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K3 external speakers

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mikerodgerske5gbc

K3 external speakers

Ok, one more question. I run some external equipment in the external speaker line with a mono plug and a mono speaker. I should be able to use that from k3 external speaker set to 2 with a stereo to mono adapter right?

I also have a set of computer speakers I can run on line out. I wonder if setting
Line out=phon allows volume adjustment thru regular volume control (af gain)

Do you see anything wrong (danger/hazard) with this?

Thanks.

I saw it on the radio!

Happy QSO'ing. Mike R

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George Thornton

Re: K3 external speakers

Amplified computer speakers have been a problem for me. They are not
well screened for RF and on occasion I have had bad feedback problems.
Eliminating the amplified speakers solved the feedback problem.
Unamplified speakers work fine and audio is adequate without external
amp with smaller efficient speakers.

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Mike Rodgers
Sent: Sunday, December 19, 2010 9:15 AM
To: [hidden email]
Subject: [Elecraft] K3 external speakers

Ok, one more question. I run some external equipment in the external
speaker line with a mono plug and a mono speaker. I should be able to
use that from k3 external speaker set to 2 with a stereo to mono adapter
right?

I also have a set of computer speakers I can run on line out. I wonder
if setting
Line out=phon allows volume adjustment thru regular volume control (af
gain)

Do you see anything wrong (danger/hazard) with this?

Thanks.

I saw it on the radio!

Happy QSO'ing. Mike R

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Jim Brown-10

Re: K3 external speakers

On 12/21/2010 10:11 AM, George A. Thornton wrote:
> Amplified computer speakers have been a problem for me. They are not
> well screened for RF and on occasion I have had bad feedback problems.

Yes, amplified loudspeakers (that is, speakers with built-in amplifiers)
are notorious for serious RFI problems, thanks to poor shielding, poor
circuit board layout, poor input filtering, and Pin One Problems. I
work in the world of pro audio, and take a VHF/UHF talkie with me to
trade shows to test for RFI immunity in various products. Over a period
of about ten years, I've seen only a couple of RFI-proof loudspeakers,
and they were in the $3K range. And I've seen lots of loudspeakers in
that range (or even higher) with nasty RFI problems. :)

The loudspeaker output stages in the K3 are sufficient to drive an
external passive (unamplified) loudspeaker of reasonable efficiency to a
more than enough level for those who aren't seriously hearing impaired.
A number to look for in loudspeaker specs is 85dBSPL or more for 1
watt at one meter into 8 ohms. Most of us would set a loudspeaker
within 20 inches or so, which increases the level by 6dB, and, as I
recall, the K3 has a 1 watt output stage. That puts a peak loudness of
91 dB in our ear for CW, and about 10dB less for SSB.

73, Jim Brown K9YC
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k5oai

Re: K3 external speakers

I use a pair of amplified Labtec computer speakers
with my K3's rear Stereo speaker output
I like the ability to either listen on headphones and speakers
or turn down the speakers and have a quieter room using the cans

although I did have some rfi initially
it was getting in from the little wall wart power supply for the speakers
a simple fix was 8-9 wraps of the power cord where it entered the speaker
around a small yellow toroid salvaged from a dead computer supply

later I upped my power to 400w with an AL-811
and and the rfi from the speakers was back
this time I did a 6 turn wrap
through one of the square snapon toroids
this was placed on the line coming from the K3 to the speaker input
at the end right next to where it entered the amplified speaker

all I'm saying is don't just throw out the idea of using
a set of cheap computer speakers you may have around the shack
it may be a really simple fix to get the going.

GB & 73
K5OAI
Sam Morgan

On 12/21/2010 6:24 PM, Jim Brown wrote:

> On 12/21/2010 10:11 AM, George A. Thornton wrote:
>> Amplified computer speakers have been a problem for me. They are not
>> well screened for RF and on occasion I have had bad feedback problems.
>
> Yes, amplified loudspeakers (that is, speakers with built-in amplifiers)
> are notorious for serious RFI problems, thanks to poor shielding, poor
> circuit board layout, poor input filtering, and Pin One Problems. I
> work in the world of pro audio, and take a VHF/UHF talkie with me to
> trade shows to test for RFI immunity in various products. Over a period
> of about ten years, I've seen only a couple of RFI-proof loudspeakers,
> and they were in the $3K range. And I've seen lots of loudspeakers in
> that range (or even higher) with nasty RFI problems. :)
>
> The loudspeaker output stages in the K3 are sufficient to drive an
> external passive (unamplified) loudspeaker of reasonable efficiency to a
> more than enough level for those who aren't seriously hearing impaired.
> A number to look for in loudspeaker specs is 85dBSPL or more for 1
> watt at one meter into 8 ohms. Most of us would set a loudspeaker
> within 20 inches or so, which increases the level by 6dB, and, as I
> recall, the K3 has a 1 watt output stage. That puts a peak loudness of
> 91 dB in our ear for CW, and about 10dB less for SSB.
>
> 73, Jim Brown K9YC
> ______________________________________________________________

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David Cutter

Re: K3 external speakers

In reply to this post by Jim Brown-10

>From memory, (ie the regs changed I should check first) over here in Eu we
have working place regulation set at 85dBA as a maximum for continuous 8
hours listening environment, but it is advised (not mandatory till another
3dB) to use some kind of ear protection; then 88dBA for 4 hours, 91dBA for 2
hours, etc and there is a maximum somewhere around 90s duration. I think
*most* folk would find 85dBA very tiresome over 8 hours. I think what I'm
saying is that the K3 output is more than adequate and if it isn't for
someone, then headphones would be better so as not to waken the family /
neighbourhood.
73 and season's greetings
David
G3UNA

>
> The loudspeaker output stages in the K3 are sufficient to drive an
> external passive (unamplified) loudspeaker of reasonable efficiency to a
> more than enough level for those who aren't seriously hearing impaired.
> A number to look for in loudspeaker specs is 85dBSPL or more for 1
> watt at one meter into 8 ohms. Most of us would set a loudspeaker
> within 20 inches or so, which increases the level by 6dB, and, as I
> recall, the K3 has a 1 watt output stage. That puts a peak loudness of
> 91 dB in our ear for CW, and about 10dB less for SSB.
>
> 73, Jim Brown K9YC