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Hello all,
yeah, well, once being amateur, means mostly always
an ham, hihi.
and that means...............exact........I just
can't give up.............
so, had an closer look at the 'remains'
sofar..........
I haven't checked the waveform as Angelo suggested,
but it might well be a
possible trouble source involved.
Maybe with help of the 136-community around here I
might be able to solve
the problems and become QRV with a decent
signal.
Well, here is what I've done sofar:
I am using an 4049 as an oscillator, with some of
it's ports used as buffer.
I'm using a little lowpass filter behind the VFO,
and the ouput is somewhere
around -5 to 0 dBm.
I rebuild (yes, I did.........) the divided
circuit, first another lowpass filter so, now
having a fairly 'clear' 2192kHz available. (second
harmonic more then 60dB down)
This around -5dBm signal goes into pin 11 of an
74HCT4060.
(I put an 10M resistor between pin 10 and
11)
Pin 12 and 8 are grounded; Vcc on pin
16.
It draws 30mA (!) at 12V so, I now put a 150 Ohm
resistor between pin16 and the 12V supply,
in order to limit the current.
Of course I put the usual capacitor to ground at
pin 16. (330nF)
I get +17dBm out on 137kHz now.
There are a lot of harmonics in the (unfiltered)
output; especially the 3f, 5f, 7f etc.
So, at least I am producing a signal on 137kHz (and
maaaaaaaaaaaany other freqs) now.
At this point I am not sure what to
do.....filtering or not??
I suppose I get these harmonics again in later
(driver) stages so, maybe better to
do it at the end..........
How to key is the next question.
I want to leave the VFO on all the time for better
stability.
The 4060 will be switched off in RX situation, to
aviod having a signal on 137kHz,
and in my receiver blocking the
RX..........
I did some tests with the keying circuit used by
OM2TW and DF3LP/DJ1ZB in their designs
using 2 stages with BC549, from which the first one
is switched in its emitter.
However, this did not work fine.
I was able to key, but the output level was much
lower then it's input, and the level of
harmonics etc where worse, compaired to the input
signal of the circuit.
I do have some TDA2030's and my plan is to use the
OM2TW design in order to get
5Watt or so, driving the
rest...........
I do have some core's that might be usuable.I
ordered defect computer SMPS powersupply's
in order to get some
junk-components.............
One of the core's is likely an T106-26, and I do
have a pair of T50-18's as well.
Wonder if the last ones can be used for the step-up
transformer in OM2TW's design......
Well, now having some sleep....looking foreward to
see some comments tips...
By the way, I still have 2 stacked beverages of
400m length, pointing towards USA up........
Maybe find some time next weekend to listen on
137kHz with it.....
73 Dick, pa4vhf (desperate trying to get on 137kHz,
hihi)
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