UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Origin of terms "Roofing filter" and "Reciprocal mixing"

John KC0G · 19th Mar 2017, 11:06 am

You are reading it correctly.
The first local oscillator runs from 81.8 to 109.8Mhz in 2MHz steps.
The first IF is at 79.8 to 81.8MHz with a bandpass filter
The second LO runs from 49.8 to 51.8MHz in 1Hz steps
The second IF is at 30MHz with a crystal roofing filter
The third LO is at 32MHz
The third IF is at 2MHz, with LSB, USB and carrier filters for independent sideband reception.

I now see that Sosin also used the term "roofing filter" in his 1971 paper

19th Mar 2017, 11:06 am	#3
John KC0G Hexode Join Date: Mar 2009 Location: Minneapolis, Minnesota, USA. Posts: 279	Re: Origin of terms "Roofing filter" and "Reciprocal mixing" You are reading it correctly. The first local oscillator runs from 81.8 to 109.8Mhz in 2MHz steps. The first IF is at 79.8 to 81.8MHz with a bandpass filter The second LO runs from 49.8 to 51.8MHz in 1Hz steps The second IF is at 30MHz with a crystal roofing filter The third LO is at 32MHz The third IF is at 2MHz, with LSB, USB and carrier filters for independent sideband reception. I now see that Sosin also used the term "roofing filter" in his 1971 paper