Richard Clark wrote:
On Tue, 26 Apr 2005 21:09:07 -0700, Roy Lewallen
wrote:


I believe "takeoff angle" is in the same category as "capture area" and
"S-unit" -- terms which nobody except amateurs seem to need.


Hmmm,

Capture area of antennas, 899, 927 of Terman's "Electronic and Radio
Engineering. The 899 reference appeals to aperture. The 927
reference gives a value of 1.5 or 0.12 lambda² (also called intercept
area or antenna cross section) for a common dipole.
. . .

I stand corrected. Spurred by your response to do a more exhaustive
search, I found "capture area" in the indices of 3 out of the 12 antenna
texts and handbooks I have, plus in Terman's _Radio Engineering_. While
aperture is more commonly used (judging by this sample), "capture area"
is indeed in use outside the amateur community.

Think I'm likely to find "S-Unit" if I look hard enough?

Roy Lewallen, W7EL

On Thu, 28 Apr 2005 00:11:44 -0700, Roy Lewallen
wrote:

Think I'm likely to find "S-Unit" if I look hard enough?

Hi Roy,

One could see stars in the middle of the day if they squint their eyes
hard enough. Seems to me Collins literature covered S Units
adequately and they were certainly the Cadillac of the pro's.
Hammerlund is another probable source. National another. RCA as
early as 1941.

On the other hand, I certainly wouldn't waste my eyes scanning the
shelves of the engineering library.

73's
Richard Clark, KB7QHC

On Thu, 28 Apr 2005 00:40:11 -0700, Richard Clark
wrote:

On Thu, 28 Apr 2005 00:11:44 -0700, Roy Lewallen
wrote:

Think I'm likely to find "S-Unit" if I look hard enough?

Yep.



Hi Roy,

One could see stars in the middle of the day if they squint their eyes
hard enough. Seems to me Collins literature covered S Units
adequately and they were certainly the Cadillac of the pro's.
Hammerlund is another probable source. National another. RCA as
early as 1941.

On the other hand, I certainly wouldn't waste my eyes scanning the
shelves of the engineering library.

Scanning my library I spy:

"Fundamentals of Single Side Band", 2nd Edition, Sept 1959, Collins
Radio Company, Cedar Rapids, Iowa.

On page 13-7, in describing the circuitry of the 75S-1 it says in
part:

"The S-meter is calibrated in S-units and dB. The S-unit scale is
standard up to midscale (S-9). The db scale reads relative signal
strength above the avc threshold which is approximately 1 microvolt.
Thus 40 dB on the meter is 100 microvolts of signal (which also
corresponds to S-9 on the S-unit scale). To read dB over S-9 on the
S-unit scale, subtract 40 from the corresponding dB reading. For
instance, a 60-dB reading would be 20 dB over S-9 (100 uv) or 10,000
uv of signal at the antenna. This reading is then 60 dB over the dB
scale reference of one microvolt and 20 dB over the S-9 reference of
100 uv"

Whew.

Next to it I find:

"Amateur Single Sideband", 1st Edition, 1962, Collins Radio Company,
Cedar Rapids, Iowa.

Its only reference to S-meters is on page 111 where, in a section on
distortion tests with a receiver, it states in part:

"Variations and nonlinearities in S-meter calibration can introduce
considerable error in the measurement of signal levels by means of a
receiver. The commonly used figure of 6 dB per S-unit is appreciably
higher than the actual response of many amateur receivers. The meter
in the S-Line receivers, for instance, is calibrated to read
approximately S-9 with and input signal of 100 microvolts. The agc
threshold is set nominally to 1.5 microvolts, and varies slightly from
band to band. Therefore, the total range from S-zero to S-9 under
normal conditions can represent 30 to 40 dB or from approximately 3.3
to slightly over 4 dB per S-unit."

On Thu, 28 Apr 2005 00:40:11 -0700, Richard Clark
wrote:

On Thu, 28 Apr 2005 00:11:44 -0700, Roy Lewallen
wrote:

Think I'm likely to find "S-Unit" if I look hard enough?

Yep.



Hi Roy,

One could see stars in the middle of the day if they squint their eyes
hard enough. Seems to me Collins literature covered S Units
adequately and they were certainly the Cadillac of the pro's.
Hammerlund is another probable source. National another. RCA as
early as 1941.

On the other hand, I certainly wouldn't waste my eyes scanning the
shelves of the engineering library.

Scanning my library I spy:

"Fundamentals of Single Side Band", 2nd Edition, Sept 1959, Collins
Radio Company, Cedar Rapids, Iowa.

On page 13-7, in describing the circuitry of the 75S-1 it says in
part:

"The S-meter is calibrated in S-units and dB. The S-unit scale is
standard up to midscale (S-9). The db scale reads relative signal
strength above the avc threshold which is approximately 1 microvolt.
Thus 40 dB on the meter is 100 microvolts of signal (which also
corresponds to S-9 on the S-unit scale). To read dB over S-9 on the
S-unit scale, subtract 40 from the corresponding dB reading. For
instance, a 60-dB reading would be 20 dB over S-9 (100 uv) or 10,000
uv of signal at the antenna. This reading is then 60 dB over the dB
scale reference of one microvolt and 20 dB over the S-9 reference of
100 uv"

Whew.

Next to it I find:

"Amateur Single Sideband", 1st Edition, 1962, Collins Radio Company,
Cedar Rapids, Iowa.

Its only reference to S-meters is on page 111 where, in a section on
distortion tests with a receiver, it states in part:

"Variations and nonlinearities in S-meter calibration can introduce
considerable error in the measurement of signal levels by means of a
receiver. The commonly used figure of 6 dB per S-unit is appreciably
higher than the actual response of many amateur receivers. The meter
in the S-Line receivers, for instance, is calibrated to read
approximately S-9 with and input signal of 100 microvolts. The agc
threshold is set nominally to 1.5 microvolts, and varies slightly from
band to band. Therefore, the total range from S-zero to S-9 under
normal conditions can represent 30 to 40 dB or from approximately 3.3
to slightly over 4 dB per S-unit."