[RTTY] FT1000D FSK

[Ian White GM3SEK]

Tyler Stewart wrote:

>From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On
>Behalf Of Ronald A. Stunden
>Sent: Tuesday, March 14, 2006 1:36 PM
>To: rtty at contesting.com
>Subject: [RTTY] FT1000D FSK
>
>Thanks to all that answered, It boils down to this the 1000D  and the
>MP Mark 5 series are totally different, The D has a built in AFSK osc
>which is keyed from the RTTY plug on the radio. and is set up using
>the ALC, I have found that about 9-10 position on the ALC scale is
>about right. Listening to the signal on the FT990, The audio tends to
>get a bit distorted at a higher level. Page 34 of the manual explains
>the operation and setup. The  MP and Mark 5 are pure (if you will )
>FSK keying. as I understand it. As far as I can remember the FT990 is
>also FSK. I am using the PK232 FSK output for keying and it works
>fine on either radio... MMTTY now has an add on for FSK using MMTTY
>which works as well.. The radio is run in RTTY/LSB....
>I hope this explains it... Cheers Ron
>_______________________________________________


>Don't know about the Mk 5, but the original MP is also a digitally
>synthesized AFSK generator, not "pure" FSK.
>
>Ty K3MM

There is an error in the MP user manual about FSK, that affects all the 
original series and possibly some of the MkV. Yaesu used text from the 
old 1000D manual which does not apply.

In the 1000D and the 990, the mode that is labeled "FSK" is generated by 
frequency-shifting an internal audio tone generator. Because this is 
really AFSK, the 1000D and 990 manuals show how to set the audio and ALC 
levels correctly to avoid distortion.

But if you try to follow that same procedure for an MP, it won't work. 
The MP user manual is telling you to set the level for an audio 
generator that doesn't exist! Starting from the original MP, Yaesu have 
used true FSK, and the keying line goes directly into the chip that 
controls the frequency synthesizers.

Two or three years ago, a number of people ploughed through the manuals 
to get the story straight, so it should be in the list archives. If I 
remember correctly, the error is in all the MP "Mk1" user manuals, and 
continued into the first issue of the MkV manual. Yaesu finally 
corrected it when they released the MkV Field.


To update the story, does anyone know how FSK is generated in the 9000 
series?


-- 
73 from Ian GM3SEK