Cobra 29 LX Max no xmit...

[brandon7861]

@Hawkeye351 Awesome to hear you got it going! I would have never guessed that 1Ω resistor. I'll have to pay more attention to those!

@guitar_199 Thanks for the kind words! I'm sorta glad we didn't start with the 'scope because I wouldn't have had to try to make sense of it. I didn't know that kind of bias would be slightly negative until yesterday going between the schematic and the book. Had to go see it for myself on my 25 (which ended up being between -0.2v to -0.3v). I learned a bunch too!

 

[guitar_199]

@Hawkeye351 Awesome to hear you got it going! I would have never guessed that 1Ω resistor. I'll have to pay more attention to those!

@guitar_199 Thanks for the kind words! I'm sorta glad we didn't start with the 'scope because I wouldn't have had to try to make sense of it. I didn't know that kind of bias would be slightly negative until yesterday going between the schematic and the book. Had to go see it for myself on my 25 (which ended up being between -0.2v to -0.3v). I learned a bunch too!

In fact... the negative makes sense when I think about it.

The transistors are NPN.
The emitter is grounded.
The positive peaks of the incoming RF will be shunted to ground through the P-N junction.
But the NEGATIVE peaks will still be there (THAT is the rectification is that you talked about in another post!). So while it is largely "unfiltered" it is still all negative RF signal. So a meter WILL tend to see a negative average.

WOW. You have really led me into the light here!
Thank you again!

 

[Hawkeye351]

Thank you guys. This site is so helpful when I get stumped. The other techs on here are the most knowledgeable people I've ever had the privilege of speaking with, very detailed to learn from. They don't just tell you what to do, they explain how the circuit works so you'll learn from it. I always tell those I know to come to this site for info on radios and who to keep up with on here as far as knowledge.

We all need guidance at times, not only in the radio world, but the real world also.

 

[Handy Andy]

Then you might want this...

Not sure if these are in the WWDX Gallery, but if you need the OLDER AM only versions - here you go.