Pat can I suggest an easier way, Given something close to quarter wave or
even much shorter but top loaded, the way to approach it, is as follows.
Construct the vertical to be somewhere close to resonance at 1.9mhz or
slightly below, then add a hairpin coil directly across the feed point to
bring the SWR at 1825 to 1:1. Much much easier than linear (low Q ) loading
and will match easily.
73 Clive GM3POI
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Patrick
Armstrong
Sent: 21 December 2016 20:43
To: W0MU Mike Fatchett
Cc: topband@contesting.com; Petronel Postolache
Subject: Re: Topband: New user, some advice needed.
I have noticed several times that people talk about being able to put up
a full .250 wavelength vertical and I have wondered why almost never do they
think about making it .270 wavelength instead of .250 wavelength. The little
extra length gives a feed point impedance of 52 ohms with some inductive
reactance which can be canceled with a series capactor. This gives a more
efficient feed than a .250 wavelength and using an inductor to get a match.
I designed my 75/80m vertical this way and with 65 radials ( odd number
'cause that's all the wire I had) it has allowed me to work 280 entities
with100 watts, all SSB. (Blasphemy I know, I have an ear condition which
made 13 wpm almost impossible for me).
I also use this antenna on 160m by using linear loading and an inductor
for matching. Linear loading seems to be overlooked in a lot of discussions
of antennas on this list and I wonder why. Am I missing a downside to these
matching systems? If so I would like to hear about it.
Pat Armstrong KF5YZ Heart of Texas
On Tue, Dec 20, 2016 at 12:00 PM, W0MU Mike Fatchett <w0mu@w0mu.com> wrote:
> https://www.dxengineering.com/search/product-line/dx-enginee
> ring-160-meter-thunderbolt-vertical-antennas?autoview=
> SKU&keyword=160%20vertical&sortby=BestKeywordMatch&sortorder=Ascending
>
>
> On 12/20/2016 10:24 AM, Petronel Postolache wrote:
>
>> I can't find the Vertical from DX Engineering. If you can send me a
>> link it will be great.
>> One solution might be top hat vertical, similar with
>> http://dl2kq.de/ant/3-1.htm . Not sure how much power is lost in the
>> matching unit L1, C1.
>>
>> I would love a Waller Flag too. Imposible to buy one from here (too
>> expensive) but I might wanna try build one. Preamp will be the
>> biggest problem.
>>
>> Petronel
>> YO8SEP / YP8W
>>
>> On Mon, Dec 19, 2016 at 9:30 PM, W0MU Mike Fatchett <w0mu@w0mu.com
>> <mailto:w0mu@w0mu.com>> wrote:
>>
>> Check out DX Engineering. They sell a vertical that uses 3 top
>> hat wires. Sloping back down is ok. For 80/160 you need to stop
>> the 80m energy with a coil/trap My 80 uses a very fast taper and
>> the top is only 3/8 inch or less so It cannot support a coil or t
>> wires. I probably should have planned that out better. I was
>> also going to try to phase two 80 elements over time but that will
>> not happen any time soon.
>>
>> With all the metal in the yard the AY loop may not work very
>> well. Waller Flag on the roof maybe. I would love one.
>>
>> W0MU
>>
>>
>> On 12/19/2016 12:24 PM, Petronel Postolache wrote:
>>
>>> I can try to put a 21-22m (68-70 foot) telescopic aluminium pole,
>>> made from pipes 2" to 1" diameter.
>>> It will be a bit too long for 1/4 on 80m. I can put a T top hat
>>> or run an InvL, but probably need to slope it from 70 foot to
>>> about 40 foot. What will be better ? and will I be able to
>>> match/use the antenna on 80m also ?
>>>
>>> About K9AY, I understood that the loop is influenced by close
>>> metal objects, and the property is full of wire fences, vineyard
>>> rows and other "metal" structures. That's why i was thinking
>>> about using some flag/loop at 10 feet or more above ground.
>>>
>>> 73, Petronel
>>> YO8SEP
>>>
>>> 160 and 80 will be difficult. Can you get another vertical up
>>> about 60 feet? You can top load that with a trap for 80 and have
>>> "t" wires at the top that also act as guy wires. You can also
>>> bottom load for 160 and maybe that will be good enough for you.
>>> Radials whatever you can do will help.An Inverted L with about
>>> 50ft of vertical will work ok....If you can keep the horizontal
>>> end up in the air around the same height or more. It doesn't
>>> sound like you have any tall trees to work with.For receiving I
>>> have been very impressed with a K9AP loop. 25 ft up and about 15
>>> feet out at the corners. It does not take up much space and you
>>> can reverse the direction easily with a relay. A flag or pennant
>>> will work too. You can never have enough rcv or xmit antenna! HI!
>>> Welcome to the club!
>>>
>>> W0MU
>>>
>>>
>>
>>
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