Hi Stefan, MF
Sunshine again here (standard weather ON) :-)
The vertical antenna is an Ultrabeam, SteppIR like. So it is a glass fiber wip with the electric conductor inside
In order to get top capacity the idea is to hang a T wire from the top of the fiber whip. Using a pulley I can get
down the wire antenna easily, and still keep the dynamic vertical antenna for other purposes. So I'll have a
11m vertical side and a pair of lines on top which can be up to 10m long each. I can also make an inverted L with
only on horizontal line. I will use the big coil as
variable coil to find the optimal value
Will get the
1.5mm^2 What is available here is multi wire (litz ??) single wire is no longer in the market, so they said.
Is it recommended also for the coil ?
Looking for bigger coils I recall that beer coolers uses a nice metal pipe coil in the heat exchange stage. This stuff
can be found in scrap from used or failed units and looks interesting
73 de Luis
EA5DOM
Hi Luis,
Lol. Yes, maybe an antenna analyzer helps to understand things.
For the coil i would use isolated mains electric wire. We have 1.5mm^2 and 2.5mm^2 here in DL. Also there is 0.75mm^2 for some installations. 0.75 or 1.5 is a good choice for you i would say. I think you can get a Q of 250 or so, which is fine. But sooner or
later you will need a bigger PA, HI :-)
73, Stefan
Am 19.10.2015 17:24, schrieb VIGILANT Luis Fernández:
Hi Fausto, Stefan, MF
That's what I need. Discussion and brain storming ! :-)
Yes. The coil has too many wounds and should be about 3.9mH
It is the first time I ty to make such a thing so I used all the wire I had to see what I can get. I can redo it and it is part
of the game. No problem
The internal variometer is what everybody uses in such a big coils. So, has sense to go that way
>>have you an idea about the Q of this coil?
Hi Luis,
Nice looking coil. It has a good ratio between diameter and length although it would have been better to have a small gap between the wire turns. And i didn't expect that you need so much L. What is the L of this coil? Looks like 3 mH or so. You will need about
2 mH. But i can't se the actual number of turns. Probably it is just right :-)
I would build my own variometer, i.e. drill 2 holes into the tube, add an axis and put another coil on this axis.
https://dl.dropboxusercontent.com/u/19882028/MF/20141027_203720.jpg Like this image. Ehm, what you can see there will not
happen to you i think. But anyway, be careful with high voltage!
Good luck!
73, Stefan
Am 19.10.2015 12:52, schrieb VIGILANT Luis Fernández:
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