[R-390] Comparing R390A w/Period Devices

[Don Reaves]

I've played with WSPR extensively on 500KC, running a WSPR beacon for years
under the ARRL 600 meter experimental license.  Its best to lock WSPR
monitoring receivers to a very accurate stable reference oscillator - like
a GPS conditioned oven.  My transmitter was synced to the external output
of an HP-3586B SLM oven that was quite stable after 2 weeks of 24x7
operation.  Same with the WSPR decoding computer - it needs to be synced
with an NTP time source.  Bob is right - bandwidths for WSPR are quite
narrow, so any frequency drift or time drift gets out of the passband in a
hurry.

The beacon was taken off the air under my experimental license after I got
UTC approval for normal 630 meter operation under my primary ham license.
It's still off the air while I update some of the station components, and
the recent cold weather has kept me out of the basement working on that.
Currently I'm playing with a SDRPlay RSP2 SDR receiver and it may become my
primary 630 meter receiver.  Sadly the R-389 will have to serve as a backup
only for LF/MF duty.

I've used SDR receivers as panadaptors for the IF output of various analog
receivers - R-390, R-390A, ARR-15, among others.  Just set the input of the
SDR to 455 or whatever is the output of the target receiver and away you go.

The ARR-15, an early cousin of the R-390 series, in its original non-hacked
form is especially nice with an SDR panadaptor as the receiver bandpass by
design is quite wide, which enables the SDR to chew on more signals.   A
secondary benefit is you can use the SDR as a SSB detector with excellent
audio out.

Don W5OR