Hi Scott, LF,
Am 23.09.2011 04:10, schrieb Scott Tilley:
Hi Stefan
In the past three years since I began prolonged 'low noise' listening
November has traditionally been the beginning of good opportunities
for EU/VE7 DX. However, DCF39 has surprised me this year with decent
showings already! A couple of nights ago it reached audible levels!
OK so we will go on trying. But let me stay at QRSS-60 first, until the
signal was seen at any active RX station in US/CA (east and middle). IF
DCF39 is audible i think it must have about almost 40 dB S/N in a 22 mHz
window? And DCF 39 is about 50 dB above a 1 W ERP signal, so not many
dBs are missed!?! That sounds as if a "6000-test" must be successful
these days, as long as QSB and phase changes are reasonably low!?
BTW today i collected a 1.2 m long and 0.3m diameter glass tube (got it
for free, it was a rest of a 1.5m 400 EUR tube! ;-) ). This will be for
my new loading coil! :-)
I'd tweek out that system of yours and be ready to lobe some RF over
this way as I have a feeling that we may get some good opportunities
this season... Timing is key...! You need to be ahead of the curve
here.
And timing is focused on my local sunrise, thus not to complicated.
My personal goal is to see if it is possible to detect an amateur EU
station in VE7. I have no concerns about the usability of the signal
until we demonstrate that its even possible.
Yes, a doubtless detection is always the first goal, just like on VLF.
Does not need to be a full call to be received, as VE2IQ luckily got.
As a suggestion on how to get QRO with 100% keydown, consider using
many smaller stages combined to produce lots of power rather than one
stage pushed to the edge of meltdown.
Actually i tried the PA at 1.4 kW key down (longer than all thermal time
constants) on a 50 Ohm dummy load and it was not much more than hand
warm after the test. The limiting factor is my variometer and the
loading coil. I can see the antenna current decreasing a bit during a
QRSS-120 dash ;-) I'll wind a new one out of HF litz wire soon.
Since then I've logged hundreds of hours on the same transistors.
Oh, on that H bridge PA is already lost about 10 FETs (in contrast to
the 120W class E PA) but this is not due to thermal reasons...
Just make sure you use one LO path and only ONE digital division
device to drive the driver ICs. The reason for only one digital
division device is based on the fact a Type D flip flop (or otherwise)
can start in any one of four phases on power up.
Understood, yes. Since a few weeks i use a IQ TX-converter that adds
SL's 11.172 kHz signal from the soundcard to a 125 kHz LO. That a
circuit based on the design of G4JNT. It works excellent and due to
locking the LO and soundcard, the signal accuracy seems to be below 1
mHz, apart from some seldom phase glitches (about 1 to 3 per hour).
Looking forward to the season. We're in the beginning of that! :-) The
detections at W1VD last night were very promising!
Best 73, Stefan/DK7FC
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