[TenTec] Orion Synthesizer Design

[John]

The article cited by Bill Tippett is very interesting--for an OMNI VI owner.

The curves on the phase noise graph for the OMNI VI  show an amazingly 
quiet receiver.

A comparison of the 2003 Ten-Tec graph with what appeared in QST (1/93) 
as a graph of OMNI VI transmitted composite noise shows a wide 
discrepancy. For one thing, the QST graph shows a lot of spikes, 
indicating a "dirty" transmit signal. For another, the  average noise 
seems to be higher by  a considerable  degree  than that shown in the 
Ten-Tec phase noise graph.

Given the discrepancies, I'm wondering if it is true, as the ARRL lab 
has been saying, that transmit composite noise is a good proxy for 
receiver phase noise? Certainly in the case of these two graphs, it 
seems not to be so. (For its test of the Orion,  ARRL actually did test 
the receiver phase noise and the resulting graph showed a phenomenal 
-140 dB at 2 kHz (per my recollection).)

Can someone explain the seemingly large discrepancies between the 1993 
QST transmit composite noise and the 2003 Ten-Tec phase noise graphs for 
the OMNI VI?

73,
John, W3ULS