No line out when AGC is off

[wa9fvp]

While operating RTTY, in order to prevent amplitude variations caused by static crashes, I like to turn off the AGC.  It always worked with my Icom 746 and I didn't care if the audio was distorted.  It provided an amplitude limited FM signal to my Hal DXP-38.  

When I turn off the AGC on the K3, with the RF gain set to max position.  The signal disappears on the line out port.  Using an X/Y oscilloscope, there appears to be noise but no signal.    I can hear the very loud RTTY signal on speaker audio and it never cuts out.     When I reduce the RF gain, the signal appears or sometimes during fading, the RTTY signal reappears on the X/Y scope.

 

I’m using Firmware Rev. 4.36, and DSP 2.73

 

[Don Wilhelm-4]

  Jack,

It is only a quick guess, but I would think you might want to check the
setting for the AF Limiter - that is active when AGC is off, by default.

73,
Don W3FPR

On 7/9/2011 6:44 PM, wa9fvp wrote:

> While operating RTTY, in order to prevent amplitude variations caused by
> static crashes, I like to turn off the AGC.  It always worked with my Icom
> 746 and I didn't care if the audio was distorted.  It provided an amplitude
> limited FM signal to my Hal DXP-38.
>
> When I turn off the AGC on the K3, with the RF gain set to max position.
> The signal disappears on the line out port.  Using an X/Y oscilloscope,
> there appears to be noise but no signal.    I can hear the very loud RTTY
> signal on speaker audio and it never cuts out.     When I reduce the RF
> gain, the signal appears or sometimes during fading, the RTTY signal
> reappears on the X/Y scope.
>
>
>
> I’m using Firmware Rev. 4.36, and DSP 2.73
>
> te.html

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[wa9fvp]

It didn't help

[Don Wilhelm-4]

  What didn't help?  A few explanatory words are usually required.  A
simple statement that "it didn't work" is never helpful and will not
generate any additional assistance.

73,
Don W3FPR

On 7/9/2011 11:12 PM, wa9fvp wrote:

> It didn't help
>
> -----
> Jack WA9FVP
> Willco Electronics
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/No-line-out-when-AGC-is-off-tp6566530p6566932.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[wa9fvp]

Please accept my apology,

The speaker volume changes when I change the AF Limiter but
the line output is the same, that is,  the AF limiter has no effect
on the line level.

The signal still dissapears when the RF gain is at max and the
signal is still audible at the speakers.

[wa9fvp]

Withe the AGC off, if the line level is above a setting of 10, the signal,
if you will, falls apart.

I did a test where I tuned to WWV at 10MHz with the AGC off.  I must have
increased the setting at one time to 20.  The default is 10.  The line out falls
apart when the setting is 11 or higher.   I now have it at 5.

[Don Wilhelm-4]

  There is a warning about that sort of thing in the manual on page 20 -
Section on Line Out.

The audio increases substantially when you turn the AGC off, and you are
likely to drive the transformers into high distortion levels.  This was
discussed at length early in the life of the K3 - see the archives for
more information.

73,
Don W3FPR

On 7/10/2011 12:16 PM, wa9fvp wrote:

> Withe the AGC off, if the line level is above a setting of 10, the signal,
> if you will, falls apart.
>
> I did a test where I tuned to WWV at 10MHz with the AGC off.  I must have
> increased the setting at one time to 20.  The default is 10.  The line out
> falls
> apart when the setting is 11 or higher.   I now have it at 5.
>
>
>
> -----
> Jack WA9FVP
> Willco Electronics
>

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[wa9fvp]

It's been about 3 months since I made the adjustment.  If I remember, I was feeding
the line out to the computer sound card and the level wasn't very high.  I was trying
out the MT63 software.  I'll probably invest in a Rig Blaster.

[Joe Subich, W4TV-4]

 > I'll probably invest in a Rig Blaster.

If you're looking for more level from the Line Out (or more drive to
a sound card), don't bother with a RigBlaster.  If you look at their
documentation, you will find there is no receive audio connections
(except for the RigBlaster Advantage that is a "me too" copy of the
microHAM USB Interface III entry level product)!

The RigBlasters are all essentially feature limited transmit interfaces
that duplicate the function of the K3 Line In.

73,

    ... Joe, W4TV


On 7/10/2011 2:38 PM, wa9fvp wrote:

> It's been about 3 months since I made the adjustment.  If I remember, I was
> feeding
> the line out to the computer sound card and the level wasn't very high.  I
> was trying
> out the MT63 software.  I'll probably invest in a Rig Blaster.
>
>
> -----
> Jack WA9FVP
> Willco Electronics
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/No-line-out-when-AGC-is-off-tp6566530p6568283.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> 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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[wa9fvp]

“Rigblaster” is a generic name I use to describe a PC/radio interface.  

Barely noticeable in my photo, just above the K3 is an interface I built back in 1985.   It has line level I/O with gain adjustments and I used it to interface 3 transceivers or receivers to tape recorders.  It also works well with soundcards.  Since I moved into my new QTH I never hooked it up to my station.   I’ll probably use it instead.