Re: Build Experimental Loop for LF to HF.


Allan Isaacs
 

Interesting, but do the advantages outweigh the disadvantages?

The fact that you’re tuning a specific signal with a significant degree of selectivity means that you’re unlikely to notice the effects of a strong out of band signal? If you do get problems you can null out the unwanted signal by turning the ferrite rod. The end result will be much the same as using a portable radio with its ferrite rod.

Would switching diodes used in some front ends have much the same problem?

 

I’ll do some experiments when I have time.

I suppose if the aerial coil is tuned to a really strong SSB signal the varicap voltage will swing a little and widen the tuning response curve?

 

Allan G3PIY

 


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jdow
Sent: 06 December 2020 12:49
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Build Experimental Loop for LF to HF.

 

How do you keep the varicap from causing all manner of IMD, some of it pretty exotic? Don't forget that the tuning voltage is "modulated" by the signal voltages in the tuned circuit.

{o.o}

On 20201206 02:19:50, Allan Isaacs wrote:

Hi Paul

Try a varicap and a ferrite rod.

A lot easier to handle and you do not need a ladder to adjust it when on top of a pole.

http://www.radiomuseum.co.uk/active.html

Allan G3PIY

 

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