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W6JPK
02-09-2011, 11:57 PM
I just got a low pass filter since when I tune 20 meters using my AL-811 the yl cannot watch TV. On 40 meters no problem. What is the best way to put this into service. I have the xmtr then tuner then the amp. I was going to install it at the output of the amp but recently read a few things that said no..What is the best way to install a low pass filter ?? Jim w6jpk

W5RKL
02-10-2011, 12:16 AM
Do you experience the same TVI when operating without the amplifier?

Typically the filter is between the exciter and the antenna. In your case it would be between the amplifiers output and the antenna feed line. I assume the filter can handle at least 1KW.

You said you are using a tuner between the exciter and the amplifier. Why?

The AL-811 amplifier has tuned input networks for each band that can be individually adjusted for lowest SWR between the exciter and the amplifier eliminating the need for the tuner.

73s
Mike

W6JPK
02-10-2011, 12:41 AM
Mike,
Thanks for the feedback and I just like using a manual tuner even though the xmtr has an auto tuner. I don't have any problems with out the amp. Thanks again for your answer and I will install it today..73 Jim today

WB2WIK
02-10-2011, 01:33 AM
Anything's possible but I doubt the filter will help.

The filter should be installed between the amp and the tuner, for sure.

But most "TVI" problems are not due to harmonics from the transmitter or amplifier, and the best low pass filter in the world won't help if it's fundamental overload. It's possible that a harmonic problem exists, but that would be fairly rare.

W5RKL
02-10-2011, 03:43 PM
I could be wrong but I agree with Steve. Your problem appears to be fundamental overloading of the television when using the amplifier since the problem does not exist when operating without the amplifier.

I will agree that it is your choice to use a tuner between the exciter and the amplifier. Using a tuner between the exciter and the amplifier does not eliminate an improperly tuned input tank circuit in the amplifier, it only "masks" the problem. Each time you change bands you most likely have to readjust the tuner for lowest SWR between the exciter and the input to the amplifier. Why do that? The typical SWR between the exciter and the input to the AL-811 amplifier is less than 2:1 on all bands. If your amplifier shows higher SWR indications on all bands then the individual tuned networks are not adjusted properly and as I said above, the use of a tuner does not fix that problem, only "mask" the problem.

Just my 2 cents.

73s
Mike

W8JI
02-11-2011, 11:14 AM
I just got a low pass filter since when I tune 20 meters using my AL-811 the yl cannot watch TV. On 40 meters no problem. What is the best way to put this into service. I have the xmtr then tuner then the amp. I was going to install it at the output of the amp but recently read a few things that said no..What is the best way to install a low pass filter ?? Jim w6jpk

That is an improper configuration. If you need an antenna tuner, it goes AFTER the amp.

I doubt you need a low-pass filter.

Are you on cable vision or what for TV reception???? No one can even guess about whether a filter will help without knowing if you receive signals off the air on an antenna, and what channels on the TV are bothered.

To know what a low pass will do....it is absolutely necessary to know what channels are bothered and if you have an outside antenna or are on cable or some other service for TV signals.

I always wonder how we answer questions in forums when the necessary information was never given. It's like magic. :-)

W6JPK
02-12-2011, 05:22 PM
Thank you all for your reponses. The big issue is I'm in a confined space (condo) and the RG8 coax and cable to the tv run side by side at one point. The problem is only on 20 and 10 meters. I run full power on 40 and have tried 15 and not a peep. I put the low pass filter between the amp and tuner and now I getting trouble at under 100 watts on 20 and 10 meters with or without the filter. Oh I'll miss 20..A friend has made some suggestions and I will also check into some of them . The last resort is to move..Jim W6JPK

W8JI
02-12-2011, 07:28 PM
Are you on cable vision or what for TV reception???? No one can even guess about whether a filter will help without knowing if you receive signals off the air on an antenna, and what channels on the TV are bothered.

To know what a low pass will do....it is absolutely necessary to know what channels are bothered and if you have an outside antenna or are on cable or some other service for TV signals.

I always wonder how we answer questions in forums when the necessary information was never given. It's like magic. :-)

No answers to questions, no real help is possible. :-)

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