R-390 and Long Wave

[bill]

Although the spec says the R-390's range ends at .5mhz the
dial and tuning mechanism continue on down. Has anyone ever
looked at what it would take to make the R-390 receive Long
Wave?

bill

[Scott Dorsey]

Post by bill
Although the spec says the R-390's range ends at .5mhz the
dial and tuning mechanism continue on down. Has anyone ever
looked at what it would take to make the R-390 receive Long
Wave?

Not with the IF frequencies where they are. You could add a
converter to the thing, but then you'd have much poorer S/N
because of the broadband converter. Make it narrower and tie
it to the tuning, maybe, but at that point you might as well
just get another receiver.
--scott

[bill]

Post by Scott Dorsey

Post by bill
Although the spec says the R-390's range ends at .5mhz the
dial and tuning mechanism continue on down. Has anyone ever
looked at what it would take to make the R-390 receive Long
Wave?

Not with the IF frequencies where they are. You could add a
converter to the thing, but then you'd have much poorer S/N
because of the broadband converter. Make it narrower and tie
it to the tuning, maybe, but at that point you might as well
just get another receiver.
--scott

Not sure I understand. Are you saying that it won't work if
you go below 455 or because of proximity? If proximity, I
would think it would work for frequencies below 400 as it does
for above 500.

It was really just a thought. I would love to be able to
listen to the two ham radio LW bands (I still haven't found
much offered as xmtrs) and who knows what else might still be
going on down there. I miss WGU20. :-)

bill

[Scott Dorsey]

Post by bill
Not sure I understand. Are you saying that it won't work if
you go below 455 or because of proximity? If proximity, I
would think it would work for frequencies below 400 as it does
for above 500.

You'd need an additional antenna transformer for the new band, along with
an additional tuning circuit on the front end... and you'd need another
position on the megacycle control in order to select them. Then the tuned
circuit on the 2213 stage would also need an additional set of constants
since the first variable IF would be 17-25kc instead of 17.5-25kc. This
would put it too close to the 17kc first crystal oscillator to separate that
out. But even so the upconverting would be better than downconverting
for the first IF.

Post by bill
It was really just a thought. I would love to be able to
listen to the two ham radio LW bands (I still haven't found
much offered as xmtrs) and who knows what else might still be
going on down there. I miss WGU20. :-)

A transmitter on 2200m could be a pair of 2N3055s self-excited with an
iron coil and a capacitor to set frequency. Or you could use a crystal
with a divider, then just fire off the 2N3055s from the divided-down signal.
I think on 2200m you are limited by EIRP, and since antenna efficiency
for reasonable sized is so terrible down there you probably need to pump a
lot of RF power into your antenna. So it's good that cheap audio power
transistors are readily available today.
--scott