Richard .
This bit may of been missed
////// Any ideas?
////// Incidentally, am I best to measure current in the link or in the
aerail
////// wire?
The ammeter 'has' to be at the point of feed to the Ae and 'not'
within the ATU ie in a link .. the circulating currents within the tuner
may be extremely large and peak voltages also may be vast , due in part to
the Q of the tuner
.. my home brew 80 mtr tuner used to un-solder the tap's on the coil
and the ww2 cellulite coil separators used to flash over ....
As for measuring power with the ammeter into the antenna this is
virtually impossible , unless you have a calibrated power meter and are
able to , measure the losses in the tuner and the power supplied to the
tuner/Ae with a near perfect match , the current value then may be
extrapolated and used as a relative measurement .. for that frequency . with
that Ae at that time due to the load being 'complex'
G ..
--------------------------------------------------
From: "Richard Newstead" <[email protected]>
Sent: Friday, May 15, 2009 5:01 PM
To: <[email protected]>
Subject: LF: Aerial current
After my success in getting more current into the aerial yesterday I
decided to measure the RF current in the link (link coupled ATU) with a
proper RF ammeter. I was somewhat surprised that the current pinned my 1
Amp RF meter. How can that be? I can think of some possible reasons:
1) The meter is wrong (it must be nearly 70 years old)
2) The impedance is not 50 Ohms which is odd because I assume the TX is
designed to have a 50 Ohm output and I carefully adjusted the link for
maximum power transfer last night).
3) The transmitter is giving out far more power than expected (seems
unlikely).
Any ideas?
Incidentally, am I best to measure current in the link or in the aerail
wire?
73
Richard
PS - beacon on again 501.6kHz.
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.287 / Virus Database: 270.12.29/2114 - Release Date: 05/14/09
06:28:00
|
