[TenTec] Orion II - Tech Topics

[wa3fiy at radioadv.com]

I realize those limitations.  What I was getting at, apparently not very well, 
was that mixing schemes may indeed be able to minimize the effect of drift 
in oscillators.  I was using the Wadley Loop as an example of such a mixing 
scheme.  I have not seen the block diagram for the Orion front end but 
obviously, it does not suffer from limited dynamic range.  I am pretty sure it 
does not use the Wadley Loop.  I think Ten Tec's point is that the mixing is 
arranged such that the reference oscillator drift causes drift in one direction 
at the output of one mixer stage and drift in the opposite direction at the 
output of another mixer stage, hence, cancelling or reducing overall drift.

73,

-Lee-
WA3FIY


On 8 Aug 2006 at 10:37, Dr. Gerald N. Johnson wrote:

> On Tue, 2006-08-08 at 12:11 -0400, wa3fiy at radioadv.com wrote:
> > What about the Wadley Loop?  It is my understanding that it provided a 
> > high degree of stability using a tunable (read drifty) VHF oscillator and a 1 
> > MHz crystal oscillator rich in harmonics along with a unique mixing scheme.   
> > Several commercial receiver designs took advantage of the Wadley Loop 
> > design including the Yaesu FRG-7, Drake SSR-1 and some RACAL 
> > receivers.
> 
> Yes, it works, so long as you don't mind not having any real selectivity
> until after it, and don't mind the extra mixer noise and limited dynamic
> range because if you put selectivity in that first IF the drifty LO will
> surely move the desired signal away from that first IF selectivity
> causing a loss of sensitivity.
> 
> TANFL.
> 
> 
> -- 
> 73, Jerry, K0CQ,
> All content copyright Dr. Gerald N. Johnson, electrical engineer
> 
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