To: Tom - K5RC
Really enjoyed reading your posting about the 'high' dipole
that you & others put together for K5XI. It reminded me of
one of my own FUN and effective high-dipole stories.
During the mid 1960's, I lived in Tucson AZ while going to
the Univ of Arizona. While there, I was a Broadcast radio
station engineer in afternoons, evenings, and weekends. KTKT
was the local Rock & Roll station on 990 KHz A.M., ran 10 kw
to 5 separate phased towers.
In those days, being a radio station broadcast engineer was not
a very 'pressing' job. My work-mate was K8IHD (now KE7QM).
We both liked messing with antennas, and right outside the radio
station shack were these 5ea. 300 foot tall towers. of course
being in our teenage years, we thought about disconnecting the
antenna system from the Radio Station transmitter and driving
our ham rig + amplifier directly into them, but the station was
a 24 hour/7 day station. Never went off the air -- just changed
So, we absorbed all the technical info we could from the ARRL
Antenna book, and noted the curves in there that gave radiation
angle as a function of height above true ground. A 1/2
Wavelength high dipole theoretically gave us a very low angle of
radiation for a flat-top dipole. Seems as though I recall the
curve having a (sine X) / X shape.
The 80 meter band was interesting to us...I think the year was
about 1963 or 64...can't recall precisely. My buddy Jim and I
designed ourselves a folded dipole....built it out of TV Twin
Lead, and put it up 1/2 Wavelength between two of the towers
that gave us a broadside direction of NorthWest and SouthEast.
(JA and South America). We wanted a broadband antenna, which
was achievable with a folded dipole and T-match tuner.
Since the feedline was also twin-lead, we had to build a crummy
little 50 ohm to 300 ohm RF tuner. We found some stuff around
the station and built a T-match for 80 meters, and it worked
grea --after a few RF flashes in the output capacitor.
The first day with that antenna in the air, we tuned it up at
about 4 or 5 pm in the afternoon, and looked abound the band.
Rig was T4/R4A Drake twins, and a home brew pair of 811A's
One of the very first QSO's we had -- and I think it was on SSB
using my old call sign W7CFJ -- we worked some young skinny guy
in the Dominican Republic whose call sign was HI8XAL. God, we were
extatic working someone so far away, in the late afternoon, on
75 meters. Just being able to HEAR someone way off in the
Caribbean from our little radio station in Tucson was absolutely
amazing to us....but to be able to WORK them was outta site.
That one QSO some 35 years ago is STILL one of the memorable
QSO's (out of a few hundred thousand Q's) I've ever had, and
we did it with a brand new off-beat Folded Flattop Dipole up
130 feet or so.
Over the years I've had the very deep pleasure of working that
tall-skinny guy (physically like me -- then and now) many
dozens of times. You OT's with remember him of course, but many
of the folks that have gotten licensed and on the air since the
mid 60's will know him as K3ZO today.
Fred --- That QSO with a new Folded Dipole (which was a
Broadband antenna) is still one of my very MEMORABLE ones, And
it continues to be at the forefront of my shoulder mounted
memory bank!! Thanks for the QSO OM!!
That folded dipole was unquestionably the best dipole antenna
I've ever used. It was LEVEL....because we were able to mount
it at a optimum height between two very tall towers, and it was
over a jillion miles of copper ground wire under the broadcast
towers. We ran a rope from the middle of the diple up to the
top of one tower to hold the middle up, because there was a
couple hundred feet of twin-lead from our shack up to it. It
was heavy in the middle, and we needed to compensate for it.
In retrospect I have no idea how we impacted the radiation
pattern of the broadcast station. I suspect we didn't do it
any good though. That issue was not very high on our priority
list then though!!
At 06:06 PM 4/27/98 EDT, K5RC wrote:
> In a message dated 4/27/98 2:29:51 PM Pacific Daylight Time,
> email@example.com writes:
> Or, how do you get bandwidth on a dipole? >>
>1. Use a 1:1 ferrite choke at the feed point (Aztec preferred)
> or a coax choke.
>2. Use 12 gage wire (14 minimum)
>3. Make it horizontal and get it at least a half wavelength
> in the air.
> I modeled 80 meter and 160 meter antennas for K5XI for endless
> hours. We wound up with dipoles between the 260', the 220'
> and the 140' towers that were killers. Of course, it's nice
> to be able to get an 80 meter antenna over 1/2 wavelength in
> the air.
> At my QTH, my 80 meter dipole is under 2:1 from 3.520 to
> 3.800 since I started using a choke at the feedpoint.
> Tom, K5RC/7
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