QRP'er wrote:
I'm building the ADC-40 made by KD1JV.
I would like to know what kind of 10.7 FI is used as filter because
there are several type of FI with different characteristics spotted
by different color.

He says he used a Mouser 42IF123 "green" IF transformer but he notes
that 42IF122 "brown" works too. It's there primarily to be a easy 7
MHz resonant circuit although the impedance transformation is a useful
side effect here.

Thanks a lot Tim.
But it is amazing because the two FI have very different impedances :
42IF122 = 15K/0.3K
42IF123 = 25K/4K
Which are rather distant from one another...

OK I will try

I think the objective of the 10.7 MHz IF transformers here is their ability
to be retuned to resonate in the 40M band (7000-7300 KHz). The actual
impedances aren't critical as long as 40M resonance can be achieved.

--
David
masondg44 at comcast dot net