Hello Laurence,
Glad to hear the design is working fine. Though there are now more than 120
around, as far as I know, it is the first one in Asia!
The only difference to the original design is a slightly longer (cap)
aerial, added another few cms there, and the inter-stage coupling
increased to 680pF from 560pF, only because thats what they have and not
to improve the LF side <<
This value is not very critical, but it should be in the order of > 100 nF
(0.1 �F) to achieve good VLF performance. 680 pF is a little on the low
side, I guess.
Adding a few cm length to the PCB antenna does not make much of a
difference.
Doubling the size gives only 3 dB(m) more signal. It has been designed to
prevent overload of the receiver, but again nothing critical.
I am following your endeavers with great interest.
Best regards,
Roelof Bakker, pa0rdt
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