[ICOM] IC756 PRO 3 PROBLEM with DSP

Larry Dajnowski Larry at amiloan.gccoxmail.com
Mon Dec 20 18:48:42 EST 2004


Believe it or not I have seen these type spikes
with the IC-7800 here.  It has been internment
so have not been able to track down the cause.
Noticed on 40 meters mostly.

73, Larry AJ2W

  ----- Original Message ----- 
  From: Steve N4LQ 
  To: ICOM Reflector 
  Sent: Monday, December 20, 2004 5:43 PM
  Subject: Re: [ICOM] IC756 PRO 3 PROBLEM with DSP


  Thanks. I tried sending this to the reflector last night but it never posted 
  for some strange reason. Anyway, I called AES this morning and have orders 
  to ship it in for them to evaluate. I already know they won't be able to 
  duplicate the problem hence the reason for the jpg. I may even make a .wav 
  file for them to QSX.
  No the Omni VI+ has a very wide roofing filter, 2 poles at 15khz. The 
  problem here isn't filtering. The DSP is working but I think it is actually 
  producing the spikes as a result of clipping. The spikes do not seem to 
  affect the agc either because they are too fast, or because they are beyond 
  the last agc loop.
  I can hear these through anything including speakers, headphones but by 
  feeding the audio out to the PC's sound card and using hi-fi speaker, they 
  really show up!
  Steve N4LQ
  ----- Original Message ----- 
  From: "Dave Meitzen" <dmeitzen at comcast.net>
  To: "ICOM Reflector" <icom at mailman.qth.net>
  Sent: Monday, December 20, 2004 6:31 PM
  Subject: RE: [ICOM] IC756 PRO 3 PROBLEM with DSP


  > Does the Onmi VI+ have a narrow CW roofing filter? Think heavy QRN bleed 
  > in
  > to the PRO III IF? Thanks for shareing this with the group -- excellent
  > info. Like to know the resolution I have a Pro III :>))
  > Thanks
  > Dave
  >
  >
  > -----Original Message-----
  > From: icom-bounces at mailman.qth.net
  > [mailto:icom-bounces at mailman.qth.net]On Behalf Of Steve N4LQ
  > Sent: Monday, December 20, 2004 5:20 PM
  > To: ICOM Reflector
  > Subject: [ICOM] IC756 PRO 3 PROBLEM with DSP
  >
  >
  >
  > Subject: IC756 PRO 3 PROBLEM with DSP
  >
  >
  > I received a new PRO-3 last Thursday from AES. The DSP has a problem
  > especially when using the NR. The problems is distortion products 
  > resulting
  > in large noise spikes, far outside the bandwidth setting.
  > Last night I made some recordings using Spectrogram. Band, 80m, 
  > Conditions-
  > Heavy QRN, BW-250hz, NR ON, DSP CW-soft. I recorded both  the OMNI VI+ and
  > PRO-3 connected to the same antenna. Please see the scope patterns at this
  > link:
  >
  > www.webham.com/PRO3.jpg
  >
  > When listening through wide range headphones which are plugged directly 
  > into
  > the PRO3, the spikes are very annoying and make copy almost impossible.
  > Turning off the NR helps some. There is certainly a problem with the DSP. 
  > At
  > this time I do not know if it's just my rig or an engineering problem.
  >
  > Note: Before this, I owned a PRO2 for 2 years so I am quiet familar with 
  > how
  > the radio SHOULD function.
  >
  > I am contacting AES tomorrow. Hopefully they will provide an exchange.
  >
  > Stay tuned for further developments.
  >
  >
  > Steve N4LQ
  >
  > IC756PROIII
  > IC-756PRO3
  > IC756 PRO 3
  > ----
  > Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
  > Win a new Icom IC-756 PRO III and help QSL/QTH.net
  > Details at: http://mailman.qth.net/
  >
  > ----
  > Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
  > Win a new Icom IC-756 PRO III and help QSL/QTH.net
  > Details at: http://mailman.qth.net/
  > 

  ----
  Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
  Win a new Icom IC-756 PRO III and help QSL/QTH.net
  Details at: http://mailman.qth.net/


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