Re: Topband: elevated 4-square

[Brian Machesney]

Jeff,

You can also use EZNEC to simulate the effect of the driving point
impedance on the array's behavior. It doesn't take too much additional
effort to learn how to incorporate lumped elements, transmission lines and
transformers into your antenna model.

If you have a copy of the most recent edition of ON4UN's "Low Band DXing,"
there are numerous example models on the CD that you could adapt to your
situation.

73 -- Brian/K1LI


On Fri, Aug 16, 2013 at 1:46 AM, Jeff Blaine  wrote:

> What affect is there of vertical *resistance* variations are the common
> 4-square boxes?
>
> N6LF’s QEX article shows quantitatively the performance hit associated
> with using non-resonant elevated radials.  Which is interesting because
> non-resonant radial lengths reduce the sensitivity of individual elevated
> radial variations from ideal.  However, by altering the relative lengths of
> the vertical/radial, the feedpoint R moves around.
>
> I ran a simple test case pair in EZNEC.  First was the resonant radial
> case (length is the same as the vertical radiator).  Second was shortened
> radials (about 10%) with the vertical lengthened to restore the same X=0
> frequency.  The feedpoint R moves from 32 ohms in the symmetric case to
> about 40 ohms in the short-radials case.
>
> The R has got to translate into a drive impedance shift - but I am
> wondering what the expected impact to the array should be?
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
> _
> Topband Reflector
_
Topband Reflector

Re: Topband: Symbol Rates (was [ARRL-LOTW] BoD votes LoTW initiatives)

[Brian Machesney]

Joe,

I don't understand your objection to removal of the symbol rate language.
Under the existing band plan, CW is expected to co-exist with other
"digital" modes of all kinds.

Now, I don't like to hear even narrow-bandwidth PSK or RTTY signals when
I'm operating in the "traditionally CW" portions of the bands, but I don't
believe this is even primarily a question of symbol rate. When CW contest
activity extends into, through and beyond the "traditionally digital"
portions of the bands, I find it very difficult to pick a CW signal out of
a densely-packed cluster of PSK carriers or RTTY stations. In my
experience, it is not the symbol rates of the PSK and RTTY stations that
cause the interference, but the ability of my brain to discriminate against
the natures of modulation of those signals.

I agree with you that we need to review the band plans. But to me that
doesn't mean that we should allow the persistence of language which may
hold back technical progress.

73 -- Brian/K1LI

On Tue, Jul 23, 2013 at 10:46 PM, Joe Subich, W4TV  wrote:
>
>
> Save us from a Board of Directors that would not know Digital Operation
> if it bit them on the ass.  All we need is a bunch of 2.8 KHz wide
> chunks of "white noise" across the entire "non-voice" spectrum.  If
> they want to remove the symbol rate, the bandwidth better be compatible
> with that of CW (100 Hz or less) in the majority of the shared non-voice
> spectrum.
>
> As usual, the ARRL BOD has proven how little they know about amateur
> operation!
>
> 73,
>
>... Joe, W4TV
_
Topband Reflector

Topband: VK6HD

[Brian Machesney]

I don't know if it comports with Australian regulations and/or traditions,
but I sent the following message to the Australian Communications and Media
Authority:

Mike Bazley of Albany, WA recently became what we in amateur radio circles
call a "silent key." Mike represented Western Australia to amateurs
worldwide in the best spirit of the service, with unfailing courtesy,
patience and dedication. The "Topband" email reflector is ringing with
testimonials to the appreciation so many of us feel for Mike's unswerving
commitment to providing contacts with the elusive "zone 29" on the 1.8 MHz
and 3.5 MHz bands. To honor Mike's devotion to our hobby, I request on
behalf of amateur radio operators around the world that Mike's call sign,
VK6HD, be retired from reassignment.

Respectfully,

Brian Machesney, K1LI
Craftsbury Common, VT USA
All good topband ops know fine whiskey is a daylight beverage.
_
Topband Reflector

Re: Topband: Help with RFI

[Brian Machesney]

Wrapping everything in ferrite did not solve my 160m RFI problems. OZ7C
provided a filter circuit that I use successfully:

http://www.ddxg.dk/oz7c/adsl/adsl_160m_filter.pdf

G3VMW has done additional work:

http://www.rsars.org.uk/ELIBRARY/BBCONNECT.pdf

73 -- Brian K1LI

On Sat, Jan 12, 2013 at 10:38 PM, Mike Waters  wrote:

> I wrap a few turns of the CAT 5 Ethernet cable coming into the back of my
> shack PC around a few stacked 2.4" diameter #31 ferrite cores. Works for
> me.
>
> 73, Mike
> www.w0btu.com
>
> On Sat, Jan 12, 2013 at 4:48 PM, W7KW  wrote:
>
> >
> > I am having a problem with RF getting into my Ethernet cables.  Anyone
> > have any recommendations for a clamp-on filter that would help remove 1.8
> > MHz RF?
> >
> _
> Topband Reflector
>
_
Topband Reflector

Re: Topband: KAZ Antenna

[Brian Machesney]

The Wellbrook Communications web site has good pictures of the DKAZ and
similar antennas. Navigate to "Components" then "FLAG, KAZ ANTENNA
AMPLIFER"
(sic) and click on links to pdf's at the bottom of the page.

K1LI
___
It is undesirable to believe a proposition when there is no ground whatsoever 
for supposing it is true. - Bertrand Russell

Re: Topband: Why the DX doesn't always work split? Especially low bands.

[Brian Machesney]

>> Murtada is a very experienced DXer, and I think he was not hearing a lot
of
>> the stations because of local QRM.  He even mentioned this as a problem,
>> which is why he probably did not consider the need to go split.

I concur with Mark's assessment. Murtada was only able to hear stations
that were S7 or better, according to the reports he handed out to the few
stations he worked.

The "plus or minus 200Hz" demonstrates considerable expertise on the part
of the callers. They know how to stay in the DX station's receiver passband
while not creating an "Internet spot pileup" that would have prevented
Murtada from working anyone. There were also several callers up 500Hz and
more even before he attempted to evade the QRM by going split.

The callers demonstrated DXing skill and consideration for each other by
alternating their calls in time, allowing Murtada to potentially start
working through the list of callers. Watch "A Beautiful Mind" to see game
theory at work. Conversely, someone was transmitting "LSN" at intervals,
which was not helpful, as I very seldom heard anyone double with Murtada.

73 -- Brian K1LI
___
It is undesirable to believe a proposition when there is no ground whatsoever 
for supposing it is true. — Bertrand Russell

Re: Topband: : antenna question

[Brian Machesney]

Mike,

"...a 300 ohm TV twin lead dipole is not all twin lead, but the twin lead is
shorter than a half wavelength  and at each end a wire continues to make
half wavelength length of the dipole..."

This technique could be applied to shorten a half-wave dipole by using the
twinlead as a T-match. Some quick simulations with NEC2 show that the
slower velocity of propagation in the twinlead allows it to replace an
open-wire structure of substantially greater spacing. The twinlead would be
fed in the middle of the of the lead to which the "extensions" were NOT
connected and series capacitance would be inserted in each arm of the "T"
to compensate for the inductive reactance of the match. Depending on the
construction and power levels, the matching caps could be required to
withstand substantial RF voltages.

Like all such shortened antennas, the SWR bandwidth is reduced considerably
compared to a full-sized structure.

Brian K1LI
___
Topband reflector - topband@contesting.com

Re: Topband: Toroidal common mode choke

[Brian Machesney]

>> Tom wrote: "There should be more focus on telling people how to find
problems, and less on treating every system the same."

That is a great suggestion, Tom. Can you recommend a resource that gives a
"cookbook" approach to identifying and resolving problems?

Brian K1LI
___
Topband reflector - topband@contesting.com

Topband: Helpful article on ferrites

[Brian Machesney]

Since ferrites are discussed so often on the forum, I thought this article
in High Frequency Electronics (edited by K9AY!) might be interesting:

http://www.highfrequencyelectronics.com/Archives/Jun11/HFE0611_Hamilton.pdf

Lots of good information on ferrite "hows" and "whys."

73 -- Brian K1LI
___
Remember the PreStew coming on October 20th.  http://www.kkn.net/stew for more 
info.

Re: Topband: Propagation to Conway Reef

[Brian Machesney]

While trying not to whine (or winge, as the case may be), I second Herb's
remarks re: Pacific DX to eastern NA. Reviewing my logs, I see that a
number of stations were pounding in during the hours after *their* sunset,
which - being the wee small hours here - may deliver a better rate to the
DX by virtue of less QRM. The converse has also been true; perhaps we are
louder at the DX during our sunrise, but they have often been weaker.

Fingers crossed, I'm still grateful to have put them in the log from 10m
through 40m.

Brian K1LI

On Sun, Sep 30, 2012 at 5:08 PM, Herb Schoenbohm  wrote:

> Again the same thing with past rare pacific DX-peditions,3D2C did not
> start on Top band today as in other days until 1/2 hour after local Eastern
> Caribbean sunrise.  Not to worry for me as I already have Conway Reef
> confirmed on 160.  I only make this mention since there are others out here
> that need it on TB and will not have a chance under this schedule. The
> problem with many DX-peditions today rather than in the past is they rely
> on SR/SS charts for the East Coast before they even check the band for a
> few test CQ's prior to what the charts or the computer tells them what to
> do.  The same pattern holds true when rare African and Indian ocean
> operations completely forget about the great sunset openings here to that
> region and only take Europeans at 2230-2330 and give their first QRZ NA an
> hour or so later when the line moves up the East Coast and the Big Guns are
> pounding away.  Timing I guess *is* everything.  So either way at times it
> is beyond belief how strong some rare DX-peditions are here when they are
> stringing Euros but you never have a chance in breaking that wall.  I liked
> the remarks of Jerry WB9Z who said from NH8S as soon as they got the TB
> antennas up that "tonight we will be on 160 from before our local sunset to
> after our sunrise. " That was music to my ears!
>
>
> Herb, KV4FZ
>
>
>
>
> On 9/30/2012 3:53 PM, N3XX wrote:
>
>> They were weak here earlier this morning, but the signal came up nicely
>> at around 1115Z, about 15 minutes before sunrise here.  Made the contact
>> for a new one at 1122Z.
>>
>> Good luck.
>> 73,
>> Tim - N3XX
>>
>> - Original Message - From: "Wayne Willenberg" <
>> wewill...@gmail.com>
>> To: 
>> Sent: Sunday, September 30, 2012 2:26 PM
>> Subject: Topband: Propagation to Conway Reef
>>
>>
>>
> __**_
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: American Samoa on TB?

[Brian Machesney]

Bob, W7YAQ, celebrated his 70th birthday as 5W0YA in 2010. He did a great
job on the low bands with 100W and verticals.

Brian K1LI
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Topband: Still life in the ol' band...

[Brian Machesney]

Having only my gamma-fed tower for TX and RX, I worked half a dozen S5, SV
and G "regulars" before their sunrise on 26 March, with some of the
strongest signals I've ever heard. True 599+ signals overcame static
crashes from thunderstorms to the southeast.

It's a good time of year to be on 160, particularly, I'm sure, if you have
a directional RX antenna to cut the QRN.

73 -- Brian -- K1LI
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: Hindering factors in the science of back yard 160m vertical installations

[Brian Machesney]

Mr. Fry,

I'm confused by your assertion that, "The [BL&E] data gathered is
applicable to other frequencies for antenna systems having the same
conductor dimensions in wavelengths."

Your paper titled, "Frequency and Earth Conductivity as Factors in MW Field
Intensity(1)," indicates that frequency has a pronounced effect on field
intensity. Further, you write that, "Groundwave radiation in the AM
broadcast band... can penetrate the earth to the depth of several tens of
meters." According to my limited understanding of "skin effects," such
penetration decreases with increasing frequency. Would your assertion not
be true only in the case of earth which is homogeneous with respect to
conductivity to a depth of several tens of meters?

73 -- Brian -- K1LI


(1)
http://rfry.org/Software%20Download/Freq%20and%20Conductivity%20as%20Factors%20in%20MW%20Field%20Intensity.pdf

On Tue, Nov 8, 2011 at 6:27 AM, Richard Fry  wrote:

> >Tests for a given frequency need to be done on that frequency.
>
> The BL&E tests were designed to determine the "efficiency" of monopole
> antenna systems, as shown by the groundwave field they produce close enough
> to the monopole so that the effects of frequency and earth conductivity are
> negligible.  The data gathered is applicable to other frequencies for
> antenna systems having the same conductor dimensions in wavelengths.
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: Need help feeding tower on 160 AND 80

[Brian Machesney]

Thanks for all the responses.

One respondent recalled hearing of success with a similar setup on the
Towertalk reflector. By searching the archives for "shunt bands" I found an
"existence theorem" at:

http://lists.contesting.com/archives//html/Topband/1997-12/msg00194.html

I followed the prescription to connect the gamma wires for the two bands to
different tower legs, then realized that I had made a serious mistake by
failing to reduce the tower-to-gamma wire
spacing for the 80m feed.

With these two changes, I am able to get the desired behavior on both bands,
by switching from one series cap to the other.

73 -- Brian -- K1LI

On Tue, Oct 25, 2011 at 10:07 AM, Brian Machesney wrote:

> Gang,
>
> I have an 80-ft tower topped by an KT34XA (elements insulated from 32-ft
> boom) and 40-2CD (only reflector electrically connected to 22-ft boom). I
> have 8 x 50-ft lengths of 4-ft wide welded, galvanized steel fence for a
> ground screen. No other radials.
>
> I have successfully matched this on 160 with about 350-pF series capacitor
> to a 45-ft #12 gamma wire spaced about 3-ft from the tower.
>
> I also want to feed the tower on 80. I have been hoping that the 160 gamma
> wire would "disappear" electrically when it is open-circuited. Given the
> complex configuratino of the GAP vertical antennas, this may be but a faint
> hope. I'm having trouble creating a good match on 80 with a simple gamma
> feed scheme.
>
> Has anyone on the reflector tried to feed the same tower on two bands?
>
> Please reply off-reflector.
>
> Thanks and 73,
>
> Brian K1LI
> ___
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>



-- 

-- The hallmark of a successful parasite is that it never kills its host --
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Topband: Need help feeding tower on 160 AND 80

[Brian Machesney]

Gang,

I have an 80-ft tower topped by an KT34XA (elements insulated from 32-ft
boom) and 40-2CD (only reflector electrically connected to 22-ft boom). I
have 8 x 50-ft lengths of 4-ft wide welded, galvanized steel fence for a
ground screen. No other radials.

I have successfully matched this on 160 with about 350-pF series capacitor
to a 45-ft #12 gamma wire spaced about 3-ft from the tower.

I also want to feed the tower on 80. I have been hoping that the 160 gamma
wire would "disappear" electrically when it is open-circuited. Given the
complex configuratino of the GAP vertical antennas, this may be but a faint
hope. I'm having trouble creating a good match on 80 with a simple gamma
feed scheme.

Has anyone on the reflector tried to feed the same tower on two bands?

Please reply off-reflector.

Thanks and 73,

Brian K1LI
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: Fence "ground screen" instead of wire radials?

[Brian Machesney]

Thanks to NI0C for reminding me that this info was presented by NC0B, Rob
Sherwood, at the Dayton antenna forum. It's available at www.nc0b.com.

73 -- Brian -- K1LI

On Fri, Sep 2, 2011 at 11:05 AM, Brian Machesney wrote:

> Gang,
>
> I remember seeing an article on this subject recently, I think in QST or
> QEX, but I can't seem to track it down. The author used various numbers and
> lengths of wire fencing instead of a "conventional" wire radial field.
>
> Can someone out there with better searching skills point me to the
> reference?
>
> Thanks,
>
> Brian K1LI
> ___
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Topband: Fence "ground screen" instead of wire radials?

[Brian Machesney]

Gang,

I remember seeing an article on this subject recently, I think in QST or
QEX, but I can't seem to track it down. The author used various numbers and
lengths of wire fencing instead of a "conventional" wire radial field.

Can someone out there with better searching skills point me to the
reference?

Thanks,

Brian K1LI
___
UR RST IS ... ... ..9 QSB QSB - hw? BK

Re: Topband: Boring Report - December

[Brian Machesney]

I found George's thoughts particularly interesting and reminiscent of the
longstanding discussion around 10m in times of poor propagation. In that
light, I thought it might be interesting to review contest entry stats from
the past few years:

ARRL 160   CQ WW 160 CW

2006: 1052 2007: 1801
2007: 1197 2008: 1860
2008: 1281 2009: 2220
2009: 1336 2010: 2390
2010: 1283

Note that I paired ARRL 160 and CQ WW 160 by "season" rather than by
calendar year, since that better reflects the situation on top band.

I believe this supports George's suggestion that hams want to get on the
band when there are other stations to work. Since both contests accept
"within country" as well as "between country" contacts, it doesn't seem to
matter to many of the entrants whether the QSO is to another section,
another zone or another country. Perhaps it's just not in our DNA to brave
the challenging nature of the band on a daily basis year-in and year-out.

-- 
73 -- Brian -- K1LI
___
UR RST IS ... ... ..9 QSB QSB - hw? BK