"Joe" ) writes:
Hi Ed..
I downloaded the manual from BAMA.
Interesting.
It says you can use an AM receiver to adjust the deviation control to make
the signal no wider than an AM signal until the audio is perfect. (quote
form manual)
Can be used on AM?
Hooked up to a Central Electronics low drive amplifer might make a
respectable transmitter.
MmMmMmMmmmm...; )
Josh

It can be used on AM if you've got an external modulator.

It dates from a brief period when quite narrow FM was touted as a new
and advantageous mode for HF. No big modulator needed, and if it's narrow
deviation, doesn't fill up the band. Use "slope detection" to receive
it on an AM receiver; you mistuned the receiver a tad so the signal is
on the slope of the receiver's IF selectivity. Thus as the signal is
modulated, the frequency variation causes the signal in the receiver to
vary in amplitude as it moves along the IF slope. This can then be
demodulated in the AM detector.

Whether or not narrow deviation FM was a good replacement for regular
AM, SSB came along at about the same time and won out.

Michael VE2BVW

"Edward Knobloch" wrote in message
news:gXmcd.662$UX3.379@trndny03...
Joe wrote:
Hi..
I cam across a Sonar VFX-680 exciter.
It appears to have a VFO in the 75 meter band.
A 6L6..maybe 5 watts out?
It's not in bad condition.
Will need a recap etc.
I am looking for info on it and specs.

Hi, Joe

There's an ad for the Sonar VFX 680 in Apr 1947 QST, page 88.
It looks like an interesting find.
Here's the ad copy:

Everything in one complete unit, containing
Narrow Band FM on all bands* - an exclusive Sonar circuit.
CW on all bands - free from all chirps and key clicks.
Two band operation with one set of plug-in coils for top efficiency.
"VFX" rubberizes any cut xtal.
VFO or xtal - just plug in the xtal and you are set - no switching.
CW monitor ideally suited for the bug operator.
Phone monitor - no auxillary equipment required.
RF output power 4 to 6 watts on all bands except 6 meters.

* NBFM at present permitted on 11 meters and above 29 Megs.

73,
Ed Knobloch