The Elmac AF-67 has NBFM. Central Electronics uses NBPM, which has a
similar effect. The HT-19 is a 100 watt Hallicrafters rig that uses only
NBFM for modulation. One of the reasons for using it was to avoid TVI,
which came on suddenly with the advent of tv.

I connected my AF-67 up one night and tried to check in to a local SSB
roundtable using NBFM. No one could understand me. AM receivers will slope
detect, but product detectors are not tolerant of fm.

I purchased a Sonar VFX-680 at a local radio store in the late 50's for
$9.00. It was unique but more a novelty than anything else. It was sure no
Collins in terms of stability or dial readout.

Colin K7FM


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.775 / Virus Database: 522 - Release Date: 10/8/04