>
>> The most important thing to understand is that a connection to EARTH has NOTHING
>> to do with RFI, or RF feedback, or any of the problems you are describing.
>>
>
> It's amazing how widely the concept of ground is misunderstood. For
> years the ARRL Handbook repeated the myth that you need a good earth
> ground to prevent TVI. I think we finally got that straightened out.
>
> People say that your low-pass filter won't work without a ground because
> the shunt capacitors need to be "grounded" but then they are at a loss
> to explain how low-pass filters work in satellites.
>
> I think the fundamental problem is that people don't understand (or
> forget) that "voltage" means "potential difference", the difference in
> electrical potential between two points. It makes no sense to speak of
> the voltage "at" a particular circuit point unless you define the
> reference point -- the place the other lead of your voltmeter or
> oscilloscope is connected to.
>
> There can be 1000V difference in potential between earth and the chassis
> of your radio and the radio will continue to work perfectly normally as
> long as it is completely isolated from earth. What matters is the
> potential difference between the circuit nodes inside the radio, not the
> voltage with respect to earth.
>
> Al N1AL
>
>
> ______________________________________________________________
> 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
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.733 / Virus Database: 271.1.1/2707 - Release Date: 02/24/10 02:34:00
>
>

Steve Ellington

Re: K3/100 -Second floor- no RF ground ??

Speaking of lightning grounds. MFJ says use soild wire or flat copper for
ground wire and never use stranded or braided wire. They claim the latter
has high impedance to lightning.
Ok, fine....so if my antenna is stranded wire, does it have high impedance
to lighting? Would it be less safe to make ones antenna from solid
conductors? Yes...a weird question but it's been bugging me.
Steve
N4LQ
----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: <[hidden email]>
Cc: <[hidden email]>
Sent: Wednesday, February 24, 2010 11:11 PM
Subject: Re: [Elecraft] K3/100 -Second floor- no RF ground ??

> Thanks for that Alan,
>
> I have been saying the same thing for years. Earth grounds are for AC
> safety and Lightning safety. They have nothing to do with RF Ground
> reference. Yes, RF "Ground" is nothing but a reference point for the RF
> voltage (or current).
>
> For our purposes, think of it only as a low impedance (ideally zero, but
> normally higher) for RF at the frequency of operation. A truly balanced
> antenna will have that point halfway between the feedline conductors at
> the feedpoint. While that may be 'stretching science' a small amount,
> it is the closest I can get with a visual example.
> When the currents (and voltages) are equal and opposite, RF "Ground"
> will be the value midway between those voltages (or currents).
> Since a balanced feedline should have equal and opposite (differential)
> currents on the two conductors (that is the definition of balanced), if
> the antenna is balanced and the feedline does not pick up radiation from
> the antenna, that RF Gound reference point will be conducted into the
> shack by the feedline.
>
> The problem is that the feedline does pick up radiation from the antenna
> - and that is carried by the feedline into the shack as well - that is
> called common mode current. If that common mode current exists, it will
> bring RF into the shack and must be dealt with by either bleeding it off
> into a low impedance for RF (the counterpoise wires mentioned earlier of
> an artificial RF Ground), or eliminating it at the source by proper
> feedline placement if the feedline is balanced.
>
> Coax fed antennas are a bit different than those fed with balanced
> feedlines. Due to skin effects, a coax feedline has 3 effective
> conductors - the center conductor, the inside of the shield and the
> outside of the shield. The currents inside the coax are actually
> balanced - they must be equal and opposite. When the end of a coax
> feedline is connected to two wires of equal length, the center conductor
> sees only the antenna half for the current to flow onto, but the side
> connected to the shield sees two conductors - one is the antenna half
> and the other is the outside of the coax shield. If current does flow
> onto the outside of the coax shield, it is common mode current when it
> arrives at the shack end. The cure is to use a current balun at the
> antenna feedpoint, and run the feedline at right angles away from the
> radiating elements for as great a distance as possible so the coax does
> not pick up radiation from the antenna.
>
> A choke balun is nothing more than an RF Choke - it can be formed with
> ferrite beads over the coax, or by coiling the coax into an inductor.
> The reactance of the inductor thus formed should be greater than 5 times
> the antenna feedpoint impedance (note that this may or may not be not be
> the characteristic impedance of the coax feedline). The required
> impedance is determined by the antenna, and not by the feedline. I know
> there have been a lot of things published about "forcing balance" by
> using a balun - I just do not buy that concept. My education in
> antennas is much more simplistic and clear (to me), and it is based on
> one principle - the current at the end of an antenna *must* be zero.
> Think about that for a while and you may change your thinking about
> anteennas - one does not "force" an antenna to be balanced, that is
> determined by the relationship between the feedpoint and the ends of the
> antenna. The radiating portion of the antenna sets the "rules" - any
> differences are dissipated as heat.
>
> 73,
> Don W3FPR
>
> 73,
> Don W3FPR
>
> Alan Bloom wrote:
>> On Wed, 2010-02-24 at 18:16 -0800, Jim Brown wrote:
>>
>>> On Wed, 24 Feb 2010 14:18:50 -0800 (PST), callen1155 wrote:
>>>
>>>
>>>> I'm planning on purchasing a K3/100 but am concerned about my second
>>>> floor
>>>> shack and RF problems.
>>>>
>>> The most important thing to understand is that a connection to EARTH has
>>> NOTHING
>>> to do with RFI, or RF feedback, or any of the problems you are
>>> describing.
>>>
>>
>> It's amazing how widely the concept of ground is misunderstood. For
>> years the ARRL Handbook repeated the myth that you need a good earth
>> ground to prevent TVI. I think we finally got that straightened out.
>>
>> People say that your low-pass filter won't work without a ground because
>> the shunt capacitors need to be "grounded" but then they are at a loss
>> to explain how low-pass filters work in satellites.
>>
>> I think the fundamental problem is that people don't understand (or
>> forget) that "voltage" means "potential difference", the difference in
>> electrical potential between two points. It makes no sense to speak of
>> the voltage "at" a particular circuit point unless you define the
>> reference point -- the place the other lead of your voltmeter or
>> oscilloscope is connected to.
>>
>> There can be 1000V difference in potential between earth and the chassis
>> of your radio and the radio will continue to work perfectly normally as
>> long as it is completely isolated from earth. What matters is the
>> potential difference between the circuit nodes inside the radio, not the
>> voltage with respect to earth.
>>
>> Al N1AL
>>
>>
>> ______________________________________________________________
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>>
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>> ------------------------------------------------------------------------
>>
>>
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>> Checked by AVG - www.avg.com
>> Version: 9.0.733 / Virus Database: 271.1.1/2707 - Release Date: 02/24/10
>> 02:34:00
>>
>>
> ______________________________________________________________
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14:34:00

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Don Wilhelm-4

Re: K3/100 -Second floor- no RF ground ??

Steve,

That is a bit of a strange question - because I never though of my
antenna wires as being a conductor for lightning. While the antenna
wires will pick up lightning surges, I don't think that is what is being
considered. What they are talking about is how to dissipate whatever
lightning surge that makes it into the shack to ground. For that - yes,
you would use solid conductor (of heavy guage) wire, or better yet flat
copper strap with its large surface area for the station safety
ground. Conduct the energy out of the shack and into the earth ground
where it can dissipate. The greater earth surface that you can
distribute that energy, the better - be that several connected ground
rods separated by twice their length or a system of buried conductors
like a perimeter wire around the building where the shack is housed.

In fact, I would think that an antenna that has higher resistance to
lightning surge is better - the strength of the surge will be reduced by
the time it reaches the shack. The path from the shack to your
lightning protection ground is a different matter, and should be low
impedance at all frequencies if that is possible - it is not, so we do
the best we can with conductors having greater surface area and plenty
of conducting capability for high currents as well.

So stranded wire is OK for antennas, but not for the run from the
station to the safety ground.

73,
Don W3FPR

Steve Ellington wrote:

> Speaking of lightning grounds. MFJ says use soild wire or flat copper for
> ground wire and never use stranded or braided wire. They claim the latter
> has high impedance to lightning.
> Ok, fine....so if my antenna is stranded wire, does it have high impedance
> to lighting? Would it be less safe to make ones antenna from solid
> conductors? Yes...a weird question but it's been bugging me.
> Steve
> N4LQ
>
>

Julian, G4ILO

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by callen1155

Chuck, I have an almost identical setup to what you are proposing. It's really difficult to get an effective RF ground on an upper story because the ground connection has resonance which may result in a high impedance at higher frequencies. Some people have suggested an MFJ Artificial Ground but that basically tunes up a wire counterpoise inside the house and I can't see how that can be good either for low noise or RFI immunity because the wire must pick up noise and radiate signal.

My two HF antennas are an MFJ magnetic loop and a multiband dipole. I have a balun on the dipole, and I have never experienced RF on the radio though I do get a strong field from the magnetic loop that can cause the computer to act up at high power. I don't regret getting the 100W PA for my K3 as I was getting frustrated with QRP during the years of no sunspots and now I'm used to having it I can't easily put the genie back in the bottle, but QRP is really preferable for many reasons in this kind of situation.

I have experienced the common mode pickup that has been mentioned where RF radiated by one antenna was picked up by the feeder of another and fed back down to the shack. It really started when I added 2m antennas to my attic antenna farm. I would probably never have noticed if I was not a keen PSK31 operator and have an IMD meter but the effect is noticeable as poor transmit IMD on some HF frequencies. The problem is really only solvable by getting rid of the 2m antennas, but I have managed to mitigate it to some extent by making copious use of clamp-on ferrite suppressors on every cable that goes into the K3. I also found that "grounding" the equipment to the copper pipes of the central heating system was actually making it worse.

If you just have the one antenna then hopefully you won't have the problem this bad and won't need to go to such lengths, but I have been trying to push the envelope of what can be achieved with an indoor antenna system.

callen1155 wrote

Hello guys,

I'm planning on purchasing a K3/100 but am concerned about my second floor shack and RF problems.

First of all:
1) I don't have an RF ground (don't really want to drill thru the house and siding for the ground strap) and

2) my antenna is a semi-indoor/attic dipole (HOA).
I'm running a coax from the second floor radio to the attic where i attach to a dipole (no balun) and the dipole runs the length of the house each way and out the eaves where both wires run out about 35 yards to the trees.

Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html

Steve Ellington

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by Don Wilhelm-4

Don:

You answered my question when you said:

"In fact, I would think that an antenna that has higher resistance to
lightning surge is better - the strength of the surge will be reduced by
the time it reaches the shack. "

I have never seen this issue addressed.

So bottom line:
Using stranded wire for antennas improves ligtning protection.

Steve
N4LQ
----- Original Message -----
From: "Don Wilhelm" <[hidden email]>
To: "Steve Ellington" <[hidden email]>
Cc: <[hidden email]>; <[hidden email]>; <[hidden email]>
Sent: Thursday, February 25, 2010 12:13 AM
Subject: Re: [Elecraft] K3/100 -Second floor- no RF ground ??

> Steve,
>
> That is a bit of a strange question - because I never though of my
> antenna wires as being a conductor for lightning. While the antenna
> wires will pick up lightning surges, I don't think that is what is being
> considered. What they are talking about is how to dissipate whatever
> lightning surge that makes it into the shack to ground. For that - yes,
> you would use solid conductor (of heavy guage) wire, or better yet flat
> copper strap with its large surface area for the station safety
> ground. Conduct the energy out of the shack and into the earth ground
> where it can dissipate. The greater earth surface that you can
> distribute that energy, the better - be that several connected ground
> rods separated by twice their length or a system of buried conductors
> like a perimeter wire around the building where the shack is housed.
>
> In fact, I would think that an antenna that has higher resistance to
> lightning surge is better - the strength of the surge will be reduced by
> the time it reaches the shack. The path from the shack to your
> lightning protection ground is a different matter, and should be low
> impedance at all frequencies if that is possible - it is not, so we do
> the best we can with conductors having greater surface area and plenty
> of conducting capability for high currents as well.
>
> So stranded wire is OK for antennas, but not for the run from the
> station to the safety ground.
>
> 73,
> Don W3FPR
>
> Steve Ellington wrote:
>> Speaking of lightning grounds. MFJ says use soild wire or flat copper for
>> ground wire and never use stranded or braided wire. They claim the latter
>> has high impedance to lightning.
>> Ok, fine....so if my antenna is stranded wire, does it have high
>> impedance
>> to lighting? Would it be less safe to make ones antenna from solid
>> conductors? Yes...a weird question but it's been bugging me.
>> Steve
>> N4LQ
>>
>>

Don Wilhelm-4

Re: K3/100 -Second floor- no RF ground ??

Steve,

Just don't "bet your life on it" - the difference between stranded and
solid wire will be minuscule for a lightning surge.

Good surge suppressors for every feedline are a must here in North
Carolina, and most other parts of the world. If you do nothing else,
get some gas discharge tubes and solder them across the antenna feedline
at the point where the feedline enters the building. Bournes 2027-35-B
are rated for 350 volts DC and 600 volts sparkover - that should be good
up to about 1000 watts. For higher power, two in series should do the
job. These are only $1.36 each in single quantity from Mouser (catalog
page 591). For parallel feedlines, use one on each side of the line.
To be effective, the coax shield (and surge suppressor) should be
connected by a good conductor to a good ground system at the entry
point, failure to do so will reduce the effectiveness of whatever type
surge suppression is used.

What do I use? I have polyphaser suppressors on each coax line - but
that is 150 coax feet away from the shack, so I add gas discharge tubes
at the shack end for additional safety. At each point, I use wide
copper strap to connect to the ground system - 1/2 inch of width for
each coax. All control lines have Varistors to ground at each end.
The ground 'window' is a 16 inch square of copper sheet purchased from
McMaster-Carr.

73,
Don W3FPR

Steve Ellington wrote:

> Don:
>
> You answered my question when you said:
>
> "In fact, I would think that an antenna that has higher resistance to
> lightning surge is better - the strength of the surge will be reduced by
> the time it reaches the shack. "
>
> I have never seen this issue addressed.
>
> So bottom line:
> Using stranded wire for antennas improves ligtning protection.
>
> Steve
> N4LQ
> ----- Original Message -----
> From: "Don Wilhelm" <[hidden email]>
> To: "Steve Ellington" <[hidden email]>
> Cc: <[hidden email]>; <[hidden email]>; <[hidden email]>
> Sent: Thursday, February 25, 2010 12:13 AM
> Subject: Re: [Elecraft] K3/100 -Second floor- no RF ground ??
>
>
>
>> Steve,
>>
>> That is a bit of a strange question - because I never though of my
>> antenna wires as being a conductor for lightning. While the antenna
>> wires will pick up lightning surges, I don't think that is what is being
>> considered. What they are talking about is how to dissipate whatever
>> lightning surge that makes it into the shack to ground. For that - yes,
>> you would use solid conductor (of heavy guage) wire, or better yet flat
>> copper strap with its large surface area for the station safety
>> ground. Conduct the energy out of the shack and into the earth ground
>> where it can dissipate. The greater earth surface that you can
>> distribute that energy, the better - be that several connected ground
>> rods separated by twice their length or a system of buried conductors
>> like a perimeter wire around the building where the shack is housed.
>>
>> In fact, I would think that an antenna that has higher resistance to
>> lightning surge is better - the strength of the surge will be reduced by
>> the time it reaches the shack. The path from the shack to your
>> lightning protection ground is a different matter, and should be low
>> impedance at all frequencies if that is possible - it is not, so we do
>> the best we can with conductors having greater surface area and plenty
>> of conducting capability for high currents as well.
>>
>> So stranded wire is OK for antennas, but not for the run from the
>> station to the safety ground.
>>
>> 73,
>> Don W3FPR
>>
>> Steve Ellington wrote:
>>
>>> Speaking of lightning grounds. MFJ says use soild wire or flat copper for
>>> ground wire and never use stranded or braided wire. They claim the latter
>>> has high impedance to lightning.
>>> Ok, fine....so if my antenna is stranded wire, does it have high
>>> impedance
>>> to lighting? Would it be less safe to make ones antenna from solid
>>> conductors? Yes...a weird question but it's been bugging me.
>>> Steve
>>> N4LQ
>>>
>>>
>>>
>
>
> --------------------------------------------------------------------------------
>
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.733 / Virus Database: 271.1.1/2708 - Release Date: 02/24/10
> 14:34:00
>
> ______________________________________________________________
> 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
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.733 / Virus Database: 271.1.1/2707 - Release Date: 02/24/10 02:34:00
>
>

David Christ

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by Steve Ellington

A most interesting statement. Here in the upper midwest where we
have plenty of summer lightning, it was quite common to install
lightning rods on barns and houses. The wire they used for grounding
the rods was loosely braided copper about 3/4 inch in diameter. Go
figure.

David Christ

At 11:44 PM -0500 2/24/10, Steve Ellington wrote:
>Speaking of lightning grounds. MFJ says use soild wire or flat copper for
>ground wire and never use stranded or braided wire. They claim the latter
>has high impedance to lightning.
______________________________________________________________
Elecraft mailing list
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Jerry T. Dowell

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by callen1155

Chuck,

I operate a K3/100 from a 2nd story shack and have significant RF ground
problems. I do have a good powerline ground, but that is irrelevant. My
antenna is a 100 ft sloper, centerfed with over 100 ft of 450 ohm window
line (perpendicular to the antenna for 75 ft). It will "load up" on all
bands 160M through 6M, with varying degrees of effectiveness. I cannot run
my amplifier (Alpha 78) at more than 200-300 watts on most bands without
significant RF problems, including tripping GFIs. I intend to try to
alleviate the problems with a tuned ground, using a series-tuned resonant
circuit in a counterpoise system hanging out the window, an arrangement
similar to the MFJ 931. (If you look inside one of those, you will see that
it is very cheaply made. You can do much better with your own coil,
capacitor, and RF ammeter.) By the way, I can operate the K3/100 barefoot
without apparent adverse effects due to the bad RF grounding.

Another issue only distantly related to grounding is that the K3, like the
K2, is extremely susceptible to ESD strikes. That is a huge problem for me
in the dry, high desert of Nevada. You cannot touch anything here without
drawing a significant spark, any time of year. I quickly caused expensive
major damage (destruction of firmware, etc) to my K2/100 by touching it,
even though it was carefully grounded to power system ground. The K3 is
upset by such strikes also. I try to avoid damage by using an operating
table with conductive paint (Walmart) and a good (DC) ground system, so that
I can continuously discharge myself before and while operating. The reason
for the ESD susceptibility of the K3 and K2 is flawed shielding design and
(apparently) lack of ESD mitigation in the circuitry/layout.

Jerry AI6L

-----Original Message-----
From: callen1155 [mailto:[hidden email]]
Sent: Wednesday, February 24, 2010 2:19 PM
To: [hidden email]
Subject: [Elecraft] K3/100 -Second floor- no RF ground ??

Hello guys,

I'm planning on purchasing a K3/100 but am concerned about my second floor
shack and RF problems.

First of all:
1) I don't have an RF ground (don't really want to drill thru the house and
siding for the ground strap) and

2) my antenna is a semi-indoor/attic dipole (HOA).
I'm running a coax from the second floor radio to the attic where i attach
to a dipole (no balun) and the dipole runs the length of the house each way
and out the eaves where both wires run out about 35 yards to the trees.

I'm using my K2/15 and don't have problems but previously with my old Knwd
TS 830 at about 100 watts the vibroplex bug would 'bite' me. I'd also get
some RFI on the TV (didn't try any filters to prevent it).

I know both of the above arrangements are potential sources for RF problems.
What I don't know is whether RF problems (both the 'burn' and RFI) are radio
related; i.e. are some radios more prone cause issues and how is the K3/100
in this regard as compared to the TS 830? (this may be a non-question-- i
just don't have enough experience with different radios to know).

So I'm wonder if any of you operate a K3/100 from a second floor shack, with
no RF ground, (guess it's too much to ask about a semi-indoor antenna) and
if you're experiencing RF problems?

Also, if I experience RF problems with the K3 do any you have any experience
with an "Artificial RF Ground" such as the MFJ-931?

Sorry about being long winded.

Hope I'm not 'destined' to order a K3/10 instead.

thanks again.
chuck
af4xk
--
View this message in context:
http://n2.nabble.com/K3-100-Second-floor-no-RF-ground-tp4628979p4628979.html
Sent from the [K3] mailing list archive at Nabble.com.

______________________________________________________________
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George & Jan

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by Don Wilhelm-4

At the voltages & current available from a lightening strike only an
infinite impedance will help! The wire type will mostly be a moot point.

George
AI4VZ

--------------------------------------------------
From: "Don Wilhelm" <[hidden email]>
Sent: Thursday, February 25, 2010 8:02 AM
To: "Steve Ellington" <[hidden email]>
Cc: <[hidden email]>
Subject: Re: [Elecraft] K3/100 -Second floor- no RF ground ??

Steve,

Just don't "bet your life on it" - the difference between stranded and
solid wire will be minuscule for a lightning surge.

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

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Steve Ellington

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by Jerry T. Dowell

As for ESD....Someone here suggested going barefooted. I've verified this.
It works. Socks are not allowed! This also lets you run "barefoot" while
running the amp. Replacing carpet with wood flooring helps too but a bit
more expensive.

Your RFI problems sound like common mode current on your feeder. I would try
changing the length.

My final solution here was to put the MFJ-998 1.5kw auto tuner out at the
antenna "130' inverted L" and run coax into the house.
Steve
N4LQ
----- Original Message -----
From: "Jerry T. Dowell" <[hidden email]>
To: "'callen1155'" <[hidden email]>; <[hidden email]>
Sent: Thursday, February 25, 2010 12:58 PM
Subject: Re: [Elecraft] K3/100 -Second floor- no RF ground ??

> Chuck,
>
> I operate a K3/100 from a 2nd story shack and have significant RF ground
> problems. I do have a good powerline ground, but that is irrelevant. My
> antenna is a 100 ft sloper, centerfed with over 100 ft of 450 ohm window
> line (perpendicular to the antenna for 75 ft). It will "load up" on all
> bands 160M through 6M, with varying degrees of effectiveness. I cannot run
> my amplifier (Alpha 78) at more than 200-300 watts on most bands without
> significant RF problems, including tripping GFIs. I intend to try to
> alleviate the problems with a tuned ground, using a series-tuned resonant
> circuit in a counterpoise system hanging out the window, an arrangement
> similar to the MFJ 931. (If you look inside one of those, you will see
> that
> it is very cheaply made. You can do much better with your own coil,
> capacitor, and RF ammeter.) By the way, I can operate the K3/100 barefoot
> without apparent adverse effects due to the bad RF grounding.
>
> Another issue only distantly related to grounding is that the K3, like the
> K2, is extremely susceptible to ESD strikes. That is a huge problem for me
> in the dry, high desert of Nevada. You cannot touch anything here without
> drawing a significant spark, any time of year. I quickly caused expensive
> major damage (destruction of firmware, etc) to my K2/100 by touching it,
> even though it was carefully grounded to power system ground. The K3 is
> upset by such strikes also. I try to avoid damage by using an operating
> table with conductive paint (Walmart) and a good (DC) ground system, so
> that
> I can continuously discharge myself before and while operating. The reason
> for the ESD susceptibility of the K3 and K2 is flawed shielding design and
> (apparently) lack of ESD mitigation in the circuitry/layout.
>
> Jerry AI6L
>
> -----Original Message-----
> From: callen1155 [mailto:[hidden email]]
> Sent: Wednesday, February 24, 2010 2:19 PM
> To: [hidden email]
> Subject: [Elecraft] K3/100 -Second floor- no RF ground ??
>
>
>
> Hello guys,
>
> I'm planning on purchasing a K3/100 but am concerned about my second floor
> shack and RF problems.
>
> First of all:
> 1) I don't have an RF ground (don't really want to drill thru the house
> and
> siding for the ground strap) and
>
> 2) my antenna is a semi-indoor/attic dipole (HOA).
> I'm running a coax from the second floor radio to the attic where i attach
> to a dipole (no balun) and the dipole runs the length of the house each
> way
> and out the eaves where both wires run out about 35 yards to the trees.
>
> I'm using my K2/15 and don't have problems but previously with my old Knwd
> TS 830 at about 100 watts the vibroplex bug would 'bite' me. I'd also get
> some RFI on the TV (didn't try any filters to prevent it).
>
> I know both of the above arrangements are potential sources for RF
> problems.
> What I don't know is whether RF problems (both the 'burn' and RFI) are
> radio
> related; i.e. are some radios more prone cause issues and how is the
> K3/100
> in this regard as compared to the TS 830? (this may be a non-question-- i
> just don't have enough experience with different radios to know).
>
> So I'm wonder if any of you operate a K3/100 from a second floor shack,
> with
> no RF ground, (guess it's too much to ask about a semi-indoor antenna) and
> if you're experiencing RF problems?
>
> Also, if I experience RF problems with the K3 do any you have any
> experience
> with an "Artificial RF Ground" such as the MFJ-931?
>
> Sorry about being long winded.
>
> Hope I'm not 'destined' to order a K3/10 instead.
>
> thanks again.
> chuck
> af4xk
> --
> View this message in context:
> http://n2.nabble.com/K3-100-Second-floor-no-RF-ground-tp4628979p4628979.html
> Sent from the [K3] mailing list archive at Nabble.com.
>
>
> ______________________________________________________________
> 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

--------------------------------------------------------------------------------

No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.733 / Virus Database: 271.1.1/2709 - Release Date: 02/25/10
02:34:00

______________________________________________________________
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Jerry T. Dowell

Re: K3/100 -Second floor- no RF ground ??

Steve, I have tried the "barefoot" approach here, nothing seems to work. One
draws sparks in our rooms with wood flooring also. NV is an extreme
environment!

I have had "RF ground" problems here while using various antennas, some fed
with coax, some with balanced feed, baluns, etc. One problem, of course, is
having the rig connected to the power line ground, which is on the opposite
side of the house, and you know how big the ground leads are that are run
through the house. RF pickup on the ground system is substantial.

Jerry AI6L

-----Original Message-----
From: Steve Ellington [mailto:[hidden email]]
Sent: Thursday, February 25, 2010 11:46 AM
To: Jerry T. Dowell; 'callen1155'; [hidden email]
Subject: Re: [Elecraft] K3/100 -Second floor- no RF ground ??

As for ESD....Someone here suggested going barefooted. I've verified this.
It works. Socks are not allowed! This also lets you run "barefoot" while
running the amp. Replacing carpet with wood flooring helps too but a bit
more expensive.

Your RFI problems sound like common mode current on your feeder. I would try

changing the length.

My final solution here was to put the MFJ-998 1.5kw auto tuner out at the
antenna "130' inverted L" and run coax into the house.
Steve
N4LQ

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Jim Brown-10

Re: K3/100 -Second floor- no RF ground ??

In reply to this post by Jerry T. Dowell

On Thu, 25 Feb 2010 09:58:47 -0800, Jerry T. Dowell wrote:

>bands 160M through 6M, with varying degrees of effectiveness. I cannot run
>my amplifier (Alpha 78) at more than 200-300 watts on most bands without
>significant RF problems, including tripping GFIs. I intend to try to
>alleviate the problems with a tuned ground, using a series-tuned resonant
>circuit in a counterpoise system hanging out the window, an arrangement
>similar to the MFJ 931.

That has NOTHING to do with your problem. It's a bad GFI. Your antenna is
doing exactly what it is supposed to do -- radiate RF! The power lines are
also acting as an antenna, receiving that RF, and coupling it to the GFI.

>I can continuously discharge myself before and while operating. The reason
>for the ESD susceptibility of the K3 and K2 is flawed shielding design and
>(apparently) lack of ESD mitigation in the circuitry/layout.

To be more precise, it's "pin 1 problems" at cable connection points. See the
tutorials on my website for details of this problem, first discovered by
audio professionals.

http://audiosystemsgroup.com/publish.htm

One thing that can help a LOT is to carefully bond together the chassis of
every piece of equipment in your system, bond that to the power system ground
(the green wire), and also to your station ground.

73,

Jim K9YC

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