[600MRG] "The Lowdown Amateur Radio Antenna for 630 Meters Model 630.PD"

Tue Jan 11 11:12:43 EST 2022

>Remote
> tuning of the variometer would also be really great.

Yeah remote tuning really is a must as tuning can change over the
course of an operating session, particularly if wx is unstable and
temp/moisture changes.

I use an old archer antenna rotator mounted on its side to move the
vario.  Only really had to move 90 degrees max.  No need to worry
about limit switches like with servos.

I use a drill motor on my shunt C for matching and don't use limit
switches there either... it only moves very small amounts depending on
weather and season.  A quarter turn is a lot.

Some guys don't like varios because of their inherent loss but since
we are regulated by EIRP rules and not PEP and are allowed up to 500
watts TPO to play with to achieve legal 5w EIRP limit, its easy enough
to run more power to make up for losses and adds convenience /
simplicity to the build and install.  Power is cheap and easy to make.

I think right now most of the active crew are reporting full legal
power under 150 watts TPO.  Those concepts run afoul of engineers that
have spent their careers optimizing things sometimes, however.  For me
I prefer to be on the air operating rather than fooling with a design
but you have to do what works best for you.

73!

John..

On 1/11/22, Greg KF5N <greg.electricity at gmail.com> wrote:
> We didn't use a variometer on the Lowfer beacon I helped construct.  We
> made the highest Q possible series inductor, with the value being such that
> the inductor plus antenna resonated slightly above the transmit frequency.
> A small shunt variable capacitor was connected from the base of the antenna
> to ground.  So this small cap was used to "tweak" the system to resonance.
> We had an ammeter to observe the peak as the capacitor was tuned.
> This worked well, as it was a beacon only and was operating on a fixed
> frequency.
>
> But now with a real "band", a variometer seems like the way to go.  Remote
> tuning of the variometer would also be really great.
>
> 73 Greg KF5N
>
> On Tue, Jan 11, 2022 at 10:17 AM Les Rayburn <les at highnoonfilm.com> wrote:
>
>> In the “olden days” of Lower (160-190 kHz) operations, we used RF current
>> meters to adjust the taps and position of variometers on our TX
>> verticals.
>> Taps on the loading coil were used as a “broad” matches, and then you
>> adjust the variometer for fine-tuning until you achieve peak RF current
>> in
>> the antenna. Before antenna analyzers this was the preferred method—and
>> it
>> still works great.
>>
>> LItz wire allowed for very high Q loading coils and minimal losses.
>>
>> Fortunately, physics doesn’t change much over the decades. It still works
>> great today.
>>
>> 73,
>>
>> Les Rayburn, N1LF
>> les at highnoonfilm.com
>> 121 Mayfair Park
>> Maylene, AL 35114
>> EM63nf
>>
>> NRC & IRCA Courtesy Program Committee Chairman
>> Member WTFDA, MWC
>>
>> Perseus SDR, Elad FDM-S2 SDR, AirSpy + Discovery, SDRPlay RSP-2 Pro, Sony
>> XDR-F1HD [XDR Guy Modified], Dennon TU-1500RD, Sangean HDT-1X, Ray Dees
>> RDS
>> Decoders, Korner 9.2 Antenna, FM-6 Antenna, Kitz Technologies KT-501
>> Pre-amps, Quantum Phaser, Wellbrook ALA1530 Loop, Wellbrook Flag, Clifton
>> Labs Active Whip.
>>
>> “Nothing but blues and Elvis, and somebody else’s favorite song…”
>>
>> On Jan 11, 2022, at 8:33 AM, John Langridge <kb5njd at gmail.com> wrote:
>>
>> I'm a big fan of the bucket variometer and if you take the time to
>> wind it with taps every other turn minimum, you can resonant a 30 foot
>> capacitively top loaded vertical in about 2 minutes just by checking
>> each tap and watching what X is doing with your on your analyzer.  No
>> calculations required to do that.
>>
>> Then is just a matter or matching to the feed line and there are a
>> bunch of options there and minimal math required.
>>
>> John Molnar, WA3ETD, wrote a great article for CQ a few years ago that
>> is more of less on his website with details for how he winds buckets:
>> https://wg2xka.wordpress.com/the-variometer/
>>
>> So there are easy options for resonating and matching existing
>> vertical antennas on 472 for someone willing to put in a little elbow
>> grease.
>>
>> 73!
>>
>> John..
>>
>>
>>
>>
>> On 1/11/22, Dwight Blevins via 600MRG <600mrg at mailman.qth.net> 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'sKW7TColorado
>>
>>    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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