[GreenKeys] Optimistic but clueless seller

[epvgk at limpoc.com]

On Fri, Apr 23, 2021 at 10:39:47AM -0500, Robert Nickels wrote:
> has listed a Northern 153 dual frequency shift keyer with some entertaining
> comments:
> 
> https://www.ebay.com/itm/265133627883
> 
> The manual can be found on the TMC History site;  custom plug-ins determine
> the tone frequency and the module that can be read is for 2167.5 Mark and
> 2082.5 Space, i.e. 85 kHz spacing.   The front panel tag shows another pair
> to be 2337 and 2252 Hz, also 85 Hz spacing.   So that would translate to
> 153Z12 and 153Z13 modules in this unit.
> 
> Frequency-determining modules were sold by center frequency which is shifted
> +/- 42.5 Hz  and recommended 170 Hz channel spacing at 100 wpm, and the
> output of up to 18 channels can be combined. Eighteen keyers would fill one
> rack, then of course you'd need a couple of racks full of demodulators on
> the other end, which is why Northern came out with the transistorized
> version that put all 18 tone keyers and converters in less than 16" of rack
> space:
> 
> http://tmchistory.org/NorthernRadio/Manuals/northern_230_235_tm.pdf
> 
> It would be interesting to hear what 18 FSK tones would sound like over HF
> but according to the manual, these 18-channel systems were intended for use
> on microwave or wireline circuits.
> 
> 73, Bob W9RAN


Making a software defined radio program to talk to that would probably be a
pretty easy project actually! Then you'd only need one behemoth instead of two :) 



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