[Elecraft] K2 Lowpwr on SSB

[Don Wilhelm]

Stewart,

FB on purchasing that K2 already built.

First, that probe in TP2 is not an RF Probe, it is the internal counter
probe.  It is required to run CAL PLL or CAL FIL, and it measures frequency.

You will find a schematic of an RF Probe in Appendix E page 9 of the K2
manual.  If you do not have an RF Probe or a 'scope with a 10x probe,
you will need one to do the measurements that I must ask you to do.
Elecraft sells a kit of parts for an RF Probe for $10, but it takes very
few parts, so you may either have them already or can beg them from a
fellow ham.  You just need some kind of insulating material to keep the
parts in place.  For the frequencies to be measured, the probe does not
have to be neat and tidy, it just has to "be together".

The filter settings are within reason, but are probably not optimum.
You will want to optimize them using Spectrogram (if you have not
already done that) and the instructions on my website for setting the
SSB filters.

OK, with that out of the way - we know that you can get SSB output on 40
and 80 meters for LSB.  Try those bands on USB with the same 'whistle
test' and see what the power output is - it should be about the same as
on LSB

First, set the menu CAL CUR parameter to 3.50 Amps, and be certain your
power supply is capable of producing 4 amps or more without
significantly dropping the voltage at the K2.  The next thing to try is
set the POWER control to max clockwise rotation and see what the TUNE
power is on each band - connect a good 50 ohm dummy load (we really
can't tell much with certainty when using an antenna).  If you have the
KAT2, either remove it or set the ATU menu parameter to CALP.  Read the
K2 display to see the indicated power, and tell me what that value is.
Again, with the power control set all the way to max, try the whistle
test on 40 and 80 again, for both LSB and USB.  If you see a Hi-Curr
warning with any of these tests, please let me know what the band and
conditions were when that happened.

The reason for these tests is that I have trouble believing only the SSB
power output is band dependent - there is no way that it can be, so I
believe you will find that you can transmit both LSB and USB, but there
is some other problem in the transmit RF chain.  The gain of the K2 is
greatest on 80, 40 and 30m, so you may be able to produce 4 or 5 watts
on all bands easily even with a fault in the transmit RF stages.  The
test at max power should show up the gain differences between the bands.

73,
Don W3FPR

Catherine Flick & Stewart Fletcher wrote:
> Hi Don:
> Thank You very much for the advice on where to start to figure out 
> this problem.
> I did the alignment, and found that I had the filters incorrectly on 
> the wrong side of center for CW.  For SSB I tweaked them a little, but 
> not much. I was not the builder of this K2 or SSB module so I do not 
> have the calibration number for the SSB crystals..I started with 3.6 
> as suggested in the manual.  Here are two spreadsheets: one for my 
> whistle pwr out test and one for my new filter settings.   The RF 
> probe is built and attached to TP2 in the hole in the SSB module.  So 
> where do I go from here?
>
> Thanks!
> Stewart KE7LKW
>
>
> ----- Original Message ----- From: "Don Wilhelm" <w3fpr at embarqmail.com>
> To: "Catherine Flick & Stewart Fletcher" <stewart at gorge.net>
> Cc: <elecraft at mailman.qth.net>
> Sent: Saturday, October 11, 2008 2:29 PM
> Subject: Re: [Elecraft] K2 Low/No pwr out on SSB except 80 and 40m
>
>
>> Stewart,
>>
>> There is no band dependency in the KSB2, so your problem is most 
>> likely associated with your filter setting for SSB FL1, particularly 
>> the USB BFO setting.
>>
>> While the settings given in the KSB2 manual are usually a good 
>> starting point, they are not optimum for any one particular set of 
>> crystals.  I strongly suggest that you use Spectrogram to align the 
>> filters.  If you are not familiar with Spectrogram, take a look at 
>> Part 3 of the K2 Dial Calibration article on my website www.w3fpr.com.
>>
>> If you have trouble after aligning the filters with Spectrogram, we 
>> can provide additional help, and if you have not yet constructed the 
>> RF Probe from the parts provided with your K2 kit, it will likely 
>> come in handy for that troubleshooting.
>>
>> 73,
>> Don W3FPR
>>
>> Catherine Flick & Stewart Fletcher wrote:
>>> K2 gurus:
>>> I have a K2 with 160m mod, DSP, NB
>>> Into a dummy load, I have good power out on all bands in TUNE, and 
>>> CW Mode.
>>> In L/USB I ONLY have good power out on 80 and 40m determined by the 
>>> whistle test and weekly check-ins to several nets(LSB only)
>>> Other bands are either very low or 0 watts out.
>>> I just finished the tx alignment procedure in manual.
>>>  Any ideas?
>>> I have very little experience/knowledge of what is going on here.
>>>
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