----- Original Message -----
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
To: <tentec@contesting.com>
Sent: Tuesday, August 08, 2006 1:41 PM
Subject: Re: [TenTec] Orion II - Tech Topics
> On Tue, 2006-08-08 at 13:15 -0700, Ron Castro wrote:
>> I notice such things...even that net control of the Sunday 20 meter TT
>> net
>> is always 20 Hz low in frequency on his Jupiter!
>
> Are you SURE its not your ear that's tuning 20 Hz off. Have you analyzed
> the bass voice harmonics to be certain they come out of your speaker at
> 3 x the fundamental, not 3 x +/- 20 Hz?
Very sure...when harmonics are not aligned harmonically (as they should
be!), they become dissonant, much like IMD as opposed to harmonic
distortion, which is more musical and less irritating. Unless the audio has
very little bass, or is distorted to begin with, it's very noticeable on a
good receiver like the Orion with the PBT set at 0.
>
>> And I hate it when I'm in
>> a round-table or a net and not everyone is on the same frequency...even
>> 10
>> Hz is noticeable to me. The Orion's drift about 20 Hz during a warm up
>> period that takes up to three hours (unless you do my fan mod) at 15 MHz
>> WWV, which equates to 40 Hz on 10 meters. If you're driving a
>> transverter
>> for multi-mode on two meters, that results in 200 Hz drift, which is way
>> into 'Donald Duck' territory!
>
> Nope. The 2m multimode LO isn't derived from the Orion LO so its error
> and drift are independent, and probably a couple KHz in error most of
> the time because most have independent mixer oscillators not controlled
> by the PLL or the master reference.
True, unless you're running a multiplier stage, which admittedly wouldn't
work for SSB or even AM, but would work for FM (in fact that's how it's done
in the broadcast industry), CW and perhaps some digital modes
>
>>
>> Ron N6AHA
>
>>
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