About 2 weeks ago I mentioned an intense and troublesome carrier on
about 36 kHz which produced a very strong second harmonic on the ham band
at 72 kHz. From the strength of the second harmonic I deduced that it was
local but I could not locate it.
Since then I have done further tests and found that it is
associated with the Datong converter. The receiver used with the converter
was an ICOM 735. I then tried it with an ICOM 740 but there was no change.
I then tried another Datong converter and the signal dissappeared from 72
kHz but appeared, as large as life, on 65kHz with a fundamental on 32.5
kHz. The only way that I can subdue it is to reduce the d.c. supply to the
converter to 3 volts but it is still faintly present.
The Datong converter is a bit of a "black box" with an integrated
circuit at its heart. I have no deails of this integrated circuit and I am
very puzzled by the phenomenon.
The 4th harmonic is also quite detectable and with some converters
it may well appear arround 136 kHz so it may be useful to us all to find
the solution.
Can anyone help?
73.
Roger. G2AJV.
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