I've been very busy and have not been following
the AM transmission topic as close as I probably
should be. But I thought to mention...
The very popular and common MC1496 or "1496"
chip provides a practical method to generate ssb
and am signals. It might even be the most common
used chip for this function as found in most SSB
type CB's and a lot of amateur radios. There's
probably a similar AN type chip doing said, I have
seen one used in various rigs. Anyone tell me who
has the data book for AN series labeled chips?
AM generation is done low level, then amplified
in successive linear rf stages.
I haven't seen a newer LPB transmitter, but the
equivalent AM unit by Radio Systems uses said
chip and a rather novel limiter circuit. If enough
interest happens, I'll put the circuit diagram up
on the http://sonic.ucdavis.edu server amateur
The earlier tube version LPB AM transmitter
manual along with circuit diagram and related
information is already on the server and available
for free down load. I have at least one of each
type in my collection, along with the carrier current
interface. They work very well up on 160 meters.
I often see these transmitter for sale on Ebay,
prices go from $50 up to $350. Regular
broadcast transmitters can also be found for
sale. So are much am transmitter parts which
include modulation transformers.
From: John Lyles <email@example.com>
Using a 4 quadrant balanced modulator to create the AM signal does
appeal in a simple way. It only requires a linear amplifier to follow
it. In some of the small 20 watt carrier current AM transmitters that
LPB (Low Power Broadcast Co) made, they used this approach. And, as
Rich says, it is used in some of the rice boxes for both AM and SSB
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