Re: ubitx spurs? Added LPF
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Good point.? Earlier in this thread it
was recommended that I add
a LPF to get rid of the spurs on 15, 12, and 10m.
It was my understanding that the following (from Ashar I believe)
is the one (though #1 is backwards).
I've picked up some 0.33 uH SMD inductors I'll try today.
If that's not the right one, I could use a pointer to it.
On 4/13/2019 12:45 PM, Curt via Groups.Io wrote:
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John
You aren't clear in this message which spurs you are trying to
solve, nor where you are putting this new filter?
If this is an added 45 MHz filter, adjacent to the mix to and from
RF, then its objective is to reducing non harmonic mixing spurs
typically found on 15, 12, and 10 meters. A common problem with v3
and v4, maybe less so on v5. Note this mixing only happens on ssb.
In the last dB or to audio drive is a big deal. If my rig measured
say 41 dB down at full output, note if I ran digital at less
output I would likely be okay. For voice one might debate the last
dB since our voices don't stay at peak amplitude.
Curt
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