[CQ-Contest] Bandpass filters for M/S or M/M environment

[Mike Gilmer]

Certainly this is an issue with solid-state radios 
hooked directly to an antenna ("low-power" operation),

but for guys running high power, does not the out-of-
band TX crap get significantly attenuated through the 
amp?

Mike N2MG

--- k6xx at juno.com wrote:
> Someone commented that one need only use 
> the filters on receive, not transmit. This 
> is NOT true with many (most?)solid-state 
> transceivers. Their output low-pass 
> filtering passes lower frequency broadband 
> hash (phase noise, etc.) right to the 
> antenna. Sure, its low-level, but this low 
> level is still strong QRM to a co-located
> receiver. You must use the filters on the 
> transmitter output to remove the hash 
> generated in the transmitter -- a receive
> -only filter cannot discriminate between 
> in-band hash and in-band signals. This 
> condition affects the situation where a
> higher-band unfiltered transmitter is run 
> with a lower-band filtered
> receiver, but not the opposite.


	
		
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