[GreenKeys] Optimistic but clueless seller

[Alf Fisher]

Hey Bob,
The instruction manual for this unit is at 
http://tmchistory.org/NorthernRadio/Manuals/northern_153_instr.pdf

Your link below appeared to refer to a transistorised unit - you know 
those transistors are the fastest fuse on 3 legs.

73, Alf G3WSD


On 23/04/2021 16:39, 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
>
>
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