[Elecraft] K2 freq calibration...

[Don Wilhelm]

Brett,

What is the width of your OP1 filter?  The initial ones were 2.1 kHz 
wide for best use with a QRP K2, then it was changed to 2.4 kHz for 
better fidelity.  A 2.6 kHz width will sound even better.  Elecraft 
offers a capacitor kit to allow you to change the width to either the 
2.1, 2.4 or 2.6 kHz width.

Yes, the variable filter looks a bit 'ratty' at wide widths, but if the 
filter passband is positioned properly (low frequency corner at 300 Hz), 
it provides a means of cutting out QRM while listening to SSB despite 
the great passband ripple.  It is never used for transmitting SSB.

73,
Don W3FPR

Brett Gazdzinski wrote:
> Today, I could pick up the time signal on 20 MHz and did the setup with 
> moving the probe between tp1 and tp2 to get the readings the same.
> It seems spot on now, and I was in a qso on 80 meters and was right on 
> frequency on both TX and RX.
> Same report as far as the audio goes, restricted but clean.
> Its likely to sound a bit better with a real microphone.
> The station I was talking to sounded VERY nice using an external speaker.
>
> I have been told the variable xtal filter looks bad on ssb with spectrogram, 
> and assume that is normal.
>
> I am really pleased with the K2 and the ssb part of it also.
>
> Who needs a K3!
>
> Brett
> N2DTS
>
>
>
> ----- Original Message ----- 
> From: "Don Wilhelm" <w3fpr at embarqmail.com>
> To: "Brett Gazdzinski" <Brett.gazdzinski at verizon.net>
> Cc: <elecraft at mailman.qth.net>
> Sent: Thursday, January 29, 2009 10:36 PM
> Subject: Re: [Elecraft] K2 freq calibration...
>
>
>   
>> Brett,
>>
>> You ask several questions, and I will delay on all of them except the one 
>> about calibration.
>> You are relying on too many variables when setting the 4 MHz reference 
>> oscillator.
>> To reduce those variables, use the "N6KR" method that is documented at 
>> http://www.elecraft.com/Apps/K2%20C22%20Adjust%20App%20Note.pdf.  If you 
>> can tune WWV accurately, all other variables are cancelled out by that 
>> method.
>>
>> You may also find helpful information in the K2 Dial Calibration article 
>> on my website www.w3fpr.com.  For your restriceted SSB audio, consider the 
>> comments in that article about the low frequency corner of the SSB filter 
>> passband carefully - 300 Hz is the 'magic' frequency.
>>
>> After you get the dial calibration correct (within 20 Hz or less), ask 
>> about the other items.
>>
>> 73,
>> Don W3FPR
>>
>>
>> Brett Gazdzinski wrote:
>>     
>>> I am having a hard time getting the frequency calibration on my K2 closer 
>>> than 80 Hz.
>>> I set the osc to exactly 4Mhz, plus or minus a Hz on the pro3 switching 
>>> between usb and lsb, it also agrees with the HP spectrum analyzer, I then 
>>> run the cal pll, and the bfo calibration, and when tuning in ssb signals, 
>>> they sound normal 80 or more Hz higher than they should (as tuned in on 
>>> the pro 3).
>>>
>>> Is this as good as it gets on ssb?
>>> I have compared CW signals between the two rigs and they are very close, 
>>> within about 10 Hz on 80 meters anyway.
>>>
>>> It seems the freq counter, pll cal, and bfo all sort of interact, but if 
>>> the freq counter calibration is spot on, why the 80 Hz difference?
>>> (80 Hz is as close as I have gotten it in many attempts)
>>>
>>> Also, is it normal for the non ssb filters to look SO bad on 
>>> spectrogram??
>>>
>>> I got the ssb option on Tuesday, it was done Tuesday night, the antenna 
>>> tuner was done Wednesday, no problems with them, no missing parts, no 
>>> issues, I made my first ssb contact yesterday on 80 meters using the hand 
>>> mic from the pro 3.
>>> SSB from the K2 sounds good in the pro 3, the report I got said it 
>>> sounded a bit restricted, the hand mic sounds poor on the pro 3...
>>>
>>> What would be a nice sounding microphone to use with the K2?
>>>
>>> Also, I have been thinking of taking down the home made G5RV and trying 
>>> an alpha delta dx-lb plus (160 through 10), the G5RV does not seem to 
>>> work as good as the 40 meter dipole on 40, and its likely worse on other 
>>> bands...
>>>
>>> Anyone got anything bad to say about the dx-lb plus, I know its not as 
>>> good as a full size 160 m antenna, but I have about 110 feet max between 
>>> trees.
>>>
>>> I sure am enjoying the K2!
>>>
>>>
>>> Brett
>>> N2DTS
>>>
>>>       
>