Ed... Bob-K2TK and I enjoyed some New England hospitality during our tour of
ARRL headquarters last November and saw for ourselves your setup and the
room where "You are shielded from government spies and alien mind readers".
Ignoring tech specs I think an even more impressive test room is that one
reserved for employees to set up their personal rigs and operate during
lunch hours. When the Orion arrives I'd like to drive it up there during
W1AW code practice on 20M...point the headquarters beam at the Maxim Station
beam and vice versa and see how close to W1AW I can hear my Argonaut running
5W from home.... Now THERE's a real world test!
----- Original Message -----
From: "Hare,Ed, W1RFI" <w1rfi@arrl.org>
To: <tentec@contesting.com>
Sent: Thursday, March 06, 2003 3:10 PM
Subject: ARRL Lab Test Equipment (was RE: [TenTec] Ed Hare)
> > Thanks every so much for you very informative post to
> > me and to the Ten Tec reflector. That, coupled with your
> > willingness to discuss your techniques with Jim, the techniques
> > and the process/procedures you and your staff use for generating
> > your results, certainly produces a heretofore nonexistent, positive
> > impression of what really is going on within the ARRL.
>
> Thanks, Tom. That is why I join in these discussions. I agree that ARRL
can and should
> do as thorough a job as possible telling members how we do things. Of
course, in one
> sense, we did, because the test procedures manual and several articles
available at:
>
> http://www.arrl.org/tis/info/rigbuy.html
>
> Explain a lot of it. Unfortunately, the world has become diverse and
something put in
> one venue may not be seen by someone who looks in another venue. The flip
side,
> of course, is that assumptions are even more dangerous than the lack of
information.
> Hopefully, the three posts I will make, and the expected followup
discussion, will
> help on all counts.
>
> The ARRL Lab has a reasonable suite of test instrumentation. The newer
stuff is
> not quite top of the line, but is right up there, chosen to help ARRL
extend its test
> capabilities into the future. The older equipment is quite servicable and
is very much
> up to the task at hand, with better specifications than needed for the
performance of
> the equipment being tested. The Lab's ability to easily test microwave
equipment is
> somewhat limited, although Zack Lau is quite skilled at microwave design
and has been
> able to design nearly any test fixturing needed. Most of ARRL's Product
Review testing
> has been for equipment operating at 1.2 GHz and below.
>
> All equipment used for major Lab Product Review testing is calibrated per
the cycle
> recommended by the equipment manufacturer. We use an external calibration
service,
> Essco, near Boston, MA. Every November, Mike Tracy drives the equipment to
cal,
> and picks it up a week later, with the cal usually sandwiched in between
Product
> Review testing. Other, less-critical, Lab-owned equipment is self
calibrated, using the
> calibrated equipment and the good judgement of the Lab engineering staff.
(By "less
> critical" I generally mean equipment that will not be used for Product
Review, publication
> or advertising acceptance.)
>
> The majority of the Product Review testing takes place in ARRL's shielded
screen room.
> The room is well grounded and the power-lines going into the room are
voltage
> conditioned with a Stabiline BCR3205U voltage regulator, 5.5 kVa. The
output voltage
> will stay at 234 V +- a couple of volts over a wide range of input
voltages. The power
> is then run through an EMI filter, to help keep the RF gremlins out. With
the door closed,
> the room has about 100 dB of isolation.
>
> The room is not temperature or humidity controlled, other than by the
building heating
> and air conditioning. Normally, about 75 F or so, and the building
humidity ranges from
> about 10% in the winter to up to about 40% in the summer. For some of our
testing,
> we use a small Tenney, Jr temperature chamber, typically testing that
equipment still
> functions at the low and high temperatures we expect the human users could
tolerate.
>
> I won't go over every single piece of equipment the ARRL Lab owns, but
will give
> the highlights of the more important and heavily used equipment. It
should give a good
> overview of the test capabilities of the Lab. In addition to the
equipment I will describe,
> the Lab has the usual collection of cables, connectors, adapters,
attenuators and the like.
> Only cables that have been tested by the test engineer can be used for
Product Review
> testing, and at the least sign of trouble, they are discarded, or
relegated to the other Lab
> uses.
>
> For receiver testing, the centerpiece are the two IFR 2041 signal
generators, +13 dBm,
> LF-2.4 GHz. These are used in conjunction with calibrated step attenuators
and a few
> hand selected MiniCircuits two-port combiners. This fixture has been
tested to at least
> +40 dBm IP2 and +85 dBm IP2, with an independent verification using the
Lab's 2nd
> receive test fixture, which uses 1 W ultra-linear amplifiers donated by
Ulrich Rohde
> and attenuators and the like. For miscellaneous bench use, we also have a
pair of
> HP8640B generators. They are currently "self-cal" but in good working
order, used
> for miscellaneous tasks around the ARRL Lab.
>
> The receiver output is measured with an HP-339A distortion test set. This
is an older
> instrument, but in excellent working order and perfectly suited to RMS
readings of the
> receiver output, distortion measurements for SINAD sensitivity and the
like. Its analog
> meter actually makes it more useful in many cases than would a more
modern, digital
> readout. If a measurement is not affected by noise, it will give the same
results as one
> might get making the receiver output measurements on a spectrum analyzer,
but, as
> I had said in an earlier post, with a much better absolute accuracy.
>
> If needed, our HP-8563E spectrum analyzer (DC-26.5 GHz) does handle audio
analysis
> well. We also own a couple of National Instrument A/D cards and can
digitize any signal
> at up to a 500 kHz rate and use the accompanying Lab Windows CVI software.
We use
> CVI to control all of our test equipment and have written routines to
program the spectrum
> analyzer for various measurements. This package is the top-of-the line
industry standard
> test software, one step up from LabView.
>
> We also occasionally use the HP8970A noise-figure meter to measure
preamplifiers and
> the like.
>
> For transmitter testing, the HP8563E spectrum analyzer is the pride and
joy of the ARRL
> Lab! It is good from DC to 26.5 GHz. We ordered the high-stability option
and its
> minimum resolution bandwidth is 10 Hz. It can be used, with care, to
measure harmonics
> and intermod down to about 90 dB below the reference level. If needed, we
do have some
> VHF and UHF notch filters that could be used to attenuate the fundamental,
to make
> measurements well below that. The analyzer is used primarily for transmit
spurious
> emission and transmitter IMD measurements. We kept our old HP-141T
analyzer frame
> and plug ins and sometimes use it for various Lab tasks.
>
> For "gross" power measurements, we have a number of Bird wattmeters, with
elements,
> all in current calibration. We self-cal the elements because the times we
have sent them out,
> even to Bird, we were not happy with the results. For accurate power
measurements, we use
> an HP-437B microwattmeter with various power sensors (all calibrated by
HP). To make
> power measurements, the Lab connects a transmitter to a power attenuator
whose exact
> attenuation has been previously measured. We measure the power at the
output of the
> attenuator, then add back the value of the attenuator. This gets us power
readings to within
> about 4% or so, better than the Bird in most cases.
>
> For frequency measurements, we use a portable Optoelectronics counter,
with the high-
> stability TCXO option. We have recently acquired a pair of HPZ3801
GPS-conditioned
> 10 MHz frequency references that are now being integrated into the
frequency counter,
> to get accuracy down to a fraction of a Hz. We can also measure frequency
into the
> microwave range with the HP5351B counter, with 1 Hz resolution.
>
> This year, the Lab purchased a long-overdue digital storage scope, a
Tektronix TDS3052B.
> This will be used for our keying and T/R turnaround meaurements, replacing
our older Tek
> scopes.
>
> The Lab has some excellent "homebrew" equipment, too. For phase noise, we
use a test
> fixture designed and built in the mid 80s by Zack Lau. A few years back,
we tested a rig and
> then sent that rig to Ulrich Rohde, for testing on his $100K+ phase-noise
set up. We found
> correlation, +- about a couple of dB, across the entire range.
>
> A number of years back, Jon Bloom designed a 9600-baud bit-error-rate test
fixture that is
> used for some of the digital radios.
>
> Perhaps the most impressive homebrew fixture we have it the one that we
use for amplifier
> IMD testing. It uses a 100-w coaxial power combiner whose terminations
have been carefully
> controlled with matching networks to give at least 60 dB of port-to-port
isolation on 14 MHz
> for up to a 3:1 input SWR on an amplifier under test. With this fixture,
we can measure
> amplifier performance down to -60 dB PEP on third order and about -70 dB
on the higher-order products. This is much better than amplifiers we have
tested, and we have on at least one
> occasion measured an amplifier 10 dB better than the manufacturer, who had
tested the same
> amp, indicating that the amplifier manufacturer had measured his test
setup, not his amp!
>
> While not all of this equipment is brand new, it is all quite suitable for
the task at hand. ARRL
> has carefully characterized its test setup and knows its capabilities and
always ensures that
> its published data are that of the equipment under test, not the test
equipment. The only
> exception I know to that occured before my time, where the Lab used the
spectrum analyzer
> to measure a transmitter's phase noise, only to realize later that the Lab
had measured the
> phase noise of the analyzer local oscillator.
>
> Although newer equipment would improve the usability for the test
engineer, and may gain a
> dB or two of accuracy in some measurements, the differences would not be
night and day.
> Those reading our results can feel comfortable that they are accurate,
human foibles
> notwithstanding, within a reasonable and acceptable accuracy.
>
> I hope the Ten Tec list readers will find this description useful. My
wish list for new equipment
> is appended, if anyone wants a nice tax writeoff! :-)
>
> 73,
> Ed Hare, W1RFI
> ARRL Lab
> 225 Main St
> Newington, CT 06111
> Tel: 860-594-0318
> Internet: w1rfi@arrl.org
> Web: http://www.arrl.org/tis
>
> 1. Agilent 8753ES Network Analyzer
> 2. Agilent 35670A FFT Dynamic Signal Analyzer, DC-102.4 kHz
> 3. Agilent 5504B Phase Noise Test Set
> 4. Agilent 6542A power supply
> 5. Agilent 85640A Tracking Generator
> 6. Tektronix TDS-5052B (with Opt. "PS" - multiple option package)
> 7. Tektronix TDS-3052B (with TDS3AAN, TDS3BAT and TDS3GV options) - qty 2
> 8. Agilent E4407B Portable Spectrum Analyzer with E1779A battery pack
> 9. Rohde & Schwarz FSH3 Portable Spectrum Analyzer
> 10. Agilent 34401A Digital Multimeter - qty 5
> 11. Radar Engineers Model 240 HF-UHF RFI Locator
> 12. Radar Engineers Model 250 Parabolic Ultrasonic Pinpointer
> 13. Radar Engineers Model 247B Hotstick Line Sniffer
> 14. Simplex Inc. Watt-Muncher Jr. Portable Load Bank
> 15. Rohde & Schwarz ESIB26 EMI Receiver
>
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