[K2] Crystal filter impedance

[Sergey Dan]

Hi
How must be K2's variable-bandwidth crystal filter in/out impedance (W2,W3 points) with
FL1 1.5 CW choosen?

Thanks in advance
Sergey
4Z5TV

[Don Wilhelm-4]

Sergey,

I believe the crystal filter is designed for 150 ohm termination - at
least that is the input termination used with the -5dB post mixer
amplifier pad, and since the IF filter is symmetrical, its input and
output impedances should be the same.

The design point for the variable filter is 400 Hz if I recall
correctly, and the capacitance changes to permit different widths.  I do
not believe the impedance changes a lot over the 1.5kHz to 200 Hz range,
so I would assume it is close to 150 ohms.

73,
Don W3FPR

Sergey Dan wrote:

> Hi
> How must be K2's variable-bandwidth crystal filter in/out impedance (W2,W3
> points) with
> FL1 1.5 CW choosen?
>
> Thanks in advance
> Sergey
> 4Z5TV
>  
>  

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