[MRCA] Grab & Run Antenna series update

[Dennis]

I have updated the Grap & Run Antenna series of pictures, & added some text as seen below:

<http://groups.yahoo.com/group/milpack/photos/album/1108482620/pic/list>

This "Grab & Run Station Antenna" is in effect a scaled down version of the 21ft "Portable 
Station" pictured in our archives. That antenna though very effective is hard to reproduce 
because it uses a coil that can not be easily duplicated. This idea is based on a coil that 
is currently available from an Ebay vendor. Other parts are readily available or can be 
easily fabricated. More on that later.

Picture #1, Coil on Tripod:
With M422 & 12ft of MS-116 type mast sections. Set up like this, with one 16ft
counterpoise wire attached, the antenna will make it down to 3.536mc. The beauty of this 
coil is that it can be tuned very close to the operating freq simply by listening & sliding 
the coil/tap up & down. The "Dog Knot" is just big enough that hand capacitance has little 
effect on resonance.

Picture #2, Coil & AT-271 on Tripod:
Here I have added some mast below the coil made from the first section of an old
AT-271. The coil is small enough that it could be used Pedestrian Mobile. With the AT-271 
whip the coil will work down to 3.854mc(the extra section below the coil is not required but 
I like it). The tripod was used for testing & would probably not be part of my grab & run 
kit. While the antenna will easily resonate 75mtrs with whips of 9ft & above, a 16ft 
counterpoise is not long enough to get a usable match to a none tuner equipped radio.

Picture #3, Bag & antenna ideas:
Pictured is a standard CW-503 PRC-25/77 antenna bag. Everything to it's right
will fit in the bag with room to spare for some coax, counterpoise wires, parachute cord guy 
wire(if longer whips are used). 17ft of AB-21 type mast sections are shown to the left. 
These or MS-116 type mast sections, combined with an M422 adapter(available from Fair radio) 
would also work very nicely.

Picture #4, Coil Close Up:
Design of this coil is quite unique. Rather than turning a coil form with grooves to fit 
bare wire, this design uses enameled copper wire tightly wound, then the outside edge shaved 
off. It makes for a very nice, compact & rugged package.

Picture #5, Tape Antenna Just For Fun:
Here the coil is mated with a home brew goose neck base & PRC-25/77 Stanley Tape antenna 
AT-892(or similar) antenna. The thread adapter was made from a defunct CB fiberglass whip. 
This antenna will radiate down to 6.3mc. Believe it or not, this antenna will work. I have 
made many contacts on 60, 40, 20, & 17mtrs with even smaller antennas of this same 
configuration.

Picture #6, Coil Comparison:
The coil on the right is one I made over 20 years ago. It too will resonated an AT-271 down 
to 75mtrs. It has seen a lot of use over the years. Note my signature coil-spring tap 
method. It works good but is not nearly as fast as the sliding "Dog Knot".

Picture #7a, 18ft Ground Mounted Vertical:
Here the coil is assembled as an 18ft ground mounted vertical using AB-21 type mast 
sections. This complete set can be bundled up & will fit under the seat in your car.

Picture #7b, Vertical & guy Ropes:
I prefer four guy ropes on my portable verticals mainly because it's easier for a single 
person to set up. Ropes here are Parachute cord anchored with aluminum guttering nails.

Picture #7c, Coil Stake Vertical Close up:
M422 whip adapter can be seen on top the coil. Ground stake & misc all came from the junk 
box. Coil tap is shown set for 7296. Though AB-21 sections are used here, MS-116 type 
sections will also work. There are a couple 5 way binding post provided for counterpoise 
connection.

Picture #7d,Weather proofing the coil is pretty easy. This plastic pop bottle with the 
bottom cut out works very well & is easily stored with the rest of the kit. Simply slide it 
up out of the way to adjust the coil.

Picture #7e, 18ft verson of this antenna was set up in the fall & used all winter on 75 & 60 
meters. At times it outperformed the B&W T2SD I have up at 20ft.

Picture #8a, Grab & Run kit contained in a padded nylon assault rifle bag obtained on ebay. 
The Springfield Armory M6 illustrates the small size of this kit.

Picture #8b, This kit is built around AB-21 family mast sections because of their short 
length when collapsed(24"). MS-116 type mast sections will work equally well but have a 
collapsed length of 39". 18ft worth are used in this set even though only 8 feet are 
required for 75-10 meter coverage. An additional 24" mast section was made from aluminum 
stock & threaded 3/8x24 on each end. This to be place under the coil when/if needed to 
improve system efficiency extending the antenna over all length to 22ft. It's not normally 
needed but nice to have. Also seen is the coil, M422 whip to 3/8x24 adapter, small bank bag 
for parts, pop bottle weather protection, & group mount stake made from a GRA-4 military 
antenna guy stake. The shop rag is handy to have for multiple reason especially as I have 
coated the mast section threads with Noalox(a graphite based electrician's grease).

Picture #8c, Accessories include 50ft coax, 4ea counterpoise wires w/lead fishing sinkers on 
the ends, 4ea guy ropes made of parachute cord & aluminum guttering nails, some extra 
parachute cord(you can never have enough), 2 pairs of pliers & a couple pieces of rubber 
from an old truck inner tube. The later are must have items when using AB or MS mast 
sections. The rubber between the jaws of the pliers will aid in disassembly of the mast 
sections when they stick together(& they will stick!). When loosening stuck mast sections do 
not apply steady pressure, but instead use quick jerks to break them loose. Also included is 
a spring made from a defunct AB-15 antenna base. I've threaded it 3/8x24 just to add a 
little more versatility to the set.

Picture #9a, Miniature Grab & Run Antenna kit. This set is composed of coil combined with a 
standard AT-271 & contained in a CW-503/PRC or similar canvas bag. I carry this one behind 
the seat of my Jeep. This kit will work 75-10mtrs.

Picture #9b, Miniature Kit Contence; AT-271 whip antenna(about 9ft), AB-129/PR spring base, 
20ft RG-174 coax, extra 17" mast section made from a first section of a broken AT-271 & 
threaded 3/8x24 on both ends, modified AB-1135/PR(re-threaded 3/8x24 & binding post added 
for counterpoise connection), 2ea counterpoise wires(more would be better), water bottle 
weather protection, coil.

Does it work?
While testing on the tripod with the AT-271 whip attached, I gave a call on 7296
with five watts at 15:00 central. Conditions were not optimal & there was some
broadcast interference. I'm in Missouri, KM4V heard me while mobile in East
Tennessee. When he got home we could easily pass traffic & did for several
minutes. I was running an FT-817. Yep, I'm embarrassed to say that not all my
radios are green, & a few are of oriental origin.

Later at around 19:00 on 3.996mc, with 15ft of MS-116 mast sections I was able
to carry on a QSO with KM4V in Tennessee, WA4VAG In Kentucky, & made contact with KA8TUR in 
Michigan, KW1I & K1JHM(on a PRC-47) in New Hampshire. And before going to bed talked with 
KJ5GT in New Mexico on 60mtrs. All this with less than 100 watts.

Other Ideas:
You might be able to side saddle this coil to a "Witches Hat" AT-1011 base
for use of this whip without a tuner on 60 & 75 meters. Remember, the
MS-116/AB-21 type mast sections will self support to 18ft but they get a little
gangly at that length especially if there is any wind. I use some parachute
cord for my taller verticals as guy ropes with aluminum guttering nails as
ankers.

Here are some figures as to antenna length & lowest usable frequency:
18ft-2.80mc
15ft-3.00mc
12ft-3.53mc
9ft-3.85mc
6ft-4.48mc
2ft-6.50mc

Some Notes on Counterpoise Wires:
On 75mtrs a longer counterpoise was required for a suitable match(even though
the  antenna/coil was resonant). I had  to shorten that same counterpoise to about 30ft for 
60mtrs. It  was after dark & I do not know the exact lengths. I did not do much 
experimenting with counterpoise lengths & nor do I plan to. You will need at least one, & 
longer is not always better! 

A trick I use with all my pack sets is one counterpoise/drag wire that is 8ft long. This drag wire is made from assault demolition wire used to detonate Claymore mines. It's looks for all the world like 14ga zip cord but it is rubber coated & super flexible. The ends of this wire are shorted together on the far end so the the doubled over length is resonant at the high end of 20mtrs. Like this the wire will not load worth a 
crap on 17mtrs so I unshort the far end making it's electrical length about 8ft. This works great for all freqs above 20mtrs. A similar arrangement might be scaled for use with this antenna system.

The coil is available for $50 from ebay vendor:
hamdudedanielchristopher
He has just placed a large order for parts & consented to sell to us outside ebay for 
$45(cheaper for larger orders). Believe me, there is a lot of work in one of these & the 
price is well worth it. Tell him you want it made just like the one he made for Dennis Starks! He can be contact via email at: <danielchristopher14 at yahoo.com>

I've been after him to design & produced a scaled down version of this coil for lower powered Pedestrian Mobile & QRP use. He has come up with a couple prototypes but his progress has stalled. Nag him about this if you get a chance.

Be patient with him, he's a good guy but new to ebay selling. Currently these coils are 
being made to order with about a ten day turn around time. Tell him I sent you.
Sure, other antenna systems are available like the P-1, MP-1, & Buddy Sticks. But those you 
can't just get the coil & tailor the antenna to your needs. None of those are a strong as 
this coil either.

I get really put off by those who use the excuse for never being on the air that they have 
no place for an antenna, or live in an antenna restricted area. BS, get busy!

Dennis Starks
KB0SFP
HFpack/Milpack Monitor(all USB):
3996, 5403.5, 7296, 14342.5, 18157.5