Re: [softrock40] Re: UK residents only
----- Original Message -----
Sent: Wednesday, April 01, 2009 1:19 PM
Subject: [softrock40] Re: UK residents only
--- In firstname.lastname@example.org, Michael Fleetwood <mfleetwood@...> wrote:
> I am considering placing an order for a quantity
> of Triad Magnetics SP70 600 ohm matching
> transformers which have a 300 Hz to 100KHz
> frequency response. If I get enough interest to
> place an order, I can post them out to UK
> addresses for £10 each or possibly less depending
> on the size of the overall order.
> You can access a data sheet on them
> Please email me off list if you are interested.
> Payment would be by cheque or Pay Pal.
> Mike G3XEF.
> Mike Fleetwood
> Canberra Australia and Sidcup UK.
> Worldwide email address is: mfleetwood@...
Below 300Hz thay maybe non linear! above 300HZ you maybe ok but I tried two
tx's out of old modems and they were both non linear causing the noise floor
to go up and down across the spectrum in the SDR software. Good luck Steve
Those were isolation transformers designed for modems. The characteristics
would have been different.
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>>You may want to consider replacing the 0.1uF caps on the opamp outputs
> Below 300Hz thay maybe non linear! above 300HZ you maybe ok but I tried two
> tx's out of old modems and they were both non linear causing the noise floor
> to go up and down across the spectrum in the SDR software. Good luck Steve
to 1uF. The raising of the noise floor you are most likely seeing in
the low kHz range is due to ringing, resonance between the 0.1uF
output capacitors and the inductance in the transformer. You may also
be seeing a big dip below 1kHz. Larger caps, for instance 1uF, will
73 de Loftur, ve/tf3lj