[UK-CONTEST] 80m and ADSL

[Pascal Grandjean - F5LEN]

Hello the list,

First please excuse me for my poor english.

Ian J Maude a écrit :
> Graham Diacon wrote:
>> I have exactly the same problem here with my ADSL connection. I've tried
>> ferrite cores (as opposed to clip ons) on all the cables into and out of the
>> router but without success. I've come to accept that as 3.5MHz is within the
>> ADSL bandwidth there's little that I can do. I'd be delighted if someone
>> could prove me wrong.
>>
>> Graham
>> G8EWT
>>
>> -----Original Message-----
>> From: uk-contest-bounces at contesting.com
>> [mailto:uk-contest-bounces at contesting.com] On Behalf Of John Lemay
>> Sent: 11 January 2008 08:51
>> To: uk-contest at contesting.com
>> Subject: [UK-CONTEST] 80m and ADSL
>>
>> Morning all
>>
>> Maybe a little off topic, but I know there's a mine of information out there
>> !
>>
>> I might be giving our local (Colchester) club a bit of support in some of
>> the 80m contests this year (AFS and CC). With just 100w to a Butternut I
>> won't be exactly challenging the leaders, but it's the group effort which
>> will benefit.
>>
>> Anyway, to get technical:- Whenever I run more than 20w or so on 80m, I
>> notice that my ADSL connection is interrupted. As far as I can tell, the
>> landline phone itself is not affected. I'm a bit concerned I may be having a
>> similar affect on my neighbours.
>>
>> I have simple "clip-on" ferrites on all leads but suspect that at relatively
>> low frequencies like 3.5MHz these might not be effective enough? The cable
>> just passes through the ferrite; there are no multiple turns.
>>
>> I've noticed in addition that for other unknown reasons, I occasionally lose
>> my ADSL for a minute or two. I can't be watching the leds on the wireless
>> router all the time, so I'm wondering if there's any bits of software I can
>> monitor my connection with over a long period? A "Google" has not been
>> fruitful.
>>   
> I had this problem some time ago.  As you can imagine, it is a little 
> difficult when the router drops and everyone loses their link to the 
> cluster!
> My own personal solution was to use a DLink router.  I have tried all 
> the other major brands (apart from Cisco).  Most of them turn up their 
> toes at the merest sniff of RF but the Dlink one seems fine, even at 
> 400W (for a contest over anyhow).
> 
> Ian
> 

I had this problem when I start on 160m two years ago.
Also on 80/40m with some power. I use a modem router provided by my ISP.
ADSL "Synchro" was lost with less than 30W on 160m.
On 80/40 same troubles with ~500W (I now it's enought!).
After trying some tips like ferrite on power supply, on network cable 
(never on the phone line!) I found a first solution:
I put two small caps (10nF) just at the input of the phone line on the 
pcb of the modem.
See here some pics:
http://www.f5len.org/articles/adsl/
Results are good but the speed of the adsl may be affected.

So the other solution wich is more efficient was found here:
http://pagesperso-orange.fr/ph-martin/f6eti/realisations/filtre_adsl/index.htm
and original article here:
http://www.ddxg.dk/oz7c/adsl/adsl_160m_filter.pdf
It's a pass band filter. Great results on 160m and up.

Anyway, to avoid or minimize this kind of problem we have to take care 
with our feedlines and how antenna (load) is balanced.

Hope this help
...and you can understood what I wrote :-)

73's Pascal - F5LEN