coil winding - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: January 21, 2024, 08:18:11 pm
content: 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?

author: p.larner
author_rank: Frequent Contributor
timestamp: January 22, 2024, 09:16:27 pm
content: can no one answer this before i wind the next coil/torroid an fit it?.thanks in advance+73

author: vk4ffab
author_rank: Frequent Contributor
timestamp: January 22, 2024, 09:19:01 pm
content: Quote from: p.larner on January 21, 2024, 08:18:11 pmI 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.

author: p.larner
author_rank: Frequent Contributor
timestamp: January 22, 2024, 10:19:31 pm
content: I want to use this with a twin cross needle meter,i just wondered if it would make one meter read wrong?.

author: jwet
author_rank: Frequent Contributor
timestamp: January 23, 2024, 03:21:23 am
content: 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.

author: RFDx
author_rank: Regular Contributor
timestamp: January 23, 2024, 04:31:19 am
content: Quote from: p.larner on January 22, 2024, 10:19:31 pmIf 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.

author: A.Z.
author_rank: Super Contributor
timestamp: January 23, 2024, 06:53:41 am
content: check the infos herehttps://vk8rhradioprojects.com/power-swr-meter/about the coupler, also look at the coupler schematic, also seehttps://electronics-diy.com/electronic_schematic.php?id=952notice that the AD8307 modules (willing to use them) are easily available at aliXpress and other sites

author: berke
author_rank: Frequent Contributor
timestamp: January 23, 2024, 08:28:07 am
content: For reference, found this nice detailed analysis of the Stockton aka Tandem coupler:https://k6jca.blogspot.com/2015/01/building-hf-directional-coupler.html

author: p.larner
author_rank: Frequent Contributor
timestamp: January 23, 2024, 11:08:39 am
content: 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?.

author: p.larner
author_rank: Frequent Contributor
timestamp: January 26, 2024, 07:32:19 pm
content: 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?.

author: A.Z.
author_rank: Super Contributor
timestamp: January 26, 2024, 08:45:34 pm
content: 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