Just to add to the historical note aspect, Jerry:
In 1947 I ran NBFM on ten meters using a Sonar XE-10 NBFM adapter. I
worked the world on FM running an 807 at about 50 watts input and a
4-element yagi at about 20 ft. All this also near Dallas at Bonham, Texas
- about 65 miles northeast of Dallas.
72/73, George AMA 98452 R/C since 1964
Amateur Radio W5YR, in the 54th year and it just keeps getting better!
AutoPOWER Systems, Fairview, TX (30 mi NE Dallas) Collin County
QRP-L QRP-ARCI FISTS NORCAL ZOMBIE ARS 10-X 33.2 N 96.6 W EM13RE
"Dr. Gerald N. Johnson, P.E." wrote:
>
> NBFM probably hasn't been used on ham bands in 30 years though the
> whisperers on 2m "wide" fm are that narrow. Truly NARROW band FM has the
> same band width as AM, about 6 KHz, no second order modulation products.
> But copied exalted carrier on an SSB receiver it has a great sound. In
> the mid 60's around Dallas, Texas, several of us used that mode on the
> bottom of 2m. It sounded super, better than SSB, in my 75S3B. I planned
> to, but never did, build a NBFM receive adapter. It can be slope
> detected in an AM receiver (not with crystal or mechanical filters) but
> that's not the best way to do it.
>
> Mathematically, this truly NARROW fm has the same spectrum as AM, just
> the carrier is 90° different in phase. There would be few on 40 with AM
> receivers that would understand that blank carrier, though those using
> SSB receivers would copy just fine. And the neighbor's TV wouldn't
> notice any modulation.
>
> 73, Jerry, K0CQ
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