[ARDF] LZ1PPL ARDF receiver for 3.5 MHz

[Bruce]

On 14/08/2019 5:16 am, Kenneth E. Harker wrote:
>         Plamen LZ1PPL is looking for feedback on his latest 3.5 MHz ARDF receiver project.  The article itself is reasonably technical, for those interested in receiver electrical design.
>
> http://www.lz1ppl.com/projects/ardf-fox-huntreciver-3-5mhz/ <http://www.lz1ppl.com/projects/ardf-fox-huntreciver-3-5mhz/>

Some random feedback ideas:

  * I can't imagine an ARDF receiver that attenuates only the audio
    being much use at all (as mentioned in the text) !  You might get
    away with it for FoxOrs maybe, but for ARDF it'd just be useless.
    Hard to believe.
  * I wonder if you could reduce the number of plugs (and hence water
    entry points into the receiver) by charging using the headphone
    connector. The only reason you couldn't do this with the existing
    circuit is the 100uF isn't bipolar. You could make a cheap /pretend/
    bipolar by using two 100uF in series with opposite polarity, and a
    high-R to gnd in between. In fact, you probably don't need such a
    large cap really for headphones. Perhaps 2x33uF (effectively 16uF)
    would do for bass response.
  * The sentence "The capacitors C49, C53, C54 and the resistor R46 are
    used to tune the ferrite antenna." appears twice.
  * Could the BF999 overload from off-frequency (or out of band) large
    signals, and cause spurious responses, as it effectively has no
    tuned circuits protecting it ?


>
> --
> Kenneth E. Harker WM5R
> kenharker at kenharker.com
> http://www.kenharker.com/
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-- 
Cheers,
Bruce