[Elecraft] SSB cal fil problem

Tue Oct 15 14:00:59 2002

hello,

I aggree with Jerry : I have noted the same behaviour : same BFO settings
for FL1 es FL2 do not produce the same audio frequency on a reference
transmitter.
Attempts to correct that by adjusting BFO's do not work when you exit the
MENU mode. But I have noted that "often !!" the modifications are correct
after exiting MENU if you  move through the different FL parameters after
modifying one BFO.

This is not a problem on SSB, nor CW. It becomes a problem when using
digital modes (RTTY, and more on PSK), where TX and RX frequencies must be
very closed (i.e : much less than 10 Hz for PSK). In my case, using same
parameters for FL1 (OP1) for SSB and RTTY, gives a shift of 30 hertz between
RX frequencies. After many tests, I was unable to find a better settings of
BFO parameters, so I stay like that ...

But I am curious to read an explanation about this behaviour ..

best regards and 72/73

Chris / F6FTB / K2 #644 + KPA100 (waiting for the KAT100 !!)

----- Original Message -----
From: "Jerry Hancock" <[email protected]>
To: "George, W5YR" <[email protected]>
Cc: <[email protected]>
Sent: Tuesday, October 15, 2002 6:48 AM
Subject: RE: [Elecraft] SSB cal fil problem

> I don't have a problem with dial calibration as much as not understanding
> the operation of FL1 and FL2.  Setting the BFO to the same number for both
> filters should give the same results, shouldn't it?
>
> -----Original Message-----
> From: George, W5YR [mailto:[email protected]]
> Sent: Monday, October 14, 2002 9:44 PM
> To: [email protected]
> Cc: [email protected]
> Subject: Re: [Elecraft] SSB cal fil problem
>
> > I applied both the SSB filter mods.  I am using OP1 for filter 1 and 2.
I
> > have both BFO settings at 209.  I would assume that this would make both
> FL1
> > and FL2 the same.  When I zero beat WWV and watch the tones (as per an
> > earlier post) I see the 500hz and 600hz tones at the correct place in
the
> > spectrum using sound forge spectrum analysis.  When I switch to FL2 with
> the
> > BFO settings at 209, the tones shift up about 39hz in the FFT.
> >
> > If I go back to CAL FIL and adjust FL2 to say 207, the spectrum display
> > changes and I can get FL2 to match FL1 (as to the position of the
tones).
> > If I then exit FL2 and loop back to FL1, FL1 is correct.  Pressing XFIL
> once
> > to select FL2 and the BFO setting is at 207 but the tone is back where
it
> > was, 39hz off.  Setting the BFO for FL2 to 205 corrects it until I loop
> back
> > around again.
> >
> > If I change FL1 to 211 I can make the tone move and leaving FL2 at 209,
If
> I
> > loop through the filters, it is ok.
> >
> > This happens on LSB on 14mhz.  The difference seems less on 40m.  I can
> > leave the USB filters at the same BFO settings without an audio shift.
> >
> > So what gives?
> >
> > Thanks, I enjoy this radio to no end.
>
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