[TenTec] O2 output level with PSK aux
wa3fiy at radioadv.com
wa3fiy at radioadv.com
Wed Feb 11 15:22:37 EST 2009
A PSK31 signal is a two tone signal. That likely accounts for what you are
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.
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.
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