At 09:32 PM 8/10/98 -0500, you wrote:
>
>I know the MFJ-259 puts out a weak signal. How weak is it
>really? Has anyone used the MFJ-259 as a signal generator
>standard to check coaxial cable runs? That is, feeding the
>output of the 259 directly to the antenna input of the radio to
>baseline the s-meter reading, then feeding the 'antenna' end of a
>coax run and reading the radio s-meter?
>
>It seems like a step attenuator would be appropriate, but has
>anyone done it successfully without one?
>From KH7M:
>>Per the manual, the new 259B has an ouput into a 50 ohm load
>>of about 20 milliwatts, or +13dBm, or 3 volts, peak-peak., harmonics
>>-25 dBf.
First:
For reference, most S-meters are (supposed to) be calibrated to read
S9 at 50uV. That correlates to -73 dBm. +13dBm is 80dB stronger.
Your 20dB attenuator will still have the signal pegged at +60dB over S9.
Second:
There's always been a major debate as to the calibration of S meters.
3dB per division, 5dB per division, 6dB per division, etc.
So, even if you could use an attenuator to get the 259 in range, you
have no idea of what the calibration of your S-meter.
The new MFJ-259B really kicks butt!!! Just disconnect the antenna/load
and it reads loss right on the screen! Well worth the $190.
---
Chad Kurszewski, WE9V e-mail: WE9V@qth.com
The Official "Sultans of Shwing" Web Site: http://www.QTH.com/sos
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