LF: Field strength of PA0SE and DCF39

["Dick Rollema" <d.w.rollema@freeler.nl>]

To All from PA0SE,

This morning I measured the field strength of my transmitter again, after
improving the insulation at the feed-through of the aerial to the shack,
using the centre conductor plus insulation of RG-213 coax, surrounded by
a paxolin tube through the hard wood window frame.

In the open countryside  at 5.83km from the aerial field strength
was 610 microvolt/m. From this follows a radiated power of 140mW
EMRP.

Transmitter output 300W
Aerial current 3.2A
 From this follows:
Total resistance in the aerial-earth system is 300/(3.2 x 3.2) = 29.3
ohm.
Loss resistance in the coil  9.3 ohm.
Earth resistance  29.3 - 9.3 = 20 ohm.

When measuring FS I always measure the FS of DCF39 as well.

This morning  I found FS = 1.29mV/m in the countryside. This is
remarkably low.
On 12 April 2000 I found 1.93mV/m
On 4 December 2003 it was 2.13mV/m.
                     
But when I measured FS in the afternoon in the shack it was back at 
2.13 mV/m again.  (On an earlier occasion I have found that FS of
DCF39 in the shack does not differ from what I measure in the open
country, which is rather remarkable.)
So it seems DCF39 suffered a temporary power reduction this
morning.

73, Dick, PA0SE