----- Original Message -----
From: "WE0H" <[email protected]>
To: <[email protected]>
Sent: Tuesday, October 08, 2002 10:39 PM
Subject: LF: RE: RE: Re: RE: Lasso alias loop
Hi Mal,
I would be interested in hearing your test results of adding the
transformer
and series resonating the loop wire. That would give us guys some idea of
how a real big loop works. See my web page for an idea of a Loop Tuner
Box.
It shows the transformer and caps so you can get an idea of what Bill is
describing to you. I thing high voltage Door Knob caps would work for
resonating the loop wire to 136kc. You should be able to use one of those
Phillips ferrite cores for a transformer. Please don't be offended by any
of
the US guy's comments. As Bill said, we like to joke around and laugh with
each other on the reflectors. If you can, would you email me some pictures
of your loop and vertical. I would like to see what you use.
Thanks and 73's,
Mike>WE0H
Hi Mike
I am not offended by any observations and welcome constructive critisism. At
times I disagree with others if I think they are wrong or missing the point.
Usually we can all learn something from another persons experiences.
My loop is parallel resonant and matched at the feed point of the loop to 50
ohms, which as you say is the correct place for the matching. Some use the
matching network at the shack end for convenience and it works but not the
correct place in my opinion.
I have not yet tried series resonating the loop as you suggest but will try
this when I get time
I know the technique with the capicators and the matching transformer.
As you suggest lowering the power level because of the capacitor voltage
limitations and checking the loop against the vertical would be a realastic
comparison.
Having gone to all the trouble building a rig to generate the necessary
power in conjunction with my vertical to give 1W erp it would defeat the
object by reducing the power to accommodate the loop. Even if I could get
capacitors to handle the voltage on the loop the current would be colossal
for 1W erp, someone in the past calculated 40-50 amps RF, whereas with my
vertical it is only around 5 amps or less and manageable.
The permitted operating power and antenna limitations on LF at present in
the USA suits experimenting with loops but when you hopefully get something
similar to the UK/EU power levels then antenna requirements would need a
rethink, and the best approach is the vertical under normal circumstances.
(Think ZL is 5W erp)
I could realistically get a larger loop up and firing E/W like the present
loop on LF and when I get time in the future might try this. This would keep
the RF amps down.
One other point is location and space for some, and since amateur radio
antenna situation is a no choice approach often, then what works for one
does not work so well for another.
I am not keen on the big RF amps for small loops, and dont want to set the
UK on fire !!!!!
however small loops on RX are a different story and suit some because of
environmental noise, especially rotatable types also the convenient size.
I suppose everything has a use on earth.
I would like to hear/see some LF signals soon from your direction, all ready
this end just waiting for the smoke!!
73 de Mal/G3KEV
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