[TenTec] Sample-to-Sample Variations

[Robert & Linda McGraw K4TAX]

To that end, good points are raised.

In my case, I've "hand picked" several components that are used in my Omni
VI series.  The result is I find a noticeable improvement of receiver
performance .  Now this is to say that the performance was good to start
with, but by hand picking some of the balanced mixer products and switching
diodes, yet another level of performance can be attained.  This is not
something that I view any manufacturer can or would be willing do on a
production basis.  Too costly, too time consuming.  At the same time, there
are some receivers on the market that do attain this level of performance
but the cost is in excess of $12,000 each.

This is no different than an production automobile and a car that's run on
the drag strip on Saturday evenings.  The drag car starts out as a street
car and then has hand selected and tweaked components to enhance
performance.  One vehicle costs $20,000 total, while the other one has a
$20,000 engine, transmission and rear end.

To that end in production radios, unit to unit variations can be expected in
production runs with regard to minute performance issues.  Otherwise, most
folks won't know the difference in either one.  The good news is, "they all
work!"

73
Bob, K4TAX


----- Original Message -----
From: "John Rippey" <w3uls at 3n.net>
To: <tentec at contesting.com>
Sent: Friday, March 14, 2003 8:02 AM
Subject: [TenTec] Sample-to-Sample Variations


> On Mar. 9, Ed Hare, W1RFI, said:
>
> "Alas, to my knowledge, no one doing testing looks at more than a sample
of
> one. The ARRL Lab ends up spending about 20-30 test hours on a major rig
> and it really isn't possible to do complete testing on more than one. We
do
> sometimes look at a few other samples, from staff equipment to one
borrowed
> for a few hours from a local dealer. If we find anything interesting, it
is
> put up in the expanded test result reports. In the ones I have looked at,
I
> have seen significant variation in things like dynamic range and the
like."
>
> To underscore Ed's point, I just came across the January '92 QST review of
> the Ten-Tec Argonaut II/Delta II transceivers. The ARRL lab found IP3 of
> the Argonaut to be -11 dbM while the Delta II IP3 tested at +2 dbM. Other
> indices showed considerable variations as well. The reviewer, Dave
Newkirk,
> noted that the receiver portions of the two rigs were identical. He went
on
> to say: "The receiver variations we found . . . reflect sample-to-sample
> variations in a single radio product."
>
> It was a coincidence that ARRL had two radios with identical receivers to
> go over since, as Ed states, ARRL usually tests only one sample. So the
> variations noted by Dave Newkirk would have gone unreported otherwise.
>
> Were the significant sample-to-sample variations found by ARRL in 1992
> limited only to Ten-Tec radios of that vintage, or to just that one
> manufacturer? I go back to my recent experience vis a vis an FT-920 I had
> vs the new Argonaut V during a CW contest and have to wonder how many
> radios we buy actually attain the performance measurements in ARRL's tests
> or the manufacturer's claimed specs? It looks as though the chances of our
> getting a particular rig that meets those measures are uncertain at best.
>
> Of course, reducing the uncertainty means tighter quality control which
> translates into increased production costs. So, as buyers in a small
market
> we really cannot expect that, I guess.
>
> 73,
> John, W3ULS
>
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