[Elecraft] RIT/XIT

[Don Brown]

Hi

To add a little more to this all of the pots R1, R2 and R5 are read by the
same A to D port. Each pot is enabled by grounding the CCW end of one pot at
a time so the A to D can read the voltage. When the other pots not being
read are high, the diodes disconnect them so they don't affect the reading
on the pot being read. Its all a bunch of firmware magic.

Don Brown
KD5NDB


----- Original Message -----
From: "Lyle Johnson" <wa7gxd@fidalgo.net>
To: <elecraft@mailman.qth.net>
Sent: Friday, January 24, 2003 11:42 AM
Subject: RE: [Elecraft] RIT/XIT


> > To save me bothering Gary again (he's busy enough as it is) is there
> > anyone out there who can explain how the RIT or XIT offset is applied to
> > the K2.  I can see it originates from the Front Panel and the voltage
> > from the pot goes to U3 pin 16, but thats where I lose it.  Any ideas
> > are most welcome :-)
>
> The output of the front panel control is a DC voltage read by an
> analog-to-digital converter internal to the main PIC processor (U6,
control
> board).  The processor calculates the PLL offset settings (applied to the
> synthesizer chip [U14, RF board] on 5 kHz "boundaries" as well as to the
DAC
> [U5, RF board] that drives the PLL reference oscillator) and applies them
on
> transmit (XIT) or receive (RIT), as appropriate.
>
> 73,
>
> Lyle KK7P
>