Your problem must be that you have a relatively high resistance, which drags down the overall Q.

What resistance do you calculate given the known Q, inductance, etc?

I get ~160R, which sounds about right (say, 40R for antenna, 60R for losses, 60R for Earth).

...... Zim

I get ~160R, which sounds about right (say, 40R for antenna, 60R for losses, 60R for Earth).
>>>>>>>

Sorry - don't know how to calculate those values. I got a value of 76 ohms at resonance for the lot? see other post, page1.

http://www.midnightscience.com/rapntap/topic.asp?topic_id=5505&forum_id=9&Topic_Title=Ground+resistance&forum_title=Rap+N+Tap+Clubhouse+-+Basic+Crystal+Radio+Fun!&M=False&S=True

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I think you need to build a noise bridge.

............. Zim

With a series loading coil, put a low value (~10 ohm) resistor to ground, peak the coil, and measure the volts across the resistor with your CRO.

Then substitute a higher value resistor (~100R), measure the volts again, and with a little mathematical jiggery-pokery calculate the third and missing resistor (eg the antenna resistance).

Should keep you quiet for a bit :-)

Simple case of proportionality?

Too good for me, can't form a connection between the two. Not enough info?

Current through ground is the same as that through each of the respective resistors but not equal in the 2 cases.

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I get
Total Antenna resistance = 57.5 Ohms
and
Antenna voltage source = 47.25 mV

Now that you have series R, as well as Freq and Q, you could calculate the theoretical antenna L and C and compare it with what you measured earlier.

.......... Zim

Q=1/R*sq.rt(L/C)

Substituting assumed values for R and L (previous posts),

Q=1/57.5*sq.rt(18uH/184.5pF)
Q=5.432

Measured value (3dB B/W method)
Q=5.42

QE "freak-in" D

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.......... Zim

Don't understand the question?

Can't measure antenna L, that was calculated from previous experiment, see thread. Antenna to ground C was measured and inserted in the Q formula, along with the calculated Ant. L and your calculated R.

C & L of tank was not measured in this final experiment.

Measured the "unloaded" coil Q, on the HP (at the current core setting), at 963kHz, for a Q = ~900.
(Yes, that is my best core, 17mm diam x 240mm long.)

Obviously the Q of the antenna swamps the coil Q.
ie. With a good coil, the measured Q of a single tuned series set would be the Q of the antenna?

"Real" Q of the antenna is probably fractionally above that measured ( probably by a factor of 5.4/900? (0.6%).

..............

How accurate the measured C is?

And the inductor measured in the Q meter?

Measuring L on the Q meter is not as accurate and "real" values have to be recalculated from graphical approximations.

If you need me to do a special test and measure particular values of components under particular circumstances, you would have to list them in very basic terminology.
(There are two L's and two C's involved in the inductively tuned set.)

As requested in the other thread, anyone willing to corroborate my findings at other frequencies would be appreciated (it's a pretty simple setup for anyone with the right equipment).

(Can't understand the deathly silence - I hereby enter the words "free energy" and "oatbox" as a discussion stimulant.)

That's what I was curious about.

The AADE measures at DC or audio (I think) so I was wondering if measurements at the operating frequency would differ.

The capacitance for instance is distributed along an inductive wire...

But I guess that would require a RF bridge or similar...

........... Zim

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It would be interesting to know if the method is actually viable across the range of less than 1/4 wave antennas though.

As long as there was reasonable accuracy I would be happy.

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