K2 BFO alignment - pls check my values

[ub5_073_oleg]

Hi,

I've just done BFO alignment and freq. calibration on my K2
and have some

questions.

I can zero beat AM stations around 7130 kHz with +-10Hz.

1) BFO range:
High freq. = 4917.13 KHz (>= 4916.3 -> ok)
Low  freq. = 4913.08 KHz (not <= 4912.7 !!!)
Range 4.05 kHz (>= 3.6 kHz -> ok)

Should I have concern about BFO low freq. is 1.1kHz too
high?


2) BFO alignment: I did not found any instructions on how I
should use filter
crystals frequency written on the bag. It is "3.6" in my
case.

Nevertheless I am able to get all FL1-FL4 into desired
range, using RF noise and
SpectranV2 on my PC. The pitch does not change when I toggle
"cw" and "cw rev."

Are my BFO alignment values ok?

+-------+-------+---------+-------+
|Mode   |FL1    |       BF1       |
+-------+-------+---------+-------+
|CW norm|1,50   |bF1t103c |4913,60|
|CW rev |       |bF1t148c |4914,71|
|LSB    |2,20   |bF1t092l |4913,51|
|USB    |       |bF1t181u |4916,00|
+-------+-------+---------+-------+

+-------+-------+--------+-------+
|Mode   |FL2    |      BF2       |
+-------+-------+--------+-------+
|CW norm|0,70   |bF2 033c|4913,22|
|CW rev |       |bF2 137c|4914,21|
|LSB    |2,00   |bF2 114l|4913,70|
|USB    |       |bF2 171u|4915,70|
+-------+-------+--------+-------+

+-------+-------+---------+-------+
|Mode   |FL3    |       BF3       |
+-------+-------+---------+-------+
|CW norm|0,40   |bF3 021c |4913,18|
|CW rev |       |bF3 136c |4914,17|
|LSB    |1,80   |bF3 090l |4913,50|
|USB    |       |bF3 168u |4915,59|
+-------+-------+---------+-------+

+-------+-------+--------+-------+
|Mode   |FL4    |         BF4    |
+-------+-------+--------+-------+
|CW norm|0,20   |bF4 013c|4913,14|
|CW rev |       |bF4 135c|4914,13|
|LSB    |1,60   |bF4 090l|4913,50|
|USB    |       |bF4 161u|4915,31|
+-------+-------+--------+-------+
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[Don Wilhelm-3]

Those frequencies look to be within reason, but I cannot say for certain
since I do not have the Spectrogram (or SpectranV2) plots to see.

You BFO range SHOULD be a bit lower (but if you change it now, you will have
to re-align your filters).  You could try padding it down a bit with a
capacitor between U11 pin 6 and ground - start with 10 pf and experiment a
bit with values until the frequencies (both high and low) are within range.

The consequence of inadequate BFO range is that you may not be able to align
all the filters as you want.  But if you are satisfied with the filter
alignment as you have it, I would not change the range until you find a need
to do it.  The problem with the BFO range usually shows up when attempting
to align a narrow RTTY filters to a high center freuency (I commonly use
1000 Hz and an FL4 width of 0.40, and that combination may give trouble).

Since you aligned your filters with a computer spectrum display, the numbers
on the crystal package are no longer of any consequence.

73,
Don W3FPR

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]]On Behalf Of ub5_073_oleg
> Sent: Sunday, January 21, 2007 4:27 PM
> To: [hidden email]
> Subject: [Elecraft] K2 BFO alignment - pls check my values
>
>
> Hi,
>
> I've just done BFO alignment and freq. calibration on my K2
> and have some
>
> questions.
>
> I can zero beat AM stations around 7130 kHz with +-10Hz.
>
> 1) BFO range:
> High freq. = 4917.13 KHz (>= 4916.3 -> ok)
> Low  freq. = 4913.08 KHz (not <= 4912.7 !!!)
> Range 4.05 kHz (>= 3.6 kHz -> ok)
>
> Should I have concern about BFO low freq. is 1.1kHz too
> high?
>
>
> 2) BFO alignment: I did not found any instructions on how I
> should use filter
> crystals frequency written on the bag. It is "3.6" in my
> case.
>
> Nevertheless I am able to get all FL1-FL4 into desired
> range, using RF noise and
> SpectranV2 on my PC. The pitch does not change when I toggle
> "cw" and "cw rev."
>

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