Yesterday, I commented on frequency drift seen when using
extremely narrow bandwidths. I assumed the cause was my IC-706
Mk1. However, on further investigation, I found the problem was my
Datong converter. This was wandering and drifting with temperature.
For normal CW or even QRS this is not a problem as the movement
was only one or two Hz over a period of several minutes. For 30s
dot QRS it is a disaster.
I am now using my IC-706 directly on 136kHz, with a pre-amp/filter
and this works fine. Nothing seen of Larry yet but I have some fine
photographs of noise and very stable QRM lines.
Now for the transmit side. I very recently managed to persuade my
keyer to give me 10s dots, but the stakes have been increased and
there is no way it will go up to 30s. Next job is to build a computer/Tx
interface and do everything with the PC.
Those following the story of my burnt insulators may like to see the
pictures which are now on my web site. Also a demonstration of why
you should join together the far ends of a multi-wire top section.
Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net
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