Subject: [TenTec] Ten Tec Performance
Hi, Jon,
Thanks for asking for comments. I do have a few.
Please see a previous post on this reflector
(http://www.contesting.com/_tentec/200003/msg00242.html) for a perspective
on frequency accuracy in amateur radio receivers.
If the frequency error is annoying, or if the other problems you've
identified are too bothersome to simply overlook, that is understandable.
You may not be a suitable candidate for a Ten Tec receiver. In that case, by
all means keep the Yaesu. Many hams who love their Kenwoods, Icoms and
Yaesus just can't understand why anybody would use a Ten Tec.
When people say that Ten Tec receivers are the best-- a fairly common boast
these days-- what exactly do those people mean when they say that?
I believe that the primary advantage of the Omni VI lies in an attribute
which is currently out-of-fashion in the general amateur community. In the
ham world at-large, the design emphasis in recent years has been
predominantly in three major areas: 1/ more features, especially those
involving digital signal processing (DSP), 2/ reduced size, and 3/ front
panel appearance. DSP has allowed radios to do some amazing and complex
things to both the received and transmitted signals. And yes, hams are
fascinated by the ability to fit lots of radio into their compact cars. The
quest for "the look" has led to LCD displays, intricate multicolor readouts,
and clever controls that deviate from the standard rotary controls and
single-throw switches.
However, the one area of receiver design that is *still not perfected*, not
as good as it could be, and for many, frustratingly not getting any better,
is basic performance.
Let's say that you've been shopping for a cell phone. You have read
everything you can find. You've done research on the Internet, in Consumer
Reports, at the store, and you finally decide to buy the latest phone with
amazing features.
You buy one. You start using it. After a few weeks, you realize that a large
percentage of the time, you get cut off in the middle of a phone call. You
talk to other people. They all have the same experience with their phones.
It's just something they've learned to live with. They all just accept the
fact that the cell phone system isn't perfected yet, that it's just not as
good as the good ol' corded rotary phone which always sounded great, felt so
good in your hand, rarely suffered from RFI when you were transmitting on 20
meters, survived numerous falls onto the hard floor while you stretched to
reach a beer in the fridge during a phone conversation. Isn't that the way
it is?
There are many reasons, design decisions, that make folks claim their Ten
Tecs hear better. The decision to produce a ham bands-only receiver allowed
Ten Tec to use individual band pass filters for each band in the front end
which reject energy outside the ham band you're listening to. That's not
easy to do in a general coverage receivers like the 1000mp, which typically
use a really wide bandwidth low pass filter that lets everything up to 30
MHz to simultaneously hit the first mixer. But any time you can limit the
signal energy hitting the first mixer, assuming comparable mixer designs,
you necessarily have created a system which has better basic performance
because it is going to have a lower distortion level.
Another reason for better basic performance involves reciprocal mixing and
local oscillator phase noise. The modern general coverage receiver has
several IFs and therefore several mixers, a VCO that has to tune a (usually)
VHF first IF, and digital synthesizing techniques. For each IF, there is one
local oscillator and if that LO isn't pure, with very low noise sidebands,
those sidebands are mixed, transferred onto, every signal in the passband,
raising the effective noise floor. Digital synthesis, especially of a wide
bandwidth VHF VCO, cannot yet outperform analog signal generation techniques
such as is used in the Omni. (Forgive me if you knew this already, I just
want to make sure everyone is at the same level.) As the total signal power
hitting the first mixer increases, as we have already stated it does, the
noise level increase is more severe. (And we haven't even talked about
spurious signals yet.) This is a basic attribute of a receiver, and yet for
whatever reason most receivers compromise their performance in this area to
gain other features. Remember the cell phone?
You can simply look at a receiver's front panel and say, "Hey, this rig has
cooler features than that one," but you can't usually say, "Oh, this
receiver has better basic performance." That doesn't become obvious until
you either measure it or experience it in a demanding situation.
(By the way, a friend of mine just bought one of the latest, greatest rigs,
and when I asked him to turn up the mic gain he said, "Okay, let me get into
that menu," so even the front panel test may fail in the future as more and
more 'stuff' gets crammed into more and more menus!)
Finally, as I've stated on this reflector before, it's very likely that, due
to surface mount designs now in all new rigs, the Omni VI is going to be the
last transceiver that can be repaired by the competent ham. The vast
majority of hams just aren't set up to work on the surface mount stuff which
is only getting smaller and harder to repair. The new 0201 size chip
components are, no joke, about as big as a grain of sand. Of course, if
you're not into repair, calibration, modification, or tweaking of your own
gear, this isn't a concern.
A receiver is supposed to downconvert and detect a signal without adding any
distortion or noise of its own. For the reasons I've stated and others, many
believe that the Omni VI is simply better at performing this *basic*
receiver function.
Why don't you give the Omni another shot, this time appreciating the great
basic performance, at (sigh!) the expense of other bells and whistles? Keep
the Yaesu for the times when you want to play with the transmit audio and
listen to shortwave stations. Just kidding. Good luck whatever you choose.
Thanks for reading,
Al W6LX
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