RadioBanter - View Single Post - Current in antenna loading coils controversy

November 5th 03, 07:39 PM

On 05 Nov 2003 14:39:57 GMT, oSaddam (Yuri Blanarovich)
wrote:

We are back to this line of "reasoning":
.....and if we rip all four legs off the frog and say "Frog jump", frog doesn't
jump. The "conclusion" is - Froggie is deaf :-)

....

I am gathering material for test setup allowing to measure RF current in every
foot of the loaded antenna, I have two 8 amp meters, so I will have to use some
power for full deflection, but it will be just another level of the same thing.
You are all invited to witness! I will document it, take pictures and video.

Hi Yuri,

Good engineering starts with a plan. You start with the instruments
you have available. This is the line of "reasoning" where, if you
have only a hammer, all problems are nails.

It took no more than 1 minute to summon up my EZNEC file of your test
set-up (which you have still failed to confirm, deny, amend, or
specify) to observe that your comment:
so I will have to use some power for full deflection
which is rather low on specifics to observe for myself this must mean
100W as the base current for the model comes quite close to the 8
Ampere full scale deflection for 100W drive.

However, we get into issues of your having done work at the 100mA
levels and we thus turn to my earlier comments about accuracy.

100mA on an 8 Ampere full scale 3.5 inch meter is slightly more than
1% deflection (less than the width of the needle). The 100W
excitation current levels near and through the model's solenoid
exhibit values in the 1 Ampere region or at 12% deflection for an
instrument that is arguably as accurate as 10%. This does not bode
well for a compelling exhibition of any conclusive results.

NOW, if I were wrong to presume that 100W is going to be the
excitation - is that MY fault? If we jack up the power applied
(easily within the means of an amateur so empowered, so to speak) then
that region can certainly be forced into readings of vastly improved
accuracy relative to the available metering. HOWEVER, this now
inhibits doing the full length survey because the lower section would
clearly overload the metering. You can't win for losing.

Well, you can win if you are accomplished at the bench (a rare talent
in this ivory tower where merit is weighed by angel population counts)
by modifying your metering through shunts. I will warn you, however,
it is incumbent upon you to reveal how that was accomplished, how it
was confirmed and the data to support that too. You will also have to
measure the surface temperatures and conspire to replicate them to
your metering (something that you have not really responded to) to
observe the systematic error introduced by these ever growing power
applications. This, in a sense, is a turn of "you can't win for
losing, but you can get close, but you still might lose anyway."

I might add that you stand every chance of being slow cooked while
taking readings. Both for safety's sake and accuracy (so as to not
disturb the fields and those readings) use a telescope. We don't want
your video to appear on FOX. I will add for the sake of anticipating
the gowned one's suggestions, remote readings through extended leads
will invalidate everything.

73's
Richard Clark, KB7QHC