deep seeker problem

[george]

Hi. I made the receiver of deep seeker but don't work properly. Q4 of the broadband amplifier works in class C (cut off), so the sensitivity is very low.I change the bias(r12) but now i have self oscilatorsat about 300 Hz.
Does anyone has a solution or know the problem?
(I run the rec at 160 Khz with IF transformer to potcore)
thanks
george

[Ken H.]

Re: deep seeker problem

George,

If you are writing about the "Deep Seeker" by Phil Wait and Roger Harrison, a two box detector, Q4 is not biased by R12.

I believe C11 and R12 form a filter to direct the 100khz signal to ground, and just allow the modulated 800 hz signal to pass on to the speaker.

The receiver sensitivity is set by the bias on Q1 and the emitter bypassing of Q3 by variable resistor RV1 (1K).

Hope this helps.

[george]

Re: deep seeker problem

Hi Ken.H

R12 with C11 form a filter but in dc R12 with R10 form a voltage divider.I change the R12 with a trimmer 100K and now the sensitive is very good except the self-oscilators who provided from Q1.I"ll change the T2 winding and maybe to fix the problem.
Thanks George