[Elecraft] Re: K3 Audio

[Alexandr Kobranov]

I just made two basic samples using K3 and TS-850 using Firebox 
external soundcard and Winrad SW.

You can see screenshot from K3 line-out audio on

http://www.ok1kei.org/K3_audio/line_out_firebox_winrad.jpg

This is K3 with 400Hz roofing filter on some stable carrier.
LINE OUT setting on level 9.

Then the same signal with the same af level (no change in Firebox 
input mixer settings) with TS-850

http://www.ok1kei.org/K3_audio/ts850_af_firebox_winrad.jpg

This is my TS-850 with 400Hz inrad filter and output from phones jack.
There are also some "ghosts" in af spectrum, generaly more noisy, but 
no "image" of passband af signal visible.

As I do not believe in overloding of the Firebox soundcard (the same 
conditions for both RIGs so if overloded so in both cases...), there 
is something to explain.

Comments?

Thanks for your attention,
73!
Lexa, OK1DST
K3/10 #727




Alexandr Kobranov napsal(a):
> I can confirm cca 20dB lower level of 3rd harmonics on front panel 
> phones output against rear panel line out. Main versus 3rd harmonics is 
> 50dB resp. 7OdB on line-out resp. phones output here.
> Just tried with on-board sound card od my Dell workstation.
> (using Spectran SW and output level adjusted for the same peak out level 
> on Spectran screen).
> Maybe later will try with Firebox sound card which has better parameters.
> Lexa, ok1dst
> 
> Joe Subich, W4TV napsal(a):
>>
>>> There is still a bit of a problem on receive audio.  This has been 
>>> there for some time and exists in the form of harmonics.  The 3rd 
>>> harmonic is quite easy to see and repeatable.  I used HRD to show 
>>> this on the waterfall after a conversation with a friend. You can 
>>> clearly see the harmonic at..
>>
>> You are overdriving your sound card or the line out transformer in the 
>> K3. 
>> I have measured the third harmonic using an audio spectrum analyzer
>> at both the line out and headphone jacks of my K3.  Until the level 
>> becomes excessive (> .7V RMS on the Line Out) the third harmonic is 
>> more than 50 dB down (Line Out) and more than 70 dB down (headphones). 
>> 73,
>>    ... Joe, W4TV  
>>
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