Hi!
Thank You all for the many answers :)
Amazing to learn more about the 500kHz-Experiment in USA!
> Von: "Dave Sergeant" <dave@davesergeant.com>
> What puzzles me about this thread is why you need such a narrow receive
> filter anyway.
Dave, I'm not an hf-engineer.
So, at first, it's my plain curiosity to sit some hours and model and change
parameters and learn and see and learn, how such a band-filter behaves, at
least theoretically.
2. Most of the time there is a terrible broadband noise present in my home
location, which blocks everything below 14MHz and even degrades Polskie Radio I
on 225kHz and BBC4 198kHz (with the rx loop outside the house in a tree).
That's the reason why I did not report any reception on 500kHz in the last
weeks. There simply wasn't anything to receive... Although in a few kHz
bandwidth this broadband noise of course does not equal the fieldstrengh of a
local broadcast station, the broader the filter, the higher the level,
unneccesary loading the mixer.
3. I'm playing with some nice mechanichal filters, ex GDR, IF = 200kHz.
This puts the LO to 700kHz or 300kHz, and the image either right into the MW
broadcast band or directly to the LORAN's 100kHz. So I think it is a good idea
to have a good preselection.
Think I will go for a maybe even narrower than 12kHz filter, because this would
allow tuning "by ear", peaking it lower or higher than the average european
500-505kHz if needed, so nothing lost ;)
vy73
Dennis
DL6NVC
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