wrote:
How exactly does one see 60db down?



Very carefully!

--
Brian Denley
http://home.comcast.net/~b.denley/index.html

In article ,
"Brian Denley" wrote:

wrote:
How exactly does one see 60db down?



Very carefully!

Things start getting pretty dark after 40dB down so be very careful!

--
Telamon
Ventura, California

On Fri, 13 Jan 2006 05:10:44 GMT, Telamon
wrote:

In article ,
"Brian Denley" wrote:

wrote:
How exactly does one see 60db down?



Very carefully!

Things start getting pretty dark after 40dB down so be very careful!

--
Telamon
Ventura, California

Many thanks to everyone who invested their time and effort to help me
with my filter shape measurement problem. Your advice has been very
valuable to me and I am now back on track as a result. I will report
what I'll find.

Michael

I'm not sure why the XY display, but seeing 40db is about the limit.
You really need test equipment to get any meaningful results. Network
analysers that cover a few MHz aren't that expensive. You can also just
use a RF generator and power meter, which is a cheaper solution since
you don't need phase measurements to see attenuation.


Telamon wrote:
In article ,
"Brian Denley" wrote:

wrote:
How exactly does one see 60db down?



Very carefully!

Things start getting pretty dark after 40dB down so be very careful!

--
Telamon
Ventura, California

wrote:
I'm not sure why the XY display, but seeing 40db is about the limit.
You really need test equipment to get any meaningful results. Network
analysers that cover a few MHz aren't that expensive. You can also
just use a RF generator and power meter, which is a cheaper solution
since you don't need phase measurements to see attenuation.



If you DON'T have a spectrum analyzer (most don't) or if you DON'T have
expensive test gear, a decent Oscope with x-y and a sweep generator can be
used as a poor man's spectrum analyzer. 50 years ago, there was no other
way to do it, in fact. If you look at, say, a Hammarlund receiver manual,
that's exactly the recommended way to adjust the IF filter response curve.
You don't have to go down to 60 db to see a bad shape factor.

--
Brian Denley
http://home.comcast.net/~b.denley/index.html