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" <[email protected]>
To: <[email protected]>
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...
[email protected] 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" <[email protected]>
To: <[email protected]>
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
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