using the BITX on RTTY

Charles Darley

Hi all

I was at my local radio club the other night and was discussing the
possibility of using the BITX on RTTY .. This prompted the following
responce from one of the members ...

"The elegant way for RTTY is to have a carrier, and this is shifted
for one of the tones. A small amount of capacity added across an
oscillator is the usual way, switched by the RTTY signal coming from
(say) the teleprinter contacts - or today a computer output from the
com port. This results in a purer outgoing signal than two tones into
the mike socket, as the amplitude of the tones is identical, which
does not happen when tones in the mike socket is used. (Check the
output power of the TX on mark, and then space, when using audio in
the mike. Not the same!!"

So this prompted me to look for information on the varicap ...

I came across this site :-

I have printed off all of the data and this will be another display
project to show members ( or have them build it and then discover )
as stated in the article "any diode is a varicap diode".

Hans I wonder if you would like to confirm one or two items which
are not clear to me...
1. that the volts into the 4060 are 12V
2. that the 14MHz xtal could be changed for one of the 10MHz xtal
already obtained ( through you ) for the project ...
3. could I / a student use ugly construction for the test project ???

This whole BITX project is enabling so many teaching side lines that
the students will not realise that they are learning so much.

73 all

Charles G4VSZ

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