Steve N4LQ wrote:
Would someone please explain to me what changing the filter from
2.4khz to 2.8khz has to do with carrier balance.
I see no relation. The carrier is nulled by balancing the dc voltage
on U4 of the TX Audio board. No filter is anywhere near there. U4
feeds DSB into the 9mhz filter but the carrier must be nulled before
it gets there so whats going on with all this carrier balance talk I
keep reading about?????
Since the DSB output of the balanced modulator goes to the 2.4 or 2.8
kHz filter, changing the filter could possibly change the loading on the
balanced modulator, requiring readjustment for best carrier null. I
think that difference in filter loading on the balanced modulator is
rather unlikely to make a significant difference. However since the
filter is wider, and the point of this modification is to improve audio
fidelity, lower frequency audio sidebands AND the carrier will be
attenuated less by the wider filter. So in order to acheive the same
carrier supression as with the narrower filter, the carrier null has to
be adjusted more precisely.
DE N6KB
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