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NEW INFORMATION: Well Don's been at it again! You've been
asking for a higher power version, well here it is! Don has
changed the PVC material around the coil to be able to handle 250W without any trouble. We
keep getting a lot of requests for a for at least 500W, but we haven't gotten any negative
feedback so far with these new units. About 1500 of them are now in use in the
field.
Yes you can paint the outside of the antenna housing to
match a vehicle, but do NOT paint the coil! Updated as of 4-5-06
W6AAQ DK-3
For Orders Please e-mail me for
availability kc6fry@sbcglobal.net
YES Don Johnson W6AAQ is still
alive and making antennas!
This is the real McCoy, the original, not a copy, DK-3
Screwdriver Antenna from Don Johnson W6AAQ. Yes he is also the one who wrote the book 40+
years of mobiling. Continuous coverage from 6-80 meters. This is your tuner and antenna
all in one package. No need for a separate antenna tuner. You provide the switch, whip, & wire to your car battery, mount it and
your ready for some fun DX.
Extra Stuff I now carry
the DPDT momentary switch if you do not have one, or don't want to spend the
time to find one.
Quick Look at specs:
Height- 42 inches tall in closed position. Coil will
travel approx 14 inches max extended position. Add whip length of 66 inches and
your about 9 ft tall overall. Weight just over 6 lbs. Tube diameter 2
inches. Current draw, we've seen between 1.25-1.75 amps, depending on
weight load used as weather cover. Power Handling 200 Watts or less. You
can go higher if your amplifier has a very clean output, IE No Parasitic's. To
Quote Don " why try to talk further than you can hear"! General rule
of thumb, if you can hear them, they can most likely hear you! they may not wish
to answer back if they are in a pile up looking for certain Call Signs!
DK-3 Shown with Weather Cover with UV resistant Tie Wrap
W6AAQ Original DK-3
Screwdriver Antenna
Please Note Weather covers are a
must for warranty!
 Mobile-RVs-Portable-Condo's,
Boats,
Mobile Home Parks, even Motorcycles!
Can be used in any orientation from
Horizontal to Vertical – or even upside – down
Continuous coverage ALL frequencies
80 thru 6 meters
CB WARC MARS CAP
SWL Broadcast Easily assembled, installed and
operating in minutes. No tuning, tweaking or tip pruning.
No Jumpers. No Taps
No Shorted or Open turns Does not require a
tuner No test equipment needed to set up
Turn on receiver, move coil up or down to
peak for maximum receiver noise and start talking.
Longer whip requires modified resonating
procedure when antenna is physically longer than quarter wave
Antenna is into 13th year.
Thousands in use World Wide
CONTINUOUS COVERAGE OF ALL HF FREQS
For Radio Amateur work: Continuous coverage from 3.5
up through 54 mHZ. The antenna is
resonated to desired operating frequency from
operators position without stopping or exiting
vehicle. Originally designed for HF Mobile
operation, however, has found favor for many fixed
stations where full sized arrays are not permitted
or possible.
DESCRIPTION The antenna
operates as a center loaded device. The loading coil slides up and down inside
the lower mast. The turns submerged into the mast are no longer turns due to the
low RF reactance; consider them the same as part of the mast. The antenna
absolutely DOES NOT require a tuner.
DON’T PANIC ! That sliding rattle you hear is the clutch springs sliding on
jackscrew. DK3®
INSTALLATION WIZARD
ANTENNA MOUNT Screwdriver Antenna™
A simple one inch diameter mounting stud is shipped with the antenna;
temporarily stuck in the bottom of the mast.. .There’s about 1 ½ inch of 3/8s
by 24 threads in the bottom of the stud . Mount he stud permanently onto the
vehicle... . The DK3 sets on the slightly tapered stud To remove the antenna
from the mounting stud, give a quick twist while pulling the antenna up. Acts as
a quick-disconnect This is the only type of HF Mobile mount we have used in over
50 years -- never had one bounce off. NEVER NEVER NEVER use a spring mount. The
base of the antenna is connected to the vehicle ground ---- both mechanically
and electrically
VEHICLE GROUNDING AT THE ANTENNA LOCATION
The mounting stud supplied with the antenna is permanently mounted directly
to the motor vehicle metal. ..-no insulator. An additional large low
inductance grounding strap -- braid – must be connected from one of the
connector clips at the bottom of the antenna mast to the vehicle frame. The
connection to the frame must be kept clean and free of corrosion. Keep after
it -- requires constant attention.. All this is true for any type of Mobile
HF Antenna. Also a separate ground braid is required at the receiver grounding
post à connected with shortest possible route to
firewall.
TOP WHIP DK3 accepts the standard mobile fitting, 3/8 by 24
thread. Antenna is designed for 66 inch top whip, however, plus or minus a foot
or so either direction is OK. Different whip length will affect either upper or
lower frequency limit. Suggest using the Radio Shack # 21-988 whip.
POSITION OF ANTENNA ON VEHICLE The ACTIVE part of the coil and the top
whip must clear any vehicle metal by 18 inches or more. Fiberglass RVs may have
metal studs. –Careful ! The lower mast can be as close as 3 or 4 inches.
ANTENNA MOTOR CONTROL
Number 20 + or - zip cord [lamp cord] from the operating position to the
motor power cord. The control switch MUST BE Spring Loaded - Center Off -
DPDT. Use a Radio Shack # 275 - 709. Polarity to the switch is not important.
The motor floats electrically.
SWITCH Radio Shack # 275 - 709 à
The SPST switch and 2 or 3 ohm resistor, shown as shaded, are not normally
installed. Can be used as a refinement to slow the motor speed for fine
tuning . The DK3 is so simple to resonate it is almost obscene.
After a short familiarization it is possible to zip around from band to band
as fast as the coil can be positioned. A Field Strength Meter is superior to a
SWR bridge. Schematic in any of W6AAQ HF Mobileering books. Also in this manual.
Screwdriver AntennaÔ Design
and Invention by DK Johnson W6AAQ 1991
A GOOD RF GROUNDS ARE AN ABSOLUTE NECESSITY A
DC (ohmmeter) GROUND IS NOT NECESSARILY AN RF GROUND. Also DO NOT depend on
the mechanical mounting stud for the RF Ground. There are two (2) ground
clips at the base of the antenna. Use one for the co-ax shield. The 2nd
ground clip must be grounded with heavy grounding braid or strap directly to
vehicle frame. The co-ax shield is not to be considered as the antenna ground. Use
that 3rd clip to vehicle frame.
RF GROUND RF GROUND RF GROUND RF GROUND RF GROUND
The first Screwdriver Antenna TM patent disclosure was
filed on 18 March 1991. There have been subsequent filings.
The manuscripts and construction manuals have copyright protection.
Our 1993 data-base documents transactions with many of the current bootlegger
manufacturers who purchased a DK3
.. Screwdriver AntennaTM from
the original designer and then went into full commercial production without even
so much as a "by your leave, sir" . No mention was made as to where
they ‘picked’ up the design. Some reprinted the copyrighted materials --
using white-out to remove references to
W6AAQ. Identifying headers and footers were blanked
out. They photo copied pages from the books and then sold them at swap meets.
One went so far as to construct a new cover page --- misspelling the word ‘antenna’
in 3 inch high letters! Buncha bums!
Honorable hams – eh? We tell ham friends that when we steal one of their
ideas, at least they receive credit for a couple of weeks before it is claimed
as our own brain child!!!! All contributors are credited in our books and
compendiums.
FIRST TIME TUNE UP 75 meters: Run the coil all the way out of the
lower mast until you hear the first ‘click’. Select your 75 meter
frequency on the antenna analyzer (or your rig with a little carrier
inserted) ---lower the coil down into the tube. Soon you will see the Field
Strength peak --- if you do not stop the coil movement at the precise position,
the field strength will decrease quickly. STOP, to sneak back, give the switch a
tap or two in the opposite direction until the antenna is back on resonance.
With a little practice it will be a breeze. It is important to watch the output
very closely --- it is possible to zip right by during a ‘blink’ of an eye.
You’ll soon educate your safe-cracker fingers. When close -- just
lightly tap tap the switch.
Let’s try that on the way to 40 meters: Put the receiver on the
selected 40 meter frequency à start moving the
coil into the tube. It’s going to take 30 seconds or more. The antenna will be
in the 40 meter range with about 4 inches of the coil exposed -- exact amount
will depend on length of top whip See chart on page 10. .OK, now insert some
carrier and jiggle the switch up or down until whatever indicator is used shows
the antenna is right on resonance. Tap-Tap The same procedure is used
for 20 meters & the higher frequencies.
W6AAQ never uses a SWR bridge…..use a Field Strength Meter ---- it
is so simple ---- just hold the transmit switch down (AM or CW) until the meter
needle maxs out. OR if you don’t mind living dangerously, here’s a
system which works OK. Let’s say you have a TS-50: Get the antenna coil in the
approximate position; Put the xcvr on AM..(don’t talk) key the rig with the
mike button and move the antenna into position by watching the power-output bar
on the TS-50. [or any other rig] That’s all !!
More info à For longer top whips and
other approaches to FREQS above 20, 17 or 15 meters A whip longer than
66" may be used. CB whips might be 102" to 108".
They are OK if you can keep from knocking out overpasses. The longer whip
will give up to 3dB more gain on 75 meters. Ahhhh, that’s only a half S unit
---- but maybe you want to fool yourself anyway. With the longer whip, the
overall length of the antenna may be over a quarter wave on the highest bands
..... now you’ll never find resonance on 10 –or will you ? à
read on
Using a long CB whip: A system was demonstrated by a visiting out of
state ham -KC5VWB. He had a schedule on 10 meters while here. 1st he ran
all the coil out of the lower mast ...(that sorta confused me right at the
start). Next he put his TS-50 on CW [I use AM position] on the ten
meter frequency. With carrier inserted he started moving the 15" coil
down into the mast The coil went down only slightly below the 75 mtr
position...maybe 2 or 3 turns..... [About 11 inches of coil was still exposed ] à
there the power output bar on the TS-50 maxed out! I was absolutely
dumbfounded! He explained the same procedure could be used for 17, 15, 12, CB as
well as ten meters. Terrific ! Fool around. .Six meters can be located
the same way. A San Francisco ham also finds a 2 meter spot…
WEATHER COVER FOR THE COIL To keep out road grime & bugs:---
DayStar Series #69 Motorcycle fork boot. Or splice of two the cheap 1.5
liter water bottles end to end. Do not use anything real heavy --- inverted
pendulum -- Physics 101 again.
POWER The PVC coil form will get pretty dicey [limber} with 500 watts +,
especially if a ‘dirty’ solid state linear is used. Most of them are! Coming
up on 70 years as an amateur -- never been over 100 watts. Why send farther than
you can receive. Ego trip? Receiving is usually the main problem while mobile.
AUTOMATIC TUNER? Don’t you even dare think about it. The DK3 is
the tuner. Those automatic positioners are pretty stupid also. You still have to
‘tweak’ them by hand.
Another PT Barnum scam. TO GET ON RESONANCE? Use a Field Strength
meter. Forget about a SWR bridge. Most of the ‘on-the-air’ experts will lead
you astray. Listen to the OM! PAINT THE ANTENNA: Paint the entire thing
[except the moving coil]
Suggest auto lacquer. DO NOT CRUSH OR ‘DING’ THE LOWER MAST. The
coil will freeze up!
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Fork Boot Cover only.
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QUESTIONS? Airedale E-
Mail 
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SORRY OUT OF PRINT!
Please contact WorldRadio www.wr6wr.com
and let them know your interested in getting the book reprinted. Thanks
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Don's new CD in now available!
* 40+5 Years of HF Mobileering
* Everything You Forgot to Ask About HF
Mobileering
* The Little Pistol's Guide to HF
Propagation
* Plus the Bonus Worldradio 2000 Archive
The CD-ROM contains the books 40+5 Years of HF Mobileering, Everything You
Forgot to Ask About HF Mobileering, and the Little Pistol's Guide to HF Propagation
in Acrobat PDF files. In addition to these great books all of the Worldradio
2000 issues are on the CD in Acrobat PDF files. And, if you don't have Acrobat Reader to read the files – Don't worry, it's
on the CD too!
MINIMUM SYSTEM REQUIREMENTS
PC / MACINTOSH
Pentium 200 or compatible PowerPC
Windows 95 System Mac OS 7 or greater
32MB of RAM
8X CD-ROM
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