In a radio communications circuit with a logarithmic signal strength display,
10% is
less than 1/2 dB and the meter increments are typically 1 S unit of 6 dB, that
1/2 dB
error is not detectable. And since propagation over any but very local paths
varies
instantaneously more than that being half a dB short or long on power has no
practical
effect on successful communications. So while it affects the heat to the dummy
load as
measured by the wattmeter, it doesn't affect communications in a practical
manner.
73, Jerry, K0CQ
---------- Original Message -----------
From: Richards <jruing@ameritech.net>
To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Sent: Thu, 10 Dec 2009 02:48:57 -0500
Subject: Re: [TenTec] Omni VII Query
> With my learner's permit in hand, I wonder how you
> tested output - CW... SSB ... or some more exotic
> measure?
>
> Also what is the error tolerance (+/-) of the meter, I
> have read some have as much as 10% variance +/-
> and if so, it could be that you are getting 95 watts out
> and reading only 85 ?
>
> Also, when you tested, what was the load - antenna, or
> dummy load, or can/do you test at a point earlier in
> the system? I am taking it that the "lab grade" 50 ohm
> load is a high quality dummy load (i.e., a known quantity).
>
> I am not being critical... just looking to learn and apply
> a limited knowledge at this point.
>
> Thanks.
>
> ============= JHR ==================
>
> Val Erwin wrote:
> > Omni VII-ites'
> >
> > I have an Omni VII that is appx. 2 years old. Over time, I have noticed a
> > gradual
decrease in RF output power.
> >
> > With 13.8 VDC measured at the radio power connector, the Omni VII
> > digi-panel states:
"Power 100W". Yet, when the RF output power is measured with a lab-grade
50-ohm load
and either a Bird 43 or a calibrated oscilloscope, the measured RF power is
actually on
the order of 85 watts output, regardless of band.
> >
> > I suspect I have an aging component sitcheeashun'..........Is there an
> > internal
control to crank the RF back up to spec??
> >
> > TNX in advance for any feedback.........
> >
> > Val / W5PUT
> > _______________________________________________
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> > TenTec@contesting.com
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> >
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------- End of Original Message -------
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