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In-Reply-To: <4D9A146C.25841.206191E@mike.dennison.ntlworld.com>
References: <4D9A146C.25841.206191E@mike.dennison.ntlworld.com>
Date: Mon, 4 Apr 2011 19:13:47 +0100
Message-ID: <BANLkTimzk0wrUVWR+acBvGfV=Wh-sd2pmQ@mail.gmail.com>
From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Decca faulty transformer?
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Disconnect all windings and measure the inductance.   If the
transformer is OK, the L will be high - with Xl many times the
operating impedance.   A shorted turn - which is what it looks as if
you may have - will drastically lower L to a value that should be
evident

Andy
www.g4jnt.com



On 4 April 2011 18:56, Mike Dennison <mike.dennison@ntlworld.com> wrote:
> I have a fault on my Decca 5501 LF transmitter. It appears that the
> main output transformer / combiner is faulty. Each Tx module takes
> current when connected to the transformer, even when the output is
> disconnected. And there is no power out of the transformer.
>
> I have some questions:
>
> According to the the circuit diagram, the transformer's output
> winding has a 3.3nF capacitor across it. However, it seems to be
> invisible! Does anyone know where it is? Is it inside the pot core?
>
> Does anyone have a spare transformer for sale?
>
> Has anyone had a similar fault?
>
> Is it difficult to disassemble the transformer?
>
> It is very difficult to test for shorted turns because the resistance
> is extremely low.
>
> Any ideas?
>
> Mike, G3XDV
> ==========
>
>
>