[TenTec] Delta 580 questions

[Jason Reber]

Greetings;
I just picked up a Delta 580, and I really like the size and layout of 
this rig. Hoewever, this unit has a few issues that I'm hoping someone 
may have encountered before.
1st, there is a astable tone being generated whenever the VFO is set to 
xx.046 MHz (USB or CW), or xx.050 LSB.  The tone is about 1 KHz, and 
alternates on and off at about 2Hz. Again, regardless of band, when the 
VFO is set to 46 Khz (USB or CW), or 50Khz (LSB), this on/off tone 
appears. It only persists for about 1 KHz either side of 46 Khz.  
Something must be resonating on the back end, and coupling the tone into 
the audio, but I'm perplexed as to why it's intermittent- on/off at 
about 2Hz, and with a 50% duty cycle.

2nd, does anyone find that they need to switch the attenuator (rear 
panel switch) in to get decent RX performance? If I don't switch it in, 
I get extreme, brassy noise and poor AGC performance. I may just need to 
check out the AGC circuit and look for problems, but I'd appreciate any 
comments. The S-meter performance seems sluggish, and the audio seems 
like its getting cut off below 500 Hz- very brassy, harsh audio. None of 
the other TT rigs I've had (Omni D, Scout, Jupiter) have ever sounded 
like this.

Finally, if anyones had a Delta with the crystal filter, would you 
advise getting one (Inrad available, I think)?

Thanks for any comments or suggestions,
Jason  AC7JW