[Elecraft] what is the use of IF TX quartz filter on the KREF3 board ?

[Bob Cunnings]

>From the K3 Owner's Manual, "Theory of Operation" section for KREF3:

"In addition to the TCXO and dividers, the KREF3 provides the 2nd transmit I.F.
mixer, which converts the DSP's 15-kHz transmit I.F. output to 8.215
MHz. This signal passes through a wide crystal filter to ensure good
rejection of the carrier and other mixer products before being routed
to the RF70 board."

Bob NW8L

On Sun, Nov 23, 2008 at 5:05 AM, Giuliano <giulianori at virgilio.it> wrote:
>
> I see on the K3 KREF3 schematic a quartz filter ( 8215 KHz BW= 4 KHz) . It
> is switchable...
> someone know what is the use ? In what modes it is switched on? Exist a
> detailed bandwidth  diagram?
>
> Thanks for help
> Giuliano I0CG
> Italy
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