[TenTec] Omni VI Plus audio

[Fraser Robertson]

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 > reasonable 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 additional 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 different 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
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