Mark
I apologise if I am repeating what has already been said but I saw your mail
and having just returned from Dayton, I have a bunch of stuff still to catch
up on. Anyway fwiw.
Unless your Orion is faulty, the overload problem you see is not caused by
hardware. I can say that quite categorically, because the effect was not
apparent before 1.372. Personally, I wouldn't waste time looking at D30/D31
or the front end devices.
Orion has two agc loops. One of these controls the gain of the analogue
front-end circuitry and the other the dsp back-end. These are necessary
because the dsp i/f itself does not have adequate dynamic range to cope with
the range of signal levels we experience.
Firmware 1.372 combines adjustment of analogue rf gain together with dsp
gain using the single rf gain control. This has been done in an attempt to
make adjustment of the Orion rx less fiddly and intimidating. The problem
is that the algorithm used to make the adjustment is imperfect. The
consequence is this is that the dsp gain can be set too high and therefore
overload in that part of the circuitry can occur. I believe the new V2
firmware will resolve this.
Whilst intuitively it seems a nonesense to believe the overload is a product
of the firmware, this is nonetheless the case. As has been suggested
already, the hardware is pretty much rock solid as evidenced by the various
reviews which have been carried out by third parties. A temporary
regression to firmware 1.371 should confirm this for you.
Of course, if your findings are at odds with the above, then conceivably you
have a hardware problem with your Orion and I am sure Ten Tec will be able
to help. More likely, you will find what I have described.
73 Bob, 5B4AGN
----- Original Message -----
From: <wq7x@cox.net>
To: <tentec@contesting.com>
Sent: Tuesday, May 24, 2005 5:19 PM
Subject: [TenTec] My new Orion
> Bill:
>
> Thanks for very comprehensive response. I agree with you 100%.
> 1. Orion is the best for BDR and IMD but not with 1.372.This just kills
the RX.
> 2. Orion is not as good as K2 or IC7800 with 1kHz spacing and S9+35dB
signal only because of 1.372 firmware.
> 3. I know that people in EU reporting great results for BCI overload. That
is why I'm puzzled why I have this problem.
> I will borrow from my QRL the spectrum analyzer and check what is
going on. However some others in private
> emails did report similar problems. Look at the schematic-there are
two protection diodes at the input of the
> RX -D30 and D31. I think that AM station drives them in nonlinear
region. I will check that. Orion attn. doesn't
> improve overload, so it has to take place before the attenuator.
External high pass filter eliminates the problem.But than I can't receive
anything below 1.3MHz.
>
> This is the second time that I have purchased the ORION. First time almost
two years ago.
> This time I will not send it back to Ten Tec. Many problems are fixed
(including hardware NB -was really ON in OFF position)
> It is so close to be superb TRX. That doesn't mean that we should be quiet
about some remaining problems.
> Orion has very quiet RX. Pleasure to lsn. at night. Also, WOW no fan
noise. Where is the fan? Hi Hi. Great.
> Audio quality in SSB on RX and TX - out of this world. I liked better than
IC7800.
> To me narrow roofing filters and very low phase noise is necessary in
well design RX. I use to design and build many RX myself.
> I'm really happy that there is a company which understands the basics of
good RX design. In Japan they are still learning.
> We all should agree that IC7800 is very well designed TRX and mechanically
is the best. Very solid and high quality.
> They just forgot about basics of the RX design. Still don't understand how
could Icom not pay attention to the phase noise.
> Their DSP in CW however is just incredible. But this is just not good
enough for me.So, Orion is my main Trx now.
> Best 73! Mark WQ7X
>
>
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