[GreenKeys] 66 WWPM ITTY

[WA5CAB at cs.com]

Early FSK exciters (military, commercial and ham) generated the shift by 
switching in and out a small padder capacitor (generally a variable).  For 
whatever reason (maybe the relay driver tube tube was an inverter) the padder 
was switched in for SPACE.  So MARK was high.  Which on HF is I think still 
the standard.  The mnemonic reminds that SPACE is low.  Hence MARK is high.  
This practice was carried over to later military and commercial rigs that 
generated FSK by feeding AFSK into the USB channel.  With the same output 
sense.  Why hams mostly use LSB and turned everything over is another subject 
that I could explain from a historical context but probably not without 
derogatory comments slipping in.

In a message dated 2/7/2011 5:33:33 PM Central Standard Time, 
boatanchor at martasystems.com writes: 
> In the late 1960's, my RTTY Elmer told me to remember the cigarette ad 
> for
> Lucky Strike "LSMFT". But in this case, it was "Lower Space Means Fine
> Teletype". I was young then and didn't understand why, and now that I'm
> old(er) I forget why...
> 
> Anyone ?
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480