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Author Topic: HAM band notch  (Read 920 times)

konrado5

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HAM band notch
« on: August 14, 2017, 10:58:06 PM »

My ISP doesn't want to remove HAM band notching on 1.8-2.0 Mhz. They insist that without this notch the circuit would be unstable. However in Poland I've not heard about any amateur radio on these frequiences. My ISP also insist that CB radios work on this frequiences. Are my ISP engineers incompetent?
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tbailey2

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Re: HAM band notch
« Reply #1 on: August 15, 2017, 08:59:37 AM »

To the best of my knowledge, 1.8 - 2.0Mhz ('Top Band' as radio amateurs know it) is available worldwide to all licenced operators unless something has changed very recently. I used it all the time from 1968 -1989. (I am G3WPO)
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4candles

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Re: HAM band notch
« Reply #2 on: August 15, 2017, 09:26:35 AM »

Agreed re 'Top Band'.


1.8 - 2.0MHz has never been allocated to any CB service.


The original analogue cordless phones in the UK used frequencies around 1.7MHz for the base to handset direction. Maybe they're still in use in Poland?
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konrado5

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Re: HAM band notch
« Reply #3 on: August 16, 2017, 05:41:57 PM »

My ISP disabled HAM band mask on my card. Following there are new graphs.
« Last Edit: August 16, 2017, 05:45:38 PM by konrado5 »
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kitz

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Re: HAM band notch
« Reply #4 on: August 17, 2017, 02:40:28 PM »

Youre very lucky that they did.   :thumbs:
iirc your MSAN was the same make as those used by BE* here in the UK and they were by default configured with that particular HAM notch.  Lots of people for a while tried to get it removed, but it never happened.  Mind you that would now be about 10yrs ago!
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konrado5

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Re: HAM band notch
« Reply #5 on: August 17, 2017, 09:06:14 PM »

Quote from: kitz
That specific type of HAM masking isnt something that Im aware of that is in use by any of the UK ISPs (BE did a total block rather than the U-interface mentioned in that document).
Quote
http://forum.kitz.co.uk/index.php/topic,13849.msg260718.html#msg260718 
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kitz

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Re: HAM band notch
« Reply #6 on: August 17, 2017, 09:30:10 PM »

lol...  that was over 3yrs ago.   I cant remember what I had for dinner most days  :lol:
haha I do recall though that the tones were in a similar region and they were I think using the same equipment.
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konrado5

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Re: HAM band notch
« Reply #7 on: August 18, 2017, 12:15:43 AM »

On target SNR margin 6 dB I have now 19215 kbps instead 15000 with HAM PSD mask.
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Octal

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Re: HAM band notch
« Reply #8 on: September 13, 2017, 07:12:26 AM »

Just as a matter of interest, my modem now notches itself when I use 1.8MHz



What I have had to do is to put a common mode choke on the incoming line, just 9 turns around a FT240-43 ferrite core, before that eveytime I went on the air it killed my modem stone dead with just a few watts, now I can run 100W without any problems. It's also cleaned up my connection somewhat, which is nice.
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JGO

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Re: HAM band notch
« Reply #9 on: September 13, 2017, 08:21:57 AM »

Congratulations Octal !      Someone who appreciates that there are grades of ferrite with different RF properties.
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burakkucat

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Re: HAM band notch
« Reply #10 on: September 13, 2017, 07:09:18 PM »

Here is a link to a somewhat old document that has relevance to xDSL and "Top Band".
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Octal

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Re: HAM band notch
« Reply #11 on: September 13, 2017, 08:02:08 PM »

Congratulations Octal !      Someone who appreciates that there are grades of ferrite with different RF properties.

Thanks, I think 31 mix might have been a better choice, but 43 was all I had which is intended for the higher HF bands, but it seems to have done the job for me.

Here is a link to a somewhat old document that has relevance to xDSL and "Top Band".

I have built one of those and they do indeed work, but the cut-off is about 1.7MHz, so the download speed is reduced by about 2 or 3meg as I'm on ADSL2+ which has an upper frequency of 2.2MHz, with the ferrite I at least just lose a few tones around Top Band and the speed is only reduced by a few hundred K.

I've still got a notch at 909kHz which comes from the Brookmans Park transmitter, it's about 15 miles away, I can just see the top of the main mast from here, so it's a strong signal, the ferrite hasn't changed that, so it's probably not coming in on common mode.
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konrado5

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Re: HAM band notch
« Reply #12 on: September 14, 2017, 07:48:50 PM »

Octal: Could you also attach your Hlog and QLN (for curiosity)?
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Octal

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Re: HAM band notch
« Reply #13 on: September 14, 2017, 08:16:04 PM »

Octal: Could you also attach your Hlog and QLN (for curiosity)?

Sure, but you have to point me to where I'll find it please, I'm using DSLstats, so it must be one of the tabs, which one?
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konrado5

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Re: HAM band notch
« Reply #14 on: September 14, 2017, 08:29:44 PM »

 Hlog and QLN tabs. Perhaps you have disabled these tabs in configuration/items to monitor.
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