[Central-Electronics] Ce 20A alignment questions

[Laurence Szendrei]

You may get a better answer, but this is what I’d do in the absence of better information. Leave the position of L2 where it was when you got the rig, until and if you need to change it during alignment. Set the resonant frequencies of L1 and L2 (including parallel & circuit capacitance) to the internal xtal frequency (9 MHz). All 3 of these adjustments are part of the sideband suppression adjustment procedure. I’ve always been able to get 30dB suppression without moving L2 in its slot, and I was happy with that. (I’ve aligned several of these rigs over the years.)

Probably a more important consideration than the precise positioning of L2 is the bandwidth of the audio being fed into the audio phasing network. Whatever energy exists outside of the network’s ability to maintain a 90 degree shift between the two channels will show up in the opposite (undesired) sideband. There was at least one modification article published to further reduce the high frequency response of the speech amp prior to phase splitting in order to address this.

Also, if you have a local SDR with a spectrum display use this to do your sideband suppression procedure - it’s so much better at telling you directly what is happening regarding sideband suppression than using a scope or any receiver lacking a spectrum display. CE didn’t have these when it developed the procedure in the manual ;-).

73/GL,
-Larry/NE1S
Sent from my Model 33 Teletype

> On May 3, 2026, at 11:20 PM, Jon Kannegaard via Central-Electronics <central-electronics at mailman.qth.net> wrote:
> 
> I hope someone can tell me the preset resonant frequencies for L1 and L2. My manual says  use a grid dip meter to set them to the frequencies in the Alignment Data Chart, Figure B, before doing the alignment. But my Alignment Data Chart doesn’t seem to have those numbers.
> 
> I also would like tips on the positioning of L2. It’s mounted in a slot so it can be moved nearer or farther from L1. The manual doesn’t seem to say how to make this adjustment. If it does, I missed it.
> 
> Thanks,
> 
> Jon
> 
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