References: <1934937394.20160518170418@chriswilson.tv>
From: Mal Hamilton <g3kevmal@talktalk.net>
In-Reply-To: <1934937394.20160518170418@chriswilson.tv>
Message-Id: <8D8E6474-E8CF-4C87-B097-6502B8180CE3@talktalk.net>
Date: Wed, 18 May 2016 22:23:18 +0100
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: Can LF damage a mains input filter?
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Status: O

Chris
Avoid TV amps 
Change over to Freesat to avoid all the problems you describe
It is cheap and easy to install yourself
De Mal/g3kev


G3KEV


On 18 May 2016, at 17:04, Chris Wilson <chris@chriswilson.tv> wrote:

> 18 May 2016
> 
> 
> Long story, but since stopping LF 136kHz TX for a while in lieu of
> some HF working all the digital TV's in the house freeze or totally
> blank on all bands above top band, up to 50MHz when I transmit at more
> than about  5 or 10W. I have a loft mounted UHF TV aerial feeding an
> amplifier cum distribution box. It has an internal mains PSU. Without
> it we receive hardly any channels. It's been fine for years, and I
> have never had TVI. My HF set up is unchanged from when I had no
> issues. I put the TV antenna co-ax direct into my SA and on circa 531
> MHZ see a broad digiTV signal that's strong. If I TX on say 20 meters
> at high power into my antenna I see zero change in the TV signal. I
> have also fed the output of my HF TX (TS-590 Kenwood) into the SA via
> an attenuator and the output looks spotless on all bands. However, if
> I connect the TV aerial amp / distribution box up and look at the
> output from it the TV signal immediately drops into the noise when I
> TX.  My neighbours have no issues at all.
> 
> This seems to have occurred since I have been active on LF, and I had a
> stage  where  full power would trip the main RCD in the consumer unit,
> so  RF  was  getting  into  the mains. Is it conceivable something has
> occurred  to perhaps a mains filter in the TV amp? I looked inside the
> plastic  case  and  it  has  a small mains transformer that feeds feed
> throughs  into  a  screening  can  with all the RF stuff within it. If
> there is any mains input filtering it must be on the low voltage side
> of the transformer. The unit has a moulded on three pin mains plug, but
> with a plastic earth pin, so the unit is not grounded.
> 
> Is  it  possible to make a mains input filter for a piece of equipment
> that would filter 136kHz but not affect normal 50Hz mains operation?
> 
> Has anyone experienced anything like this?
> 
> I  have  ordered  a  new amp / distribution box of known make, and will
> just  try  replacing it, but would also like to know if my LF activity
> could have done this?
> 
> Thanks.
> 
> 
> 
> -- 
> 
> 
> Best regards,
> Chris  2E0ILY                           mailto:chris@chriswilson.tv
> 
> My        part        time        LF        grabber       is       at
> http://www.chriswilson.tv/grabber.html
> 
>