P3 SVGA external monitor freezes - RFI?

[mike]

When using KPA500 my external monitor (and the P3 display) often freezes, sometimes up to 5 seconds, after I transmit. With the external display disabled, the P3 does not freeze (and incidentally it refreshes much faster without the ext monitor enabled.) I also notice a slight flickering of the monitor screen while transmitting. I take this to be a RFI problem. I have added four snap on ferrite beads on each end of the VGA cable. The monitor is as far away from the amp and feedlines as I can get it and all equipment K3, P3, KPA500, KAT500 are bonded to a ground bus. This is not unique to this monitor as it happened with a different smaller monitor I used before.

This has always been a problem, and I would like to eliminate it as it is very disruptive to is usefulness in finding a clear spot to break through a pileup. Not sure what else to do. Has anyone else had this issue?

 ..mike  AI6II

[KC6CNN]

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[mike]

Not a Samsung, it is a BenQ. But it happened with Dell and ASUS monitors as well. I just put four beads on  the power line as suggested and it seems to be better. I will see how it goes and maybe add additional beads.

Thanks. 73 ..mike


<quote author="KC6CNN">
Hi Mike
Is it a Samsung monitor?
And did you put beads on the power line in too?
Gerald

[KC6CNN]

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[KC6CNN]

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[Jim Brown-10]

On 11/5/2014 9:32 AM, mike wrote:
> When using KPA500 my external monitor (and the P3 display) often freezes,
> sometimes up to 5 seconds, after I transmit. With the external display
> disabled, the P3 does not freeze (and incidentally it refreshes much faster
> without the ext monitor enabled.) I also notice a slight flickering of the
> monitor screen while transmitting. I take this to be a RFI problem.

Probably yes. Perhaps a bad cable between the monitor and the P3.

Beads on cables do not solve problems with HF RFI. Multiple turns
through a bead or core are needed. Study k9yc.com/FRI-Ham.pdf

A neighbor ham gave me a Samsung monitor that has very bad RFI
susceptibility, and it also generates RF trash. It runs on 12V, but
running from a 12V battery does not help, and I've not been able to
solve it with chokes. RF coupling is via internal wiring and poor
shielding.

73, Jim K9YC


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[mike]

Thanks for your input Jim. I attended your talk at Pacifcon and have been implementing some bonding improvements including tying all the earth ground rods, tower etc. with #4 wire as well as better equipment grounding in the station.

The beads on the power cable (only 110v AC no DC) appear to have improved the situation, but I understand it would be better to use multiple turns though a ferrite core on the VGA cable. Without clipping and re-wiring the end connector I have not acquired a big enough ferrite core to do the job.

The BenQ does not appear to generate any trash at least to the level I notice it in my operations. At Pacificon, you did suggest a way to connect the monitor's DB-15 connector to the station ground through the small screws that hold the cable connector in place. I might try that.

Tnx es 73  ..mike  AI6II


Probably yes. Perhaps a bad cable between the monitor and the P3.

Beads on cables do not solve problems with HF RFI. Multiple turns
through a bead or core are needed. Study k9yc.com/FRI-Ham.pdf

A neighbor ham gave me a Samsung monitor that has very bad RFI
susceptibility, and it also generates RF trash. It runs on 12V, but
running from a 12V battery does not help, and I've not been able to
solve it with chokes. RF coupling is via internal wiring and poor
shielding.

73, Jim K9YC

[Mike K2MK]

Hi Mike,

I think multiple ferrites will help but you might be surprised to find that it works best when applied to a cable you haven't yet tried. Take off all of the clamp-ons and get things set up to reliably cause RFI. Then put 4 or 5 clamp-ons on one cable at a time. Try this on every cable in and out of your equipment. Such as the DC cable from your power supply to the K3. Then move onto the various PC cables.

One of those cables is bound to show a reduction in RFI. When that happens just keep loading on the ferrites. For serious RFI one or two ferrites on a cable is never enough.

73,
Mike K2MK

mike wrote

When using KPA500 my external monitor (and the P3 display) often freezes, sometimes up to 5 seconds, after I transmit. With the external display disabled, the P3 does not freeze (and incidentally it refreshes much faster without the ext monitor enabled.) I also notice a slight flickering of the monitor screen while transmitting. I take this to be a RFI problem. I have added four snap on ferrite beads on each end of the VGA cable. The monitor is as far away from the amp and feedlines as I can get it and all equipment K3, P3, KPA500, KAT500 are bonded to a ground bus. This is not unique to this monitor as it happened with a different smaller monitor I used before.

This has always been a problem, and I would like to eliminate it as it is very disruptive to is usefulness in finding a clear spot to break through a pileup. Not sure what else to do. Has anyone else had this issue?

 ..mike  AI6II

[Jim AB3CV]

Seriously consider getting some of the 31 mix snap ons.

jim ab3cv

On Wed, Nov 5, 2014 at 5:33 PM, Mike K2MK <[hidden email]> wrote:

> Hi Mike,
>
> I think multiple ferrites will help but you might be surprised to find that
> it works best when applied to a cable you haven't yet tried. Take off all
> of
> the clamp-ons and get things set up to reliably cause RFI. Then put 4 or 5
> clamp-ons on one cable at a time. Try this on every cable in and out of
> your
> equipment. Such as the DC cable from your power supply to the K3. Then move
> onto the various PC cables.
>
> One of those cables is bound to show a reduction in RFI. When that happens
> just keep loading on the ferrites. For serious RFI one or two ferrites on a
> cable is never enough.
>
> 73,
> Mike K2MK
>
>
> mike wrote
> > When using KPA500 my external monitor (and the P3 display) often freezes,
> > sometimes up to 5 seconds, after I transmit. With the external display
> > disabled, the P3 does not freeze (and incidentally it refreshes much
> > faster without the ext monitor enabled.) I also notice a slight
> flickering
> > of the monitor screen while transmitting. I take this to be a RFI
> problem.
> > I have added four snap on ferrite beads on each end of the VGA cable. The
> > monitor is as far away from the amp and feedlines as I can get it and all
> > equipment K3, P3, KPA500, KAT500 are bonded to a ground bus. This is not
> > unique to this monitor as it happened with a different smaller monitor I
> > used before.
> >
> > This has always been a problem, and I would like to eliminate it as it is
> > very disruptive to is usefulness in finding a clear spot to break through
> > a pileup. Not sure what else to do. Has anyone else had this issue?
> >
> >  ..mike  AI6II
>
>
>
>
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/P3-SVGA-external-monitor-freezes-RFI-tp7594411p7594420.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Don Wilhelm-4]

An alternate approach is to keep the RF energy outside in the antenna
field where it belongs.
Jim Brown K9YC in his RFI tutorial shows the use of quite effective
common mode chokes.  4 or 5 type 31 stacked ferrite toroid cores with 5
or 6 turns of coax wound through the stack.  Use of one of those at the
antenna feedpoint, and another where the feedline enters the shack will
kill most all of the RF being brought into the shack on the outside of
the coax shield.

If you can keep that RF out of the shack by attacking it at its source
and keeping it in the antenna field where it properly belongs, you may
have little or no need for additional ferrite RFI suppression inside the
shack.

If you do need to use ferrite clamp-on cores on your in-shack cables,
use ones with a large enough center that you can wind several turns
through the core rather than adding more ferrite cores along the length
of the cable - it is much more effective - you are building an inductor
to choke off the common mode currents.

73,
Don W3FPR

On 11/5/2014 5:33 PM, Mike K2MK wrote:

> Hi Mike,
>
> I think multiple ferrites will help but you might be surprised to find that
> it works best when applied to a cable you haven't yet tried. Take off all of
> the clamp-ons and get things set up to reliably cause RFI. Then put 4 or 5
> clamp-ons on one cable at a time. Try this on every cable in and out of your
> equipment. Such as the DC cable from your power supply to the K3. Then move
> onto the various PC cables.
>
> One of those cables is bound to show a reduction in RFI. When that happens
> just keep loading on the ferrites. For serious RFI one or two ferrites on a
> cable is never enough.
>
> 73,
> Mike K2MK
>
>
> mike wrote
>> When using KPA500 my external monitor (and the P3 display) often freezes,
>> sometimes up to 5 seconds, after I transmit. With the external display
>> disabled, the P3 does not freeze (and incidentally it refreshes much
>> faster without the ext monitor enabled.) I also notice a slight flickering
>> of the monitor screen while transmitting. I take this to be a RFI problem.
>> I have added four snap on ferrite beads on each end of the VGA cable. The
>> monitor is as far away from the amp and feedlines as I can get it and all
>> equipment K3, P3, KPA500, KAT500 are bonded to a ground bus. This is not
>> unique to this monitor as it happened with a different smaller monitor I
>> used before.
>>
>> This has always been a problem, and I would like to eliminate it as it is
>> very disruptive to is usefulness in finding a clear spot to break through
>> a pileup. Not sure what else to do. Has anyone else had this issue?
>>
>>   ..mike  AI6II
>

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[Byron Servies]

Hi Mike,

My Samsung monitor includes the screw holes to attach it to a standard
VESA monitor mount. One of these has a little triangle next to it and
my ohm meter informs me it is connected to the VGA port D-shell.  I
have bonded it to the rest of my system via this point.

Now, I don't have a KPA500 or P3 (sob!) but it might be something to try,

73, Byron N6NUL

On Wed, Nov 5, 2014 at 9:32 AM, mike <[hidden email]> wrote:

> When using KPA500 my external monitor (and the P3 display) often freezes,
> sometimes up to 5 seconds, after I transmit. With the external display
> disabled, the P3 does not freeze (and incidentally it refreshes much faster
> without the ext monitor enabled.) I also notice a slight flickering of the
> monitor screen while transmitting. I take this to be a RFI problem. I have
> added four snap on ferrite beads on each end of the VGA cable. The monitor
> is as far away from the amp and feedlines as I can get it and all equipment
> K3, P3, KPA500, KAT500 are bonded to a ground bus. This is not unique to
> this monitor as it happened with a different smaller monitor I used before.
>
> This has always been a problem, and I would like to eliminate it as it is
> very disruptive to is usefulness in finding a clear spot to break through a
> pileup. Not sure what else to do. Has anyone else had this issue?
>

--
- Northern California Contest Club
- CU in the Cal QSO Party 3-4 Oct 2015
- www.cqp.org
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[mike]

All excellent replies, thanks to all. Right now I have the vga cable with two loops through a large snap-on of unknown mix (I have just ordered a couple of large 31 mix snap-ons) and placed seven snap-on beads of unknown mix on the AC cable. It looks like the situation is better as it now requires about a five second keydown to freeze the monitor, (not something that happens a lot, just a test.) I tried swapping the small beads on the AC line with a double loop through a snap-on (like the one I now have on the vga cable) but that was much worse.

Regarding keeping RF out of the shack, Don, the 40/80 meter inverted vee has a several looped coax choke at the center feedpoint and the SteppIr vertical has a large DX Engineering one-to-one balun/choke. The Mosley 2 element Yagi has a common mode choke made of a string of beads originally used for a Spyderbeam. The coax feedlines are all between 75 and 100 feet. I will look into more suppression at the shack entrance.

And Bryon, I will check to see if the BenQ mounting holes (I am using mounts) are connected to the D-shell.

Thanks.  ..mike  AI6II

[mike]

Actually, it is not working better. Just worked W1AW/7 on 40m and darned if the monitor didn't freeze when I was simply sending my callsign a couple of times in a row. Will get back at this when the new 31 mix cores arrive.  73  ..mike  AI6II

[Jim Brown-10]

On 11/5/2014 12:51 PM, mike wrote:
> Without clipping and re-wiring the
> end connector I have not acquired a big enough ferrite core to do the job.

That's why they make and we buy clamp-on ferrites. :)  Our club recently
made a group purchase of 0.75-in i.d. clamp-ons for exactly this purpose.

73, Jim K9YC


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