I could not see either picture on this chromebook.
You plan to be transmitting and receiving at a frequencies of 8.222 and 8.746mhz.?
The Bitx40 bandpass filter is used for both transmit and receive, so the simplest solution would
be to have a single bandpass filter using fixed components with a 500khz bandwidth.
Making this filter tunable during manufacture to properly align the rig may be a good idea
if the fixed parts are not precise enough to give the same center frequency for each rig built.
But this makes building and aligning rigs more complicated.
If you wind up using filters narrower than 500khz for some reason, it may be necessary to?
have one bandpass filter to transmit and one to receive, selected perhaps by relays.
A significant complication, best to avoid this.
Allowing the user to tune the filter seems unnecessary, as this will be operating on fixed
transmit and receive frequencies near 8mhz.
The transmit low pass filter can almost certainly be left about as it is with slight
adjustments made to inductor and capacitor values, no need for that to be tunable.
?
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On Thu, Mar 1, 2018 at 03:59 pm, <qonita.salimah@...> wrote:
In this picture below, the Band Pass Filter is using a tunable inductor. But in the schematic files in hfsignals.com using a fixed inductor and capacitor.
Is there any advantage and disadvantage for these two types of passive components?
