On Thu, Sep 20, 2018 at 10:36 AM, Joe Puma wrote:
Okay I¡¯ve been reading posts in this group for a while, I¡¯m somewhat familiar. Is this similar to the issue with Spurs because of board layout?
Yes as best I can figure.? There appears to be a ground loop between the Raduino and the?
board for all three oscillators and the IF sections.? If I bent the pin for Raduino osc0
down the main board and substituted a external?separate oscillator it it was better by
8db!? The external osc I used for that was a crystal osc?identical that of the analog
Bitx40 using a 12Mhx crystal and? coil in series to move the crystal down to about
11.99675mhz (for mine). The oscillator was built in smaller mint tin (was handy and
cheap, mints were only ok) borrowed 12V from the board with a short length of thin
coax to the modulator.? ?I later took the modulator off the board and put that in the
tin to see If I could get better carrier suppression (it was better by about 6 more db.).
Another thing tried is to connect all the crystal cases in the filter to ground via several
small (several 0.0037 inch holes to ground plane) which also bought maybe 2-3DB
improvement.
I was trying to get what I expct from my radios that being carrier reduced to less
than -43 to -50dbc being the goal.
Allison
