beat balance pinpointer

[sinclairuser]

hi all, i have built and been playing around with a beat balance circuit(t.scarborough), with a view to building a pointer using this method, the basic detector works well but i'm a bit stumped how to wind the coils.
the basic circuit uses two mono coils overlapping like I B but only in the sense that it makes the detector "beat", the fine tuning that IB coils must have is not required here, only enough overlap to make the circuit heterodyne, how can i make small ferrite pointer coils that overlap?
how are IB pinpointer coils wired?, any help would be welcomed.#
i know IB pointer coils wont work off the bat but they may help me understand how overlap is achieved.
thanks,
aly.

[Skippy]

I would think the crystal earpiece would be one reason this would make an impractical pinpointer?
Though I have no familiarity with the circuit, I assume the modest overlap indicates that weak coupling between the two coils is required. Putting two coils on a ferrite rod will give excellent coupling between them, regardless of where you position them.

Sunray probes are IB, and used a stacked concentric arrangement, three coils all on the one axis.

You would have more luck with Scarborough's EPE mini-pinpointer, a reasonably conventional BFO design.

[Carl-NC]

Sunray probes are IB, and used a stacked concentric arrangement, three coils all on the one axis.

RX- TX RX+

I used the same arrangement on the White's TRX pinpointer.