to judge them with common sense. And then it easily would
appear, that the laws of physics apply even in today's modern
times (o.k., Einstein changed some views of the Newton based
physics theory, but the general concepts - like wavelenght,
propagation time of a wave in a medium and the else - are
still in place - also for antennas). To me it appears pretty
much the same like with those "audiophiles" that claim to have
invented the ultimate bass loudspeaker producing substantial
sound pressure at 20 hertz yet having only 5 liters in cubical
volume - something, that is hard to proove by physics.
Back to the issue of our Drake's: What Bob Drake did, is simple
yet very necessary serious thinking: He applied the laws of physics
- maybe also intuitive - to the gear he designed. And that means
in
example: Only a inductor of substantial mechanical size and proper
mechanical construction will have a high Q - and there are a lot
of
them to be found in an R4-C or an SPR-4, for example. That means,
that receivers and transmitters need a sturdy mechanical construction
in order to maintain some frequency stability. That means, that
one have to close the window as much as possible for unwanted signals
(to preselect them) by means of passive high-quality devices before
the first active nonlinear device (preamp or, even worse, the mixer)
sees them.
In todays money-driven world, however, this is a expensive con-
struction and manufacturing technique because it can not be pro-
duced on a fully automated assembly line - it needs human interven-
tion. Furthermore, it is believed, that it could not be expected
from
the modern ham to manually tune a preselector because it is a lack
of comfort. So, how are receivers designed nowadays? Preselection
-
if present in any serious way - is done by means of octave-band-bass
filters or something similar, which worst case may be tuned by
varac-
tor diodes (inherent nonlinear devices). The large signal behaviour
of such a receiver is then tried to be optimized by running the
preamp and the mixer at high bias currents and with high LO-levels
(+20 dBm LO-level or so is nothing exotic in some of todays gear
that claims to have high IP values - with the same 100 mW one could
build a nice QRP transmitter). If the equipment is battery operated,
this consequently contributes to power consumption. I own a SPR-4,
which has a total power consumption of less than 2.5W at 12V DC,
and more than half of this power is consumed by the dial-light
bulbs (which could be turned off by means of a switch). In the
moment, i'm in the construction phase of a (modern) kit for a
shortwave transceiver, which is respected for it's performance
data,
yet the transistors of the preamplifier as well as the one for
the
post mixer amp draw large amounts of collector current (one of
them
really carries a heat sink) to overcome the large-signal IP-problems
due to the lack of a sharply tuned preselector. This transmitter
draws
around 250 mA at 12V DC in receive - this is appr. 3.25W, and it
does
not even have power hungry dial-light bulbs! O.k., it's smaller,
lightweight, has more fancy knobs to use (and misuse!) and so on
-
the basic job of a good to excellent shortwave receiver, however,
has been performed by the SPR-4 and maybe others (which i do not
know
from personal experience) much the same way for now more than
30 years very well - a real improvement in technology, isn't it?
And
this discussion could be endlessly continued - as an example only
named the efforts to get the phase noise level of synthesized local
oscillators down to a reasonable value - this was not even a matter
of discussion in the days of high quality, temperature compensated,
L or C tuned free running VFO's, because the spectral purity of
the
signal of such a (proper constructed) VFO was and is excellent.
I'm pretty sure, that if Bob Drake would have lived nowadays (and
if the economy and the market of his business would have allowed
him to do so), we would have seen some very reasonable and high-
quality ham stuff from his company - for sure he would have applied
recent technology like double balanced mixers, DSP's etc., but
in a
down-to-earth way.
I'm in no way a uncritically fighter for yesterdays technology -
it is only my intention, to sharpen the view for things and techni-
ques that have proven to be good and funtional in the past - and
maybe to apply those methods with today's abilities in terms of
components, materials, techniques etc.
So, this was a lot of stuff to read - thanks to all of the Drake
gang for the patience to follow my long and detouring thoughts....
Herbert, DG7MCC
Lee Bahr schrieb:
"Lee Bahr" <[EMAIL PROTECTED]> made an utterence to the drakelist gang
----------------------------------------------------------------------
I have no interest in the author or his contraption. This is just like the
auto inventions that gets you 100 miles per gallon by just inserting the
device in the fuel line! This reminds me of the TV antennas you plug into a
wall outlet so you can pick up TV signals from all over the world. They out
perform an outside antenna, you know! Maybe you should try one of these
antennas on your highly modified Drake rig. I don't happen to subscribe to
perpetual motion devices that defy logic and science. If you have an
interest in this type stuff, go for it. A sucker is born every day. I'll
put my time and money elsewhere. This guy is probably looking for suckers
to "invest" in his new company. Once he has gone through the funds, the
company will fold and he will come up with a "new" contraption and form a
new company for new investors. I think this guy is nothing more then a tech
at this school anyway. He probably figured out how to bilk our Federal
government out of some research grant money. (Easy to do). No, I'll just
keep using my unmodified Drake rigs with proven technology antennas. In the
meantime, I wouldn't hold my breath if I were you. Sure wish we could talk
about Drake here and leave this antenna for the Alchemy list.
Lee, w0vtPS: I am selling Dr Vandegraph antenna wax for only $10.95 a jar, today
only! (Normally $19.95) Put it on and then take it off! A little bit goes
a long way! (Leave it on too long and you will have antenna lock). It will
boost your signals a minimum of 10 db if applied properly. It is amazing
what it can do for your station. Some of our customers tell us they no
longer turn on the amp now that they are using Dr Vandegraph Antenna Wax.
You will be glad you tried it. (patent pending) Please, one jar per
customer only!----- Original Message -----
From: "K7OV" <[EMAIL PROTECTED]>
To: "'Lee Bahr'" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Saturday, August 07, 2004 11:06 PM
Subject: RE: [drakelist] Interesting? Not Really!> If you think it a hoax or nonsense, why don't you write the University of
> Rhode Island and ask about him and the exact patent name to search under?
>
> 73,
>
> Mike - K7OV
>----------------------------------------------------------------------
On Behalf of "Lee Bahr" <[EMAIL PROTECTED]>
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