I have been building a converter using a Double Balanced Mixer and a 4
Mhz clock osc as a LO. The advantages is its ability to handle HIGH
levels of signals. I need to rebuild my RF amp and have ordered the
parts to repair it. { oops }
The mixer I am using is good from 2 Khz to 10 Mhz and I am using a 4 Mhz
IF. It is by Witkons, Johnson Co. and was free. Mini Ckts. has a similar
device for under 30 Dollars , the clock Osc is 2 dollars. If it works as
well as it appears to would be a minimum parts High performance
converter. Needs up to a +7 DBM for the LO and the Clock Osc is just at
the edge for that level of injection. I have had no spurs with it ,so far
but the RF stage went and I need to do more evaluation .
Oh,there are lots of options for the RF stage.
Bob K3DJC
On Thu, 21 Oct 1999 15:37:03 -0400 "Prof R. Jennison"
<[email protected]> writes:
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
bandat 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
integratedcircuit 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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