Re: LF: Receiver protection

[DK7FC <selberdenken@posteo.de>]

Hi Paul,

It strongly depends on how your front end is designed.

Am 10.07.2018 14:04, schrieb N1BUG:
> Now I have a pair of back to back 1N4148 diodes across the receiver
> front end but I don't think this offers real protection because they
> allow too high voltage before conducting.
I don't think so. They work until several 100 MHz so they are extremely 
fast. Further you can switch a small R (depending on the design) in 
front of the diodes. This also builds a RC lowpass which can help to 
rise the performance.
I'm also using 1N4148 diodes but not back to back, rather one against 
ground, the other against +, while the center is at V/2.
>   Also there is a preamp
> after the didoes which can bring the RF to dangerous levels!
>    
How? The output voltage of the preamp can't be higher than the supply 
voltage.
73, Stefan