[TenTec] ICOM PROIII saga update

[Steve N4LQ]

I promised to give an update on my experience with the PROIII so here goes:
(note: I am posting this on the TenTec reflector because the Omni VI+ is compared)

Here's an update on my PRO III saga.
I sent the rig back to AES for evaluation. I included the Spectrogram 
print showing the distortion products.

http://www.webham.com/Noise%20Pulses.jpg

 Miles, the chief technician called me today. He compared my rig to others and said he was 
unable to hear anything unusual. He also claims to have called ICOM and says
they had "never had a complaint". (Isn't that what they always say)?
Miles put in touch with Mike Hanson, store manager, who agreed to a 
total refund. What a relief! So far, I'm impressed with AES and give them high marks. 

It is my conclusion that the PRO series suffers from distortion when 
presented with signals having a very fast rise time. This includes most 
cw, especially from hard keying transmitters and static burst. These distortion products exit the 
speaker as short duration clicks from QRN and sharp, leading edge thumps 
on cw. This is largely irrespective of signal strength and is actually 
emphasized to some degree when activating the NR function. 

Adding attenuation, reducing RF gain and turning off Pre-amps has no effect. This is most obvious to the ear when using narrow
 bandwidths such as 250hz or less. The distortion products fall far outside the bandpass, up to 3 khz!

Having used a PRO II for 2 years, I believed ICOM's claims of lower distortion in the PRO III. Maybe there is less distortion by some measurement or some condition but certainly not CW and I believe the PROIII is somewhat worse than the PROII in this regard.

BTW: I do love the bandscope and especially the newer version. Also, although annoying and tiring to listen to, the PROIII is still able to pick weak signals out of QRN better 
than a few other rigs I have tried.

To answer a few FAQs:

The two rigs were connected via shielded cable from their low level audio outputs to the sound card input. The gain of each input was adjusted for near equal amplitude. The lower waveforms are the important ones. You are not seeing amplitude spikes here. You are seeing noise pulses of various frequencies. The center frequency was 600hz. This would be in the center of the dark blue area. Note the spikes kicking up to 3 khz. These are head in the headphones or speaker as clicks. There is no cw signal other than static here. A cw signal would produce a solid yellow line through the blue area. Nothing should be seen beyond the 250hz bandpass.
No. I wasn't overdriving the sound card. 

Steve N4LQ