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Author Topic: Monitor blank out  (Read 196 times)

WA5YOM

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Monitor blank out
« on: June 20, 2022, 09:00:53 AM »

When operating over 300 watts on my 40 meter bazooka, both of my monitors blank out. I installed toriods on my video line....but no success curing the problem....ANy suggestions?



Ins
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WA2EIO

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Re: Monitor blank out
« Reply #1 on: June 20, 2022, 09:39:52 AM »

Common mode currents on the antenna feed line, or the AC power line(s)?   Is the station well grounded?
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W0CKI

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Re: Monitor blank out
« Reply #2 on: June 20, 2022, 09:58:40 AM »

RF is getting into your shack big time. The toroid's are unlikely to cure the problem. You need to have a common mode current choke in your feedline to the antenna.
Tell us more about how you are feeding the antenna and your grounding.
GL, Gary W0CKI
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G8FXC

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Re: Monitor blank out
« Reply #3 on: June 20, 2022, 10:15:09 AM »

I had exactly this - and no quantity of chokes made any difference. My monitors had both HDMI and DVI connectors - I switched to DVI and all the problems want away.

Martin G8FXC
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WA3SKN

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Re: Monitor blank out
« Reply #4 on: June 20, 2022, 11:48:53 AM »

Sounds like "fundamental overload".
A better description of your present station, please!

-Mike.
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WA5YOM

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Re: Monitor blank out
« Reply #5 on: June 20, 2022, 03:38:28 PM »

Everything is grounded to a common point and connected to the tower ground…station is upstairs….SWR is very low….neither antenna has a common mode choke..monitors are 4k with hdmi connection.
The station operating position is in one room, equipment in another room..
All Flexradio, 6700, PGXL, TGXL, 4O3A antenna switch…
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G8FXC

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Re: Monitor blank out
« Reply #6 on: June 20, 2022, 11:30:49 PM »

Everything is grounded to a common point and connected to the tower ground…station is upstairs….SWR is very low….neither antenna has a common mode choke..monitors are 4k with hdmi connection.
The station operating position is in one room, equipment in another room..
All Flexradio, 6700, PGXL, TGXL, 4O3A antenna switch…

If you don't have any alternative to HDMI on the monitor, try experimenting with cables. HDMI seems to be more vulnerable to RFI than any of the other video connection types.

Martin (G8FXC)
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W9IQ

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Re: Monitor blank out
« Reply #7 on: June 21, 2022, 04:08:02 AM »

I installed toriods on my video line....but no success curing the problem....ANy suggestions?

The mix of the ferrite makes a substantial difference. Mix 31 is best for the HF bands. Mix 43 if you happen to have them on hand will work second best.

You should also consider proper ferrite common mode chokes at the antenna feed point and just before the coax enters the shack. Reducing common mode current at the source is the best RFI suppression technique.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

WA3SKN

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Re: Monitor blank out
« Reply #8 on: June 21, 2022, 04:16:45 PM »

The RF may be getting into the HDMI lines or it may be getting in via the power cords.  Since your cables are fairly long, you might try shielding them with aluminum foil tape from the hardware store.  How near is the transmit antenna to the monitors?

-Mike.
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WA5YOM

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Re: Monitor blank out
« Reply #9 on: June 22, 2022, 07:25:58 AM »

So, the upstairs is one long room e we ith a divider wall that turns this long room into…two rooms….the operating position desk is lined up with the divider wall, on the other side of the wall is all the radio equipment, so the monitors  are only 2 to 5 feet from the antenna switch….
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