Mini Pulse Rev. D PROBLEMS

[boficle]

I just finished Rev. D, checked all components before soldering, checked all steps with voltmeter, all good solder connections, everything checked out good untill step 9, my coil ( 300 uH) does not react to any metal at all, went back to test each step, and in step 4 my headphones no longer pickup any sound, I tried 2 sets of phones, I am stumped, does anybody have any ideas, I really need some help. PS, back around 1980 I bought a Fisher VLF 555-D and it still works like new.

[Qiaozhi]

I just finished Rev. D, checked all components before soldering, checked all steps with voltmeter, all good solder connections, everything checked out good untill step 9, my coil ( 300 uH) does not react to any metal at all, went back to test each step, and in step 4 my headphones no longer pickup any sound, I tried 2 sets of phones, I am stumped, does anybody have any ideas, I really need some help. PS, back around 1980 I bought a Fisher VLF 555-D and it still works like new.

Was Step 4 working previously?
If Step 3 is ok, then the most likely problem is that your coil is not connected correctly.

[boficle]

Yes, step 4 was working in the build, I tried the coil on Mini Pulse C and the same problem, I tried a 500 ohm Pot for R1 and still nothing, yet the coil still reads 300uH, I'll take a look at my coil connections again. Thanks for the help.

[boficle]

Thankyou Qiaozhi, You were right, I connected the coil different from the picture I had and it works now.