Re: HF Preselector revised

Nicolas Kulaga

Hi Chris.

I just ordered a preselector some days ago. 

Will I get the revised version ?

Le dim. 29 sept. 2019 à 21:40, Chris Moulding <chrism@...> a écrit :
We have recently been building a small batch of HF Preselectors and found that the variable capacitor we use in them is no longer available. I couldn't source an alternative.

As a result it has now been redesigned to use varactor diodes for tuning. It now uses an array of four diodes that cancel out any IP3 and IP2 effects from high RF voltages on the DC tuning voltage applied to the varactors.

It now has a 2.1mm DC socket on the rear so that 12 -15 V DC can be applied. It takes 1.2 mA.

One interesting possibility is that if the tuning control (variable resistor) is set fully clockwise the DC input could be a variable voltage between 15V and zero allowing the Preselector tuning to be remotely controlled.

The text on the web page has been updated, I'll add a revised photograph of the rear of the Preselector soon.

The web page is:



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