In the past when I have copied the SAQ transmissions it was with
extra capacitance across the tuned input of my LF converter (circuit
on my website somewhere!). I had long since tidied up the converter
and the right capacitors were nowhere in sight. Just before the 0830
transmission I decided to have a listen anyway and had a frantic
seach in the capacitor draw for a suitable sized one. These days
there is no strong signal on 16kHz, but by trial and guesswork I
found with 8.2nF across the air ganged tuning capacitor I could just
hear SAQ - so I copied what was left of the message with my holding
the cap across the terminals with my fingers!
I was out for the rest of the morning, but came up after lunch around
1215z. Out with the soldering iron and the 8.2nF cap soldered
temporarily in place. SAQ was already testing! Further playing around
showed I needed more capacitance, so an extra 1000pF was dabbed
across, now SAQ was a good 589 signal but competing somewhat with the
TV SMPSU racket. Amazing how sharp the resonances are down here -
1000pF was sufficient to move the resonance down from the 18kHz data
transmission to 17kHz.
Most of the 1430 transmission copied, but there was noticeable QSB
and some of the letters seemed foreshortened, making it a little hard
to copy the actual text under the TV racket. I understand now there
were keying problems which explained that.
Hardly in the same category as Jim's mechanical receiver (did you dig
it out again?), but certainly somewhat Heath Robinson here!
Caps now unsoldered (but left in the box for next time). TV racket on
73kHz found 20 over 9, so no chance there. Certainly an early morning
band before the neighbours get up!
73 Dave G3YMC
[email protected]
http://www.dsergeant.btinternet.co.uk
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