[hpsdr] Preselector schematic.

[Henry Vredegoor]

> -----Original Message-----
> From: hpsdr-bounces at hpsdr.org 
> [mailto:hpsdr-bounces at hpsdr.org] On Behalf Of Henry Vredegoor
> Sent: vrijdag 16 maart 2007 5:48
> To: hpsdr at hpsdr.org
> Subject: Re: [hpsdr] Preselector schematic.
> 

> 
> Two observations:
> 
> - There must have been a design issue for using relays on the 
> LOWER BANDS;
> maybe also the lower (zero) resistance of the relay contacts

> - The are having the relays switching a (small) current on 
> purpose, I think
> to keep the contacts clean, keep the resistance low


After studying the schematics a little more, I think it prevents the (other)
PIN diodes from conducting, stopping the HF from all not selected filters.


 1174022502.0