continuation of Part I covering the basics of
diode detectors gets
into some of the specific circuit configurations and their applications. Author Robert Scott touches on regenerative
and superregenerative feedback "tickler" circuits that are able to detect very low level signals. You have no doubt
heard of 'quenching,' but how about 'squegging?' The nonlinear devices used in the article happen to be vacuum tubes,
so stay away if you suffer from
Radio Craft Magazine
Sought by Nazi Spies
as with the poor, the spies will always be among us. This story reports on a bookstore in New York that during World
War II funneled money and technical information back to the Nazi Party in Germany. Electronics, aerospace,
and other technical publications (including
were chief among the sought-after sources. The shop was a front operation that lost a huge sum of money per the
official accounting books, but had copious amounts of funds pouring in from German 'investors.' Today's enemy money
fronting operations are largely radical...
Peregrine Intros 50 W Power
Limiter Protects 20 to 2000 MHz
Ltd. announces design and sales support for Peregrine Semiconductor’s new, adjustable power limiter providing protection
for up to 50 W pulsed RF input. For CW applications, the
handles up to 10 W of power. The adjustable power limiting threshold, from +22 to +32 dBm, enables flexibility
across different platforms and architectures. Peregrine’s UltraCMOS, monolithic solution is 8X smaller than comparable
GaAs PIN diode solutions...
Sherlock Ohms: System
Lockup Stumps Engineer
Sherlock Ohms adventures go through occasional slumps in the level of profundity and profoundness. Lately, they
have been very good, and this 'case' is no exception. Solving difficult problems that can have many possible causes
- compounded by being intermittent and not being intentionally reproducible - often involves equal amount of skill
and luck. Even the luck part requires the troubleshooter being smart enough to recognize and exploit the good fortune
he has encountered. Such is the situation here where fresh-out engineering
Alastair Stell becomes a company hero.
Cobham Antenna Systems
Has New MIMO Antenna Range
Antenna Systems, Microwave Antennas, a leading antenna producer, is proud to announce a new Multiple In Multiple
antenna range which
contains almost 100 antennas. Included in the range are omni, directional, sector, hemi-omni and blade omni antennas,
all with at least two connectors. Cobham’s MIMO range makes use of polarisation diversity; vertical and horizontal
(V+H), ±45° dual-slant or even right and left hand circular polarisations...
for Transatlantic Cable
knew that the British Post Office was ever in the vacuum tube development business? This 1957 article about the
world's first transatlantic telephone line (TAT-1) mentions that the amplifier and
frequency equalizer repeater circuits and components for the Newfoundland and Nova Scotia section of line was their
responsibility. Bell Telephone Lab handled the deep-sea portion of the system that ran between Newfoundland and
Scotland. Everything was designed to have at least a 20-year service-free lifespan. TAT-1 was inaugurated September
25, 1956, and was decommissioned in 1978 without any technical failures, thus achieving its designed longevity...
Free Engineering Magazines
& Career Advice
These publications are free for the asking... and I make a few pennies on each one to boot. Thanks.
and Systems For Dummies
Engineering for Dummies Book Bundle
Seeker Strategies to Stay Ahead of the Career Curve
Interviews For Dummies
for a New Job (Or Thinking About It?) What You Should Know First...
Guide to Microsoft's Cloud Productivity Suite - Office 365
The Jodrell Bank
astronomy has been the motivation for much research work in the design of low noise, high sensitivity receivers,
but also in determining the characteristics of the Earth's upper atmosphere. Before sounding rockets could be launched
to verify theoretical proposals, observed versus predicted behavior in radio signals being reflected off the moon
and planets needed to be explained and, if necessary, corrected for. One notable example of atmospheric perturbation
is the rotation of polarization caused by electrons in the ionosphere (the Faraday effect).
Parametric and cryogenically cooled receiver front end technology has been primarily driven...
a little difficult to make out the shape within the
puzzle grid, but it appears to be a transistor schematic symbol. Unlike the weekly
RF Cafe crossword puzzles, not all of the clues and words are
specifically related to science and engineering, but a large percentage of them are. Admittedly, I have the
advantage of a software program to help place the words within the grid. Doing it by hand is a lot more
work. I can't imagine how the people who created the New York Times' Sunday-size puzzles were able to do it without
Empower RF Systems
"Live" at EMC 2014
RF Systems is once again conducting live demonstrations of broadband,
high power amplifiers with compelling performance, industry
leading small size, and user interface / functionality that dares to challenge legacy products offered in the market.
Next appearing at EMC 2014 in Raleigh (Booth #311), we will be highlighting two different models - both covering
20 to 1000 MHz - 1 kW in a 5U chassis and 500 W in an even smaller, 3U chassis...
Featured Book: EW Receivers
& Receiving Systems
Warfare Receivers and Receiving Systems, by Richard A. Poisel. Receivers systems are considered the core of
electronic warfare (EW) intercept systems. Without them, the fundamental purpose of
such systems is null and void. This book considers the major elements that make up receiver systems and the receivers
that go in them. This resource provides system design engineers with techniques for design and development of EW
receivers for modern modulations in addition to receivers for older, common modulation formats. Each major module
in these receivers is considered in detail...
Aviat Networks Looking for
a Product Engineer
you looking for an exciting opportunity working for a Global Technology Leader? At
Aviat Networks, we take great pride in hiring a workforce
that is committed to supporting and strengthening our values and attributes. If you're a results-oriented, customer
centric and innovative thinker who also takes pride in personal and professional integrity, Aviat Networks is the
ideal next step in your career. We are looking for a
Product Engineer loves
to solve problems, enjoy change and know how to have fun so come and join a dynamic team that strives to bring communications
to the world...
Measurement System (dB-FMS)
is a million dollar idea for you to consider. I hereby dub it the "Drone-Based
Field Measurement System™" (dB-FMS™).
The concept came to me while reading a column in QST magazine discussing the use of the EZNEC antenna radiation
pattern prediction software. As you know unless a antenna is situated in a perfect, unobstructed environment like
in the middle of a desert with a perfectly uniform ground or on a space-based platform, physical obstacles and variations
in surface conductivity can significantly alter the 3-dimensional field distribution. Columnist Joel Hallas is a
master at EZNEC and is routinely called upon to model antenna systems for people. As important as length and orientation
of antenna elements are, the ground plane configuration can have a profound impact on the radiation pattern...
Dr. Stephen Maas Receives
MW&RF Living Legend Award
(formerly AWR Corporation) congratulates
Dr. Stephen Maas, who recently received the
2014 Microwaves & RF Living Legend Award. Maas was presented the award at the 2014 International Microwaves
Symposium in June in Tampa, Florida. Maas, chief scientist of AWR Group, NI and founder of Nonlinear Technologies,
has an extensive background in low-noise and nonlinear microwave circuits and systems. He is a prolific author and
educator and has authored several books, including Microwave Mixers, Non-Linear Microwave Circuits and Practical
Microwave Circuits. Maas has also held...
Notable Tech Quote
for July 29, 2014
again." That phrase is heard often in telephony conversations both wired and wireless. It was coined near the
end of World War II by Air Corpsman 2nd Lt. Byron A. Susan, as reported in the January 1945 edition of
Radio Craft magazine. Lt. Susan was responsible for setting standards for "radio
phraseology" to eliminate ambiguity between aviators and ground forces. "Say again" replaced "Repeat" because
the latter is an artillery term used to order the repeat of a gun salvo.
Half Century of Electronics
Publishing: Coherer to Spacistor
iconumerator (electronic particle counter), the vidicon tube
(TV image recorder), the Electro Importing Co.'s Telimco (world's first home wireless
outfit), the Wireless Association of America (founded before ARRL), the Dynamophone
(voice-activated switch), the "Swatties" (members of the Society
of Wireless Telegraph Engineers), the "Detectorium" (silicon crystal detector),
Ralph 124C 41+ and his sweetheart Alice 212B 423 (Gernsback sci-fi series)
were covered. Radio Amateur News predated QST as America's premier magazine for Hams, the famous
1919 "Verboten" cartoon (protested limitations on private radio operators from the wartime
era), the de Forest "Oscillion,"...
Sperry Gyroscope Company Ad
"Klystron" Bestowed to Public
is a household word these days - literally - since every microwave oven contains one. Do you know who registered
the trade name originally? Per this advertisement from a 1945 edition of Radio Craft magazine, Sperry Gyroscope
Company did. It was actually scientists at Stanford University (Russell and Sigurd Varian)
who developed the klystron tube, financed by Sperry as part of its blind aircraft landing system. In an act of magnanimity
that would never be considered in today's competitive markets, Sperry issued the following statement: "From now
on, the name Klystron belongs to the public, and may be used by anyone...
July 27, 2014 Wireless
Engineering Crossword Puzzle
the sake of avid cruciverbalists, each week I create a new
crossword puzzle that has a theme related to
engineering, mathematics, chemistry, physics, and other technical words. You will never be asked the name of a movie
star unless he/she was involved in a technical endeavor (e.g., Hedy Lamar).
big graphic with Figures 1 through 17 reminds me of the kinds of study sheets I used to make when cramming for exams
in my college circuits courses. Did I ever tell you about the wise guy instructor I had for my first Circuits class
at the University of Vermont? Anyway, this article provides an introductory level treatment of using
feedback in amplifier circuits. Lots of illustrations and formulas are included. Frequencies are at baseband,
so you won't learn any secrets for high frequency amplifier stabilization, but then even RF and microwave circuits
eventually need to convert down to baseband at some point for sampling or for use as audio or video.
Magazine Article Update
for July 25, 2014
think I skipped a week with RF an microwave magazine article updates. Those things multiply like rabbits, so there
have been a slew published since last time. Here are just a few highlights:
System Jamming, D. Pan,
N. Cheng, Y. Bian
Overview of RF Switch
Applications, P. Bacon,
D. Fischer, R. Lourens
Waveguide Filters: New
Design Techniques for
Exploiting a Mature
Technology, A. Trusler
Seeing Jitter in
Diagram, J-J. DeLisle
• Broadband Chokes for Bias
Tee Applications (p.56),
Measurements in an
D. Campbell, G. Gampala,
M. Vogel and C.J. Reddy
I ever tell you about the guy I had for my first Active Circuits class at the
University of Vermont? He was
a real wise guy. During those first few weeks our overloaded brains were bombarded with equations and Bode plots
and parameter names and circuit configurations, so the anxiety level was very high. That was in conjunction with
the same scenario in four or five other classes; you probably know of what I write. A typical class consisted of
Professor Anderson beginning in the upper left corner of the chalk board and writing at Olympic speed as he progressed
to the extreme lower right corner 50 minutes later...
Electronics Themed Comics
are a few more
from magazines of the days of yore. It is rare to find a comic in a technical or hobby magazine these days. I don't
know why that is. Enjoy.
Rosenberger Micro-RF Test
Switch Connector by RFMW
Ltd. announces design and sales support for Rosenberger’s 15K101-40ME4
switch connector. The 15K101-40ME4 Micro-RF test switch is an ultra-miniature (1.8 mm
x 1.9 mm, height 1.5 mm), low-cost, surface mount, coax "switch" connector for the verification of antenna/circuit
performance in any kind of small device. The connector can be used for applications that require a low-cost, SMD,
coax, point-of-entry to a PCB and/or a switch for temporarily disconnecting the on-board...
A Decibel Nomograph
it's another nomograph.
This one is for calculating the number of decibels required to amplify or attenuate a voltage level. The chart came
from a 1945 edition of Hugo Gernsback's Radio Craft magazine, but decibels are still defined today the
way they were nearly 70 years ago. A hard copy of a nomograph residing in a notebook or on the wall is still a handy
tool when you need to do a quick calculation. Unless you have a voice-commanded app where Siri will instantly respond
with a conversion for you, printing out one of these nomographs might be a really handy aid...
Research at the Threshold
scientists suspected as recently as early 1957 that
Earth's upper atmosphere
(ionosphere and beyond) temperature might be around 1,000° K. I say 'suspected'
because we had not yet launched instruments there to make actual measurements. Soundly posited and agreed upon theory
was validated a short time later when sounding rockets reliably reported a maximum of about 1,300° K in
the upper ionosphere. We did not know for sure what electromagnetic wavelengths and their respective energy densities
would be outside the protective layers of gases encompassing Earth. Much more was known about the depths of the
planet's oceans than of its atmosphere. Scientists knew that life was abundant...
Anatech July 2014 Newsletter
Electronics, a manufacturer of RF and microwave filters,
has published its July 2014 newsletter. As always, it includes both company news and some tidbits about relevant
industry events, regulations, and standards. This month, Sam Benzacar offers his views on the subjects of power
line EMF exposure, microwave device market growth, LTE TV, GM's LTE in-automobile hot-spot, and switching consciousness
on and off. He also has a short article titled, "Curing
Interference: Never Too Late."
Career News & Tips
time for another round of job hunting and career advice stories. There is no limit to the amount of advice offered
by helpful 'experts.' Many of these particular bits of guidance for your life come from authors on LinkedIn, Monster,
Money, etc., which typically do have good content. Considering, however, the quality of helpful suggestions offered
by your friends and acquaintances in the real world, it would be wise to learn a little about the source before
potentially risking your future.
Refresh Your Retro Resume
in 6 Steps
5 Words to Avoid Saying
During a Job Interview
Top 10 Tips for Salary
Negotiations - more...
Thanks Once Again to
ATEC for Support!
Test Equipment Rentals provides the latest models of test and
measurement equipment from top name manufacturers like
Fluke, Anritsu, R&S, Tektronix, and Yokogawa. Our primary focus is providing a complete rental solution of test
and measurement equipment to industries such as aerospace, defense, EMC, and communications.
Chalco Paper Tape Reader
Restoration by Mark Blair
Cafe visitor Mark J. Blair (NF6X) wrote to let me know about the
Chalco Paper Tape Reader that
he procured and restored. The Chalco unit was used in the
TPN-19 ground-based mobile airport surveillance and precision approach radar. Mark would appreciate being
contacted by someone who actually
worked with the reader on the TPN-19. Mark has a very interesting website that you might enjoy. Says he, "I like
to collect, restore and play with military surplus equipment, and that's mostly what this web site is all about."
Finance for Engineers
for Engineers: Evaluation and Funding of Capital Projects, by Frank Crundwell. I saw this book over on the EE
Times website and figured it would be a good subject for my Featured Book spot. With flair and an originality of
approach, Crundwell brings his considerable experience to bear on this crucial topic. Uniquely, this book discusses
the technical and financial aspects of decision-making in engineering and demonstrates these through case studies.
It's a hugely important matter as, of course, engineering solutions and financial decisions...
Unlocking the Mysteries
of Radar - AOC Webinar
TODAY, July 22 from 4-5 pm EDT.
is still time and space available to register for this afternoon's webinar presented by
Fernando C Gonzalez.
This interactive journey, from the humble electron all the way up to the self-driving car, explores sound and light,
size, wavelength and frequency. Overview of the history and evolution of radar. From the origins of radar prior
to WWII, through pulse Doppler, CW, monopulse radars, and to modern active electronically scanned arrays
(AESA), the attendee will understand the fundamentals of how radars work. A 10-15 minute
National Union Radio Corp. Ad
- Women Engineers Needed
Union Radio Corporation was ahead of its time in terms of hiring
Admittedly, they and all other manufacturers were dealing with a shortage of male engineers due to the ongoing need
by the military for fending off the scourges of fascism, Nazism, communism, socialism, and all the other 'isms'
of the day that threatened to overtake the world. However, they should receive due credit for going out of the way
to promote the sciences as careers for the fairer gender. The advertised positions required the successful applicant
to have earned a bona fide degree in physics, electrical engineering, chemical engineering...
Notable Tech Quote
is difficult to say what is impossible, for the dream of yesterday is the hope of today and the reality of tomorrow."
- Dr. Robert Hutchings Goddard
Carl & Jerry: Tussle
with a Tachometer
is a great example of how Popular Electronics and John T. Frye used the "Carl & Jerry" series
to teach some basic electronics design principles through story telling. In this adventure, the guys decide to build
tachometer from schematics they found in a magazine. They debate amongst themselves how the circuits works,
the best way to assemble the circuit, component selection, vibration- tolerant mounting, and how to properly calibrate
the tach to accurately display engine revolutions per minute.
NI's Analyst Update Reduces
Simulation Times Up to 70%
(formerly AWR Corporation) has released V11.01 of the
NI AWR Design Environment™
with enhancements to Analyst™ 3D FEM EM simulation
engine that cuts simulation times by as much as 70% over previous versions. The updates in V11.01, which are specific
to Analyst, include algorithm reformulations/enhancements to both automatic mesh refinement
(AMR) and fast frequency sweeps. For high-port-count designs
(10+ ports), the speed improvements seen with Analyst are the most pronounced...
Newly Announced K-1B Visa
for High Tech Workers
had to take the initiative to launch an improved high-tech immigrant worker program. Accordingly, I took the liberty
of creating a K-1B Visa
for high technology workers. Congress has not officially written it into law, but American politicians and executives
make no pretense of enforcing law they disagree with anymore, so it really does not matter. Here is how the K-1B
Visa program works: It is widely known that the United States now considers itself to be a country without a southern
border. All anyone needs to do to become an accepted American citizen (the new definition,
not the old) and enjoy all the freedoms guaranteed by our Constitution (well, except
Dave's & Bill's Garage
Restoration (HP Beginnings)
though you would never know by today's Hewlett Packard (HP), the company's roots are
in electronics test equipment (never thought I might have to explain that!). Most people
who have been in the electronics realm are familiar with the story of Dave Packard and Bill Hewlett starting their
business in the 12'x18' single-car garage where Dave and his wife lived at 367 Addison Avenue in Palo Alto, California.
Bill, yet a bachelor, moved into the garage in 1938 (an early entrepreneurial engineer trend
setter who literally lived in his office). Their first commercial product was the Model 200A Audio Oscillator.
Hewlett Packard went on to become the world's foremost maker of electronic test equipment for communications, medical,
TV DXing, and the
Dog on the Roof
I was born in 1951, I grew up without the benefit of 1,000 cable channels available whenever I wanted them. This
was during the 1950s and 1960s when we lived in the city of Pittsburgh, PA. Instead we had to make due with four
- that is four - VHF television stations that we could receive on a black and white TV (actually
it wasn't strictly BLACK and WHITE; there were various shades of gray). There was one TV station for each
network: CBS, ABC, and NBC, plus one 'Educational' (PBS) station. Later on, we got
two independent UHF stations. This was also the era when the 'blackout rule' was largely in effect for sports broadcasts,
and if you didn't go to the stadium for a home game...
Please Visit PMI in Appreciation
of Their Ongoing Support
organization has been setup to design, develop, manufacture, test, and market complex state-of-the-art
RF MIC and MMIC components, supercomponents, and subsystems. Unique
applications in space, military, commercial, telecommunications, and consumer electronics systems. DC to 40 GHz.
Empower RF Awarded Patent for "Broadband Linearization..."
RF Systems is proud to announce the approval of a patent on "Broadband
linearization module and method." New communication services and the use of complex waveforms have created a
demand for highly linearized power amplifiers. Deviations from linearity show up as spectral distortions and/or
modulation quality degradation (EVM) in the output of these amplifiers -that is, undesired
energy, not contained in the original signal, inside or outside...
Apollo 11's 45th
Anniversary Crossword Puzzle
tranquility base here. The Eagle has landed." Where were you 45 years ago when you heard on radio watched on a B&W
TV like I did as Apollo 11's
'Eagle' lunar module touched down on the moon - with
than 30 seconds of fuel remaining? A short while later Neil Armstrong and Buzz Aldrin became humans #1 and #2, respectively,
to step onto the lunar surface. "We came in peace for all mankind," was plaque attached to the part of the
lunar lander that stayed behind. Poor Michael Collins had to be content with orbiting the moon while is shipmates
went to the surface. I created this special crossword puzzle this morning to commemorate the Apollo 11 mission...
few new terms have been added to the
lexicon since 1958, but this list from Radio-Electronics magazine contains more than 150 definitions
that are still useful today. It is amazing that this list was created just a decade after the transistor was invented,
and now half a century later the mot commonly used terms have not changed much. In looking over the words, there
are very few that need to be added to the original (which I did).
Custom Interconnects 40 GHz
Test Reports for Fuzz Button
Interconnects announced the release of the most detailed RF characterization conducted to-date on their flagship
Fuzz Button® technology platform.
The reports are geared towards 50 Ohm impedance matching at high frequencies and include bandwidth measurements,
S-parameters and VSWR, as well as SPICE Models. The reports were released as a follow-up to the recent IEEE IMS
held in Tampa and are expected to draw a great deal of interest from the RF design community who were eagerly awaiting
Many Thanks to MECA
Electronics' Ongoing Support
1961, MECA has served the microwave industry specific to passive components in the DC to 20 GHz frequency range.
serves all areas of the RF / Microwave industries including world class network providers, and supporting supply
chain infrastructure. We have long been the "backbone" of high performance wired and air-interfaced networks such
as in-building, satellite, radar, and mobile communications.
News from the IRE 1958 Meet
International Microwave Symposium (IMS) is arguably the largest single annual event
for radio and microwave engineers. According to IMS2014 event officials the show in Tampa, Florida, boasted of a
7,500-visitor attendance. European Microwave Week (EuMW) runs a close second place
at around 7,000. In 1958, 55,000 engineers attended the Institute of Radio Engineers (IRE
- eventually became the IEEE) in New York City. IMS and EuMW would love to have numbers like anywhere near
that. Maybe the large number of attendees was because dissemination of information was not nearly as instant
(or eventual for that matter), and the absence of the Internet or...
Raytheon Radio Tubes Ad
love these old
company advertisements from the World War II era. It represented a time when minor differences between
citizens were put aside for the good of the country (yours and mine). Nationalism had
not yet been redefined by one-worlders to mean that you hated the rest of the world, but rather that you had pride
in your country of birth - or legally adopted new country - and were willing to sacrifice for the common good to
preserve your way of life. The U.S. and Great Britain were indisputably the leaders in technical invention amongst
the Allied powers. Germany and Japan led...
BeRex Adds New Family of High
Performance MESFET Chips
Inc. has begun shipping a new family of GaAs
MESFET chips, the BCF-series, which addresses the need for low phase noise with high gain and power in applications
such as single and multi-stage amplifiers, oscillators, synthesizers, etc. ranging in frequency from DC to 26.5
GHz. The BeRex BCF-series of MESFET chips are ideally suited both broad band and narrow band applications from DC
to 26.5 GHz. Typical application requires a high level of OIP3 linearity...
How to Use Radio
wave radio was a boon to both professional and amateur radio operators because of its ability to be received over
longer distances using significantly lower transmitter power. The problem was (and still is)
that short wave bands typically suffer from
ionization effects that vary depending on time of day, local weather, solar activity, pollution, and other phenomena.
Long wave's advantage was that although it required higher power and longer antennas, it was (and is) extremely
reliable. For other than the most critical applications, idiosyncrasies of short wave communications were accepted
as the price of more convenient and lower cost operation. Widespread adoption of short wave communications brought
extensive studies and characterization...
MECA Low PIM Components
& D.A.S. Equipment Catalog
Electronics' new 12-page catalog features many our extensive line of
low PIM RF/microwave components
with industry leading performance including RF loads, attenuators, directional couplers, power splitters, divider/tappers,
adapters, jumpers and D.A.S. equipment.
Electronic Components of America
Top U.S. Defense Contractors
Technology magazine just published its 2014 ranking list for the
top 100 defense contractors based on the value of contract dollars*.
It should come as no surprise that Lockheed Martin leads the pack ($10.4B) by a factor
of nearly two over the runner-up Northrop Grumman ($5.87B). My Top 10 list below has
the companies listed by value of defense contracts, whereas the original list ranked by total dollar value inclusive
of both defense and non-defense contracts. Two companies in the list, Leidos (security)
and Fluor (construction), are unfamiliar to me. The other eight design and manufacture
a mixture of electronic, mechanical, and software products for military and aerospace customers. The
CBO reports that defense spending...
Radio Frequency System
Architecture and Design
Frequency System Architecture and Design, by John W. M. Rogers, Calvin Plett, and Ian Marsland. Communication
devices such as smart phones, GPS systems, and Bluetooth, are now part of our daily lives more than ever before.
As our communication equipment becomes more sophisticated, so do the radios and other hardware required to enable
that technology. Common radio architectures are required to make this technology work seamlessly. This resource
describes practical aspects of radio frequency communications systems design...
Dilbert CEO Photo Flash
July 15, 2014, Dilbert comic strip features the CEO of his company suggesting that they figure out a way to insert
ad images into "that little spot" that stays in your vision for a few seconds after someone takes your picture using
a camera flash. I wonder whether creator Scott Adams realizes that he might have come up with a patentable idea?
Too late. By now the folks at Google or Apple have seen today's strip and have their staff patent lawyers frantically
generating applications as I write this. Subliminal
advertising has been around for a long time, and it might even be illegal in some countries, but it is not illegal...