[Central-Electronics] 20A

[Jim Candela]

Larry,
   Wow man, you have opened the door into taming the 20a phasing system! This is something I've wanted to do for quite a while. A couple of comments are in order. First a high pass & low pass are necessary since the R-C phasing network falls apart at each end of the audio spectrum. Another method in addition is to broaden the phasing network capability. 

  The thread on AM phone covers a lot of what I have done. We have corresponded about this over the years, but a re-read might be timely given your recent effort on the subject. 


Central Electronics 20A PTT

|   |
|   |  |   |   |   |   |   |
| Central Electronics 20A PTTA site dedicated for the AM Radio Amateur and vintage radio. Home of the AM Press/Exchange, The AM Forum (the largest BBS of it's kind),and The AM Classifieds, ... |
|  |
| View on amfone.net | Preview by Yahoo |
|  |
|   |

1.) At the audio driver 6U8 (I use 6MU8), make a series R-C consisting of 470K and .01uf, and place between pins 1-9. Then remove C24 in the same area. This NFB really cleans up this stage without sacrificing too much gain.

2.) To open up the top end of the phase shifter to about 5 Khz, make another series R-C of 390K and 180pf, and place under PS-1 socket at pins 2-9. Then bridge R15 at the balance pot with a 1.8K. Then re-do the phase shifter setup the usual way. You will see as ripple starts to emerge at about 3 Kc, it then diminishes going up and then at 5 Kc it starts to lose the shift like it did stock at about 2500 cps.
I hope to hear more from you as you contemplate various ideas.

73,JimWd5JKO
 

    On Sunday, October 26, 2014 12:54 PM, Jim Candela <jcandela at prodigy.net> wrote:
 

 
Hi all,
The CE reflector has been way too quiet that last few years. 

Currently there is a CE 20A related post that is ongoing at amfone.net.
http://amfone.net/Amforum/index.php?topic=37143.0
Maybe this can stir up a bit of activity.
Regards,JimWd5JKO