[Elecraft] K2 AF noise level?

[Howard W. Ashcraft]

One source of noise is in the K2 audio amplifier.  It isn't much of a problem with the standard speaker since there is a built-in high frequency roll off.  However, if you use very good quality earbuds that were designed for music, the hiss comes through loud and clear.  I like to use the buds because they block out virtually all ambient noise and let me concentrate on CW.  (I need all the help I can get).
 
I have ordered some sample chips from National Semiconductor to see if a low noise headphone amp will improve the situation.  I probably won't get the chips for another two weeks and will have to spend some time experimenting, so I probably won't be able to report for a while, but will report back when I do.
 
Howard W. Ashcraft, Jr.  W1WF
Hanson, Bridgett, Marcus, Vlahos & Rudy
425 Market Street, 26th Fl.
San Francisco, CA 94105

ph:     415.995.5073
fax:    415.541.9366
e:       hashcraft at hansonbridgett.com

________________________________

From: Darwin, Keith [mailto:Keith.Darwin at goodrich.com]
Sent: Tue 5/16/2006 6:45 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] K2 AF noise level?



Hey 'Crafters,

I'm debating between the KAF2 or an outboard audio filter for my K2.
Possible choices are the SCAF-1 and an Autek QF1A.

My goal is to greatly reduce the hiss that is there in the headphones
when the narrow CW filters are engaged.  I'd also like to add some CW
selectivity.  A notch would be great too.

KAF2 has the benefit of being integrated into the rig but doesn't offer
lots of flexibility.  The others are external but give you more control
over the filtering.

How well does the KAF2 kill the hiss?  I assume it does great for that.
Does it add any noise back in?

- Keith KD1E -
- K2 5411 -







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