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Old July 10th 05, 05:29 AM
dave.harper
 
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Default Help with AM receiver circuit

I'm trying to build the simple AM receiver shown he

http://www.electronics-lab.com/projects/rf/006/

The only modifications I've made are changing the 200uH inductor to a
100uH (ferrite rod) inductor. I'm using a 10-120pF variable capacitor
(http://murata.com/catalog/t13/t13_09e.pdf), so I believe I should be
able to pick up the higher AM frequencies (correct?). I haven't been
able to get it to work yet (usually silence or static, sometimes a
high-pitched buzz), and have a few questions:

1. One of the caps is labeled 100n. This would be the same as the
other caps (.1uF). Is this a typo, or is the diagram just not
consistant?

2. The first three voltage checks I'm getting withing a couple
hundreths of a volt. The Q3(b) voltage (supposed to be 0.62V) is
reading 7.06V. And the Q3(c) (supposed to be 3.87V) I'm getting 1.07V.
Can anyone spot a connection error I might have made that would cause
this?

Thanks in advance for any help on either question!
Dave