RF gets into computer
 

"John, N9JG" wrote in
t:

When I operate on 75 meter SSB with my transceiver, my computer beeps
and disconnects/reconnects my USB connected keyboard. Note that I do not
have this problem on 40 meter SSB. My computer is located on the second
floor of a brick house, and one end of my dipole is about 15 feet from
my shack.

From comments made by others, I may have to put RF filters on the cables
and wires connected to my computer. I am contemplating the use of
Amidon FT-240-77 ferrite toroids, which have an I.D. of 1.4 inches and
cost $9 each. If I buy in quantities of 10, is there a cheaper source
for this toroid?

Any comments or suggestions on this problem would be appreciated.



Do CW, you won't know if it's your computer or radio beeping. Problem
solved.


SC

RF gets into computer
 

In article .net,
says...
"John, N9JG" wrote in
t:

When I operate on 75 meter SSB with my transceiver, my computer beeps
and disconnects/reconnects my USB connected keyboard. Note that I do not
have this problem on 40 meter SSB. My computer is located on the second
floor of a brick house, and one end of my dipole is about 15 feet from
my shack.

From comments made by others, I may have to put RF filters on the cables
and wires connected to my computer. I am contemplating the use of
Amidon FT-240-77 ferrite toroids, which have an I.D. of 1.4 inches and
cost $9 each. If I buy in quantities of 10, is there a cheaper source
for this toroid?

Any comments or suggestions on this problem would be appreciated.



Do CW, you won't know if it's your computer or radio beeping. Problem
solved.


SC

You know nothing. You have the lowest brain capacity of any living
human in the world!!

RF gets into computer
 

I had similar issues with USB disconnects etc while operating HF QRO. I then
added a ground wire from the case of the PC to my station ground and that
resolved it for me...

--

73,Charlie-AD5TH
www.ad5th.com


"RadioGuy" wrote in message
...
In article .net,
says...
"John, N9JG" wrote in
t:

When I operate on 75 meter SSB with my transceiver, my computer beeps
and disconnects/reconnects my USB connected keyboard. Note that I do
not
have this problem on 40 meter SSB. My computer is located on the second
floor of a brick house, and one end of my dipole is about 15 feet from
my shack.

From comments made by others, I may have to put RF filters on the
cables
and wires connected to my computer. I am contemplating the use of
Amidon FT-240-77 ferrite toroids, which have an I.D. of 1.4 inches and
cost $9 each. If I buy in quantities of 10, is there a cheaper source
for this toroid?

Any comments or suggestions on this problem would be appreciated.



Do CW, you won't know if it's your computer or radio beeping. Problem
solved.


SC

You know nothing. You have the lowest brain capacity of any living
human in the world!!

RF gets into computer
 

Thanks for the reply. The problem was solved when I

1) Ran #12 wire through the 2nd-story window sill and down to a 10 feet long
copper clad ground rod. The length of the wire run is about 15 feet. While
this may seem to be an obvious step, at my previous QTH the use of an earth
ground made RF feedback problems worse on some bands.

2) Installed an Amidon FT-240-77 ferrite toroid as a common-mode choke (11
turns) in the Orion's DC power supply cable and located about 18" from the
Orion. I am using an Astron RS-35A linear power supply (the fan on the
Ten-Tec switching PS was too noisy). The cable run between the power supply
and the Orion is somewhat lengthy because the Orion is connected to an
MFJ-1129 multi-outlet strip.


"Charlie" wrote in message
...
I had similar issues with USB disconnects etc while operating HF QRO. I
then added a ground wire from the case of the PC to my station ground and
that resolved it for me...

--

73,Charlie-AD5TH
www.ad5th.com


"RadioGuy" wrote in message
...
In article .net,
says...
"John, N9JG" wrote in
t:

When I operate on 75 meter SSB with my transceiver, my computer beeps
and disconnects/reconnects my USB connected keyboard. Note that I do
not
have this problem on 40 meter SSB. My computer is located on the
second
floor of a brick house, and one end of my dipole is about 15 feet from
my shack.

From comments made by others, I may have to put RF filters on the
cables
and wires connected to my computer. I am contemplating the use of
Amidon FT-240-77 ferrite toroids, which have an I.D. of 1.4 inches and
cost $9 each. If I buy in quantities of 10, is there a cheaper source
for this toroid?

Any comments or suggestions on this problem would be appreciated.



Do CW, you won't know if it's your computer or radio beeping. Problem
solved.


SC

You know nothing. You have the lowest brain capacity of any living
human in the world!!

RF gets into computer
 

On Thu, 02 Nov 2006 14:52:20 GMT, "John, N9JG"
wrote:

1) Ran #12 wire through the 2nd-story window sill and down to a 10 feet long
copper clad ground rod. The length of the wire run is about 15 feet. While
this may seem to be an obvious step, at my previous QTH the use of an earth
ground made RF feedback problems worse on some bands.

Hi John,

Make sure to connect this in dependant ground to the service ground or
you will have created an yet undiscovered new problem.

I say this because of the clue offered in your statement above about
problems becoming WORSE (you probably didn't have that ground tied to
the service ground then too, did you?).

73's
Richard Clark, KB7QHC

RF gets into computer
 

What you have suggested is on my "to do" list. The run to the service ground
will be quite long, however.

"Richard Clark" wrote in message
...
On Thu, 02 Nov 2006 14:52:20 GMT, "John, N9JG"
wrote:

1) Ran #12 wire through the 2nd-story window sill and down to a 10 feet
long
copper clad ground rod. The length of the wire run is about 15 feet. While
this may seem to be an obvious step, at my previous QTH the use of an
earth
ground made RF feedback problems worse on some bands.

Hi John,

Make sure to connect this in dependant ground to the service ground or
you will have created an yet undiscovered new problem.

I say this because of the clue offered in your statement above about
problems becoming WORSE (you probably didn't have that ground tied to
the service ground then too, did you?).

73's
Richard Clark, KB7QHC

RF gets into computer
 

I guess I didn't answer your question. You are quite right that at the
previous QTH, the shack ground rod was not strapped to the AC service rod.

"Richard Clark" wrote in message
...
On Thu, 02 Nov 2006 14:52:20 GMT, "John, N9JG"
wrote:

1) Ran #12 wire through the 2nd-story window sill and down to a 10 feet
long
copper clad ground rod. The length of the wire run is about 15 feet. While
this may seem to be an obvious step, at my previous QTH the use of an
earth
ground made RF feedback problems worse on some bands.

Hi John,

Make sure to connect this in dependant ground to the service ground or
you will have created an yet undiscovered new problem.

I say this because of the clue offered in your statement above about
problems becoming WORSE (you probably didn't have that ground tied to
the service ground then too, did you?).

73's
Richard Clark, KB7QHC

RF gets into computer
 

On Thu, 02 Nov 2006 21:35:22 GMT, "John, N9JG"
wrote:

I guess I didn't answer your question. You are quite right that at the
previous QTH, the shack ground rod was not strapped to the AC service rod.

Notice the correlation to:

at my previous QTH the use of an
earth
ground made RF feedback problems worse on some bands.

Hi John,

This is classic ground-loop conditions. One ground may have an
elevated potential over another ground (hard to believe, but it is the
practical reality). Current flows as a consequence. This is Common
Mode current (from a Common Mode potential).

You should in the short space of those three sentences be able to
observe several terms that are bandied about, but rarely understood.
This is because they follow on mysterious problems that defy
shielding, "grounding," and almost any other ad-hoc attempt that
inevitably fails as a solution.

One classic solution for providing ground to a tower is "I let the
coax shield do that!" Rarely does the operator consider that there
could be a huge potential difference between that remote point's
ground, and that at the house. The hidden killer here is when the
operator disconnects that coax (for whatever reason) and in that act
is holding the shield of the cable and some ground. He completes the
circuit, and like a fuse, may blow out.

More often I've heard:
"Look at the sparks I'm drawing!"
as the coax plug's shell is brushed up against the socket mounting
screws. My buddy pointed this out as the current burnt out most of
his ground traces inside his rig. It only cost a couple hundred and 3
weeks down time to provide remote grounding through the coax.

73's
Richard Clark, KB7QHC

RF gets into computer
 

To reiterate what has been said by others...
There are two issues here for your elevated ham shack... RF ground and
AC/DC ground... Not the same critters and in your case one will not do
both jobs...

First, for life and limb you need an AC/DC connection to the service
panel, i.e. local electrical ground... Length of this does not
matter... Second you need an earth ground as close to the rig as you
can get... As I read this you have dropped wire out the window to a
ground stake... Excellent, now get busy and continue on with that
ground wire also along the edge of the house to the electrical service
panel ground...

Now for the really important stuff, i.e. working DX, you need an RF
ground... In your case I suggest that you use a quarter wave length
insulated wire for each band you operate, attached to the common ground
behind the rig... Hang or fan them out the window, run them through the
ceiling to the attic, run them around the walls of the room, run them
down the hall behind the baseboard, just whatever you can do to spread
them out as long as possible .... Grounding a quarter wave radial at
the far end is not a good idea... Tape the end so no one can touch the
bare wire and leave it... That should cool off your RF problems...

GL denny / k8do

RF gets into computer
 

To iterate what I have reported earlier. The problem was SOLVED,
for the bands I operate on, when I :
1) Ran #12 wire through the 2nd-story window sill and down to a 10 feet long
copper clad ground rod. The length of the wire run is about 15 feet. (Let me
worry about satisfying the "code" requirement of bonding this ground rod to
the rod at the power service entrance.)

2) Installed an Amidon FT-240-77 ferrite toroid as a common-mode choke (11
turns) in the Orion's DC power supply cable and located about 18" from the
Orion. http://tinyurl.com/qnzs3 The cable run between the power supply
and the Orion is somewhat lengthy because the Orion is connected to an
MFJ-1129 multi-outlet strip.

I thank you for your support.
John, N9JG

"Denny" wrote in message
ups.com...
To reiterate what has been said by others...
There are two issues here for your elevated ham shack... RF ground and
AC/DC ground... Not the same critters and in your case one will not do
both jobs...

First, for life and limb you need an AC/DC connection to the service
panel, i.e. local electrical ground... Length of this does not
matter... Second you need an earth ground as close to the rig as you
can get... As I read this you have dropped wire out the window to a
ground stake... Excellent, now get busy and continue on with that
ground wire also along the edge of the house to the electrical service
panel ground...

Now for the really important stuff, i.e. working DX, you need an RF
ground... In your case I suggest that you use a quarter wave length
insulated wire for each band you operate, attached to the common ground
behind the rig... Hang or fan them out the window, run them through the
ceiling to the attic, run them around the walls of the room, run them
down the hall behind the baseboard, just whatever you can do to spread
them out as long as possible .... Grounding a quarter wave radial at
the far end is not a good idea... Tape the end so no one can touch the
bare wire and leave it... That should cool off your RF problems...

GL denny / k8do