Thread: RFI: Another thought
View Single Post
  #2   Report Post  
Old December 1st 07, 04:08 AM posted to rec.radio.shortwave
Telamon Telamon is offline
external usenet poster
  
First recorded activity by RadioBanter: Jul 2006
Posts: 4,494
Default RFI: Another thought
In article
,
wrote:

Many 10 to 20 year old solid state SWL receivers use discreet logic
ICs and suffer from insufficient bypassing.

I found that bypassing all of the ICs in the R2000 lowered the
internal noise floor by slightly over 4dB. I measured this degree of
improvement on 4 R2000s.

I used 0.001 across the DIPs and 0.001 with a 1uF tantalum across the
LSI chips. I also added 1uFs willy nilly on the +5V rail.


That is an indication of insufficient ground and power planes in the PCB
otherwise your capacitor additions would not have made a difference.

The radio must have lousy PCB design.

--
Telamon
Ventura, California
Reply With QuoteReply With Quote