[TenTec] When did Ten-tec switch to Schottky diode ring mixers?

[Kevin Purcell]

When did Ten-tec switch to Schottky diode ring mixers?

If you have a Corsair or Corsair II you can help by looking at the  
schematic in the manual for the RX mixer in your TT rig. Let me know  
the diode type.

Why ... I've been trying to interpret some performance numbers from  
Sherwood and trying to find comparable measurements for 1n4148 and  
Schottky diode ring mixers to answer the question "how much worse is  
a PN diode mixer?".

<http://www.sherweng.com/table.html>

Looking at the data I have it seems to be sometime in the first half  
1980s

The TT 546 Omni C from 1981 has four 1n4148 in the primary RX mixer  
(1981).

The second version (after serial 822?) of the TT 525 Argosy  
(analogue) has four 1n4148 in the primary RX mixer (early 1980s).

The TT 525D Argosy (digital) had a Schottky diode ring mixer  
(1982-1986?)

 From W8KC's lineage
<http://mywebpages.comcast.net/w8kc/lineage.htm>
Omni C -- 1981

Corsair -- 1983

Corsair II -- 1987? (8/87) (production 1987 to 1990)

Paragon I 585 -- 1988? (5/88)
Omni V -- 1990?  (11/90)

So I think one can be pretty sure that the Paragon and the Omni V  
have Schottky diode ring mixers so that leaves the Corsair's as the  
point of the design change. But if I'm wrong let me know.

Thanks.
--
Kevin Purcell
kevinpurcell at pobox.com