TVI Low-Pass

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KB5DOH
Posts: 8
Joined: Mon Sep 29, 2003 10:13 am
Location: Norman Oklahoma

TVI Low-Pass

Post by KB5DOH » Tue Nov 04, 2003 6:23 pm

:?: Hi, Here is another question in regaurds to the neighbors television getting interference from my radio, he say it puts lines on the tv screen and he can here my voice and that some words are makeable some are not so I bought a tvi filter for the back of his tv where the rabbit ears antenna connects still no help. :( So here is what I have running from radio to antenna to radio, RG59u and I think that if I run RG8u that would help a bunch but if it do not then I plan to hook a Low-Pass filter in-line as well but I want a filter that will work but not drop my power going to antenna in/other words if I have 90 watts going from radio I do not want a filter that will drop that below 90 watts.
:idea: any thoughts or advice will be greatly recived.

Allan/KB5DOH :D

K4ICL
Posts: 663
Joined: Wed Mar 05, 2003 1:07 pm
Location: Greenville, SC
Contact:

Some RFI suggestions

Post by K4ICL » Tue Nov 04, 2003 6:43 pm

You are up against one of the longest standing problems in hamdom. Here are some things that, if done, might help.

1. First and formost, be SURE you transmitter is connected to a GOOD SOLID GROUND. Drive copper-clad ground rods and connect directly to the transmitter chassis, using heavy braided cable.

2. Install a good low pass filter (Drake, Bencher, others...) in the transmitter transmission line but first, trash all of your RG-59 cable and replace it with a good quality 50-52 ohm coax cable, RG 8/AU or RG 8/X. Most transmitters want to see 50 ohm cable, NOT 72 ohm cable, such as you are using. Low pass filters DO NOT suck power from you transmitter. The line loss due to a low pass filter is almost nil.

3. Test your new set up by transmitting into a dummy load at the antenna end of your transmission line to see if the neighbor is receiving any TVI. If not, you are one you way to success.

4. Connect the antenna and test again and good luck.
Cheers,

AL
K4ICL

kb0uzr
Posts: 9
Joined: Thu Apr 22, 2004 1:37 am

Some RFI Suggestions

Post by kb0uzr » Fri Apr 23, 2004 5:27 pm

I live in a trailer park. And I don't bother anyone. I did bother the neighbors TV and CD but got a Drake lowpass filter, and a B&W.

I put the Drake inbetween the radio and the amp, and the B&W inbetween the amp and the antenna matcher. You aren't supposed to put it inbetween the matcher and the antenna UNLESS the VSWR is real low where you don't need the antenna matcher.

And you have to make sure the lowpass filters are well grounded. And from what they tell me, they have to have a seperate ground apart from the station ground.

I have mine grounded out with the outlet that the TV plugs in and it works fine.

And another thing that helps well is, at your antenna connection wrap a 5" coil of wraps of 8 turns around the PVC pipe and strap it all together so it can't come unraveled. And that's supposed to keep RF from comming into your shack. And might also keep RF from comming into the nieghbors shack.

Of course you do that after you change coax. NOW,,,if all that doesn't help, then change the length of the feed line by 5 and 10 sections at a time and see if that works. And if all that doesn't work, then you will have to put up a different antenna, or get the different antenna, or the one you're using now in a different location and as far as you can get it away from the nieghbors house as possible.

I live in a mobile home park, and don't bother anyone now. And I talk all day and night and twice on Sundays. And I run a 922 Kenwood amp at 500w, and if I need it, 1400w and no complaints....

Good luck and 73

ps What do you think LPQ?
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-----------------------KB0UZR-----------------------

You don't know what you have until it's gone....

W0LPQ
Posts: 83
Joined: Wed Mar 05, 2003 4:51 pm
Location: Greenwood, IN

Grounding

Post by W0LPQ » Sat Apr 24, 2004 4:23 am

You NEVER ground anything like you so state to the AC plug ground. Period. That is against NEC codes. It is preferable to use the station ground which goes to an outside ground rod.

If the antenna matcher you refer to is an Antenna Tuner, then NO...you should not put the filter at the output of the amp. I have no idea what you are using for an antenna. If a tuner is necessary, then it is not a resonant antenna. The filter at the output of the transmitter should be all that is required. If it is clean at that point, then the amp only amplifies the "Clean" stuff it is given.

Concerning your dipoles, it has been done. I have not seen any written articles, although there may be some. 7dB gain......only 2 elements..probably not. What frequency?

73

Bill, W0LPQ

kb0uzr
Posts: 9
Joined: Thu Apr 22, 2004 1:37 am

RFI and Filters

Post by kb0uzr » Sat Apr 24, 2004 5:36 am

Well, now I found out that grounding Low Pass Filters to the trailer ground is against code. But it was in the middle of winter and didn't have a rod pounded in.

No the G5RV isn't resonant on anything. and I have to have an antenna matcher on everything. Well, the way I have those filters on there now works so great, I sure hate to change anything. I can't even get any interference on anything even when I try.

And if I call the Drake antenna "Tuner" an antenna tuner around some hams, they get mad and say it's an antenna matcher. So I don't know What to call it.
It says Drake MN-2000 Matching Network. So I assumed it was an antenna matcher.

And by the way, I looked quit a while in the "Internet Options" for something to get the print bigger and couldn't find anything. And since this seems to be pretty much the same system as QRZ, I thought there would be a place to get the print bigger here too..I guess I'll have to break down and get a different moniter.

Hay, that diod topic on the other thread turned into a good thread. I enjoyed it. You helped to bring some people out that really knows their stuff.

Oh, I forgot the Rotatable Dipoles. 2 40m dipoles. I live there, so I don't need much of anything for the other bands. 7db on them, huh? How do calculate the length of the boom? How far apart should I have them?

I have a chance to get a KLM brand rotatable. Would that perform just as good as the Cushcraft?

Thanks
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-----------------------KB0UZR-----------------------

You don't know what you have until it's gone....

W4AIN
Posts: 113
Joined: Thu Feb 03, 2005 11:38 pm
Location: Louisville, KY

Re: Some RFI Suggestions

Post by W4AIN » Sun Nov 09, 2008 8:18 pm

kb0uzr wrote:I live in a trailer park.

....I have mine grounded out with the outlet that the TV plugs in and it works fine.

And another thing that helps well is, at your antenna connection wrap a 5" coil of wraps of 8 turns around the PVC pipe and strap it all together so it can't come unraveled. And that's supposed to keep RF from comming into your shack. And might also keep RF from comming into the nieghbors shack.

..... NOW, if all that doesn't help, then change the length of the feed line by 5 and 10 sections at a time and see if that works. And if all that doesn't work, then you will have to put up a different antenna, or get the different antenna, or the one you're using now in a different location and as far as you can get it away from the nieghbors house as possible.


Good luck and 73
However, if none of this works, just buy 500 acres of land and build your shack in the center of it and operate QRPp into a dummy load. That should take care of the TVI problem. If even this does not solve your problem, then just take away your neighbors' TV and bury it at least 19 ft. deep in soil that has a high PH level and a VERY high iron content. Make sure to use a container that is EPA approved to keep the tree-huggers happy. :roll:
Phil - W4AIN
On The Air Communications
www.w4ain.com

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