Topband: Receivers

[Bill Tippett <btippett@alum.mit.edu>]

Hi Tom,

W8JI wrote:
>I'd say this effect amounts to only a dB or two effective
difference in signal-to-mush, but that often is the
difference between reading and not reading an ESP signal. It
also means how our ears and mind processes weak signals has
a large effect on how we like the Orion. The bottom line is
some people are just not going to like the AGC system. I
would describe it as very "mushy" sounding when looking for
weak tones in the presence of noise, unless you get the
settings correct. Some operators will be able to find a spot
they like and love it, some are going to hate it.

        I very quickly discovered Orion's AGC Threshold acts
like the traditional RF Gain control in other receivers.
For that reason, it SHOULD have been brought to the front
panel and I hope Ten-Tec may eventually do that.  IMHO they
could have swapped their front panel RF GAIN control (which
I seldom touch) with AGC Threshold which I adjust much more
frequently.

        The thing which I did NOT learn for about 6 months was
the effect of Decay and Hang on very weak signals.  Thanks
to Sinisa YT1NT, he described this in his paper below:

http://www.geocities.com/va3ttn/UsingOrionRX.pdf

To make a long story short, the following is what I learned is
very critical for receiving weak signals at the noise floor:

"AGC DECAY can be kept at 5 dB/s (slightly faster in contests), with
AGC HANG time at 0.30 - 1.00 seconds."

        I've now been using an Orion for 15 months.  Although its AGC is
the most different aspect of learning to use it, once you do its AGC can be
a major benefit.  Unlike traditional rigs, you do not need to continually ride
the RF and AF Gain controls once you get it set for a particular antenna.
This is especially noticeable in contests, and I feel it has helped me copy
more weak callers correctly the first time.  This also makes for much less
operator fatigue.

        Like you said, there is no perfect rig.  Everything has its plusses
and minuses.  For me Orion's plusses, especially strong signal handling
performance in contests and on the low bands, far outweigh its minuses,
but I'm sure others would reach the opposite conclusion as you said.

        I simply don't buy Earl's argument that Orion is a "dud" for weak
signals.  In the most recent CQ WW SSB, I had the highest number of 10m
DX QSO's of any USA station.  All multiop stations below have much larger
antenna systems, multiple operators, dual positions, packet, etc.  My NC
QTH is not the farthest south and my ears cannot be that much better than
others. If Orion is preventing me from hearing weak DX signals, I cannot
understand these results and hope someone will explain.

http://lists.contesting.com/archives//html/CQ-Contest/2004-11/msg00158.html

Total 10m QSO's:

W4ZV  1862
KC1XX  1766
W3LPL  1627
K9NS  1533
K3LR  1463 (M/2, so not really a valid comparison)
NQ4I  1458

                                        73,  Bill  W4ZV









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