Re: Topband: Wednesday 160m DX CW Activity Night

[Peter Sundberg]

Recently the geomagnetic field has been very unstable, hence a higher 
K-index and a lot of aurora, resulting in totally wiped out DX 
conditions on 160m up here.


None of the regular NA stations could be heard this week.

Then again, conditions were phenomenal during the Stew so let's hope 
for a re-occurrence of that for the upcoming CQ 160 :-)


73
Peter SM2CEW




At 21:56 2020-01-09, Roger Kennedy wrote:


Well sadly conditions were rather poor last night . . .

Also I wasn't sure how many stations made it on the band, as I had
torrential rain all night, and with the 400kV power lines a mile away that
caused a high noise level, so could only copy stations above S7.

Oh well . . . perhaps it will be better next Wednesday !

73 Roger G3YRO


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Re: Topband: Wednesday 160m DX CW Activity Night

[thoyer via Topband]

Last night for me was interesting. I worked I5JVA who was a true 599 at my
QTH in eastern PA and I never hear Europe better then 579 on the best days!
Then I worked VP5/KM3T but after that - nothing! Last week the band was much
better at my QTH. Low noise and was easily working into Europe - which is a
rarity from my QTH with my antenna and noise levels.

I'm still hoping to capture 8 more new ones to finish DXCC this winter. I
did work OY9 last week for a new one.

Tom
W3TA

-Original Message-
From: Topband [mailto:topband-bounces+thoyer1=verizon@contesting.com] On
Behalf Of Roger Kennedy
Sent: Thursday, January 09, 2020 4:57 PM
To: topband@contesting.com
Subject: Topband: Wednesday 160m DX CW Activity Night


Well sadly conditions were rather poor last night . . .

Also I wasn't sure how many stations made it on the band, as I had
torrential rain all night, and with the 400kV power lines a mile away that
caused a high noise level, so could only copy stations above S7.

Oh well . . . perhaps it will be better next Wednesday !

73 Roger G3YRO


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Re: Topband: Wednesday 160m DX CW Activity Night

[David Olean]

Hello Roger,

You had a great signal last night. At one point you called CQ and I 
answered with 5 watts, but you did not hear me. I did work I think two 
stations while running 5 watts here. One was HA0NAR. This morning was a 
big ZERO. I was up at 1000 UT and called CQ but had no QSOs and heard no 
DX. I did go and check out FT-8. RA0FF and RA0CY were both on FT8 as 
were  afew KL7 stations.  That was a bit of a bummer for me.


I am having a problem with creeping SWR that climbs up to over 2:1 if I 
am doing a lot of QRO calling.  At first, I thought it was my really bad 
temporary installation with a vise clamp holding the N connector bracket 
to the tower base and the series doorknob capacitor sitting out in the 
weather and snow. During the Stew, the SWR got so high I had to go out 
and shovel the snow and ice away from it.  I figured the snow and water 
was making the SWR bad. I built a suitable wx proof enclosure with a 
nice porcelain insulator and the type N connector input, but the heating 
is more pronounced. Apparently the ice was keeping the cap cooler! So 
now I am looking for another cap that will not overheat.


On 1/9/2020 9:56 PM, Roger Kennedy wrote:

Well sadly conditions were rather poor last night . . .

Also I wasn't sure how many stations made it on the band, as I had
torrential rain all night, and with the 400kV power lines a mile away that
caused a high noise level, so could only copy stations above S7.

Oh well . . . perhaps it will be better next Wednesday !

73 Roger G3YRO


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Re: Topband: de n7dd

[Ted Kirst]

"MaxGain Systems has a surplus Jennngs 500pF/20KV cap for about $350"

This is the one being used on my T and no problems at 1.5KW.

73, Ted: W1GL



--- Original message ---
Subject: Re: Topband: de n7dd
From: Paul Christensen 
To: topband 
Date: Thursday, 09/01/2020 10:25 AM



does anyone know of a HV (20KV) capacitor with a value of 
approximately

500 pf that has a NPO value?

Once you get above about 100pF, NP0 options are very limited.  Be 
mindful of
the RF current magnitude in the application.  Small doorknobs can heat 
and
change in value.  In fact, I am dealing with this issue now on a 160m 
T
vertical.   My hope was that a paralleled pair of HEC doorknobs would 
work
in a NEMA 4x4x2 enclosure at the base.  The fit is fine, but the caps 
are
overheating in FT8/RTTY modes.  The fix will involve replacement with 
a

vacuum cap in a larger enclosure.

MaxGain Systems has a surplus Jennngs 500pF/20KV cap for about $350.  
Also
consider transmitting mica capacitors.  Both will be quite large but 
will
meet your NP0 requirement.  Kintronic Labs sells a new 500pF/20KV mica 
for
about $650.  These are typically used in AM broadcast installations.  
In
time, you can likely find these at lower prices.  The most common used 
mica
will be manufactured by Sangamo.  If you're in a rush, be prepared to 
pay

more.

Paul, W9AC

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Topband: Wednesday 160m DX CW Activity Night

[Roger Kennedy]

Well sadly conditions were rather poor last night . . .

Also I wasn't sure how many stations made it on the band, as I had
torrential rain all night, and with the 400kV power lines a mile away that
caused a high noise level, so could only copy stations above S7.

Oh well . . . perhaps it will be better next Wednesday !

73 Roger G3YRO


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Re: Topband: de n7dd

[Paul Christensen]

You can try several paralleled doorknob caps to lower ESR, thus minimize cap 
heating.  In my case, one vacuum variable will replace the HEC doorknob pair.   

In the alternative, an air variable in a WX-proof enclosure should work fine.  
You can compute the peak voltage across the cap as well as average current in 
TLW software that's included in recent editions of the ARRL Antenna Book.  Once 
the peak operating voltage is known, you can obtain an air-variable cap with 
adequate plate spacing.

Polycarbonate tool boxes from Lowes or Home Depot make great weatherproof 
enclosures when base-feeding an antenna.  The side walls are sturdy and many 
models have a gasketed rubber seal that forms around the lid's perimeter.   
 
Paul, W9AC  

-Original Message-
From: David Olean  
Sent: Thursday, January 9, 2020 4:15 PM
To: Paul Christensen ; 'topband' 
Subject: Re: Topband: de n7dd

Hello Paul,

I am dealing with the same overheating problem. I need a 475 pf capacitor to 
shunt feed my 160 tower. I just happened to have a 500 pf
15 KV doorknob almost the size of my fist. It did work for awhile, (several 
years) but now seems to heat up and the VSWR climbs to 2:1. The unit is 
definitely heating. I measured about 95 degrees when the outside air temp was 
12 F.  I tried a single red Sprague plastic doorknob and it starts to run away 
with 500 watts of power. My next plan was to put four NEC caps together to get 
475 pf: 2X 200 PF, 1X 50 PF, and 1X 25 PF.  It sounds like maybe this is not 
going to work either.  I guess I need a bigger box and a vacuum capacitor.  My 
amplifier is capable of 1500 watts output.  There is not a lot of voltage as it 
is a
50 ohm input.  6 amps at 300 volts RMS would be 1800 watts at 50 ohms. What 
about an air variable in a wx proof box?

Dave K1WHS

On 1/9/2020 3:24 PM, Paul Christensen wrote:
>> does anyone know of a HV (20KV) capacitor with a value of 
>> approximately
> 500 pf that has a NPO value?
>
> Once you get above about 100pF, NP0 options are very limited.  Be 
> mindful of the RF current magnitude in the application.  Small 
> doorknobs can heat and change in value.  In fact, I am dealing with this 
> issue now on a 160m T
> vertical.   My hope was that a paralleled pair of HEC doorknobs would work
> in a NEMA 4x4x2 enclosure at the base.  The fit is fine, but the caps 
> are overheating in FT8/RTTY modes.  The fix will involve replacement 
> with a vacuum cap in a larger enclosure.
>
> MaxGain Systems has a surplus Jennngs 500pF/20KV cap for about $350.  
> Also consider transmitting mica capacitors.  Both will be quite large 
> but will meet your NP0 requirement.  Kintronic Labs sells a new 
> 500pF/20KV mica for about $650.  These are typically used in AM 
> broadcast installations.  In time, you can likely find these at lower 
> prices.  The most common used mica will be manufactured by Sangamo.  
> If you're in a rush, be prepared to pay more.
>
> Paul, W9AC
>
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Re: Topband: de n7dd

[David Olean]

Hello Paul,

I am dealing with the same overheating problem. I need a 475 pf 
capacitor to shunt feed my 160 tower. I just happened to have a 500 pf 
15 KV doorknob almost the size of my fist. It did work for awhile, 
(several years) but now seems to heat up and the VSWR climbs to 2:1.  
The unit is definitely heating. I measured about 95 degrees when the 
outside air temp was 12 F.  I tried a single red Sprague plastic 
doorknob and it starts to run away with 500 watts of power. My next plan 
was to put four NEC caps together to get 475 pf: 2X 200 PF, 1X 50 PF, 
and 1X 25 PF.  It sounds like maybe this is not going to work either.  I 
guess I need a bigger box and a vacuum capacitor.  My amplifier is 
capable of 1500 watts output.  There is not a lot of voltage as it is a 
50 ohm input.  6 amps at 300 volts RMS would be 1800 watts at 50 ohms.  
What about an air variable in a wx proof box?


Dave K1WHS

On 1/9/2020 3:24 PM, Paul Christensen wrote:

does anyone know of a HV (20KV) capacitor with a value of approximately

500 pf that has a NPO value?

Once you get above about 100pF, NP0 options are very limited.  Be mindful of
the RF current magnitude in the application.  Small doorknobs can heat and
change in value.  In fact, I am dealing with this issue now on a 160m T
vertical.   My hope was that a paralleled pair of HEC doorknobs would work
in a NEMA 4x4x2 enclosure at the base.  The fit is fine, but the caps are
overheating in FT8/RTTY modes.  The fix will involve replacement with a
vacuum cap in a larger enclosure.

MaxGain Systems has a surplus Jennngs 500pF/20KV cap for about $350.  Also
consider transmitting mica capacitors.  Both will be quite large but will
meet your NP0 requirement.  Kintronic Labs sells a new 500pF/20KV mica for
about $650.  These are typically used in AM broadcast installations.  In
time, you can likely find these at lower prices.  The most common used mica
will be manufactured by Sangamo.  If you're in a rush, be prepared to pay
more.

Paul, W9AC

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Re: Topband: 160m vertical saltwater grounding

[Grant Saviers]

Rob,

I considered this for my MM SSB.  It doesn't work.  Several published 
tests prove that.  Ok as an AC/DC ground.


Grant

On 1/9/2020 01:18, Herbert Schoenbohm wrote:

A very effective device called *Dynaplate* works very well as a saltwater
grounding system for boats or limited areas to run full-sized radials.  You
can get one for $100 from the link below.
https://www.jamestowndistributors.com/userportal/show_product.do?pid=13331

Herb, KV4FZ

On Wed, Jan 8, 2020 at 6:30 PM Robert Fanfant  wrote:



Am looking to activate a location with very limited space surrounded by
ocean. Think of a small rock surrounded by saltwater/ocean.  The vertical
will be a tall 60???+ fiberglass pole and made to resonate on 160m. I would
like a way to reduce the required space of the 160m antenna radial field
due to the limited physical space available. The vertical will be located
at the waters edge, or even possibly over the oceans surface. At the feed
point, will be a choke designed for 160m. We should also assume maximum
power of 1.5KW being fed into the vertical and the activation will be for a
2 week duration of time.

One idea that came up is to use a floating piece of conductive material as
the verticals counterpoise. Specifically,   a thin conductive plate
designed to float on the oceans surface. From the antenna???s feed point,
will be a short length of  ground wire say about 6??? long,  to this
conductive plate.

Question(s):

   1.  Is it possible to just use the ocean as the ground plane /
counterpoise ? That is, can this idea work?
   2.  If so,
  *   How do I determine the required square footage/size of the plate?
  *   What material should be used as the conductive plate? (Nickel,
copper, aluminum, etc..? )The thought here is to make this plate as light
as possible, yet effective. It  will need to last the duration of the
activation (~2 weeks) in/on saltwater, it needs to handle 1.5KW at the feed
point, and likely exposed to air and saltwater as it floats on the ocean
surface.

-rob N7QT



Sent from Mail for
Windows 10

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Re: Topband: de n7dd

[Paul Christensen]

> does anyone know of a HV (20KV) capacitor with a value of approximately
500 pf that has a NPO value?

Once you get above about 100pF, NP0 options are very limited.  Be mindful of
the RF current magnitude in the application.  Small doorknobs can heat and
change in value.  In fact, I am dealing with this issue now on a 160m T
vertical.   My hope was that a paralleled pair of HEC doorknobs would work
in a NEMA 4x4x2 enclosure at the base.  The fit is fine, but the caps are
overheating in FT8/RTTY modes.  The fix will involve replacement with a
vacuum cap in a larger enclosure.

MaxGain Systems has a surplus Jennngs 500pF/20KV cap for about $350.  Also
consider transmitting mica capacitors.  Both will be quite large but will
meet your NP0 requirement.  Kintronic Labs sells a new 500pF/20KV mica for
about $650.  These are typically used in AM broadcast installations.  In
time, you can likely find these at lower prices.  The most common used mica
will be manufactured by Sangamo.  If you're in a rush, be prepared to pay
more.

Paul, W9AC

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Re: Topband: 160m vertical saltwater grounding

[GEORGE WALLNER]

Rob,
This is a good reference. Only one comment: I found recently on C6AGU that 
on 160 m the 2 -3 foot tidal change cause only a small change in the SWR of 
a tuned inverted L with its metal base standing in salt-water. I tuned the 
antenna to resonance with an SWR of 1.2 at mid-tide. Between low and high 
tides the SWR remained below 1.6. (Including losses in 300' of LMR-400 
coax.)

73,
George,
AA7JV/C6AGU


On Thu, 9 Jan 2020 06:40:27 -0600
 Rob Atkinson  wrote:

Interesting information here:

http://www.arrl.org/files/file/Antenna%20Book%20Supplemental%20Files/22nd%20Edition/Seawater%20Grounds%20-%20by%20N6LF.pdf

Rob
K5UJ
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Re: Topband: de n7dd

[GEORGE WALLNER]

Larry,
It will be hard to find.
You can find HEC HT75 100 or 200 pF, 15 kV with -750 tempco. You could 
parallel them to get 500 pF. Alternatively, there are Russian 470 pF, 15 kV, 
-1500 tempco caps around.

GL and 73,
George,
AA7JV


On Thu, 9 Jan 2020 04:35:12 + (UTC)
 Larry via Topband  wrote:

does anyone know of a HV (20KV) capacitor with a value of approximately 500 pf 
that has a NPO value?
thanks in advance.
larry/n7dd
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Re: Topband: 160m vertical saltwater grounding

[Ignacy Misztal]

 I operated on a pier over salt water on 160m in 3 locations. Once with
baloon for an inv L. KW with short antenna creates special problems. See my
message yesterday.

Short radials will have extremely high voltage at a KW level. Small metal
plate on salt water may have water sizzling or would introduce losses.

I would try to have 1-4 elevated radials as long as possible. 15 to 50 ft.
Then the transformer needs to be wound with teflon wire to prevent sparcing
and heating due to high voltages.

Ignacy, NO9E
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Re: Topband: 160m vertical saltwater grounding

[GEORGE WALLNER]

Robert,
You only have to "connect" to the salt-water. Don't worry about radials or 
field of radials. From you coax shield, or whatever GND (common) you have, 
run as many wires as you can into the water. They do not have to be long: 
you just want about 6' of wire in the water (even at low tide). (RF does not 
go far in salt water. You need to have the wires in the water to make them 
(capacitively) couple to the water. You need many wires to get a low 
impedance connection.) Of course, if you can tie to a large metal object 
that is in the water, you will need only two or three wires in parallel.
I normally use #14 THHN with rocks (or other weights) tied to the ends. Four 
wires will do OK, but 6 - 8 would be better.

Look at this: http://pt0s.com/index.php?page=photo=antenna_wave

GL and 73,
George
AA7JV


On Wed, 8 Jan 2020 22:30:05 +
 Robert Fanfant  wrote:


Am looking to activate a location with very limited space surrounded by ocean. 
Think of a small rock surrounded by saltwater/ocean.  The vertical will be a 
tall 60’+ fiberglass pole and made to resonate on 160m. I would like a way to 
reduce the required space of the 160m antenna radial field due to the limited 
physical space available. The vertical will be located at the waters edge, or 
even possibly over the oceans surface. At the feed point, will be a choke 
designed for 160m. We should also assume maximum power of 1.5KW being fed into 
the vertical and the activation will be for a 2 week duration of time.

One idea that came up is to use a floating piece of conductive material as the verticals counterpoise. Specifically,   a thin conductive plate designed to float on the oceans surface. From the antenna’s feed point, will be a short length of  ground wire say about 6’ long, 
to this conductive plate.


Question(s):

 1.  Is it possible to just use the ocean as the ground plane / counterpoise ? 
That is, can this idea work?
 2.  If so,
*   How do I determine the required square footage/size of the plate?
*   What material should be used as the conductive plate? (Nickel, copper, 
aluminum, etc..? )The thought here is to make this plate as light as possible, 
yet effective. It  will need to last the duration of the activation (~2 weeks) 
in/on saltwater, it needs to handle 1.5KW at the feed point, and likely exposed 
to air and saltwater as it floats on the ocean surface.

-rob N7QT


Sent from Mail for Windows 10

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Re: Topband: de n7dd

[Tim Shoppa]

Larry, I understand most modern doorknobs (e.g. HEC's) at or below 170pF
are NPO. I think 3 170pF's in parallel may work if you truly need NPO.

Matching network or blocking capacitor?

Tim N3QE

On Wed, Jan 8, 2020 at 11:35 PM Larry via Topband 
wrote:

> does anyone know of a HV (20KV) capacitor with a value of approximately
> 500 pf that has a NPO value?
> thanks in advance.
> larry/n7dd
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Re: Topband: 160m vertical saltwater grounding

[Rob Atkinson]

Interesting information here:

http://www.arrl.org/files/file/Antenna%20Book%20Supplemental%20Files/22nd%20Edition/Seawater%20Grounds%20-%20by%20N6LF.pdf

Rob
K5UJ
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Topband: 20kv 500pf....Re: de n7dd

[Artek Manuals]

Larry

You could always use two 10KV 1000pf in series might be easier to find

Dave
NR1DX
manu...@artekmanuals.com

On 1/8/2020 11:35 PM, Larry via Topband wrote:

does anyone know of a HV (20KV) capacitor with a value of approximately 500 pf 
that has a NPO value?
thanks in advance.
larry/n7dd
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--
Dave
manu...@artekmanuals.com
www.ArtekManuals.com

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Re: Topband: 160m vertical saltwater grounding

[Herbert Schoenbohm]

A very effective device called *Dynaplate* works very well as a saltwater
grounding system for boats or limited areas to run full-sized radials.  You
can get one for $100 from the link below.
https://www.jamestowndistributors.com/userportal/show_product.do?pid=13331

Herb, KV4FZ

On Wed, Jan 8, 2020 at 6:30 PM Robert Fanfant  wrote:

>
> Am looking to activate a location with very limited space surrounded by
> ocean. Think of a small rock surrounded by saltwater/ocean.  The vertical
> will be a tall 60’+ fiberglass pole and made to resonate on 160m. I would
> like a way to reduce the required space of the 160m antenna radial field
> due to the limited physical space available. The vertical will be located
> at the waters edge, or even possibly over the oceans surface. At the feed
> point, will be a choke designed for 160m. We should also assume maximum
> power of 1.5KW being fed into the vertical and the activation will be for a
> 2 week duration of time.
>
> One idea that came up is to use a floating piece of conductive material as
> the verticals counterpoise. Specifically,   a thin conductive plate
> designed to float on the oceans surface. From the antenna’s feed point,
> will be a short length of  ground wire say about 6’ long,  to this
> conductive plate.
>
> Question(s):
>
>   1.  Is it possible to just use the ocean as the ground plane /
> counterpoise ? That is, can this idea work?
>   2.  If so,
>  *   How do I determine the required square footage/size of the plate?
>  *   What material should be used as the conductive plate? (Nickel,
> copper, aluminum, etc..? )The thought here is to make this plate as light
> as possible, yet effective. It  will need to last the duration of the
> activation (~2 weeks) in/on saltwater, it needs to handle 1.5KW at the feed
> point, and likely exposed to air and saltwater as it floats on the ocean
> surface.
>
> -rob N7QT
>
>
>
> Sent from Mail for
> Windows 10
>
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> Reflector
>
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Re: Topband: Is there Any YB land station

[Victor Goncharsky via Topband]

Anton,
Almost all YBs on 160m are working FT8.
Worked  YB1TJ, YB2DX, YF5RFU, YB9AY, YB1BA, YB4IR.
The only CW QSO was in 2013 with YC0LOW (SK)
Good luck 
>Среда, 8 января 2020, 20:17 +03:00 от Anton Moehammad via Topband 
>:
> 
>Hi All,
>Just wondering if any of You recently (2019) have heard any YB land station 
>working in TB especially in CW mode.
>Thank YouAnton
>
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--
73, Victor Goncharsky US5WE/K1WE (UW5W in VHF contests, ex UB5WE), P.E.
UARL Technical and VHF Committies
DXCC Honor Roll #1 (Mixed, Phone), 10BDXCC, 9BWAS, 5BWAZ, WAZ-160
DXCC card checker (160 meters).
 
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