Posted by
Erik Linder-2 on
Apr 29, 2012; 8:40pm
URL: http://elecraft.85.s1.nabble.com/BFO-resets-itself-after-cal-fil-K2-tp7511681p7511759.html
Don, tnx for the answer.
Yes, the difference was small. Tnx for the info about 20 Hz, then I now the
limitation of the construction.
Yes I can use the FL1 (open) as both TX and RX (well of course TX is alway
using FL1). But if I want something more narrow I like to use FL2 - FL4.
And now I know that I can get in 20 or so Hz if I work hard enough. :-)
But the main problem here is that I cannot adjust my filters at all right
now. :-(
I can move the BFO (change the pitch) as long as I am in cal fil but as
soon as I save the filter and return to listen the pitch has changed to
"default". The BFO-value _has_ changed, it _has_ been saved. (I see the
display showing BFO freq for a short time).
But still - the pitch is where it was before I changed the BFO-value.
And I have changed it much - like 50 to 100 units. USB, LSB, CW - the mode
does no difference.
So:
Received pitch of the signal transmitted from my 2:nd TRX: 1500 Hz
The BFO value is (lets say) 128
I change the BFO value too 100
I hear (and see on the waterfall) that the pitch is changing.
I press XFIL (to save)
Display shows BFO freq for a short time.
I press XFIL a couple of times to "get round" to FL1 again.
The pitch has now jumped back to 1500
The BFO-value is at it's saved 100
I can now lower the BFO value once more and when I come around the pitch
will be 1500 and the BFO is saved with the new value.
Isn't it suppose to work like:
Change the BFO to get the correct pitch
Save
Return to the filter and the pitch is where you programmed it to be.
73 de SM0RVV
./Erik
2012/4/29 Don Wilhelm <
[hidden email]>
> Erik,
>
> Do you see the BFO frequency flashed on the display when you exit? If so,
> you are verifying that the value is being saved.
>
> Fact, the DAC resolution in the K2 is about 20 Hz. If the difference is
> less than 20 Hz, it my be a situation you have to live with - you have
> reached the limit.
>
> Are you using SSB or the RTTY filter set? If so, there should be no
> difference in the VFO between RX and TX. If you are listening with a
> filter other than FL1, then yes the BFO will be switched to FL1 for TX. If
> your goal is no difference between TX and RX, then you will have to RX with
> FL1
>
> If you use an RX filter different than FL1, you will have to unlock TX and
> RX in your software to keep from "walking the band". Most packages allow
> that - I don't know about the NUE-PSK, but II would think that is a
> required condition.
>
> 73,
> Don W3FPR
>
>
> On 4/29/2012 3:28 PM, Erik Linder wrote:
>
>> Hi all,
>>
>> I decided to recalibrate the filters in my K2 because I noticed a small
>> RX-TX frequency difference which made it hard to use my NUE-PSK.
>>
>> But I didn't get the calibration working...
>>
>> I enter filter calibration menu. I select FL1 in open-mode. I adjust (in
>> RX) the BFO and watch the audio move on the waterfall (change pitch). All
>> seems 100% OK.
>> Then I press XFIL to save the value. (the freq-probe is in TP2 - duoble
>> checked).
>> When I then return to FL1 the pitch is back where it was from the start.
>>
>> I first thaught that the value did not get saved, but after re-checking
>> the
>> BFO-D/A value it has been saved.
>> I then tried to measure U8 pin 16 to see if the control voltage is
>> changing
>> - yes it is.
>> The voltage changes when I change the BFO-D/A value in cal filter. The
>> value I choose will be saved and I can measure the same voltage when I
>> return to FL1.
>>
>> But the BFO keeps resetting itself no matter what value I choose in cal
>> filter. The most strange thing is that the BFO changes as long as I am in
>> cal filter menu, it resets itself when I change filter (saving the value)
>>
>> I had the SSB option in, but in the troubleshooting I removed it. The
>> behavior is still the same with or without the SSB option plugged in.
>>
>> So... Can anyone give me a clue what's going on here?
>>
>> Tnx in advance and 73 de SM0RVV
>> ./Erik
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