[R-390] 16kHz filter and SWL/BC listening

[Tim Shoppa]

Steve Byan <stevebyan at mac.com> 08/29/05 9:03 AM wrote:

> On Aug 28, 2005, at 4:49 PM, Tim Shoppa wrote:
>> To my ear when listening to SW and BC broadcasts (voice, music, 
>> whatever)
>> the 16kHz filter setting always sounds pretty much just like 8kHz just
>> with more hiss.

>> Is this a fundamental limitation of the AF chain, or is my hearing just
>> wacky, or is there some simple technical fix?

> On SW and BC broadcasts, the transmitted signal is bandwidth-limited, 
> so there isn't much more bandwidth to let through with the 16 KC 
> filter, especially if  the 8 KC filter is tuned off to the side a bit. 
> On SW broadcast, you're lucky to get 5 KC of transmitted bandwidth.

Good point, Steve.

I suppose the 2/4/8/16 kc bandwidth progression represents
somebody at Collins liking powers-of-two.  (Note the 1-2-4-8-16
Mc bandswitching...) For my usual purposes
of CW listening it'd be nicer to have the mechanical filters at
1/2/4/8 but I'd need a time machine to fix that!

Do any other receivers have the power-of-two progression in
IF filters?  Almost all the other ham, commercial, ex-military
radios I use have less mathematical
and more one-for-each purpose approach, e.g. narrow for CW,
wider for SSB, widest for AM, with maybe an option for an additional
one for somebody who likes really-wide AM or really-narrow CW.

Tim.