[TenTec] Orion2 Problem with indication of the analog meter

[Ron Castro]

I agree that something else must be going on.  Analog meter ballistics might 
effect what you see under SSB or CW signals, but I ran my test with a signal 
generator using fixed levels and found the discrepancies shown on my website 
(http://www.n6aha.com/Orion%20S%20meter%20descrep.htm).  The 'easy' fix 
would be to make a new meter face, which could be field installed if done 
with care.  That could also address the Wattmeter problem.

Another interesting discrepancy is that the S  reading drops 6 dB when both 
receivers are on the same antenna, which makes sense considering the 
loading, but there is no compensation in the precision arithmetic when this 
occurs.  Nor is there for the preamp, which is handled in many radios like 
the TS-870 by a menu setting that allows for automatic compensation if you 
want it when the preamp is on.

An accurate S-meter may not seem like a big issue, and I have learned to 
live with it, but it is an important tool that can be used to compare 
antennas, check F/B ratios of beams and other projects.  If you have a local 
ham who can transmit a steady signal, using the claimed accuracy of the 
digital output of 1/10 dB, or even 1/2 dB, you can make meaningful pattern 
studies of beams.  If you have a SteppIR antenna, you can use that to tweak 
the settings or to explore the forward gain vs. F/B issue that all of us 
have thought about at one time or another.

Ron Castro
Chief Technical Officer
Results Radio, LLC


----- Original Message ----- 
From: "Bob Henderson" <bob at 5b4agn.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Thursday, September 14, 2006 6:12 AM
Subject: Re: [TenTec] Orion2 Problem with indication of the analog meter


> Bill
>
> I'm not sure this explanation holds water.
>
> The 8 bit D to A will reduce that 1/10th dB resolution from the precision
> arithmetic to 114/256 dB or just better than 1/2 dB.   Unless the S-meter
> movement is really bad, there's something else at work here.
>
> 73
>
> Bob, 5B4AGN
>
>> **********************************************
>> At times my S-meter doesn't seem very accurate, why is that?
>>
>> Precision arithmetic is used to calculate the S-meter measurements
>> and the (digital) output is extremely
>> accurate. The digital S-meter readings can be read over the serial
>> port using the ?S command. The
>>  s-meter numeric precision is roughly 1/10 of a dB.
>>
>> The analog meter is the analog representation of the digital S-meter
>> result. The meter accuracy is affected
>> by two things. First, the meter is electromechanical and subject to
>> manufacturing and environmental
>> variations. Second, the DSP/Logic board drives the meter through an
>> 8-bit Digital-To-Analog converter
>> which limits the meter to 256 steps.
>> ***************************************************
>>
>>         The PWR control seems to be fairly accurate
>> except at the lowest settings.  The minimum power I
>> can set on my Orion is about 4 Watts at a setting of 1.
>>
>>                                 73,  Bill  W4ZV
>>
>
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
>