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Author Topic: I thot this was a thing of the past, but….  (Read 695 times)

K3NRX

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I thot this was a thing of the past, but….
« on: August 27, 2021, 04:35:48 PM »

…whenever I transmit anywhere on Hf, my LG TV hooked up to cable goes dark for about 10 seconds….then comes back on….not good, especially with fall coming and being indoors more frequently…this seems to have started happening after some major thunderstorms moved in knocking out the power….any suggestions on how to fix this??? The other peeps in the household are getting pissed at me….someone please help…

V
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K3NRX

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Re: I thot this was a thing of the past, but….
« Reply #1 on: August 27, 2021, 04:39:51 PM »

….some info…again, this has never happened before….and seems to have started soon after a bad thunderstorm knocked out all the power…..also, my HF station has a solid rf ground, and all of the jumpers have ferrite Chokes on them….

V
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AD0AR

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Re: I thot this was a thing of the past, but….
« Reply #2 on: August 27, 2021, 04:51:16 PM »

I suggest you loosen and re-tighten all coax ends and grounds. If that fixes it, I suggest you add some Gardner Bender Ox Guard on those said connections to reduce and point to point metal oxidation (keep it off the insulator of the RF connectors and use sparingly on those RF mating connections and you should be ok.
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W6MK

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Re: I thot this was a thing of the past, but….
« Reply #3 on: August 27, 2021, 04:52:27 PM »

Your antenna type? Relationship of your antenna to the cable run to your TV?

Evidently your RF is getting into your TV despite ferrites on jumpers in your station and your "good RF ground" (whatever that may be).
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K3NRX

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Re: I thot this was a thing of the past, but….
« Reply #4 on: August 27, 2021, 05:14:45 PM »

Your antenna type? Relationship of your antenna to the cable run to your TV?

G5RV…no where near the cable line
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K0UA

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Re: I thot this was a thing of the past, but….
« Reply #5 on: August 27, 2021, 05:33:26 PM »

Have you tried asking for a new cable TV box.
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73  James K0UA

AA4PB

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Re: I thot this was a thing of the past, but….
« Reply #6 on: August 27, 2021, 05:44:21 PM »

I had an issue that every time I keyed up on 2M the TV would change channels. It turned out that RF was getting into the remote. The solution was simple - don't leave the remote pointed at the TV when you are not using it. The kids learned really fast :-)

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Bob  AA4PB
Garrisonville, VA

K3NRX

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Re: I thot this was a thing of the past, but….
« Reply #7 on: August 27, 2021, 05:54:44 PM »

Have you tried asking for a new cable TV box.

Are you asking me that b/c you think the cable tv box took a surge during those storms? The answer is no, as again, this is a problem that just came out of the blue…
« Last Edit: August 27, 2021, 05:57:41 PM by K3NRX »
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K0UA

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Re: I thot this was a thing of the past, but….
« Reply #8 on: August 27, 2021, 06:06:36 PM »

Have you tried asking for a new cable TV box.

Are you asking me that b/c you think the cable tv box took a surge during those storms? The answer is no, as again, this is a problem that just came out of the blue…

yes, I think there is a good chance something may have changed in the box from a nearby surge. After all it is hooked up to the cable 24/7  A new cable box would likely tell the tale.
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73  James K0UA

KC6RWI

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Re: I thot this was a thing of the past, but….
« Reply #9 on: August 27, 2021, 06:53:47 PM »

I would thinking about the  the switching power supply, you can have a degraded supply from power surges. Or the supply could be getting old.Most probably you set has an on board power supply.  Don't for get most smps are alway running waiting for a 5v go signal.
My Sony has an exterior power supply in a box, if that was my problem, I'd switch it or try to find the a way to give 20 volts or so, its an odd voltage.
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W6MK

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Re: I thot this was a thing of the past, but….
« Reply #10 on: August 27, 2021, 08:32:13 PM »

G5RV…no where near the cable line

Common mode choke/balun at junction of parallel line and coax?
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K3NRX

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Re: I thot this was a thing of the past, but….
« Reply #11 on: August 29, 2021, 05:21:58 PM »

G5RV…no where near the cable line

Common mode choke/balun at junction of parallel line and coax?

Yes….and I made a discovery….this new found interference with the tv does not happen while running barefoot….only with my 400w AL-84 amp transmitting…..game changer?…

V
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KL7CW

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Re: I thot this was a thing of the past, but….
« Reply #12 on: August 30, 2021, 10:34:33 AM »

The good news is that if your power is reduced by 6 dB, no RFI. So the problem is probably easily solved.  You say you have ferrite chokes on your coax.  What type, how many turns ??.  A few decades ago I had RFI both to and from an old CRT TV set.  The RFI is very bad on 160 meters, less on 80 meters, and little or none above 80.  I put about 10 or 11 turns of coax (RG-6 or RG-59 ?) on an FT 240-43 core, on the TV coax feed.  Reduced RFI by over 10 dB on 160 and even more on the higher bands.  FT240-31 would have been better for the lower frequency bands.  Since my problem was bad, I ended up using three chokes in series very near the TV set, solved RFI in each direction completely.  IF your signal is getting into the TV via the TV coax try a new cable box to TV jumper cable, and put at least 10 turns of that coax on a core, should give you well over 15 dB of attenuation on most ham bands.  Also a possibility of the cable feed from the provider into the cable box, put some turns through a core.  Also start out by simplifying your set up as much as possible.  Just run one TV at first, no splitters, etc.  Also in your ham shack just simplify things, no coax switches, SWR meters, etc.  If any of that solves the problem, just add things back one at a time.  It is very possible that one of your ham or TV coax jumper cables is bad which does happen (occasionally) for both home brew jumpers and commercially pre assembled cables.  Recently I had an RFI problem due to my 6 port (remote) antenna switch which had a slight (one ohm) DC resistance on the shield connection on one or more of the connectors on the switch.  This was an expensive switch !. It was a design fault, so I disassembled it and did my own modification.   Good Luck   Rick  KL7CW
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KL7CW

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Re: I thot this was a thing of the past, but….
« Reply #13 on: September 01, 2021, 11:26:23 AM »

I forgot to mention probably the most important suggestion.  Before I start chasing down RFI, I carefully "threshold" on what bands and power levels the RFI is present.  Often RX or TX RFI comes from several sources, so you need to see which measures help.  For example lets say you get RFI at 200 watts on a band.  You then put a choke on a coax and it reduces the RFI so now you can run 400 watts OK.  You are on the right track so another choke on that coax may or may not reduce it further.  Just continue your experiment.  You might get lucky by just putting ferrite on things at random, but not the best way.  On my receive array, about 200 feet from my shack, I eventually ended up putting chokes near the array, mid way, and finally in the shack. Did a good job reducing common mode pick up of RFI. More choking did not help.  If you are just putting ferrite beads on your coax, this is probably not enough for most HF bands, or you would need dozens of beads even for the upper HF bands.  Multiple turns through the ferrite, stacked cores, or multiple cores in series are probably necessary in most cases.     Rick  KL7CW
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K3NRX

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Re: I thot this was a thing of the past, but….
« Reply #14 on: September 01, 2021, 05:58:19 PM »

Problem cured! xfinity did a remote reset on the cable box…now every transmission with the amp has zero effect on the TV picture…I figured something got Scrooged after the storms knocked out the electricity and the power company was messing firing things back up….it’s good to have the amp power back on!

V
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