I've followed this discussion a bit over the last couple of days.
Several times I've turn around and listened to my Omni VI+ with both the
normal filters and with the 1.8KHz filters in the 9 MHz and 6.3 MHz
IF's. Since my radio was at Tentec a couple of months ago, a complete
(I presume) alignment was done. At this time, I don't really observe
any difference in symmetry between LSB and USB. Either I've gotten a
great set of filters by accident or a great alignment job which took
into account minor differences in filters. I suspect that a "black and
white alignment by the book" may not produce the best results with every
filter combination and deviation.
Just a thought.
Thomas C Jednacz wrote:
> Symmetry is absolutely required in the Ten Tec scheme because they use both
> sides of the filter. One side for LSB and CW and the other side for USB. If
> the filter is off even the slightest then you loose either lows or highs in
> the passband. LSB and CW are excellent but using the 1.8 Khz filter for USB
> can be a problem. I have tried to adjust the oscillators to get a balance
> but have not yet been successful. Have not tried the Inrad filters and maybe
> that is what I need to do.
> Tom, W7QF
> > -----Original Message-----
> > From: firstname.lastname@example.org [mailto:email@example.com]On
> > Behalf Of Paul Christensen
> > Sent: Saturday, August 25, 2001 16:11
> > To: LJL160@aol.com; firstname.lastname@example.org
> > Subject: Re: [TenTec] Passband/ Omni 6+
> > > Hi guys- Im crazy about my Omni 6+. I did notice that the USB pitch and
> > > bandwidth is not symetrical to the LSB.
> > This is common among the Ten-Tec crystal ladder filters. The
> > INRAD filters
> > do not exhibit this asymmetry, but like most crystal *lattice* filters I
> > detect a very slight increase in ringing with them.
> > -Paul, W9AC
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