DC BLOCKING CAPACITOR

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N9LCD
Posts: 330
Joined: Sat Jul 01, 2006 8:32 pm

DC BLOCKING CAPACITOR

Post by N9LCD »

I want to run the 10.7 MHz IF from an ICOM R-7000 into a spectrum analyzer (signal display unit).

CATCH: The broadband 10.7 MHZ IF output is superimposed on 9 Volts DC and I don't want to take chances with the front end of a HP analyzer.

QUESTION: What's a good value, in pf, for a series DC blocking capacitor. I think that a 25 or 50 Volt DC rating is adequate.

Thanks!

Jerry

N9LCD
k9yli
Posts: 229
Joined: Fri Aug 12, 2005 11:35 pm
Location: northwest wisconsin

Post by k9yli »

50 volts surly is adequate..

as for size.

just ry a few and use one with adequate signal.

470 pf would be a common size.

.01 mfd will let most every thing through. down to audio frequencys.

try .005
try .00047
try .000047 all in mfd.

keep going smaller untill not enough signal gets through.


ot the formula X subc = darn. mental block..
look in the hand book. mine is down stairs.

ok i had to check on the de-humidifier anyway..

x subc = 1 over 2pi times f times c

f in hertz c in farads.

pi is 3.1416

substitute say 10 ohms for Xsubc
10 000 000 for F

solve the formula.

( deal with all the zeros too)

1
Xc = ---------------------------------------
2x 3.1415 x 10 000 000 x C (in farads)


see you can draw formulas in the computer..


don.
k9yli
Posts: 229
Joined: Fri Aug 12, 2005 11:35 pm
Location: northwest wisconsin

Post by k9yli »

In the final formula the one should be over the fraction bar.


maybe you cant mess with back space and delete and get it to transmit correctly.

don
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