K2, low output in digital modes

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K2, low output in digital modes

Raimon-3
Hi Elekrafters

I need your help.

My K2/100 nr. 03529 with KSB2 SSB adapter and KAT 100 Antenna Tuner has
been working perfectly since I built it, with the exception of some
minor problems that were solved either with the help of Don Wilhelm or
after a search in the e-mail list reflector.

But now I detected a problem unnoticed until now:

I work mainly CW and digital modes.

In 40, 30 and 20 meters, in PSK 31 or RTTY, I could get easily about 40
watts output, corresponding to one bar flickering in ALC bargraf. So all
was apparently all right.

But I have tried recently the 10 m. band and noticed that when selecting
my RTTY filters configuration I can get only near 20 watts in rtty, and
less than 10 watts in rtty-r.

When I use in this band the USB or LSB configuration, and transmit RTTY
or PSK, I get about 90 watts, the same output as in CW..

I have seen now that this drop in output happens in all bands, but I
had’nt noticed it because I was able to get 30-50 watts in the lower
bands, even in RTTY configuration. The same output drop happens in QRP
configuration.

Summarizing, in digital transmissions when in RTTY the output is
significantly lower than when in SSB, and the higher the frequency the
lower the output power.

I realigned my filters with the help of Spectrogram, applying the same
settings for OP-! SSB and OP-1 RTTY (there were some small differences
before this realignment), but to no avail.

Although I can continue working digital modes using the SSB
configurations, I would like to know the reason of this behaviour and
how to solve it.

Your help will be greatly appreciated.

Best regards

Raimon

EA3EZO

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Re: K2, low output in digital modes

Don Wilhelm-4
Raimon,

If you have the RTTY FL1 filter set to OP1 and the BFO frequencies set
the same as for SSB, there should be no difference.
EXCEPT
The RTTY filter set has an independent SSBCr setting in the menu, and it
should always be set to 1-1 for data modes.
If you have the SSB menu SSBC set to add compression to the signal, that
would explain the difference, but if so, it is causing distortion on
your data signal.

Yes, you will have to increase the audio gain on the higher bands where
the transmit gain is lower.

Re-check the filter settings.  If the FL1 filter is set to OP1 and the
BFOs are set the same as for SSB, then there should be no difference if
you set the SSBC menu parameter to 1-1.

73,
Don W3FPR

raimon wrote:

> Hi Elekrafters
>
> I need your help.
>
> My K2/100 nr. 03529 with KSB2 SSB adapter and KAT 100 Antenna Tuner has
> been working perfectly since I built it, with the exception of some
> minor problems that were solved either with the help of Don Wilhelm or
> after a search in the e-mail list reflector.
>
> But now I detected a problem unnoticed until now:
>
> I work mainly CW and digital modes.
>
> In 40, 30 and 20 meters, in PSK 31 or RTTY, I could get easily about 40
> watts output, corresponding to one bar flickering in ALC bargraf. So all
> was apparently all right.
>
> But I have tried recently the 10 m. band and noticed that when selecting
> my RTTY filters configuration I can get only near 20 watts in rtty, and
> less than 10 watts in rtty-r.
>
> When I use in this band the USB or LSB configuration, and transmit RTTY
> or PSK, I get about 90 watts, the same output as in CW..
>
> I have seen now that this drop in output happens in all bands, but I
> had’nt noticed it because I was able to get 30-50 watts in the lower
> bands, even in RTTY configuration. The same output drop happens in QRP
> configuration.
>
> Summarizing, in digital transmissions when in RTTY the output is
> significantly lower than when in SSB, and the higher the frequency the
> lower the output power.
>
> I realigned my filters with the help of Spectrogram, applying the same
> settings for OP-! SSB and OP-1 RTTY (there were some small differences
> before this realignment), but to no avail.
>
> Although I can continue working digital modes using the SSB
> configurations, I would like to know the reason of this behaviour and
> how to solve it.
>
> Your help will be greatly appreciated.
>
> Best regards
>
> Raimon
>
>
>  
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