Disadvantage of patch is it is in parallel with the mic. So, if a mic
is plugged in, your transmission will include stray room noise.
Barry W2UP
On 27 Mar 2003 Doug Faunt N6TQS +1-510-655-8 wrote:
> Speaking of FT1000 and FT990's, I've also seen hookups that used the
> FSK connector for audio out, FSK in, and PTT in, and a RCA connector
> to the "patch" input for audio input. What are the pro's and con's of
> doing that? I don't have these rigs, but have used them occasionally.
>
> 73, doug
>
To: <rtty@contesting.com>
> Date: Thu, 27 Mar 2003 09:29:16 -0800
> From: Kok Chen <chen@mac.com>
>
> Hi Paul,
>
> I have used FSK on both the FT-990 and FT-1000MP (same 4-pin
> connector for the two rigs) but have not used MMTTY, so can at best
> only be half helpful.
>
> Bear in mind that there are two ways you can transmit a frequency keyed
> RTTY signal. One is usually termed FSK and the other is termed AFSK.
>
> FSK is accomplished by keying a single line with a bilevel signal. The
> two voltages causes the internal AFSK generator in the FT-990
> to produce the Mark and Space offset tones.
>
> (The FT-990 and 1000, unlike the Ten-Tec Omni, are not "true" FSK rigs,
> even though the connectors are labeled so, and the front panel switch
> say so).
>
> AFSK is accomplished by passing an audio signal to an SSB (usually LSB)
> transmitter. The transmitter literally shifts the two audio mark and
> space
> tones up to the RF region.
>
> So, AFSK is modulated by an audio signal while FSK is modulated
> by a signal which has two voltage (or current) states.
>
> That said, the signal you should be therefore be feeding to the pin
> number
> 1 of the 4-pin DIN is a keyed bilevel signal, and the front panel mode
> switch
> should be set to "FSK."
>
> If you are outputing an audio signal from a sound card, you should be
> using
> pin 1 of the 5-pin "Packet" DIN connector, and set your front panel mode
> switch to "PKT." The latter will give you AFSK on the FT-990.
>
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--
Barry Kutner, W2UP Internet: w2up@mindspring.com
Newtown, PA Frankford Radio Club
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