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Message-ID: <002201c914ac$fc131810$0201a8c0@lindavideo>
From: "Ken" <ken.h.wright@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <48C89A4D.5020008@telus.net> <001001c913f9$0e86f5c0$8d01a8c0@JAYDELL> <48C9D101.70002@telus.net>
Date: Fri, 12 Sep 2008 08:55:53 +0100
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Subject: Re: LF: Re: AC Noise on RX...
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Reply-To: rsgb_lf_group@blacksheep.org


Hi Scot.
Does the noise sound like 50Hz?, if so you probably have an 'earth loop' 
somewhere, always worth checking for earth loops.

73.
Ken M0KHW

----- Original Message ----- 
From: "Scott Tilley" <sthed475@telus.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Friday, September 12, 2008 3:16 AM
Subject: Re: LF: Re: AC Noise on RX...


> Hi Guys
>
> Thanks for the responses.
>
> This one has me still scratching my head.
>
> All of the LF bands are affected.  I have tried my RF isolation 
> transformer that worked rather well back in the city.  I have not tried 
> the AC mains iso xfmr yet.  Yes my iso is wound like yours.  No computer 
> yet.
>
> To answer others questions about a local noise source.  Can't be as I can 
> shut off all the breakers in the house save the one feeding the radio and 
> nothing else and the noise is still there.  Doesn't matter which PSU of 
> the many I have I use and the noise is still there.  Switch to the battery 
> and turn on everything and bang the noise is gone.
>
> The noise is only there AFTER I connect the antenna. So it has something 
> to do with the mains AC, coax run and the antenna...
>
> 73 Scott
> VE7TIL
>
> PS - The day we get the band back on 2200m is the day I'm back on the 
> air...  This time with a 70' high big honking flat top about 500m from the 
> ocean...
>
>
> jrusgrove@comcast.net wrote:
>>
>> Scott
>>
>> Welcome back! Agree with previous comments on checking the power supply 
>> first. What frequency range is affected?
>>
>> Is  the isolation transformer an ac mains isolation transformer or an rf 
>> isolation transformer? Even if you're using an ac mains isolation 
>> transformer an rf isolation transformer on the lead will probably be 
>> required. For this transformer I've found that a conventional wound 
>> ferrite transformer with the primary and secondary separated on the core 
>> work best. Bifilar wound transformers are not the way to go here. If you 
>> have a computer connected to your receiver a 600 - 600 ohm isolation 
>> transformer in that connection can also improve noise pickup.
>>
>> Any hope of transmitting again?
>>
>> Jay  W1VD  WD2XNS  WE2XGR
>>
>> ----- Original Message ----- From: "Scott Tilley" <sthed475@telus.net>
>> To: <rsgb_lf_group@blacksheep.org>
>> Sent: Thursday, September 11, 2008 12:10 AM
>> Subject: LF: AC Noise on RX...
>>
>>
>>> Hi All
>>>
>>> Been awhile since I've posted to the reflector.  I'm pleased to announce 
>>> I have escaped the noisy clutches of the City and bought myself a nice 
>>> piece of land up the coast in a very quiet spot.
>>>
>>> Presently I'm only using my passive RX loop which has a single turn 
>>> 'sense' loop for coupling into the main multi turn loop...  When the RX 
>>> is connected to an AC power power supply I get terrible AC growlers; 
>>> however, put the RX on a battery and bang not a peep of nasty AC noise.
>>>
>>> I presume this is due to some coupling between the AC mains and the RX 
>>> system and my isolation transformer doesn't seem to help so I wonder if 
>>> someone could set me straight on what is going on here so I can solve 
>>> the problem.
>>>
>>> Thanks for any support!
>>>
>>> 73 Scott
>>> VE7TIL
>>>
>>
>>
>>
>