Tandem Match Coupler for FWD/REV Power

[Steve Haynal]

Hi John and List,

I've been looking at your forward/reverse power board for the Hermes-Lite. The schematic says FT43-37, but I assume that should be FT37-43? What design was your design based on again? What do you think of sharing a single core as seen here?

73,

Steve

KF7O

[Steve Haynal]

I think it comes from the Hermes Alex board.

[Graeme Jury]

I would look seriously at the Bruene coupler as it goes on an FT37-43 core just nicely in the up to 25 watt region. Glenn VK3PE is the one to talk to about this as he has just done one for his QRP autotuner so is the best qualified to speak on the topic. Collins radio used these in lots of stuff and ZL1AN has done an in depth analysis of them.

73, Graeme zl2apv

[John Williams]

yes, FT-37-43. Same ferrite as used in the amp.

The design is from hermes, except the physical design of the inductor pickup is from the K3 auto antenna tuner, IIRC. Jim Veatch suggested it. A picture is on my qrz page.

John

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[in3otd]

Hello,
using a single binocular core for two windings around the "outside" of the core, where 2 cores are normally used, (sometimes/often) works because the two halves are only lightly coupled; for a BN43-202 I have measured a coupling coefficient around 0.17 for windings done as shown in the link.
A quick simulation of a directional coupler like the one there shows practically no difference w.r.t having two separate cores.

73 de Claudio, IN3OTD / DK1CG

[Steve Haynal]

Hi John and Claudio,

Thanks for the pointers John. Thanks for measurements on using two halves of a binocular core Claudio. This is useful to know as it gives more layout options.

73,

Steve

KF7O