Nice one Hans and all understood.
Good thinking !
73 de Andy
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--- In QRPLabs@..., Hans Summers <hans.summers@...> wrote:
Hi Andy
On key-up, the keying transistor Q1 is switched off, and the C1 capacitor
is also supposed to mop up any RF leakage too. However some RF *still* can
leak through to the antenna! It's many many dB down but if condx are good,
QRSS'ing can detect that stuff. Keith G6NHU sent me a beautiful screenshot
of slow-hell on the v2.02 and there was a faintly visible carrier between
words and between messages. Admittedly it was a very strong signal and only
just across the North Sea. But by moving the frequency to 6.25MHz during
key-up on Hell spaces or between Hell messages, I could eliminate that
faint key-up carrier. It was just a single function call and would fit into
the last few remaining bytes so I did it!
FYI 6.25MHz is what is used for the calibration of the 125MHz canned
oscillator when a GPS is connected, in the 13 seconds before the start of a
frame. 6.25MHz is 125MHz divided by 20. By measuring it for 10 seconds I am
able to determine the 125MHz frequency +/- 2 Hz, which is good enough.
73 Hans G0UPL
On Sun, Jun 16, 2013 at 11:39 AM, andyfoad@... <
andyfoad@...> wrote:
**
- In Hell modes, the frequency is now dropped to 6.25MHz during key-up >
in a space character or between message transmissions
Not quite sure I understand that one Hans.
Do we Hell users have to apply for an NoV ? ;-)
73 de Andy
