re :Magic box build, no sidetone


Kenneth Ketner
 

Greetings Jim:

I'm grateful for your reply. 
The MB board I am building is marked V1.2B. I have a schematic also marked V1.2B. I don't have photo capabilities just now, so I can't send a photo (perhaps later if needed). 

The build passed all the sectional tests in the assembly manual prior to the sidetone section. I hear no sidetone after trying all positions of R32. The manual mentions no keying action. I simply powered up with a 13.8 linear bench supply, no tone with working phones plugged into J6.

Q14 and 15 are 2n3904 as supplied in the kit. Q16 is 2N7000.

I get the following voltages.
   Top of R25 and R26 10V; Q14 col 4V, base 1, emitter 0.5V; top of R28 10V; Q15 col 10V, base 4V, emitter 0.0V ??fault??; R40 bottom 5V, top 4.9V; R38 top 4V; R37 top 0.0V.

I can send the whole board to you on my dime if that would help.

I'm long in the tooth myself, Jim;>)

vy 73


Ken Ketner
ARS KA5ELD
ARRL, RSGB, G-QRP
PO Box 65135, Lubbock, Texas 79464-5135

Join main@4SQRP.groups.io to automatically receive all group messages.