Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Carl -
If you have a VTVM or DMM with a 10-11M input impedance, all you need is
an RF probe.
<http://www.io.com/~n5fc/rfprobe2.htm>
Measure the RF voltage across your dummy load, (after measuring what IT
really is in ohms,) and calculate power. So if your RF voltmeter reads
71V RMS at 14.1 MHz and your load is exactly 50 ohms, your meter should
read 100W. E= sqrt(P*R) or 100 * 50 = 1500 sqrt = 70.71 VRMS.
The Drake wattmeters are pretty good, about as good as any of that type
of meter. (Breune circuit) They are by definition, NOT precision
meters, being specified as +/- 5% of _reading_, +2W on the 200W scale,
i.e., +/- 7 Watts when reading 100W. They also can vary +/- 5% from
band to band. Of course ANY standing waves on the coax will add (or
subtract!) from these errors.
You can then reverse the connections to the wattmeters and calibrate the
Reflected scale the same way.
By the way, do NOT put them all in series to calibrate, one at a time
with short coax jumpers.
And no, you can't have too many black boxes.....!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
[EMAIL PROTECTED] wrote:
Hello all,
Anyone around Ohio have the equipment to properly align W4's and an MN4C ?
Would really prefer to have the MN4C corrected first.
Using my TR5 and not changing anything, working into a dummy load (oil
can).
One W4 (which I think I trust) shows 90 W ...was not driving full
tilt, another W4 (Dayton style) shows 75 W and the MN4c which I have
been using with a TR4c says 35 W....oh yeah the MN4C is another Dayton
special.
W4 manuals have an alignment procedure, MN4C does not and I don't have
the equipment (per W4 manual) to do it anyway. Am thinking of taking
the MN4C and adjusting the pot to an average of the W4's, of course
that does nothing for the SWR readings. But then like all things the
original adjustment can't be that far off probably there is a problem,
which whatever it is ...is not apparent. All appears original, both
diodes appear functional with forward bias at .319 & .310 (mv)
restpectively.
Carl Hibbard WD8NHK
Wife once again (upon hearing me gripe) says "to many black boxes".
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