On 13 Dec 2010 21:01:30 GMT, Sébastien MEDARD wrote:

I understand better what is the purpose of this kind of map (on SDR-
Radio.com software for example). Where you can see an OM, you are pretty
sure to see this kind of map.

Hi Sébastien,

If you mean the "gray line" map - yes.

When I used to teach RTTY there were only two tones.

The reason why they call you OM ? )

Touché

This will reveal the "Law of Diminishing Returns" (the more you add, the
less you get back).

Interesting. What would be the best ratio?

You mean the best number of turns? Depending upon band, maybe as many
as 6 to 10. One is good enough. There are many options to balance.
One correspondent here, years ago (silent key), wrote extensively on
this subject - google this group (or the internet) for Reg Edwards,
G4FGQ. For instance, google the keywords in:

RJELOOP1 *
Performance of Transceiving, single-turn, magloop antennas of various
regular shapes.

RJELOOP2 *
Performance of Transceiving, single-turn, magloop antennas of
rectangular shape.

RJELOOP3 *
Analysis of receiving, multi-turn, square, loop (or frame) antennas,
ELF to HF.

I will try to find one when they are cheaper.

Try:
http://www.bookfinder.com/search/?au...ic&st=sr&ac=qr

OK. But today we probably ask more to radios than yesterday, no?

No, probably less. Being an OM, (40 years ago) I also taught classes
for repair and maintenance of Collins' famous receiver, the R-390.
EVEN NOW (40 years later), this is probably the best receiver for its
price (and even two to three times its price).

The real science of low noise is found in the distance to the source.

Lapalisse would have said exactly the same thing. He would have said that
the real science of good reception is found in the distance to the source
too )

So, my comment was a lapalissade? Certainly.

73's
Richard Clark, KB7QHC

On Mon, 13 Dec 2010 16:06:51 -0800, Richard Clark wrote:

On 13 Dec 2010 21:01:30 GMT, Sébastien MEDARD wrote:

I understand better what is the purpose of this kind of map (on SDR-
Radio.com software for example). Where you can see an OM, you are pretty
sure to see this kind of map.

Hi Sébastien,

If you mean the "gray line" map - yes.

There should free software displaying this gray line with UTC time, no?

This will reveal the "Law of Diminishing Returns" (the more you add,
the less you get back).

Interesting. What would be the best ratio?

You mean the best number of turns?

Economics is interesting too

RJELOOP3 *
Analysis of receiving, multi-turn, square, loop (or frame) antennas, ELF
to HF.

Can be find here :
http://www.zerobeat.net/G4FGQ/page3.html#S301

I will try to find one when they are cheaper.

Try:
http://www.bookfinder.com/search/?au...%27s+Receiving
+Antenna+Handbook&lang=en&isbn=&submit=Begin
+search&new_used=*&destination=us&currency=USD&mod e=basic&st=sr&ac=qr

I found the "Receiving Antenna Handbook" quite cheap, but the "Loop
Antenna Handbook" is still expensive. Between $60 to $257... I will try
the cheapest.

OK. But today we probably ask more to radios than yesterday, no?

No, probably less. Being an OM, (40 years ago) I also taught classes
for repair and maintenance of Collins' famous receiver, the R-390. EVEN
NOW (40 years later), this is probably the best receiver for its price
(and even two to three times its price).

Do you calculate that in constant dollar from the 50's?

I can imagine the teaching class. Everybody with a Collin's in front of
him/her... A one year project to restore completely one of this legendary
radio. I would like that!

With a good DSP outside (Audio DSP only), can beat every other ones?

It seems not easy to get one, especially in Europe...

The real science of low noise is found in the distance to the source.

Lapalisse would have said exactly the same thing. He would have said
that the real science of good reception is found in the distance to the
source too )

So, my comment was a lapalissade? Certainly.

You got the picture

Sebastien.

On 15 Dec 2010 20:52:22 GMT, Sébastien MEDARD wrote:

There should free software displaying this gray line with UTC time, no?

Hi Sébastien,

I'm sure there is - somewhere. GoogleEarth would be an elaborate tool
to accomplish this.

I found the "Receiving Antenna Handbook" quite cheap, but the "Loop
Antenna Handbook" is still expensive. Between $60 to $257... I will try
the cheapest.

Myself, I would not advise spending more than $20. Professional
antenna books barely give more than one section of the first chapter
to its discussion.

OK. But today we probably ask more to radios than yesterday, no?

No, probably less. Being an OM, (40 years ago) I also taught classes
for repair and maintenance of Collins' famous receiver, the R-390. EVEN
NOW (40 years later), this is probably the best receiver for its price
(and even two to three times its price).

Do you calculate that in constant dollar from the 50's?

Today's cost matched with the price of equivalent performance from an
available vendor.

I can imagine the teaching class. Everybody with a Collin's in front of
him/her... A one year project to restore completely one of this legendary
radio. I would like that!

There were two to a radio. 40 to 30 hours learning the schematic
theory of operation; and troubleshooting and tuning procedures and 30
to 40 hours in front of the radio. The class was 2 weeks long.
Complete restore unnessecary, of course, as the last class had fixed
any problem. No, we had a data bank of known problems, known
solutions, and the time to debug them averaged over at least 100
students for each problem.

With a good DSP outside (Audio DSP only), can beat every other ones?

Good for filtering, probably tighter than the mechanical filters
(theoretically), but there are many, many other considerations.

It seems not easy to get one, especially in Europe...

That seems like a very real impediment. And with it weighing in at 85
pounds (40 kilograms), the cost to deliver would add considerably.

So, my comment was a lapalissade? Certainly.

You got the picture

In technicolor and 3D.

73's
Richard Clark, KB7QHC

Hello,

On Wed, 15 Dec 2010 15:40:31 -0800, Richard Clark wrote:

On 15 Dec 2010 20:52:22 GMT, Sébastien MEDARD wrote:

There should free software displaying this gray line with UTC time, no?

I'm sure there is - somewhere. GoogleEarth would be an elaborate tool
to accomplish this.

Well... In French we say that it is like using backhoes to move a bucket
of sand...

I found some software here :
http://www.ac6v.com/software.htm#GEO

Need to be tested...

I found the "Receiving Antenna Handbook" quite cheap, but the "Loop
Antenna Handbook" is still expensive. Between $60 to $257... I will try
the cheapest.

Myself, I would not advise spending more than $20. Professional antenna
books barely give more than one section of the first chapter to its
discussion.

I totally agree, I will see what the seller proposes.

I can imagine the teaching class. Everybody with a Collin's in front of
him/her... A one year project to restore completely one of this
legendary radio. I would like that!

There were two to a radio. 40 to 30 hours learning the schematic theory
of operation; and troubleshooting and tuning procedures and 30 to 40
hours in front of the radio. The class was 2 weeks long. Complete
restore unnecessary, of course, as the last class had fixed any problem.
No, we had a data bank of known problems, known solutions, and the time
to debug them averaged over at least 100 students for each problem.



With a good DSP outside (Audio DSP only), can beat every other ones?

Good for filtering, probably tighter than the mechanical filters
(theoretically), but there are many, many other considerations.

I should try to see if there are any OM near the place I live. Could be
interesting to see those old boxes.

Well, many thanks for the basic information you gave me.

Now, I need to use it.

Sébastien.