[Milsurplus] FM, Mil vs. Commercial

[gl4d21a at juno.com]

I'll try to make this as simple as possible.  Mil gear of the vintage being considered was true Armstrong FM.  No limiters, no post-limiter filters, etc.  This means that there will always be signal content outside whatever deviation setting you choose.  About 1948, commercial receiver designs began to be sensitive to "squelch clipping" (Motorola's patented noise balanced squelch)which is what happens when signal peaks get outside the communications passband and into the squelch noise passband.  So, plan to be disappointed in trying to talk to commercial receivers, unless you want to go to all the trouble of installing deviation limiting and post-limiter filters.  If you turn the deviation down far enough to not clip, it is almost inaudible, if you turn it up, it clips.  Especially with really late receiving equipment including ham gear, as the channelization gets narrower and narrower, and rejection of adjacent channel signal content gets more critical.  Stick with Mil to Mil and you'll be OK.

HTH,
George
W5VPQ

____________________________________________________________
57-Year-Old Mom Looks 25
United Online Special: Mom Reveals $5 Wrinkle Trick Angering Doctors!
http://thirdpartyoffers.juno.com/TGL3131/4ea57d88421e3119a61cst02duc