[TenTec] Omni VI Plus audio

[Fraser Robertson]

Sorry but the padding had nothing to do with the filter, I had to pad the oscillator to get it to it's specified frequency.
 
73 Fraser G4BJM> From: RMcGraw at Blomand.net> To: tentec at contesting.com> Date: Tue, 18 Mar 2008 18:31:37 -0500> Subject: Re: [TenTec] Omni VI Plus audio> > I suspect that you may have a defective filter. The fact that you had to > pad an oscillator is a clue. Or maybe a BFO crystal is out of tolerance.> > I measured the audio frequency response of my Omni VI Plus using the > sinewave/power method. Once I did this, I was able to see the shape of the > filter and take into account the group delay which affects the "sound" of > the radio. I didn't do a squarewave response however. I also confirmed > that the DSP artifacts were present in the RX signal regardless of the NR or > Auto Notch usage.> > I've found that the mechanical Collins filters used in the Omni VII offer an > significantly enhanced signal on SSB both in transmit and receive. They are > clearly different than crystal filters regardless if they are ladder of > lattice configuration.> > 73> Bob K4TAX> > > ----- Original Message ----- > From: "Fraser Robertson" <g4bjm at hotmail.com>> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>> Sent: Tuesday, March 18, 2008 6:20 PM> Subject: Re: [TenTec] Omni VI Plus audio> > > >> > Thanks Bob, yes I'm referring to the TX signal, although RX is similar of > > course. I agree with what you say, although the Omni6+ SSB filter is > > worse than that in any other rig I've used. I did align the oscillators > > as per the manual, in fact I had to pad one of them as there wasn't enough > > adjustment range. I rarely use SSB myself so will let someone else worry > > about it! 73 Fraser> From: RMcGraw at Blomand.net> To: > > tentec at contesting.com> Date: Mon, 17 Mar 2008 20:02:33 -0500> Subject: Re: > > [TenTec] Omni VI Plus audio> > Typical of filters, the shape factor or > > each side of the slope as measured > from the -3 dB points is typically > > not identical although we'd like to think > they are and wish they were. > > Thus a modulated carrier placed on the side of > the slope, at say the -3 > > dB points, will sound different when listening to > USB or LSB output > > products of the filter. It is not a common failing, it is > a law of > > economical filter design and selection of filters that have a > rea> > sonable or tolerable amount of insertion loss as well as a host of other > > > factors such as ripple across the top, phase shift, group delay and etc.> > > > I do not discount that fact that a crystal component within the filter > > may > fail or may change frequency such that, in either case, the shape > > factor of > the filter changes. If you have means to measure the filter > > and its skirts > and insertion loss then you might find a clue as to why > > it sounds different > on USB and LSB. Otherwise, invest in a new filter > > and then complete an > alignment of the BFO oscillators. It is important > > that the alignment be > carried out in the exact sequence as described in > > the manual. There is > interaction between the adjustments. Even the FSK > > adjustments need to be > made although you may never intend to operate > > FSK.> > I trust you are speaking of transmit signal sounding different an > > not > receive signal sounding different. For receive signal sounding > > different > that may be caused by and additi> > onal factor being mis-alignment of the > PassBand tuning oscillator.> > > > 73> Bob, K4TAX> > ----- Original Message ----- > From: "Fraser Robertson" > > <g4bjm at hotmail.com>> To: <ken.d.brown at hawaiiantel.net>; "Discussion of > > Ten-Tec Equipment" > <tentec at contesting.com>> Sent: Monday, March 17, 2008 > > 6:49 PM> Subject: Re: [TenTec] Omni VI Plus audio> > > >> > Our club's > > Omni6+ option3 sounds very different on USB and LSB, and it's > > not > > possible to correct it by adjusting the BFO frequencies, so it must be > > > > down to the filter being asymetrical. I understood that was a common > > > > failing, but perhaps our filter is faulty?> >> > 73 Fraser G4BJM> >> Date: > > Sun, 16 Mar 2008 18:37:51 -1000> From: ken.d.brown at hawaiiantel.net> > >> > > To: tentec at contesting.com> Subject: Re: [TenTec] Omni VI Plus audio> > > > > > >> > Now I don't know why the higher bands are different on your rig.> > > > > >> Wonder if you have an antenna problem? > >> > > If the SSB Receive (or > > > >> transmit) audio sounds differen> > t on 10, 15, 20 > meters than it does on > >> 40, 75 meters, you should be > > comparing the sound > on USB versus LSB. > >> Your SSB audio > > characteristic should not change at > all due to changing > >> bands, > > other than because of the convention of using > USB above 9 MHz > >> and > > LSB below 9 MHz. The audio characteristics also > should not change > >> > > very much from USB to LSB. If it does change, that is > an indication > >> > > that your BFO frequencies are misaligned for one or both > SSB modes. > >> > > Another possibility, although not nearly as likely, is a > partially > >> > > failed crystal filter with a non-symmetrical passband shape. > The first > > > >> thing to do is check the BFO frequencies. If you install new> > > > > filters, of any brand, without getting the BFO frequencies right, you > > > > > will still have a problem.> > DE N6KB> > > > > > _______________________________________________> TenTec mailing list> > > > > TenTec at contesting.com> http://lists.contesting.com/mailman/listinfo/tentec> > > > _________________________________________________________________> > > > > > Share what Santa brought you> > https://www.mycooluncool.com> > > > > > _______________________________________________> > TenTec mailing > > > > list> > TenTec at contesting.com> > > > > > http://lists.contesting.com/mailman/listinfo/tentec> > > > > > > > > _______________________________________________> TenTec mailing list> > > > > TenTec at contesting.com> > > > > http://lists.contesting.com/mailman/listinfo/tentec> > _________________________________________________________________> > Who's friends with who and co-starred in what?> > http://www.searchgamesbox.com/celebrityseparation.shtml> > _______________________________________________> > TenTec mailing list> > TenTec at contesting.com> > http://lists.contesting.com/mailman/listinfo/tentec> > > > > _______________________________________________> TenTec mailing list> TenTec at contesting.com> http://lists.contesting.com/mailman/listinfo/tentec
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