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K3s Line Out (stereo)

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Dave Sublette-2

K3s Line Out (stereo)

My K3s arrived over the weekend and I have been setting it up. I am using
the rear Audio jacks to drive either headphones, or the Line out to drive
an amplifier and two speakers in the stereo mode.

The headphone jack has stereo output ok. But the line out only has right
channel audio. Left channel has nothing but a low hum.

I am testing them one at a time, using the same cable. So it is not a case
of a bad cable. The plug inserts to the same depth in both the headphone
and line out jacks, so I believe the plug is properly inserted,

I have been through both the Main Menu and Config menus, item by item. I
see nothing that would give the option to turn off the left channel of the
line out.

Anyone have any suggestions?

Thanks,

Dave, K4TO
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Dave Sublette-2

Re: K3s Line Out (stereo)

yes

On Tue, Jan 15, 2019 at 9:05 PM Charles Jack Hawley <[hidden email]>
wrote:

> Config-Spkrs set to 2?
>
> Chuck Jack
> KE9UW
>
> Sent from my iPhone, cjack
>
> > On Jan 15, 2019, at 7:01 PM, Dave Sublette <[hidden email]> wrote:
> >
> > My K3s arrived over the weekend and I have been setting it up. I am using
> > the rear Audio jacks to drive either headphones, or the Line out to drive
> > an amplifier and two speakers in the stereo mode.
> >
> > The headphone jack has stereo output ok. But the line out only has right
> > channel audio. Left channel has nothing but a low hum.
> >
> > I am testing them one at a time, using the same cable. So it is not a
> case
> > of a bad cable. The plug inserts to the same depth in both the headphone
> > and line out jacks, so I believe the plug is properly inserted,
> >
> > I have been through both the Main Menu and Config menus, item by item. I
> > see nothing that would give the option to turn off the left channel of
> the
> > line out.
> >
> > Anyone have any suggestions?
> >
> > Thanks,
> >
> > Dave, K4TO
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
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> > Please help support this email list: http://www.qsl.net/donate.html
> > Message delivered to [hidden email]
>

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Nr4c

Re: K3s Line Out (stereo)

Do you have a sub-receiver?

Without it, I don’t think you have any signal to hear.

Why use Line Out for speakers. There is a perfectly good jack marked Speakers right next to the Phones jack. Be sure and use a Stereo plug but it is for ........wait for it. Speakers!

Sent from my iPhone
...nr4c. bill

> On Jan 15, 2019, at 9:33 PM, Dave Sublette <[hidden email]> wrote:
>
> yes
>
>
> On Tue, Jan 15, 2019 at 9:05 PM Charles Jack Hawley <[hidden email]>
> wrote:
>
>> Config-Spkrs set to 2?
>>
>> Chuck Jack
>> KE9UW
>>
>> Sent from my iPhone, cjack
>>
>>> On Jan 15, 2019, at 7:01 PM, Dave Sublette <[hidden email]> wrote:
>>>
>>> My K3s arrived over the weekend and I have been setting it up. I am using
>>> the rear Audio jacks to drive either headphones, or the Line out to drive
>>> an amplifier and two speakers in the stereo mode.
>>>
>>> The headphone jack has stereo output ok. But the line out only has right
>>> channel audio. Left channel has nothing but a low hum.
>>>
>>> I am testing them one at a time, using the same cable. So it is not a
>> case
>>> of a bad cable. The plug inserts to the same depth in both the headphone
>>> and line out jacks, so I believe the plug is properly inserted,
>>>
>>> I have been through both the Main Menu and Config menus, item by item. I
>>> see nothing that would give the option to turn off the left channel of
>> the
>>> line out.
>>>
>>> Anyone have any suggestions?
>>>
>>> Thanks,
>>>
>>> Dave, K4TO
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>> Post: mailto:[hidden email]
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>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>
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K9MA

Re: K3s Line Out (stereo)

I found that the level at headphone output, at least the rear panel one,
was too low to drive two pairs of headphones in parallel in my setup,
which includes some isolation transformers. The speaker output works
fine with the headphones. (Don't try this with super sensitive low
impedance headphones.) I just wired a switch to an external speaker.

73,
Scott K9MA

On 1/15/2019 20:51, Nr4c wrote:
> Why use Line Out for speakers. There is a perfectly good jack marked Speakers right next to the Phones jack. Be sure and use a Stereo plug but it is for ........wait for it. Speakers!

--
Scott K9MA

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Don Wilhelm

Re: K3s Line Out (stereo)

Last Field Day, my K3 was used at the CW station. Two sets of
headphones. One for the operator and one for the logger.
One was plugged into the rear panel Phones jack and the other was
plugged into the front panel jack. No problem, no splitter.
Ok, if there were folks nearby who wanted to listen in, we would simply
turn on SPKR+PHONES in the menu, and the speaker could also be heard.

Very versatile. Why make it complicated - the K3 gives us the tools to
do it 'the easy way'.

73,
Don W3FPR

On 1/15/2019 11:23 PM, K9MA wrote:

> I found that the level at headphone output, at least the rear panel one,
> was too low to drive two pairs of headphones in parallel in my setup,
> which includes some isolation transformers. The speaker output works
> fine with the headphones. (Don't try this with super sensitive low
> impedance headphones.) I just wired a switch to an external speaker.
>
> 73,
> Scott K9MA
>
> On 1/15/2019 20:51, Nr4c wrote:
>> Why use Line Out for speakers. There is a perfectly good jack marked
>> Speakers right next to the Phones jack. Be sure and use a Stereo plug
>> but it is for ........wait for it. Speakers!
>
>

Nr4c

Re: K3s Line Out (stereo)

Thanks Don.

WAARC has been doing just that for about 8 or nine years. Works great. But some folks just want to make it hard.

Sent from my iPhone
...nr4c. bill

> On Jan 16, 2019, at 12:38 AM, Don Wilhelm <[hidden email]> wrote:
>
> Last Field Day, my K3 was used at the CW station. Two sets of headphones. One for the operator and one for the logger.
> One was plugged into the rear panel Phones jack and the other was plugged into the front panel jack. No problem, no splitter.
> Ok, if there were folks nearby who wanted to listen in, we would simply turn on SPKR+PHONES in the menu, and the speaker could also be heard.
>
> Very versatile. Why make it complicated - the K3 gives us the tools to do it 'the easy way'.
>
> 73,
> Don W3FPR
>
>> On 1/15/2019 11:23 PM, K9MA wrote:
>> I found that the level at headphone output, at least the rear panel one, was too low to drive two pairs of headphones in parallel in my setup, which includes some isolation transformers. The speaker output works fine with the headphones. (Don't try this with super sensitive low impedance headphones.) I just wired a switch to an external speaker.
>> 73,
>> Scott K9MA
>>> On 1/15/2019 20:51, Nr4c wrote:
>>> Why use Line Out for speakers. There is a perfectly good jack marked Speakers right next to the Phones jack. Be sure and use a Stereo plug but it is for ........wait for it. Speakers!
> ______________________________________________________________
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K9MA

Re: K3s Line Out (stereo)

In reply to this post by Don Wilhelm

My station has a relay system for switching the headphones between two
different radios, among other things. I had to add isolation
transformers for the same reason the K3 has them on the line outputs.
The loss in the transformers reduces the audio level too much for the
rear panel headphone jack to drive two sets of the low sensitivity
headphones I use. And I don't want a cable in the way to the front panel.

That's why it's "complicated".

73,
Scott K9MA

"Everything should be as simple as possible, but no simpler." -- Albert
Einstein

On 1/15/2019 23:38, Don Wilhelm wrote:

> Last Field Day, my K3 was used at the CW station. Two sets of
> headphones. One for the operator and one for the logger.
> One was plugged into the rear panel Phones jack and the other was
> plugged into the front panel jack. No problem, no splitter.
> Ok, if there were folks nearby who wanted to listen in, we would
> simply turn on SPKR+PHONES in the menu, and the speaker could also be
> heard.
>
> Very versatile. Why make it complicated - the K3 gives us the tools
> to do it 'the easy way'.
>
> 73,
> Don W3FPR
>
> On 1/15/2019 11:23 PM, K9MA wrote:
>> I found that the level at headphone output, at least the rear panel
>> one, was too low to drive two pairs of headphones in parallel in my
>> setup, which includes some isolation transformers. The speaker output
>> works fine with the headphones. (Don't try this with super sensitive
>> low impedance headphones.) I just wired a switch to an external speaker.
>>
>> 73,
>> Scott K9MA
>>
>> On 1/15/2019 20:51, Nr4c wrote:
>>> Why use Line Out for speakers. There is a perfectly good jack marked
>>> Speakers right next to the Phones jack. Be sure and use a Stereo
>>> plug but it is for ........wait for it. Speakers!
>>
>>
> ______________________________________________________________
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> Message delivered to [hidden email]

--
Scott K9MA

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Bob McGraw - K4TAX

Re: K3s Line Out (stereo)

In reply to this post by Don Wilhelm

I see no need for isolation transformers with headphones. Likely the
transformers is the reason the HP output won't drive a pair of
headphones. Isolation transformers? Are they 3 winding hybrid
transformers? I've used them in professional audio installations but
they are rare and expensive.

73

Bob, K4TAX

>
> On 1/15/2019 11:23 PM, K9MA wrote:
>> I found that the level at headphone output, at least the rear panel
>> one, was too low to drive two pairs of headphones in parallel in my
>> setup, which includes some isolation transformers. The speaker output
>> works fine with the headphones. (Don't try this with super sensitive
>> low impedance headphones.) I just wired a switch to an external speaker.
>>
>> 73,
>> Scott K9MA
>>
>> On 1/15/2019 20:51, Nr4c wrote:
>>> Why use Line Out for speakers. There is a perfectly good jack marked
>>> Speakers right next to the Phones jack. Be sure and use a Stereo
>>> plug but it is for ........wait for it. Speakers!
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
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K9MA

Re: K3s Line Out (stereo)

The headphone outputs from my radios are switched with some relays. The
switching system has a common ground, which creates a ground loop,
resulting in 60 Hz hum in the headphones. (Call it common impedance
coupling, if you prefer.) I should have isolated the headphone grounds,
but a path of less resistance was to insert the isolation transformers.
They are just common 600 Ohm transformers, like the ones in the K3 line
outputs, but they're a bit lossy driving headphones.

73,
Scott K9MA

On 1/16/2019 09:02, Bob McGraw K4TAX wrote:

> I see no need for isolation transformers with headphones. Likely the
> transformers is the reason the HP output won't drive a pair of
> headphones. Isolation transformers? Are they 3 winding hybrid
> transformers? I've used them in professional audio installations
> but they are rare and expensive.
>
> 73
>
> Bob, K4TAX
>
>
>>
>> On 1/15/2019 11:23 PM, K9MA wrote:
>>> I found that the level at headphone output, at least the rear panel
>>> one, was too low to drive two pairs of headphones in parallel in my
>>> setup, which includes some isolation transformers. The speaker
>>> output works fine with the headphones. (Don't try this with super
>>> sensitive low impedance headphones.) I just wired a switch to an
>>> external speaker.
>>>
>>> 73,
>>> Scott K9MA
>>>
>>> On 1/15/2019 20:51, Nr4c wrote:
>>>> Why use Line Out for speakers. There is a perfectly good jack
>>>> marked Speakers right next to the Phones jack. Be sure and use a
>>>> Stereo plug but it is for ........wait for it. Speakers!
>>>
>>>

Don Wilhelm

Re: K3s Line Out (stereo)

In reply to this post by Dave Sublette-2

The K3/K3S Line Out already has isolation transformers internal to the
K3. I do not understand any need to put additional transformers in the
audio path(s).

What happens if you cable to LINE OUT signals to a computer soundcard
(with both left and right channels - some only are one channel if the
input is set for MIC)? You should hear the main RX in the left channel
and the SubRX in the right.

Your external transformers/cabling raises the question of "is it the K3S
or is it your external devices that are causing the problem".

Time to strip everything down to the essentials and begin to determine
where the "failure" is occurring. Test one thing at a time.

73,
Don W3FPR

On 1/15/2019 8:00 PM, Dave Sublette wrote:

> My K3s arrived over the weekend and I have been setting it up. I am using
> the rear Audio jacks to drive either headphones, or the Line out to drive
> an amplifier and two speakers in the stereo mode.
>
> The headphone jack has stereo output ok. But the line out only has right
> channel audio. Left channel has nothing but a low hum.
>
> I am testing them one at a time, using the same cable. So it is not a case
> of a bad cable. The plug inserts to the same depth in both the headphone
> and line out jacks, so I believe the plug is properly inserted,
>
> I have been through both the Main Menu and Config menus, item by item. I
> see nothing that would give the option to turn off the left channel of the
> line out.
>

K9MA

Re: K3s Line Out (stereo)

There's no mystery at all. The headphone outputs of two radios go to a
switching system with a common ground. There inevitably is a small AC
voltage difference between the chassis of the two radios, and from the
radios to the rest of the system ground, which results in some current
flowing in the headphone cable ground wires. Bonding everything together
with braid might have helped, but it might have been hard to get the
impedance low enough. The common ground was an oversight on my part, but
avoiding it would have required third relay pole and isolated headphone
jacks. Rather than rebuild the switching system, I inserted the
transformers. They serve exactly the same purpose as the K3 internal
ones in the line outputs.

I'm not sure how other SO2R systems deal with the problem, but it has to
be either isolation transformers of switched headphone grounds. Or, as
does one of my friends, completely isolated left and right headphones.

73,
Scott K9MA

On 1/16/2019 09:36, Don Wilhelm wrote:

> The K3/K3S Line Out already has isolation transformers internal to the
> K3. I do not understand any need to put additional transformers in
> the audio path(s).
>
> What happens if you cable to LINE OUT signals to a computer soundcard
> (with both left and right channels - some only are one channel if the
> input is set for MIC)? You should hear the main RX in the left
> channel and the SubRX in the right.
>
> Your external transformers/cabling raises the question of "is it the
> K3S or is it your external devices that are causing the problem".
>
> Time to strip everything down to the essentials and begin to determine
> where the "failure" is occurring. Test one thing at a time.
>
> 73,
> Don W3FPR
>
> On 1/15/2019 8:00 PM, Dave Sublette wrote:
>> My K3s arrived over the weekend and I have been setting it up. I am
>> using
>> the rear Audio jacks to drive either headphones, or the Line out to
>> drive
>> an amplifier and two speakers in the stereo mode.
>>
>> The headphone jack has stereo output ok. But the line out only has
>> right
>> channel audio. Left channel has nothing but a low hum.
>>
>> I am testing them one at a time, using the same cable. So it is not a
>> case
>> of a bad cable. The plug inserts to the same depth in both the
>> headphone
>> and line out jacks, so I believe the plug is properly inserted,
>>
>> I have been through both the Main Menu and Config menus, item by
>> item. I
>> see nothing that would give the option to turn off the left channel
>> of the
>> line out.
>>
> ______________________________________________________________
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K9MA

Re: K3s Line Out (stereo)

In reply to this post by Don Wilhelm

On 1/16/2019 10:00, Walter Underwood wrote:
> When I need to drive two sets of headphones, I use a $25 Behringer HA400 headphone distribution amp.
>
> https://www.amazon.com/Behringer-HA400-Ultra-Compact-4-Channel-Headphone/dp/B000KIPT30

Any trouble with RFI?

73,

Scott K9MA

--
Scott K9MA

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Bob McGraw - K4TAX

Re: K3s Line Out (stereo)

In reply to this post by Don Wilhelm

I agree but in the case of using two radios, two pair of headphones, a
switching system and getting hum indicates a serious deficiency in the
station interconnection and ground scheme. Everything should be at the
same potential, thus no current would flow. As they say "sum-tin not
right".

73

Bob, K4TAX

On 1/16/2019 10:00 AM, Walter Underwood wrote:

> When I need to drive two sets of headphones, I use a $25 Behringer HA400 headphone distribution amp.
>
> https://www.amazon.com/Behringer-HA400-Ultra-Compact-4-Channel-Headphone/dp/B000KIPT30
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>

Elecraft mailing list

Re: K3s Line Out (stereo)

In reply to this post by K9MA

Like Walter, I use the Behringer HA-400 with my K3 on Field Day. You can have up to four individuals on headphones (no earthly idea why you would have four), and each can control the volume to their headsets. If you have visitors and want to use the speaker too, that can be done in the menu setting to have both speaker and headphones on.
Never had a problem with RFI, but we are only running the K3 barefoot.
Dick, K8ZTT
On Wednesday, January 16, 2019, 9:14:54 AM MST, K9MA <[hidden email]> wrote:

On 1/16/2019 10:00, Walter Underwood wrote:
> When I need to drive two sets of headphones, I use a $25 Behringer HA400 headphone distribution amp.
>
> https://www.amazon.com/Behringer-HA400-Ultra-Compact-4-Channel-Headphone/dp/B000KIPT30

Any trouble with RFI?

73,

Scott K9MA

--
Scott K9MA

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Jim Brown-10

Re: K3s Line Out (stereo)

In reply to this post by K9MA

On 1/16/2019 4:49 AM, K9MA wrote:
> I had to add isolation transformers for the same reason the K3 has
> them on the line outputs.

If you had to add isolation transformers, your station is not properly
bonded. There is NO good reason for needing transformers if all the
equipment in a station is properly bonded.
http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC

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KENT TRIMBLE

Re: K3s Line Out (stereo)

In reply to this post by Elecraft mailing list

Hi Dick . . .

Good to see you on the reflector again.

One "earthly reason" for having four people wear headphones during FD is
when you are wanting to train new operators. By monitoring both sides
of the contact they can better grasp what's going on and practice
copying the exchanges (especially so for CW students).

We have used both the Behringer AMP800
(http://www.musictribe.com/Categories/Behringer/Signal-Processors/Headphone-Amplifiers/AMP800/p/P0331)
and the Rolls HA-43 (http://www.rolls.com/product.php?pid=HA43), and
both amps work fine at 100 watts with no RFI.

They have also been useful for summertime QRP sprints (e.g., Bumble Bee
and Skeeter Hunt) where signals, weak to begin with, are further drowned
out by outdoor noises. Some QRP rigs don't have speakers and those that
do are often not usable outdoors.

73,

Kent K9ZTV

On 1/16/2019 10:47 AM, RIchard Williams via Elecraft wrote:
> Like Walter, I use the Behringer HA-400 with my K3 on Field Day. You can have up to four individuals on headphones (no earthly idea why you would have four) ...

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