Excellent. Thanks Steve for that data point. And Don, NN8B, who
replied too. Both have the Corsair 2.
So they had switched by 1986.
Anyone with an original Corsair (Corsair 1, so to speak)? I think
that might be the rig they made the switch to schottky diodes.
It would just take a second to check the schematic in the manual on
the RF Mixer board :-)
They won't be MPN-3404 PIN diodes (which appear in fours in the
Corsair too) but something else.
I'm sorry I didn't mention the quad option too (so people go hunting
for 4 diodes) as it is similar to the digital Argosy RX mixer.
TT will use either four discrete diodes (probably switching diodes
if they were still using them but they may be discrete schottky
didoes) or, more likley, a single quad schottky package, as they do
in the 525D Argosy digital which is an ND487CI.
Does the RF mixer board have a ND487CI on it?
Or a similar 4 legged package between a pair of transformers and
taking signal from the LO via a driver?
On May 20, 2007, at 9:15 AM, Steve Hunt wrote:
Kevin,
I have a Corsair II purchased new from the UK distributor on 3rd
October 1986. The serial number is 580 - 01861
The schematic shows a single component, D13, for the mixer diode
quad; its part number is given as 87C2 K38
Hope this helps.
Steve G3TXQ
----- Original Message -----
From: Kevin Purcell
To: Discussion of Ten-Tec Equipment
Cc: Kevin Purcell
Sent: Saturday, May 19, 2007 7:01 PM
Subject: [TenTec] When did Ten-tec switch to Schottky diode ring
mixers?
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@pobox.com
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--
Kevin Purcell
kevinpurcell@pobox.com
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