Hello Mike and group,
Mike wrote
Firstly, the frequency stability - presumably of my IC-706 Mk1 - was
not good enough for the 30s dot setting. After a long warm-up
period, it settled down to a ragged line that wandered all over the
screen. My son opened a window in the next room to the shack and
the Loran lines moved off the screen completely! Does anyone else
have experience of this? I believe a high stability oscillator is
available for the 706.
I am also using the old IC706 (at DF0WD) and also got some problems with its
stability (a matter of some Hertz at 10.137 MHz). The thing gets much worse
if you use it for transmitting.
I did some test with very slow PSK (and other modes) some weeks ago,
and noticed some dramatic "curves" in the loran lines after switching from TX
to RX (I use the 706 to drive a transverter).
There is indeed a temperature compensated oscillator availabe, it is a small
SMD part called "CR-502". It is specified for stability of +- 0.5ppm in the
temperature range from -30°C to +60°C (so it should be ok). The frequency of
this oscillator is exactly 30 MHz, so it can be "tied" to any 10MHz reference
because it has a frequency control input (I already drilled a hole for a BNC
connector into the housing for that purpose).
Ironically, I am waiting for two weeks for that part now. I will keep you
informed if I know more about its performance if you like.
73's Wolf.
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