Nothing40 ) writes:
Hey Gang..

I have recently become interested in the 1750 meter band (160-180
khz).I have been searching the net for
information,circuits,reports,anything I can find!
I plan on homebrewing a TX/RX pair,once I do a little more research. I
have found a few Schematics,and plans for a couple different
transmitters,and antenna's,but no plans for recievers. Can anyone help
me out? I'd prefer to go the homebrew route,mostly for experience,and
for a learning experience.I don't have much experience with RF
electronics,and have been working my way into this "grey area/black
magic" ;-) I have built a few FM transmitters,amplifiers,etc..
(I'm really proud o the FM amp I built,1 watt from a 6AK5,First RF
project I have built from scratch that worked!)

Any schematics,links,suggestions on circuits,antennas,etc,etc would be
great!

Thanks a bunch! Patrick.

I think you will rarely see a receiver for this band.

There is no, or virtually no, commercially made transmitters for
this frequency and power, so you don't have much choice but to
build. Plus, a transmitter is nice and simple, so you might
as well build it.

But due to the very low allowed power, and the low frequency of
the band (and associated inefficiencies of the antenna), you really
need to go with a good receiver. So I'm sure many would use an
existing receiver that happens to cover the frequency, with it's
good selectivity and features.

If their receiver doesn't cover the band, then they'd add a converter.
I have no idea what's on the web, but there have been a number of converters
for this band described in the magazines over the years.

People building receivers are likely building something really high
performance, maybe moving away from the common receiver schemes in order
to get the most performance for the limited conditions. I'm sure such a
receiver was described in the late Communications Quarterly in an early
issue. Unless you are willing to put in a lot of effort, duplicating
such receivers are not the route.

That said, many converter schematics can be used, so long as
you change the crystal frequency and the front end tuned circuits.
Decades ago, a common LF converter was a single transistor in
a pierce oscillator/mixer combination, and no tuned circuit (or a simple
low pass circuit) at the antenna. Likely not great performance, but
a way to get started and little to go wrong.

And just about any simple receiver design could be used to get
a simple 1750 meter receiver. Pick one with decent selectivy, and
then again modify the local oscillator and front end tuned circuits.

Michael VE2BVW