[RTTY] PK900

[Ford Peterson]

I have an AEA PK-900 and purchased the DSP mod from Timewave, which included all the latest ROM, etc.  I was all set and ready to do Roundup this weekend after missing it for about 3 years.  Print was FB.  Great selectivity.  Transmit was on frequency.  I thought it was all checked out.  I'm using an IC746 and taking the audio off the back of the radio.

But then I started tuning around a bit.  If the signal strength was not at least S1, the unit would not print or even recognize that a signal was there.  So instead of doing Roundup, I was digging into the PK-900. 

My setup was a HP608 signal generator, a frequency counter on the speaker output, and a dual channel O'
scope on the output of the PK900.  Very interesting...  The filters are all that Timewave boasts about, as long as I'm spanking the antenna connector at 4uV or so.  That's > 40 dB above my noise floor on this radio.  I found that if the incoming signal was bursting my eardrums, that didn't matter.  The signal would have to move the S meter at least a bit to get print.

The PK900 seemed to go into limiting at around 5uV and I would lose print at 3uV.  The DCD indicator would not even move at 2 uV.  Even though the signal was good enough to force me to turn down my volume control.

Anybody else experience this with the PK900/DSP/PSK/9600?

Ford-N0FP
ford at cmgate.com