Hi All,
I have been working on an Emerson 756B and was wondering if anyone could explain the purpose of V-2 on the schematic. I have a pretty good understanding of what the other tubes are doing but I am not really sure what’s up with V-2. This radio looks like an AA6 but with this extra tube. Any information on this would be great. Thanks!
<a href=" removed link ” target=”_blank” rel=”noopener”>Schematic 756B
Evan
The schematic is not attached to your post. I searched online and see that it is not a typical AA5 or AA6 design. It looks as if the oscillator has its on tube and 2 amp stages for IF, being V2 one of them. I could be a very goog performing design. I may be mistaken..
2.15.1.0
2.15.1.0
@cpechiar Oh that makes sense, I completely overlooked the oscillator function. I guess I’m used to seeing it integrated into other tubes. Yes, this seems to be a very good performing receiver. I use it in my office and am am able to pull in some distant and weak stations with my external antenna. I think the AVC action is a bit wonky though. Stronger stations seem to overload and distort. I’ll have to open it back up soon and investigate.
Also, I tried to include a link to the schematic but it didn’t work and I wasn’t sure how to attach a file. Maybe because I’m a new member?
Thanks for the reply!
Hi Evan,
Yes new members can’t post links. Once you’ve made a couple posts that have gone through moderation you should be good to go. This is done automatically to prevent spam.
-Mr Carlson’s Lab Admin
@ewiskow7 I asume you’ve already recapped it. If not, replace C4 and check R8 (both relate to the AGC circuit and its RC constant). If C4 is leaky or R8 has gone up in value AGC performance may be degraded. I see that most tubes 6BJ6. It may explain the design based on manufacturing economics rather than performance.. who knows..
2.15.1.0
2.15.1.0
@cpechiar Thanks for the advice. I did replace all the caps except for the multi-unit one awhile back but I will check R8. I was thinking that’s what it might be because a few of the other resistors had drifted up in value and needed replacement.
@cpechiar It turns out R8 and R9 were out of tolerance so I replaced them and now the AVC works much better!