[eagle] Re: 70 cm Receiver IF Spurs - Problem Solved
kk7p at wavecable.com
Sun Jun 17 21:23:48 PDT 2007
> The uglier this gets the more interesting I find it! I hope no one is
> getting disheartened. After all, this is why we all got involved in the
> first place, isn't it? If it was easy it would be boring.
No one is bored... :-)
> I just cooked up an idea for a noisy power source that could be used during
> payload development and test. I stuck my write up and a block diagram at
> the end of my current log.
> Here's the link:
> What do you think?
It would be nice to be able to add to the bench supply output a noise
source capable of a volt or more at whatever current the D.U.T. might
require. Maybe an amplifier we can feed with a function generator to
simulate a sawtooth or ??? waveform from a few kHz to a few tens of kHz
to better simulate the assumed dirty power source?
We really need to get an idea what to expect worst case from the S/C
> Shielding the CAN-Do inductor obviously won't solve all these problems but
> it might buy back 2 inches of space and that's worth the effort.
Yes, we need to shield this if we can.
> My suspicion is that the two VCOs on this receiver are also the most
> susceptible to radiated EMI from CAN-Do. I can't say for sure but it looks
> that way to me. Both are in metal cans soldered to ground. The closest one
> was about 2 inches away from the CAN-Do inductor. I've more than doubled
> that distance to 4-1/4 inches to get away from it. That's a lot of EMI!
Indeed it is. We should try and find a toroidal inductor to minimize
radiation, then put a magnetic shield around it to suppress what the
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