Re: ubitx spurs? Added LPF
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I think I'll need to find some shielded
inductors for this filter as recommended by Raj.
I used the ones I mentioned previously.
I also noticed that I had the function generator set up
incorrectly to drive 50 Ohms
as opposed to high impedance so the actual voltage at the Mic pin
on the uBitx was
more than 100mV instead of 50mV.? The power output at 50mV is very
low, just 10s of mW.
What would be a good max drive voltage for the Mic?
I'll try at different levels to see which spurs move too when I
get a chance.
For CW, all bands were clear though I didn't get a chance to test
80m which seems to be the
worst for me historically.? I updated the FW and didn't figure out
why it didn't want to operate on 80m.
On 4/14/2019 3:33 AM, Raj vu2zap wrote:
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47pf should be perfect but the inductor needs to be similar to
L5/7
Raj
At 14-04-19, you wrote:
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Thanks Raj.?? I'll pick up some 51pF caps Monday.?? My local
parts shop gets worried
if they haven't seen me in a day or two...
I'll try parts I have on hand first.?? Otherwise, it'll be time
to
put together another
Digikey order...?? I noticed I should have some Murata
LQW2BASR33J00L unshielded
parts that I picked up for a Radioberry build.
This is the placement I'm planning, mostly because I'd already
cut the
trace from R27 to C10
in two places for the previous filter and this will cover the
cuts.
- John
![[]](/g/BITX20/attachment/68473/2)
On 4/14/2019 12:28 AM, Raj vu2zap wrote:
John,
see this earlier post of mine
/g/BITX20/message/62097
Raj
At 13-04-19, you wrote:
I was about to dig into my parts bin searching for toroids and
I remembered I had those left over.
I'll probably have to order some 30 uH parts.? 27 and 33 are easy to
get locally, 30 maybe not.
Sounds like the way to go, thanks.
John
On 4/13/2019 6:28 AM, Raj vu2zap wrote:
John,
Very neat job on L5 and L7.
Make the 45MHz IF new filter with SMD parts. What seems to be the culprit
is any vertical wire leads in that area
causes trouble. Solder the SMDs directly on the board.
When I get back to town tomorrow I will try it.
Raj
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