[TenTec] O2 output level with PSK aux

Bob McGraw - K4TAX RMcGraw at Blomand.net
Wed Feb 11 15:45:16 EST 2009

I agree with all, except.......... set the Orion power output for 100 watts 
in the CW mode and then adjust the audio from the computer or interface or 
Line Gain to produce an output of 45 to 50 watts max during data 
transmission. Remember, when using the PWR control this is basically setting 
the ALC level threshold.

Yes the Orion meter and the Omni VII meter will show darn near correct PEP 
values with a PSK signal while external mechanical meters will likely show 
average values or something less than depending on mechanical ballistics, 
rectifier/detector characteristics and the weighting network.  I've found 
that the internal power indication is usually a bit lower than the actual 
output.  I attribute this to the scan rate of the processor looking at the 
power circuit.  At the same time an external meter like the Bird 43P looks 
at the power 100% of the time.

Also the PSK signal idle will show a lower average level than when sending 
data although the PEP values are the same.  I think most reports on PSK are 
average power values.  And yes if the IMD level is not running in the 30's 
with the Orion, Jupiter and Omni VII then all is not well with your 
transmission.  Just ask the receiving station to give you and IM report. 
Send about 10 sec of idle and see what the number are.  Data values will be 
in the 20's.

Bob, K4TAX

----- Original Message ----- 
From: <wa3fiy at radioadv.com>
To: <jmiller1706 at cfl.rr.com>; "Discussion of Ten-Tec Equipment" 
<tentec at contesting.com>
Sent: Wednesday, February 11, 2009 2:22 PM
Subject: Re: [TenTec] O2 output level with PSK aux

>A PSK31 signal is a two tone signal.   That likely accounts for what you 
> seeing on the 'scope.  That also accounts for the lower average power
> output reading compared to a CW output.   Somebody check my theory but I
> think a two tone signal of two equal amplitude tones having the same PEP
> as a continuous carrier will have an average power of 1/2 the continuous
> carrier.    Anyway any radio that is transmitting a PSK31 signal and is
> showing more that about 50% of the continuous carrier is non linear and
> should not be used or better, readjusted to operate in the linear range. 
> On
> my Orion here (and several other rigs as well) I set the O for 50 watts on
> CW with the PWR control.  The Power output meter shows about 52 watts.
> Makes sense.  My external power meter agrees.  When I run a PSK31
> signal JUST barely lighting the ALC led, I still show 52 watts on the O 
> power
> meter and about 25 watts on the external power meter.  That too makes
> sense if indeed the PSK two tone signal average is 50% of PEP.   My SB-
> 610 scope confirms that the CW PEP power and the PSK PEP power are
> identical.   This tells me that the O power meter displays PEP output and
> agrees very well with the setting of the PWR control.
> I have often wondered about PSK31 power reports.   When an operator
> says he is running 30 watts what is he talking about?   30 watts average 
> or
> 30 watts PEP?   2:1 difference.   Not that it makes much difference.  Just
> curious.   I always report PEP which I can read directly off the O power
> meter or the PWR control as long as I am tickling the ALC.  Finally, it is 
> OK
> to get a small alc indication on several Ten TEC's I've tested.  On both 
> my
> Pegasus and Orion, I consistently see IMD levels in the low 30's which is
> pretty good signal.
> 73,
> -Lee-
> On 11 Feb 2009 at 15:49, jmiller1706 at cfl.rr.com wrote:
>> 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
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec

More information about the TenTec mailing list