Re: ISB Receivers
I used 'General coverage' as the opposite of 'amateur bands only'
I didn't just have a prototype H2900, I had the full manuals as well, so I know it fairly well. Being professionally involved in high performance measuring receivers in the same frequency region at around that time, I found the measures to combat phase noise interesting. Sosin also knew about intermod effects in quartz filters. Racal were a jump ahead on mixers, Sosin was a jump ahead in a few other areas.
The H2900 slewed the main synthesiser to lock the IF onto a residual carrier using a phase detector at 2MHz IF.
The marine market had already got far cheaper radios which met their certification requirements. I think this thing was targeted at point-to-point use, military and spooks. Ships wouldn't have the budget.
Oh, the RA1772 has a crystal filter in the LO feed to allow sensitivity at VLF without the phase noise sidebands of the synth leaking into the IF.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
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