[Elecraft] No SSB Output

[Marshall Jose]

Treat,

I assume your scope was AC-coupled when you measured U3-4; some scopes 
misbehave when DC-coupled.

I looked at the PC layout and wondered if a solder bridge to a nearby 
pad might cause the symptoms, but it doesn't look like it. The trace 
running from U3-4 goes around a bit, but it doesn't pass by any node 
whose impedance drops when the circuit is energized.

You would do well to verify the DC voltages on U3 given in the DC 
voltage chart. Perhaps that will help you determine if U3 is defective. 
That's all I can think of.

Marshall Jose, WA3VPZ

Treat Hull wrote:

> ....First, I used my scope and verified that I had a good BFO signal to U5
> pin 6.
>
> Then I set up my audio signal generator for about 50 mV peak-to-peak at
> about 1,000 Hz and fed it into the mike connector pins 1 and 7 (which 
> I had
> wired for a Radio Shack mike with AF to Pin 1, PTT to Pin 2, and 7 and 
> 8 to
> ground).
>
> When I used my scope to trace the AF signal, I started with the K2 powered
> down. I found that I had a strong AF signal all the way to Pin 4 of U3.
> However, when I powered up the K2, I lost all AF at Pin 4 of U3. Working
> backwards, I found that I had AF as far as the junction of C32 and 
> C33, but
> no further. It's as though Pin 4 of U3 is going to ground when the unit
> powers up. It behaves the same way with PTT open or closed.
>