Hi Luis,
have you an idea about the Q of this coil?
A 11m vertical without a capacitance hat need
a coil of about 1.7 mH for resonate
at 472 KHz, so a reactance of about 5 Kohm.
If you divide the reactance with the Q you obtain
the Rloss of the coil.
I do not think that a thin wire coil wound on a PVC
support can have a Q much over 100 so,
you will have a Rloss of about 50 ohm that you must
add to the ground loss.
A 11 m vertical without capacitance hat has about
0.1 ohm of radiation resistance.
I do not know how much loss have your ground system
but you said of one 11 m wire...
I am very optimistic saying another 50 ohm. So you
will have 0.1 ohm of radiation resistance
with 100 ohm in series... a 0.1% efficiency...!!
With 100W and considering a directivity of 1.8,
you will have an EIRP of 180 mW.
I would start to consider an air wound coil made with thicker wire
or a Litz wire, with the turns spaced.
73, Fausto IK4NMF
----- Original Message -----
Sent: Monday, October 19, 2015 12:52
PM
Subject: RE: LF: EA5DOM going
vertical
Hi Stefan
This is a picture of the coil
25cm diameter pipe, 90 cm high
I can also fit this variometer on the top side of the
pipe
The -3dB of my signals yesterday are probably due to QRN on
the Rx. We had a big storm down in south EA
Another one is predicted for tomorrow just here and strong
rain. No good for installing the coil
Hi Luis,
Am 18.10.2015 21:59, schrieb VIGILANT Luis
Fernández:
For the transformer I plan to recycle the one osed for the
loop. It has two big toroids 80mm external diameter
and 8mm thick. Both joined make 16mm thick.
Unfortunately don't know which is the material
used
Hm, sounds not optimal, somehow :-) But
just start with a 1:1 transformer and a 50 Ohm dummy load as a first test. If
the transformer stays cold and the load (e.g. power consumption, or current
meter reading of the power supply) is the same with or without the
transformer, everything is fine.
Can be primary and secondary be wounded one on
top of the other ??
Yes, this is
recommended!
Tonight reports on my remote monitor are 3dB
down. I made a modification
I have finally connected a wire from top
terrace to the fire extinguish pipe which runs inside the building
down
to the basements, were pumping system is
located. The wire is not yet connected to the ground side of the
vertical
BUT the actual radial counterpoise runs
parallel to this wire for about 5m
Seems like this can be the cause of 3dB
looses.
...but maybe the situation is different
when matching the PA properly. In the moment you don't know at all what the
feed point impedance is. ...and how the PA behaves at that impedance
connected.
RR. GL,
73, Stefan
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