Richard Clark wrote in
:

On Mon, 04 Jan 2010 14:44:31 -0600, Lostgallifreyan
wrote:

Again, I wonder why they're even there. Isn't it easier to put a gain
stage after the second toroid?

A circuit serves more purposes than gain. Of course, the simple
circuitry found in the file we are discussing has limited offerings.
Of what is offered is controlling input and output Z which is not a
trivial matter.

My preference is found in using Operational Amplifiers instead of
discrete transistors. There is more design flexibility and more
purposes may be served. OpAmps will control input and output Z with
far more rigidity (it is very difficult for externalities to shift
these parameters making for a rock solid design). OpAmps will also
preserve fidelity (faithful phase, magnitude) and not introduce any
distortion, and will drive out noise not already in the signal. Other
advantages can be obtained, but this is enough.


I really like op-amps too, they have often made my life easier. Not used them
in RF though, just audio and modest DC instrumentation designs of my own..

About those amps in that scheme, I think I didn't grasp what they were doing,
other than gain, because I assumed the idea of balancing implied by the
design would be central whether they were used or not. It still seems to me
that if the line worked without them, then a single stage could be applied
after the signal passed to the unbalanced input after the second toroid. If
not (as in not possible as opposed to merely awkward), then I'm still missing
something.

If I put up conspicuous loops here I might get people bothering me about
planning permission or some other means of negative compulsion. If I
can do this with a vertical whip it will be much less awkward.

Practicality needs to be served too. Loops can be useful indoors as
well, and they needn't fill a room. They will test the limits of
balance with the nearby clutter - an opportunity to turn your
environment into an RF lab.

73's
Richard Clark, KB7QHC


I'll definitely read up on loops. (Been reading the first of two USMC radio
handbooks today, second is an update of the one I found yesterday. No loops
mentioned in first, but the second is specific to antennas. Both guides are
quickly filling forgotten gaps in what I knew, plus showing me plenty I
didn't).

Btw, how critical is the resistance of wire in a few ground radials? I have
some thin stainless steel wire that would be strong and enduring out there
but at around 1.5 ohms or more per 6 inches I can't help thinking that's too
much. I like the idea though, because clamping ends of it very firmly between
copper washers could be fast and easy for good and reliable contact.