Hi!
Thank You all for the many answers :)
Amazing to learn more about the 500kHz-Experiment in USA!

> Von: "Dave Sergeant" <[email protected]>
> 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








-- 
Neu: GMX Doppel-FLAT mit Internet-Flatrate + Telefon-Flatrate
für nur 19,99 Euro/mtl.!* http://portal.gmx.net/de/go/dsl02