[Elecraft] Elecraft technology

[Ron D'Eau Claire]

I don't know exactly what triggered it - a commercial demand, a =
breakthrough
in manufacturing technology, or just what - but the sudden rise of =
single
conversion receivers (and transceivers) followed the availability of a
commercially-manufactured 9 MHz crystal filter in bandwidths of from a =
few
hundred Hz to 2.4 kHz in the early 1960's.=20

As far as I know, this was the FIRST commercial high-frequency filter at =
a
decent price (which was still STEEP - something over $50 or, in today's
money, something over $100 or $150 just for the bare filter - and you =
needed
a separate filter for EACH bandwidth you wanted).=20

Still, the advantage of a high I.F. using a good quality filter for
single-conversion designs made this a very popular device in both home =
brew
and commercial Ham receivers and transceivers.=20

Up until then, some decent filters had been homebrewed in the 2 to 4 MHz
range, but most I.F. filters were in the 455 kHz range. The very popular
Collins "mechanical" filters, which had the best skirts and stop-band
characteristics of the day, worked at 455 kHz as well. That low of an =
I.F.
demanded multiple-conversion schemes for decent image rejection above =
3.5 or
7 MHz.=20

Of course, all of this was back in the 1960's - long, long before the =
WARC
bands. But as Bill points out, it did come about at a time when having 6 =
kHz
I.F. bandwidths for conventional "AM" reception in Ham receivers was
becoming rather unimportant to most operators. Those who were still
listening to "AM" found that doing so as an SSB signal on a narrower =
filter
was usually preferable. Doing so avoided heterodyne problems and =
selective
QSB distortion problems.=20

Ron AC7AC

-----Original Message-----
...It occurs to me that part of this technology change may have been due =
to=20
the rise of SSB over earlier AM technologies...
Bill Coleman, AA4LR