In message <1648F8F2E5061647.email@example.com>, Brian Howie GM4DIJ <firstname.lastname@example.org> writes
In message <email@example.com>, G8VLL <firstname.lastname@example.org> writes
Try ARRL handbook, or ARRL FM and repeaters for basic design,
you will have to change the coupling.
Also G3YGF designed one using 2 pieces of semi rigid soldered together,
which was published in the RSGB Microwave Newsletter Technical
Collection, which is less effort and smaller and works very well, all
the coupling data etc is in the article.
You prompted me to look in the ARRL Antenna Handbook and there is a version there. My plan was possibly to make a another slug for 9cm. I couldn't remember what was inside the slug and I didn't want to dismantle it.
More digging about produced this.
Mine is a single coupler which I can rotate for Forward/Reverse.