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ZS1AGX > WEFAX 13.03.06 11:15l 37 Lines 1412 Bytes #999 (0) @ WW
BID : 5E0121ZS1AGX
Read: GUEST DC3MR DG9NBR DG0TM
Subj: 7+ AMFM.ZIP SCHEMATIC INFO
Path: DB0FHN<DB0FOR<DB0MRW<DK0WUE<7M3TJZ<HS1LMV<TU5EX<ZS0MEE<ZS0BEL<ZS0STB
Sent: 060223/0942Z @:ZS0STB.TBG.WCP.ZAF.AF #:37927 [Satgat] FBB7.00g25
From: ZS1AGX@ZS0STB.TBG.WCP.ZAF.AF
To : WEFAX@WW
amfm (358+4093)
This circuit works with DOS based WEFAX program (eg JVFAX) to convert
2400Hz AM picture carrier (from your FM receiver) into a varying frequency
(the "FM"). This 0v/12v FM signal then connects to the DOS PC COM DSR pin.
JVFAX has to be set to expect a FM signal on the DSR pin, and the
DEVIATION (eg D400 mode) adjusted for the best contrast.
The 100k (that determines the oscillator frequency) can be shunted with a
PTC/NTC to effect temperature compensation if the circuit is at a remote
location.
This circuit delivers image header information just as reliably as much
more complex A/D serial 57600bps circuit. (But I think that the program
"ATC" must be switched off for this?)
I have had no luck in getting a decent WEFAX picture with any of the
Windows based programs (using soundcard).
I sent the circuit as a .bmp (zip to 9k) because the .gif zips to a larger
14k
73s let me know how it worked out,
Rob ZS1AGX
The audio transformer (1k CT: 10k) isn't that critical. Any little audio
tranformer is worth trying. Use the ohm-meter to work out the lowest
resistance side to connect to the radio, and the higher resistance side to
the diodes. (Just check that the two windings are indeeed not connected!)
Cicuit "offset" is provided by the optional 2.7v "adjustable zener", and
well, gain is just how much audio the circuit gets.
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