The AM Forum

I recently came into possession of what I think is an old 2 MHz marine band mobile whip antenna.  Unfortunately any manufacturers markings/model numbers are long gone.

Here are some dimensions/details:

White tapered fiberglass mast, overall length about 13 feet, feed point is a strap with a small hex bolt about 12.5 feet from the tip.

Swaged probable stainless mount hardware, has toothed locking arrangement for attachment to standard marine “Shakespeare” lay down type deck mount base.

Center loading coil very closed space turns 3 feet
long. Nominal 4 to 5 inch per turn helical spiral wound between feed point and bottom of coil and above coil
to tip.  Appears to be very fine diameter enameled wire one continuous piece for the lower and upper helical sections and the center loading coil.  Wire is under what appears to be a spiral wrapped
Fiberglas tape sheathing.

Quick check of broadband background noise in the IC-7100  with the antenna mounted on the Tacoma’s left rear corner Shakespeare mount instead of the usual Webster Bandspanner indicates it might be resonant around 2.1 MHz, makes sense since the old marine HF calling and emergency frequency was 2182 kHz.

Can anyone provide any further info on this antenna?  Thinking I was might be able to get it to work on 160 Meters with some added series L at feedpoint along with a healthy amount of feed point shunt C.  Although it’s efficiency will likely be miserable based on the really small diameter wire used in its construction.

Photo attached shows it on the Tacoma in the tilted forward for transit position.  A spring line keeps it stabilized from whipping around.

I’m thinking it might be a Shakespeare product because they were and still are big in the marine antenna market.  A quick review of their current HF marine whips indicates thier resonant frequencies are typically around 10.8 MHz, and are useable down to 2 MHz with an external
antenna tuner.  Based on the size of the coil on the antenna I have compared to those on Hamsticks, this antenna most likely does resonate around 2 MHz. 

If not anything else, it really kicks ass as a BCB receiving antenna! 

Chris AJ1G
Stonington CT

maybe it  had a life as a Shakespeare Ugly Stick surf rod   ;)

Nah…have a couple of those.  This antenna is ugly but  the same color all the way from base to tip. Ugly Sticks are usually black but have a section at tip that is kind of off white/yellow.

One thing I found out about Ugly Stick rods is that if I have one in the rod rack near my Webster Bandspanner on the left side of the Tacoma bed, is that they will knock the antenna tuning way off resonance.  There must be some sort of conductive foil or other metallic material in their composition.  I can have a huge old school Lamiglas surf rod in the same rack crossing within inches of the antenna and see no effects on the antenna tuning.

Chris,
I would just make a frequency sweep measurement for swr to determine were the antenna was originally used, for your curiosity. Next make an impedance measurement for the band of interest and determine if it's feasible to match it at the input or go to plan B.
Joe  

That’s the general plan.  Didn’t get a chance to do that today, we actually had about an inch of rain, more than we have had in many weeks.

I do miss all that rain you get. A few years ago, I went through that exercise of measuring the impedance at the end of the 450-ohm line feeding my 75meter doublet to match it for 160 meters.  Used a L network for matching, received signals were OK but transmitting I was piss weak. Extrapolated the data to account for transmission line length to determine antenna feed point impedance. The feed point resistive part was in the order of < 5 ohms, so much for efficiency. I will be curious to see what you find.
Joe         


 






   

Chris, I dont know the brand of your ant but given the hex nut feedline connector it sure sounds like a 2MHz antenna.  They are designed to feed with GTO cable rather than coax and additional base loading was usually inside the AM transceiver. Yours is a shorty, there were also 2MHz ants appx 18’ tall that were common.

Well I got it to resonate quite well with a good match right into the IC-7100 (which has no internal antenna tuner) with a nominal 120-140 uH added series inductance between the antenna and feed point and 1500
pF shunt capacity across feedpoint.  Used a TCS-12 antenna loading coil box at maximum inductance (100 uH) in series with a section of nominal 2” diameter miniductor style coil stock with an adjustable tap mounted in a plastic tool box that I normally use for base loading my 16 foot fixed mobile antenna made from an Ocean State Job Lot pool skimmer pole on 40.  Found coil tap
settings on the miniductor for the entire 160 meter band.  Picture below shows the feed point.  Don’t intend to ever operate on 160 underway will just set up the matching coils when set up to operate from a fixed location.

How well is radiating?  Tough to tell on 160 at 10
AM on a summer morning but I didn’t light up any Reverse Beacon Network CW skimmers and was inaudible on the KB1VWC Kiwi SDR out in Falmouth MA.

Will see if anyone can hear me on the 1945 kHz Grey Hair Net prenet tonight from down at Stonington Point.

Well it’s working!  Working Kevin K2XAM from down on Stonington Point, hearing myself up
To S9 on AM on the K1VL Kiwi SDR in Shrewsbury VT.  Standing by for the Grey Hair Net!

Chris, Bravo!

Those antennas were cut for 2 to 3 MHZ and used a "ground" system on most vessels done by bonding to the engine, keel (if a sailboat) and a ground plate of copper sheet about 2x3 feet. Also popular was a "ground bar" of bronze beads about 3x12". You have the smaller version of that antenna. The most common was 23 feet tall, in two sections- the lower part with the loading coil and a 9 foot fiberglass whip above. On a good day you could get the Boston Marine Operator on 2506 KC during the day from New York's Long Island Sound where I serviced AM marine radios. Very cool to see one again, especially mobile!

Thanks for all that info Chris.  Went over to Weekapaug Point RI last night around Sunset.  One of my favorite mobile operating spots on some 20-30
foot cliffs overlooking a rocky beach where you have nothing but opens ocean to the south and all
of LI Sound to the west.  No one on at first so called CQs on CW, lit up a number of Reverse Beacon Network skimmers with up to 35 dB SNRs, almost all the hits were in double digits.  Called CQ on SSB and was 10 over 9 into the K1VL Kiwi SDR up in Shrewsbury VT,  S9 down to one in MD on its NE Beverage.  Made an aircheck recordong off of K1VL which is attached along with pix at Weekapaug.

Would love to find one of the bigger HF marine antennas.  Been checking the various marine consignment shops around here, a good one in Mystic but no luck so
far.  The results from the 12 plus footer are motivating me to put something of that size together before the snow flies. Am also going to try putting together a tossable in water grounding plate to connect to the truck frame from some scrap copper flashing I
I have here.

From the values you used for the matching network, the antenna feed point Z: 19.35 -j1.55k. 19.35 ohms for a 13-foot vertical on 160 meters that's amazing.   

Interesting.  I was skeptical of how well it might work when I saw how small the wire diameter appeared under the fiberglass wrap - way smaller than even that of an MFJ helically loaded whip.  Had a nice extended SSB QSO with Ken N2DF in the Catskills on SSB this morning, was marking 58-59 there.  Also heard what
might be longline fishing float beacon transmitters up at 1915 1916 and 1926.  Sending 4 letter CW call sign followed by a long dash.  The one on 1916 was signing AWW4.  I thought those were generally down below 1800.

Chris-

   Great results for such a short antenna! If you happen to find one of the 23 foot antennas be careful: There are two versions, one with the loading coil woven into the fiberglass, the other is just a two section straight whip, no loading. That was the standard antena we used on the High Seas SSB  radios from 4 to 22 MHZ. Webster also made an aluminum two section 23 foot loaded antenna with a phenolic loading (enclosed) coil. Another one with loading was made by Basset. The best, but expensive. Those came made for specific bands, including the AM broadcast band. Every now and then you see one on a Traffic Information Station installation. The floating fishing boat beacons all operate above 1900 KHZ to my knowledge. Th0se things are very P.W. and if you hear them during the day you are doing really well.

Thanks for the info Chris.  Next iteration for fixed mobile ops will likely be a nominal 24 footer consisting of of the 16 foot aluminum pool skimmer pole with a loading coil at 8 feet between the two sections of the pole topped off with an 8 or 9 foot stinger.  Would have loading coils to work on 160 80 and 40.  I’ve base loaded the nominal 16 foot pool skimmer pole on 80 and 40 which has worked pretty well on those bands, and also
as a 20 meter quarter wave without a loading coil.

Just did some pre-sunrise Antenna A-Antenna B comparisons of the 160
mobile antenna parked in front of the house, and the home station 160 meter dogleg dipole, both with 
100 watts to antenna.  Reported reverse beacon SNRs on a few stations where I had relatively high SNRs from both setups, shows the mobile antenna signals were about 10-13 dB down relative to the dipole, or more optimistically, within around 2 s-units.  Based on a number of repeated comparisons within about a minutes.  Similar to comparisons I’ve made of other mobile antennas on 80 meters. 

 :o

Hi Chris,

Heard the chatter on 75m..

I see the two versions https://shakespeare-marine.com/product/classic-ssb-antenna/
Looks like the 393 model, 3 sections, does not have the loading and is resonant at 10MHz.  Model 390 is two sections,
They're both 23ft.  I dunno if model 390 has loading or not, haven't found details yet.

Those Shakespeare antennas are current production, and much bigger than the antenna I am using.  Neither antenna is resonant in the vicinity of 2 to 3 MHz.  They are designed for use over a wider frequency range and depend on use of an antenna matching network either within a radio or at the antenna feedpoint.

A good counterpoise is absolutely critical at those frequencies and you'll notice the greatest improvements as you begin adding radials. Try laying out four 50' wires as a start. They don't have to be 1/4 wavelength but the more the better. The goal is to couple to the earth as best as possible to complete the "RF circuit".

Clamping on to a bayside corrugated steel bulkhead would be superb if you can find one. Other possibilities include a steel cable fence, water pipe (drinking fountain), and even the copper grounding wire on a phone pole.

Did I mention that a good counterpoise is absolutely critical at those frequencies? It can't be overstated...

When I had a 27ft sailboat, I installed this copper strapping on the inside of the hull just below the water line. ALL around, front to back, both sides.  This was in 2002 before copper prices went up.  Ran a Kenwood TS-50, SST toroidal tuner and hustler mobile antenna with two bottom sections.  The copper strap was my capacitive ring coupled counterpoise, the fiberglass hull was a capacitor (dielectric).  My 2c

I recall in my childhood days, my dad (W2DU, SK) used to discuss antenna efficiency issues at the local club meetings.  One of his favorite antennas was the "underground umbrella".  It consisted of an array of wires, buried a few inches, extending in all directions for about a quarter wavelength.  He showed pictures of his cultivator attachment for a small garden tractor, with a slot and a small pulley, used to easily and effortlessly bury each of the antenna's radiators.  He espoused the the fabulous performance of this underground antenna, but he qualified his findings, with the additional statement that the underground antenna performed best if a counterpoise is employed, consisting of several quarter-wavelength wires, extending outward from the center of the underground antenna, and said counterpoise MUST BE ELEVATED as high as possible above the ground.

I’m sure I could improve performance on 160 meters  of the 13 foot marine band whip with a set of external radials.  What I’m trying to do with it at this point is see how well it will perform as a vehicular mobile antenna using only the vehicle itself as the counterpoise.  At most of the shoreside locations I operate from its not possible or practical to deploy counterpoise wires although at some
locations I probably will try dropping a grounding anode plate into the drink fairly close to the rear of the truck.

I might also try operating the 13 foot whip at the home station where I have a vertical antenna system with an approximate 8 foot above ground feedpoint and can deploy up to 16 35 foot long elevated radials and 4 more either 35 or 70 foot long elevated radials.  The elevated radials are also nominally 8 feet above ground.  I can configure the vertical radiator above the feedpoint to be either a nominal 33 foot quarter wave 40 meter vertical, a nominal 34 foot up 35 foot over 80 meter inverted L vertical, or put up a nominal 30 foot long helically loaded with top hat K6MM 160 meter vertical. The 80 meter inverted L can also be used on 630 meters with a large Homer Bucket based variometer resonated base loading coil at the feed point, and can also be run as a 33 foot up with 70 foot horizontal Marconi Tee by adding a second 35 foot horizontal wire up top.

It would be very easy to put the 16 foot marine mobile whip for 160 over the home station counterpoise to see how it plays relative to the K6MM.  OTOH would love to try setting up the K6MM at the beach using the truck body and possibly some counterpoise wires but at present it’s too much of a wet noodle to allow doing that without some extensive guying.  At present its hung over the home station counterpoise system on a halyard from a very high crowned oak tree branch about 20 feet from the tree’s trunk.  Making the best of what I can install within the limitations of the landscaping.

And then I could do what Warren, K2ORS once did - operated 160
underway mobile on the Mass Pike with a nominal 135 foot “trailing wire” counterpoise deployed behind his car.  At least for a few miles….😁

   I'm curious what you do for a ground plane?? I have 2016 Tacoma same as you but with a aluminum lock box behind the cab. The lock box has a 1/2" braid from it to the metal skin of the bed and the cab. On the passenger side of the lock box is a small ball mount, I've used it for a 10M MFJ hamstick and an Outbacker antenna while stopped. I can also clip on a 65 foot counter poise, that does really change where the Outbacker tunes. In March 2017 while parked at a camp ground in Death Valley I worked South Africa on 40M SSB and with out the counter poise. It would have been a tripping hazard in a camp ground.
 
   Later I mounted a full size ball mount to a piece of plywood in the rear of the bed and added a few 6 foot lengths of 1/2 copper braid, one to the lock box for a counter poise. Like your Tacoma mine has a composite bed. I run a Zachtek WSPR TX on 20M while traveling with a MFJ 20M hamstick.

    When stationary I can use a 17 foot MFJ telescoping mast and a SGC-230 tuner with an Icom 7100. The picture was taken at the North Rim of the Grand Canyon two years ago, almost to the day. I used a 65 foot wire to improve the counter poise. It was late afternoon on a Saturday, band conditions were not good but I worked TX, LA, MS, AL and Ontario on 20M and the West Coast on 40M
 

   

Hi Tom.  Nice setup in your Tacoma.  Yes my 2012 Tacoma does indeed have the GRP one piece bed and inner fender liner tub . I think I may have shown it to you at one of the spring Nearfests you have attended. In my opinion it’s what sets the Tacoma and the Tundra apart from the rest of pickup trucks on the market.  You can beat the crap out of that GRP bed without worrying about denting it or scratching paint.  If you ever would break it it looks like it would be easy to replace.  It’s one shortcoming for mobile HF is that it leaves a lot of potential useful  counterpoise surface wanting.  This last spring I took steps to remedy that by covering the floor of the bed with a couple of sheets of stamped aluminum wire mesh lath that Home Depot sells for abut 17 bucks for a 96 by 42 inch panel.  It’s sold in the wallboard and sheet rock aisle for use in old school plaster wall construction.  The left and right rear corners of the mesh are bonded to the tailgate pillars at the hasps for the tailgate latches.  My HF antenna feed line shield is bonded to the left side hasp at one of its  two large mounting bolts into the pillar. I have not done any other special bonding of the truck body and frame, although others highly recommend it, some to the point of obsession. The Shakespeare marine lay down antenna base mount I use for the Webster Bandspanner and the 160 meter antenna is mounted on an old Master Mobile L bracket section that is fastened to the pair of bolts on the top inboard side of the left tailgate pillar.  I picked up a pair of these brackets at Nearfest the first time I took the then new truck to the fester.  Thier mounting hole spacing was almost a perfect fit to the pillar bolt spacing.  I had to hog out one bracket hole slightly to make them fit.  The mounts originally came with plastic center insulators and a 3/8x24 female coupling for mounting an antenna on, but they eventually cracked from age and UV embrittlement and were removed. I installed both L brackets one on the left and one on the right tailgate pillar. The right one is unused at present.

I covered the added aluminum lath panels over the bed with some vinyl diamond mesh mats also sold at Home Depot, securing them to the bed with stainless steel oval head screws and shoulder washers.  Looks
pretty good and keeps stuff in the bed from sliding around better than the relatively hard surface of the stock GRP bed.

In addition to the Shakespeare lay down base, there is also one of the Toyota adjustable GRP cleats positioned at the left rear corner of the inside top of the bed that is drilled to hold a 3/8x24 female coupling for mounting lightweight antennas such as Hamsticks. The cleat is also drilled to anchor a nominal 18” long piece  of thick wall 1 1/2 inch ID PVC pipe that is also anchored on the bottom with an end cap and bolt onto the bed.  This can be used as a mast “step” for large antennas such as my large “DX Skimmer” vertical made from a 16 foot overall two section Ocean State Job Lot  pool skimmer handle. There is a picture of the feed point installation features on one of my earlier posts on this thread.