[TenTec] O2 output level with PSK aux

[Bob McGraw - K4TAX]

In thinking about this a bit more, if the slow sine modulation is seen while 
using the PSK mode then I would suspect the 2nd harmonic, being 62 Hz, of 
the PSK signal beating against the 60 Hz line freq producing a 2 Hz 
difference and modulating the PSK signal.  Now the real question, if indeed 
it is the 2nd harmonic of the 31 Hz PSK signal, then where is it being 
generated?

Typically 2nd harmonics come from a single ended stage that is incorrectly 
biased or is being over driven.  Sound card, interface box, input stage to 
the radio are all suspect and good places to start looking.

73
Bob K4TAX

----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Wednesday, February 11, 2009 1:35 PM
Subject: Re: [TenTec] O2 output level with PSK aux


> Could that slow sine modulation be the beat frequency between the 3rd 
> harmonic {180 Hz} of the AC mains and the AFSK signal since the shift 
> frequency of 170 Hz?  The difference being 10 Hz.  I would think this will 
> appear as a bit of a warble on the signal.
>
> I looked at my Omni VII output on the monitor scope using MixW2 in the 
> RTTY mode and didn't see anything that shouldn't be there.
>
> I then looked at the PSK signal at about 45 watts out and it looked 
> normal.
>
> I'd be suspicious that something isn't correct if there is something else 
> running through the signal.
>
> All of my measurements and observations were done at -3 dB below rated 
> output or at about 45 to 50 watts.  With tone, there is no ALC action at 
> this level and the SP is off.  I suspect that feeding a signal such that 
> the level is 90 watts output then one is likely getting into the ALC 
> range. This may be the cause of concern and source of results reported.
>
> 73
> Bob, K4TAX
>
>
>
>
>
>
> ----- Original Message ----- 
> From: <jmiller1706 at cfl.rr.com>
> To: "Ron Castro" <ronc at sonic.net>; "Discussion of Ten-Tec Equipment" 
> <tentec at contesting.com>
> Sent: Wednesday, February 11, 2009 2:49 PM
> Subject: Re: [TenTec] O2 output level with PSK aux
>
>
>> Thanks to all for the suggestions.  On RTTY AFSK (basically a constant 
>> carrier)I do get about 80-90 watts out on second measurement, with 
>> Navigator set to max outputs.  The Navigator still seems to be a bit 
>> light on drive for an Orion however.  Now, looking at PSK on a scope, I 
>> see that it is not exactly constant amplitude when idling, as I had 
>> assumed erroneously previously - seems to have a slow sine modulation 
>> envelope on it.  I assume that's normal (?).   This could account for the 
>> lower average power reading on the wattmeter in that mode.  When I set 
>> the wattmeter to peak/hold, it shows close to 90 watts (by capturing the 
>> peak).  Of course that's too much, but I think that explains some of the 
>> discrepancies.
>> N4BE
>>
>> ---- Ron Castro <ronc at sonic.net> wrote:
>>> I observed the same things in my O2 regarding the power output readings.
>>> While the meter only seems to be accurate at the 100 Watt level, the 
>>> power
>>> setting control is amazingly accurate.  Using both a Bird 43 and a 
>>> Telepost
>>> LP-100 the settings agree with the true output power within 2% to 5% 
>>> from
>>> about 20 Watts to 100 Watts CW out.
>>>
>>>          Ron  N6IE
>>>       www.N6IE.com
>>>
>>> ----- Original Message ----- 
>>> From: "Merle Bone" <merlebone at charter.net>
>>> To: <tentec at contesting.com>
>>> Sent: Wednesday, February 11, 2009 9:49 AM
>>> Subject: Re: [TenTec] O2 output level with PSK aux
>>>
>>>
>>> >I think it is very hard to know what the "power readings" of the Orion
>>> >meter
>>> > really mean. Actually, most,
>>> > if not all, of the Orion meter readings are "relative." The power 
>>> > meter
>>> > description says"
>>> > ----------------------------------------------------------------------------------------------------------------------------------
>>> > ANALOG METER
>>> > In transmit, the meter shows approximate output power (+/- 5%). The 
>>> > power
>>> > meter is
>>> > a sampling-type meter and will stay more or less constant when 
>>> > sampling
>>> > power output,
>>> > particularly when the transceiver is used in CW mode."
>>> > ----------------------------------------------------------------------------------------------------------------------------------
>>> > I take from this description that the meter is "some form" of average
>>> > reading meter. All Orion/Orion II
>>> > meter readings are really from "calculated" numbers from the DSP and 
>>> > then,
>>> > through a Digital to Analog
>>> > converter, drive the analog meter. "Average" meter readings are always 
>>> > a
>>> > function of the "averaging time constants"
>>> > in the meter and the "time varying levels" of the waveform being 
>>> > measured.
>>> > These are almost never the same
>>> > and, unless you are using a "very high sampling rate meter" - like the
>>> > LP-100- that then does the math to
>>> > compute an average, the readings are - at best - relative and 
>>> > approximate.
>>> >
>>> > I never use the Orion meter to give me power readings, except on CW,
>>> > because
>>> > I have never figured out what
>>> > they really meant. I think on "time varying signals," you are better 
>>> > off
>>> > to
>>> > use an external "peak reading meter"
>>> > to set the Orion peak power and then accept the average power that 
>>> > results
>>> > from the time varying input signal.
>>> > If there is concern for "intermodulation distortion," then you can 
>>> > reduce
>>> > the peak Orion RF power to a level where
>>> > you believe the Orion will be "most linear," - maybe down 3dB to 6dB 
>>> > below
>>> > the Orion's rated RF power output.
>>> > Of course, this doesn't ensure a clean output signal. You can reduce 
>>> > the
>>> > Orion RF peak power output and still have
>>> > an audio overdrive situation - creating signal distortion in the audio
>>> > before it gets to the RF drive of the Orion.
>>> > In the case of signals that are very sensitive to distortion, such as
>>> > PSK31,
>>> > an external monitor - such as the
>>> > "PSK31 Meter" display monitor may be more useful then power meters to
>>> > assure
>>> > a good output signal. If you
>>> > have a time varying signal like voice, then you can use the Orion
>>> > compression, with a high sampling rate, - which
>>> > is some of the best I have ever seen for voice (See
>>> > http://lists.contesting.com/archives//html/TenTec/2009-02/msg00075.html )
>>> > - to increase the average RF Orion output power. The Orion meter still 
>>> > is
>>> > only giving a "relative" power measurement.
>>> > 73, Merle - W0EWM
>>> >
>>> >
>>> > _______________________________________________
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>>> >
>>>
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