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dxAce wrote:
dxAce Apr 17, 3:11 pm show options
Newsgroups: rec.radio.shortwave
From: dxAce - Find messages by this author
Date: Sun, 17 Apr 2005 18:11:26 -0400
Local: Sun,Apr 17 2005 3:11 pm
Subject: splitter ?
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Yes, the calibration may indeed be off with various manufacturers,
however all things being equal it should be very easy to determine
various antenna changes with a 'particular' receiver.

Damn simple.

dxAce
Michigan
USA
---------------------------
Sadly very few radios have S-meters that behave in a "correct" way.
I have a HP calibrated step attenuator, with .5dB steps. Zin 50Ohm
Zout 50 Ohm. When checked at the electronics lab (at UK) the
error was less then .07dB worst case. I have a simple crystal osc that
is very temp stable. Zout 50 Ohms at .1V. Measured to be 0.10V.

I have had chance to check quite a few receivers. From the famous
R390, to one of the Lowe 150s. I would have to dig out my notes, if
I even still have them, and the R390 was the ony one that tracked
6dB/1S unit.

This url has better data then I can dig out out the moment:
http://www.ac6v.com/sunit.htm

Unless you know, that is have measured, your S-meter, it is only
a rough indication.

Yes, of course. (No ****, Sherlock)

You can clearly use your S meter to compare one antenna to another,
but I would be very hesitant to say that "antenna 1 is S2 and antenna
2 is S6, therefore antenna 2 has 24dB more gain then antenna 1."

No one was trying to say that.

Based on the assumption that 1 S unit equals 6 dB.
S6-S2=4 S-units, 4 X6dB = 24dB
(Math shown for those new to the hobby)

Now if you have a calibrated step attenuator you could show that:
Ant 1 gives S2
Ant 2 requires 20dB of attenuation to give a reading of S2.
Ant 2 has about 20dB more gain then Ant 1.

I bought my Hp attenuator at a surplus store for $5.
I bought 2 fox industries 50P-077 +12V BCD attenuators
that have a measured error of less then .01dB for $1each!
Coupled with some Pasternak PE7101 coaxial relays I hope
to be able to some "meaningfull" antenna experiments this
summer and next winter.

There is a vacant lot caty corner behind us and I have permission
from the lot owner, and both my rear and next door neigbors to run
an temp antenna to and across that lot. I will be able to get about
300' of wire up in a straight line. I intend to see just how length
effect
signal strength.

Next fall a frined is going to let me spend a few weekends on his
fields to check even longer wires.

Yes.. but you wasted most of the space above to say nothing.

Boggling to say the least...

I'm more and more amazed here everyday.

Continue to tote.

dxAce
Michigan
USA