coil winding

[p.larner]

I am just building this for my atu,(see pdf),does the coil winding direction mattwer as long as they are both the same,ie both wound cw?

[p.larner]

can no one answer this before i wind the next coil/torroid an fit it?.thanks in advance+73

[vk4ffab]

I am just building this for my atu,(see pdf),does the coil winding direction mattwer as long as they are both the same,ie both wound cw?

I do not think it matters, direction and the like only matters when phase is critical to the outcome, when I look at that circuit, its just tapping off some voltage and rectifying it.

[p.larner]

I want to use this with a twin cross needle meter,i just wondered if it would make one meter read wrong?.

[jwet]

It does matter really.  The circuit is adding two vector quantities and cancelling other effects to give FWD and REV power and ultimately SWR.  Reversed windings will throw the arithmetic off and give you garbage.  In many schematics, you'll see "dots" on the windings in the schematics to show phasing.  The direction of the turns doesn't strictly matter but the "phasing" does.  I would test the unit after completion and see that higher forward power give higher readings etc.  It's might be possible to reverse the secondary polarity or just rewind it and make a note.  Even with the dots, its all pretty confusing and 50/50 whether you get it right.  You can look at ARRL examples that might have the dots shown.

Good Luck.

[RFDx]

I want to use this with a twin cross needle meter,i just wondered if it would make one meter read wrong?.

If the polarity of one of the secondary windings (the coils with many turns) is reversed, FWD and REV will interchange but the displayed power(s) will remain the same for a given SWR. Try it out.

[A.Z.]

check the infos here

https://vk8rhradioprojects.com/power-swr-meter/

about the coupler, also look at the coupler schematic, also see

https://electronics-diy.com/electronic_schematic.php?id=952

notice that the AD8307 modules (willing to use them) are easily available at aliXpress and other sites

[berke]

For reference, found this nice detailed analysis of the Stockton aka Tandem coupler: https://k6jca.blogspot.com/2015/01/building-hf-directional-coupler.html

[p.larner]

as the coils on both torroids are in series i wasnt sure if that woulds alter the phaseing so one cancelled the other so no output?.

[p.larner]

well i built this using some torroid cores i had in my junkbox!,to test i setup my radio and atu and tuned for a 1-1 swr on 80m,i then connected this between my swr meter and atu,doing that made my swr meter read 3-1+ swr from 1-1,any ideas if this is down to the torroid mix?.

[A.Z.]

any toRoid is made of a given "mix" and any "mix" has different characteristics, amongst which there's a value called "permeability"

https://toroids.info/

and that, along with others vary depending from the material used to make the toRoid, so... first find the material you are using, then we may talk about your issue