[Elecraft] K2, low output in digital modes

[raimon]

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

rfuidio at telefonica.net