Re: band-passfilter location in SSB transmit chain
Posted by
wayne burdick on
Aug 14, 2006; 7:59pm
URL: http://elecraft.85.s1.nabble.com/Up-conversion-tp392867p392877.html
PE1E wrote:
>
> I was told that the absence of filtering between Tx mixer and Tx
> buffer
> amp could cause annoying IM products.
> ( The bandpass filters in the K2 are behind the Tx buffer amp., while
> in at
> least one of my other tranceivers in use here I see the bandpass filter
> straight behind the Tx mixer without interfacing amp. ).
>
> Could this observation contribute adversely to the SSB Tx audio
> quality (
> in-band IM3) or do I see a ghost ?
Peter,
The TX buffer amp is operating class A, and any IMD it contributes will
be completely negligible compared to the IMD contributed by the
class-AB final amp. So, positioning the bandpass filters after the
buffer should have no impact on observed IMD.
If you see any more ghosts, let me know :)
73,
Wayne
N6KR
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