[TenTec] Orion II - Tech Topics

[wa3fiy at radioadv.com]

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.

Here is what Wikipedia has to say:

"Of the three principal methods of such control, the Wadley Loop seeks to 
cancel any tendency for the oscillator's frequency to drift. It does this by 
mixing the received frequency up to a high IF frequency (more than 10 
MHz) and then uses the same oscillator to generate a lower frequency. 
These signals are then remixed to generate the second IF frequency."

A numerical example of how all this works is given at:

http://carboni.home.cern.ch/carboni/wadley.html

I don't think the Orion uses the Wadley Loop but perhaps the mixing 
scheme in the OII is along the same lines or at least achieves the same 
end???

73,

-Lee-
WA3FIY


On 8 Aug 2006 at 3:04, Sinisa Hristov wrote:
> 
> I do love my Orion deeply and truly, but nevertheless I find
> the persistence of the "Frequency Stability" hoax unbelievable.
> 
> It appears now in three places: on the Orion II page,
> in the manual and on this new "Tech Topics" page.
> 
> Gentlemen who design such a fine radios should not indulge
> themselves in propagating such a nonsense. The truth is very simple:
> Orion's (be it Classic or II) frequency stability does NOT
> depend at all on the "mixing architecture".
> 
> Stated generally, with all LOs locked to the same reference,
> ANY mixing architecture is equivalent to a single stage mixing
> with an equivalent LO frequency, and the output frequency drift
> is equal to the drift of that equivalent LO.
> 
> The change of the mixing scheme in Orion II may have some
> virtues, but the stability improvement is NOT one of them.
> 
> 
> 73,
> 
> Sinisa  YT1NT, VE3EA
> _______________________________________________



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