On 9/16/12 7:37 PM, Andreas Hahn wrote:
For Terry Fritz's antenna, he specifies a 20nF NPO ceramic capacitor. The largest NPO I can get is 1nF; however, I can get 20nF in X7R or polyester & polypropylene film. While Fritz does say the value isn't critical, I suspect off by a factor of 20 could hurt things... On the other hand, he does say "it should be a high performance COG type capacitor." (NPO and COG are equivalent, last I checked). Should I just go with X7R? Or am I better off using the (perhaps more inductive) poly film?
I would think that inductance in this circuit is a *bad thing*, but so is changing the value of C2, since that is the bottom of a capacitive voltage divider formed by C3 and C2
Terry gives a part number from Digikey for the cap 399-1835-1-ND (and you need two, since they're 10 nF each)
it is true that they show as "non-stock" at Digikey this afternoon (unless you wan to buy 2,500 of them at about 36 cents each)
The ROHS equivalent is in stock for small quantities at $1.39 each. 399-4520-1-ND
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