[600MRG] "The Lowdown Amateur Radio Antenna for 630 Meters Model 630.PD"
david vanhorn
kc6ete at gmail.com
Tue Jan 11 16:11:14 EST 2022
Has anyone done a magloop down here? I can see it might be pretty big.
On Tue, Jan 11, 2022 at 1:14 PM Ed Cole <kl7uw at acsalaska.net> wrote:
> Antenna design was discussed in my NDB manual. Many stations put up a
> 300-foot top hat wire with 60-foot vertical wire attached to center.
>
> Apparently the tuner in the NDB could handle tuning that. I bypass the
> internal tuner as I have the NDB in the shack instead of sitting on the
> ground below the "T" antenna. Output from the NDB is porcelain
> insulated lug and case is grounded in normal NDB installations.
>
> so your 50x300 foot invert-L is close to that design.
>
> The NDB tuner was just a tuned coil in series with output (movable slug).
>
> 73, Ed - KL7UW
>
> On 1/11/2022 10:02 AM, Brian Pease wrote:
> > My 50 ft high inverted L on 630m has a ~300 ft horizontal wire, so my
> > tuning inductor is small. It has a shunt vacuum capacitor driven by a
> > cheap gearhead DC motor from mpja.com, without a turns readout display.
> > I use a large binocular core ferrite as a transformer to reach 50 Ohms.
> > I have an analog SWR/power meter in the shack that a ham was selling on
> > Ebay designed for 630m that also works well on 160, 80, etc. I am always
> > below 2 Watts reflected for 100 Watts in. It is -4 F outside at the
> > moment and I am not about to make a 600 foot roundtrip through the snow
> > to the tower to tweak something! I used NEC4 simulations then used an
> > AIM/UHF analyzer to do the initial setup.
> >
> > On 1/11/2022 9:58 AM, Dwight Blevins via 600MRG wrote:
> >> Greg,
> >>
> >> At first I was just using my bucket coil, attached at the base of my
> >> Hustler 5 band HF trap vertical. My perception is that the trap coils,
> >> especially the big 40m thing at the top, which serves both as a trap
> >> and loading coil for 80--that all these coils were just more or less
> >> dummy loads, eating up a lot of RF. So I decide that I wanted a
> >> straight up vertical, no traps, but with the top hat wires coming down
> >> for support.
> >>
> >> Long story short, I bought one of these 19' UK hf verticals, took off
> >> the balun at the base and used that antenna instead, along with a
> >> cheap 60" whip which I mounted on top of all else. In retrospect I
> >> realized that I could have accomplished the same thing with some
> >> telescoping PVC and a big heavy gauge wire (maybe 8 to 10 gauge)
> >> running up the pvc for the vertical part of the radiator. Some of the
> >> green military telescoping fiber glass poles would do the same thing.
> >> I see them around on eBay and they are probably better than HomeDepot
> >> PVC.
> >>
> >> The tricky part is that you've got to put plenty of taps on that
> >> bucket wire so that you can find the right impedance match, both for
> >> the feed point and a tap at the top to resonate the bucket with the
> >> vertical radiator. The variometer adjustment with the bucket is super
> >> if you can get the mechanics worked out so that it's easy to adjust
> >> and stays put where you want it. I finally gave up on that because I
> >> kept having to go out to the bucket and readjust all the time. So I
> >> finally opted for the multi-tap wire bucket and that remains pretty
> >> stable.
> >>
> >> Hope all this helps. I'm old school so have to stick with 1950's
> >> technology :)
> >>
> >> KW7T
> >>
> >> On Tuesday, January 11, 2022, 07:40:58 AM MST, Greg KF5N
> >> <greg.electricity at gmail.com> wrote:
> >>
> >>
> >> Hi Dwight, thanks for the tip! What do you consider to be a "cheap
> >> 25' vertical"?
> >> I was looking at sectional aluminum flag poles and I was wondering how
> >> well that would work.
> >>
> >> 73 Greg KF5N
> >>
> >> On Tue, Jan 11, 2022 at 9:01 AM Dwight Blevins <blethn at yahoo.com>
> wrote:
> >>
> >> Greg,
> >>
> >> You asked about "something equivalent." There definitely is and it
> >> will cost you maybe $125.00 max (if that). The equivalent is a 5
> >> gallon plastic bucket, a cheap 25' aluminum vertical and a roll of
> >> solid core insulated wire (16 or 18 gauge). Add a 3-wire top hat
> >> to the vertical and ground mount the thing with the big bucket
> >> loading coil, feed point taped up from ground. I'm 75 years old
> >> and easily picked up the whole apparatus and had it up and tied
> >> off in less than an hour, once everything else was assembled.
> >>
> >> It works great on receive and my little 5 watt one tube 630m
> >> exciter loads up with ease. I can copy KB5NJD Q5 most any time he
> >> is on the air, CW. All I have for a counterpoise is that the
> >> mounting mast goes in the ground maybe 40 inches and I have that
> >> tied off to a nearby chain link fence. Again, tip of the antenna
> >> is maybe 25' up. For the top section I bought a 60 inch whip which
> >> attaches to the top of the vertical where the top hat wires are
> >> connected. They go down at a 45 angle, tied off with insulators to
> >> stakes on the ground. So the 3 top hat sloper wires serve to
> >> support the slender vertical when the wind comes.
> >>
> >> I don't know what the radiation resistance is, but the thing works
> >> great, low background noise, no BCI garbage, etc! I'm not saying
> >> don't buy the commercial antenna, but on my budget I have to make
> >> my own stuff, which is the fun part of the hobby :)
> >>
> >> 73's
> >> KW7T
> >> Colorado
> >>
> >> On Tuesday, January 11, 2022, 06:38:03 AM MST, Greg KF5N
> >> <greg.electricity at gmail.com> wrote:
> >>
> >>
> >> I like the design as I could use it even in my relatively small
> >> back yard.
> >>
> >> The availability of a turnkey antenna and other gear is good, but
> >> I'm not even sure there is that much easily available reference
> >> material if you want to build your own.
> >> I recently ordered the 2022 ARRL Handbook, and found only one page
> >> on LF propagation. Did I miss something, or is there no other
> >> information on the ham LF allocations in the latest handbook?
> >>
> >> Let's say I was a newbie interested in trying out 630 meters.
> >> Where would I go to find construction details for an antenna
> >> equivalent to this commercial offering?
> >> Long ago (1980s) I built and operated a Lowfer Beacon. There was
> >> the series of books by Ken Cornell, and a couple of enthusiast
> >> periodicals on Lowfer and other LF topics.
> >> Lots of antenna topics and construction articles in those
> >> publications.
> >> Is there something equivalent to this today for 630 meters?
> >>
> >> 73 Greg KF5N
> >>
> >> On Tue, Jan 11, 2022 at 8:03 AM John Langridge <kb5njd at gmail.com>
> >> wrote:
> >>
> >> Good morning,
> >>
> >> Jamie, N2VJ, reported this morning on SLACK that a US-based
> >> company is
> >> producing a portable, turnkey 630-meter vertical antenna system.
> >> Originally developed for BC medium wave AM as an emergency
> >> continuity
> >> system, this model has been modified for 472-479 kHz. You can
> >> see the
> >> specs here:
> https://theradiosource.com/products/antenna-630pd.htm
> >>
> >> Jamie indicated that the company is probably testing the
> >> market and
> >> the price may be somewhere in the $890 USD range. While that
> >> may seem
> >> pricey to some, there are a lot of people out there still
> >> waiting for
> >> a turnkey option and engineering and materials are expensive
> these
> >> days. Yes you can build this stuff for a LOT cheaper but
> >> there are a
> >> lot of hams today that can't or won't so here is an option to
> >> fill the
> >> void.
> >>
> >> Have a look and show some interest as doing so often drives
> >> product
> >> development and innovation.
> >>
> >> Jamie explicitly noted that he is not endorsing this product
> >> and he
> >> has no financial interest.
> >>
> >> 73,
> >>
> >> John KB5NJD
> >> ______________________________________________________________
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--
K1FZY (WA4TPW) SK 9/29/37-4/13/15
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