RTTY with K2

[Richard Haendel]

I am wondering if anyone has modified their K2 to transmit RTTY using FSK, not AFSK. It seems that if XIT were used somehow, I could get the 170 Hz shift by feeding the K2's pseudo"RS232"  connector from my lap top computer com port.  I do not want to feed audio into the mike connector for AFSK. It seems that there is more RTTY distortion and difficulty in lining up the transmit carrier with the incoming receive RTTY signal that way.

Thanks for anyone's reply
Rich W3ACO
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[Thom LaCosta]

On Thu, 10 Aug 2006, Richard haendel wrote:

> I do not want to feed audio into the mike connector for AFSK. It seems that
> there is more RTTY distortion and difficulty in lining up the transmit carrier
> with the incoming receive RTTY signal that way.

Did you actually measure the distortion?  Back in the neolithic Drake Twins/TR7
days, a lot of us used afsk with no problems....unless ya were trying to stuff a
gazillion watts of audio into the mic jack.


Thom

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[Bill Coleman-2]

On Aug 10, 2006, at 7:32 AM, Richard haendel wrote:

> I am wondering if anyone has modified their K2 to transmit RTTY  
> using FSK, not AFSK. It seems that if XIT were used somehow, I  
> could get the 170 Hz shift by feeding the K2's pseudo"RS232"  
> connector from my lap top computer com port.  I do not want to feed  
> audio into the mike connector for AFSK. It seems that there is more  
> RTTY distortion and difficulty in lining up the transmit carrier  
> with the incoming receive RTTY signal that way.

I have been using my K2/100 with AFSK RTTY using both CocoaModem and  
MMTTY with no problems.

I took some time to carefully adjust the audio levels. I used a  
second receiver to listen to adjacent frequencies and adjust for  
minimum products. The key is to avoid putting too much audio signal  
into the microphone connector -- it is really easy to overdrive most  
transceivers.

I have not had difficulty lining up the receive and transmit signals.  
However, if I am calling CQ, it is common for the responders to be  
slightly off-frequency. I use the RIT and quickly tune them in.

My only beef with the K2/100 is the lack of a 100% duty-cycle PA.  
With the stock K2/100, you can only run about 25-30 watts out in a  
contest. I've added an external fan for cooling, and have  
successfully run 50 watts out for long periods. (You can use the full  
100 watts, but only briefly, as the amplifier heat sink will heat up  
very rapidly)

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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