[Elecraft] A comment about Receiving

[Ron D'Eau Claire]

The preselectors I recall (e.g. the "R-9 er") had two major functions:

1 - Provide more attenuation of the image frequency only 910 kHz away from
the signal frequency in 455 kHz I.F. systems.

2 - Provide low noise gain to overcome mixer gain in the receiver.

These were critical functions in even the best of receivers in the 14-30 MHz
range (including my WWII vintage National HRO-5).

But, on the lower frequencies, it was completely unnecessary. 

I wonder if what people are seeing nowadays has to do with the typical
multi-section, fixed-tuned filters in modern rigs that is designed for a 50
ohm antenna system? 

Is it possible that under certain conditions of input impedance they show
excessive loss? 

Ron AC7AC



-----Original Message-----
On 3/29/2011 4:53 PM, Don Wilhelm wrote
>
> There was a time when pre-selectors were available for
> receivers, but that was way back when dirt was young.