Re: simple choke for power supply - how ?

From: Andrew Holme (andrew_at_nospam.com)
Date: 01/02/05 

Date: Sun, 2 Jan 2005 00:42:23 -0000

Skeleton Man wrote:
>>> From the minute it's turned on to the minute you switch it off it
>>> interferes (doesn't matter if it's transmitting or not)
>
>> The power lead could be radiating; you might one or more supression
>> techniques (LC filter / screening / toroidal balun / re-routing /
>> shortening) on that.
>
> So put the LC filter on the 2-way power supply and the radio, or just
> the 2-way ?

It's trial and error, I'm afraid. Try the easier things first.

> How do I calculate input/output impedance for the filter ? (so I can
> find a table listing component values)

Actually, it's not that critical. We're not matching a 50 ohm signal. I
might try a PI-network with (say) 100n capacitors to ground and (say) 100uH
in series. The capacitor leads need to be short.

Relevant Pages

  • Re: Superhet receiver and image frequency
    ... building a good filter is hard enough; ... the bandwidth of a bandpass filter with respect to it's center ... so if you want to use one in a tunable radio it has to go in the ... RF circuit design and receiver design are also informative. ...
    (comp.dsp)
  • Re: Hints on Tuning Weak Station Next to Strong One
    ... For the radio itself a better filter then the one being used could help. ... This is not likely as the offender is only 5 ... > The radio does great with pulling in hams, the utility stations I've ...
    (rec.radio.shortwave)
  • Re: What to these mean?
    ... ohm resistor attached at the input of the radio. ... and the smaller the KHz the better. ... Filter Ultimate: The maximum attenuation produced by a filter. ... to chase DX in the presence of strong signals. ...
    (rec.radio.shortwave)
  • Re: NRD-630
    ... "3rd and 4th order harmonics are so much better than any other radio ... non-SDR receiver. ... there is nothing like seeing the signals and then ... graphically dragging the filter envelope and center-of-tuning to fit ...
    (rec.radio.shortwave)
  • Re: Sangean ATS-404
    ... Sharper Image one made by Kchibo and a Grundig Travel Radio III. ... 2SK193 (FM IF amp, AM RF amp, common source in both cases) ... datasheet, FM IF amp, a single wide ceramic filter (MA8, that's 280 kHz ... The audio section with some audio filtering and the power amp follows. ...
    (rec.radio.shortwave)