[Elecraft] K3 Caution when using an external monaural speaker

[Ron D'Eau Claire]

Hello David:

Wayne asked me to reply since I prepared the application note. Only two
resistors are needed, so if you've done the mod using the daughter board
locations Wayne originally mentioned, you're all set. 

The version shown in the app note mimics what Aptos is doing as they modify
the boards in inventory. The resistors are in the same place electrically,
but they chose to put them on the main KIO3 board instead. 

We followed that in the application note so it'd be easy to tell if the
modification has been made either in the field or at the factory.

Ron AC7AC

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of David Pratt
Sent: Wednesday, January 14, 2009 1:10 PM
To: wayne burdick
Cc: Elecraft List
Subject: Re: [Elecraft] K3 Caution when using an external monaural speaker

In a recent message, wayne burdick <n6kr at elecraft.com> wrote ...
>The short version is: put 1/8-W (or larger), 470-ohm resistors from 
>each speaker output to ground. (The actual value isn't critical; 
>anything from 330 to 1000 ohms would probably work just as well.) This 
>can be done conveniently on the KIO3's audio daughter board, at its 
>single-row, right-angle male connector.

I see that the AF mod application note at
http://www.elecraft.com/K3/mods/AF_Output_Mod_Rev_A.pdf
is somewhat different to what you describe, Wayne.  The 470 ohm 
resistors appear to be in different places of the circuit.  Does this 
come to the same thing, or are the two resistors from each speaker 
output to ground also necessary?

73
-- 
David G4DMP
Leeds, England, UK
------


_______________________________________________
Elecraft mailing list
Post to: Elecraft at mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft    

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com