[TowerTalk] TowerTalk Digest, Vol 40, Issue 49
Tom Ed Moore
k5zxe at swbell.net
Thu Apr 20 01:39:50 EDT 2006
I have held 2250 watts to a dummy load(refrigerigation cooled) for over an
hour uding 5/8 heliax at 50MHz with n connectors. No problems encountered.
Also, no problem on 144 cw running legal limit during eme. The heliax was
spiral, not foam.
Tom
k5zxe
----- Original Message -----
From: <towertalk-request at contesting.com>
To: <towertalk at contesting.com>
Sent: Wednesday, April 19, 2006 11:30 PM
Subject: TowerTalk Digest, Vol 40, Issue 49
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Today's Topics:
1. Re: Power limitation for N-Connectors (Steve Katz)
2. Re: Power limitation for N-Connectors (Ron Stordahl)
3. Re: Power limitation for N-Connectors (Steve Katz)
4. Re: Jungle forest attenuation (Richard Hill)
5. Re: Power limitation for N-Connectors (Gary Schafer)
6. Re: Power limitation for N-Connectors (donovanf at starpower.net)
7. Call Book (WarrenWolff at aol.com)
8. Re: Power limitation for N-Connectors (bernard knight)
----------------------------------------------------------------------
Message: 1
Date: Wed, 19 Apr 2006 13:19:42 -0700
From: Steve Katz <stevek at jmr.com>
Subject: Re: [TowerTalk] Power limitation for N-Connectors
To: 'Ian White GM3SEK' <gm3sek at ifwtech.co.uk>,
towertalk at contesting.com
Message-ID: <C770317F90C7CE45B0C92E844FB89BD23FA6B1 at mail.jmr.com>
Content-Type: text/plain; charset="iso-8859-1"
>There is no problem with correctly assembled N connectors at these power
levels; but there is a risk of failure if the centre pin is not mated
correctly.
This can happen when N connectors with a floating centre pin are used
with semi-airspaced cables whose centre conductor is free to move
inside the cable. A hanging length of cable, and/or some flexing in a
rotator loop, can sometimes pull the centre pin partly out from its
socket, causing high resistance (especially at UHF where skin depths are
smaller) and failures at high power.
The solution is always to use connectors that have a captive centre pin,
and to take care when installing cables that have a floating centre
conductor.<
--
73 from Ian GM3SEK
::I agree with this entirely. However, another good way to assure the
center pin doesn't retract from its mate is to use a 360 degree drip loop in
the cable. That way, "gravity" is greatly reduced to only the weight of
half the loop, and not a long run of cable going down a tower leg. Doing
this, I've never seen a pin retract. -WB2WIK/6
------------------------------
Message: 2
Date: Wed, 19 Apr 2006 15:31:25 -0500
From: Ron Stordahl <ron.stordahl at digikey.com>
Subject: Re: [TowerTalk] Power limitation for N-Connectors
To: Ian White GM3SEK <gm3sek at ifwtech.co.uk>
Cc: towertalk at contesting.com
Message-ID: <44469E1D.3020301 at digikey.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
The consensus is that N connectors are fine at 1500 watts up to 30 MHz
(and probably beyond but my use is 30 MHz or lower). My problem with
N-connectors in the past, and it's a distant past, is in assembly..maybe
I had some bad ones. And I am from the old school...like to use
solder. But if the compression connection for the shield is good enough
and long lasting..apparently it must be..then fine.
The cable will be LDF5-50A which is foam.
Is there a certain connector which has a 'captive center pin' as you
mention?
My plan would be to use female connectors on the heliax, then male
connectors on the more flexible jumpers at the ends, probably short
length of 213.
Am I on the right path?
Ron Stordahl, N5IN
Ian White GM3SEK wrote:
> Steve Katz wrote:
>
>> I'd say they're wrong.
>>
>> Type Ns flashover at >3000V at STP, and that's a lot of voltage. The
>> center
>> pin can handle 6A continuously, probably 12A intermittently. 1500W is
>> 5.48A
>> in a 50 Ohm system. 1500W is 273.9V in a 50 Ohm system.
>>
>> I don't see the issue. I've used type Ns at 1500W output power on 70cm
>> for
>> eme work, and never had one fail...
>>
>
> There is no problem with correctly assembled N connectors at these power
> levels; but there is a risk of failure if the centre pin is not mated
> correctly.
>
> This can happen when N connectors with a floating centre pin are used
> with semi-airspaced cables whose centre conductor is free to move
> inside the cable. A hanging length of cable, and/or some flexing in a
> rotator loop, can sometimes pull the centre pin partly out from its
> socket, causing high resistance (especially at UHF where skin depths are
> smaller) and failures at high power.
>
> The solution is always to use connectors that have a captive centre pin,
> and to take care when installing cables that have a floating centre
> conductor.
>
>
>
------------------------------
Message: 3
Date: Wed, 19 Apr 2006 13:30:13 -0700
From: Steve Katz <stevek at jmr.com>
Subject: Re: [TowerTalk] Power limitation for N-Connectors
To: "'ron.stordahl at digikey.com'" <ron.stordahl at digikey.com>, Ian White
GM3SEK <gm3sek at ifwtech.co.uk>
Cc: towertalk at contesting.com
Message-ID: <C770317F90C7CE45B0C92E844FB89BD23FA6B6 at mail.jmr.com>
Content-Type: text/plain; charset="iso-8859-1"
Ron, the Andrew N connectors for LDF5-50 do have captive center pins, they
don't make them any other way. The problem discussed doesn't occur with
Heliax, it occurs with flex cables that use connectors having separate
center pins. You can always use captive pin type Ns on the RG-213/U or
whatever flex cable you'll be using. Just buy them that way. They're
available from many sources including Amphenol, Delta, Kings, Trompeter, et
al.
-WB2WIK/6
-----Original Message-----
From: Ron Stordahl [mailto:ron.stordahl at digikey.com]
Sent: Wednesday, April 19, 2006 1:31 PM
To: Ian White GM3SEK
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] Power limitation for N-Connectors
The consensus is that N connectors are fine at 1500 watts up to 30 MHz
(and probably beyond but my use is 30 MHz or lower). My problem with
N-connectors in the past, and it's a distant past, is in assembly..maybe
I had some bad ones. And I am from the old school...like to use
solder. But if the compression connection for the shield is good enough
and long lasting..apparently it must be..then fine.
The cable will be LDF5-50A which is foam.
Is there a certain connector which has a 'captive center pin' as you
mention?
My plan would be to use female connectors on the heliax, then male
connectors on the more flexible jumpers at the ends, probably short
length of 213.
Am I on the right path?
Ron Stordahl, N5IN
Ian White GM3SEK wrote:
> Steve Katz wrote:
>
>> I'd say they're wrong.
>>
>> Type Ns flashover at >3000V at STP, and that's a lot of voltage. The
center
>> pin can handle 6A continuously, probably 12A intermittently. 1500W is
5.48A
>> in a 50 Ohm system. 1500W is 273.9V in a 50 Ohm system.
>>
>> I don't see the issue. I've used type Ns at 1500W output power on 70cm
for
>> eme work, and never had one fail...
>>
>
> There is no problem with correctly assembled N connectors at these power
> levels; but there is a risk of failure if the centre pin is not mated
> correctly.
>
> This can happen when N connectors with a floating centre pin are used
> with semi-airspaced cables whose centre conductor is free to move
> inside the cable. A hanging length of cable, and/or some flexing in a
> rotator loop, can sometimes pull the centre pin partly out from its
> socket, causing high resistance (especially at UHF where skin depths are
> smaller) and failures at high power.
>
> The solution is always to use connectors that have a captive centre pin,
> and to take care when installing cables that have a floating centre
> conductor.
>
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 4
Date: Wed, 19 Apr 2006 07:34:47 -0700
From: "Richard Hill" <REHill at ix.netcom.com>
Subject: Re: [TowerTalk] Jungle forest attenuation
To: "Towertalk at Contesting. Com" <towertalk at contesting.com>
Message-ID: <FEEMJFAOLGCHOIEEGIJMKEJEDPAA.REHill at ix.netcom.com>
Content-Type: text/plain; charset="US-ASCII"
A number of these references are searchable via Google Scholar with links to
purchase copies from IEEE. A Google Scholar search for "radio communication
forest" will find a number of HF related articles. For example:
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?isnumber=25632&arnumber=11429
85&type=ref
Might be able to find the articles at a local college library or via a local
ham member of IEEE.
NU6T
Rich
CU in the California QSO Party (CQP)
www.cqp.org, Oct 7-8 2006
-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com]On Behalf Of Jim Lux
Sent: Wednesday, April 19, 2006 7:05 AM
To: Olivier F5MZN; towertalk at contesting.com
Subject: Re: [TowerTalk] Jungle forest attenuation
At 12:31 AM 4/19/2006, Olivier F5MZN wrote:
>Hi -
>
>I wonder if someone has any experiences on tree attenuation caused by
>jungle trees on short waves below 30 MHz for horizontal antennas. I
>googled a bit but without too much success because most of the
>informations are relative to higher bands.
As you say, the interest these days is in UHF and higher, however, there's
quite a bit of research at lower frequencies, back to the 60s and 70s.
Do you have access to IEEE journals?
You might want to look at the papers by Theodore Tamir.. for instamce:
"On Radio-wave propagation in Forest Environments", IEEE Trans on Ant and
Prop, V AP-15, #6, Nov 1967
covers 1-100 MHz
and a followup paper from 1977:
"Radio Wave Propagation Along Mixed Paths in Forest Environments", IEEE
Trans Ant Prop, V AP-25, #4, Jul 1977
Tamir shows that you can model the forest as a big lossy dielectric slab,
so what you need to know is what the properties of "your" particular forest
are.
Cavalcante and coworkers also studied HF frequencies in Brazil
"Optimization of Radio-Communication in Three Layered Media", IEEE Trans
Ant and Prop, V AP31, #1, Jan 1983
"Mobile Radio Propagation ALong Mixed Paths in Forest Environment", IEEE
MTT-S IMOC proceedings, 1999
and
"Radio Loss in Forest using a Model with Four Layered Media", Radio
Science, V18, #5, 1983
They're looking at the effects of things like clearings and roads, as
opposed to the infinite uniform slabs of Taheri.
There's a newer paper from Tewari, et al., "Radio Wave Propagation Through
Rain Forests of India", IEEE Trans on Ant and Prop, V38, #4, Apr 99
This one starts at 50 MHz, but is useful lower because of the measurments
of dielectric properties.
Googling for all these authors and the word "propagation" might turn up
useful stuff. The "gold mine" would be if some college has put a masters
thesis online that summarizes the data. The typical thesis has a nice
chapter 2 that covers the previous research, and the usual masters thesis
is written at a level that is not too obscure and arcane. Some of the PhD
theses get pretty esoteric and narrowly focused.
>--
There's also some ITU Recommendations/Reports that provide models and
tables for forest attenuation. You can sign up at the ITU website and get 3
reports for free.
http://www.itu.org/ I think..
>Actually, we are planning to add a new tower in our contest QTH which
>might not be located in a clear environment, especially for the Europe
>path where there is a small but dense forest (500-meter long) in the
>near field. Trees are about 15-meter high but the tower and antennas
>will be well above. You can have an idea on the trees with this picture:
>http://www.fy5ke.org/gallery/PICT0255.JPG
>
>How important could be the attenuation?
If the antenna is well above the forest, the effect is probably
minimal. Forest is lossy, but nowhere near as lossy as soil.
Jim
_______________________________________________
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TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 5
Date: Wed, 19 Apr 2006 17:48:28 -0400
From: "Gary Schafer" <garyschafer at comcast.net>
Subject: Re: [TowerTalk] Power limitation for N-Connectors
To: <ron.stordahl at digikey.com>, "'Ian White GM3SEK'"
<gm3sek at ifwtech.co.uk>
Cc: towertalk at contesting.com
Message-ID: <20060419214826.B26CE3191A6 at dayton.akorn.net>
Content-Type: text/plain; charset="us-ascii"
The trick in assembling N connectors is to make sure you have the shield
wires laid out flat with none overlapping one another. Use a pick to
separate them. Then cut the shield wires to the proper length with a pair of
scissors. The length is critical. Too long and they will jam up. Too short
and they will pull out. If done properly the cable will not turn in the
connector and will last a long time. No solder on the shield!
73
Gary k4FMX
> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Ron Stordahl
> Sent: Wednesday, April 19, 2006 4:31 PM
> To: Ian White GM3SEK
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] Power limitation for N-Connectors
>
> The consensus is that N connectors are fine at 1500 watts up to 30 MHz
> (and probably beyond but my use is 30 MHz or lower). My problem with
> N-connectors in the past, and it's a distant past, is in assembly..maybe
> I had some bad ones. And I am from the old school...like to use
> solder. But if the compression connection for the shield is good enough
> and long lasting..apparently it must be..then fine.
>
> The cable will be LDF5-50A which is foam.
>
> Is there a certain connector which has a 'captive center pin' as you
> mention?
>
> My plan would be to use female connectors on the heliax, then male
> connectors on the more flexible jumpers at the ends, probably short
> length of 213.
>
> Am I on the right path?
>
> Ron Stordahl, N5IN
>
> Ian White GM3SEK wrote:
> > Steve Katz wrote:
> >
> >> I'd say they're wrong.
> >>
> >> Type Ns flashover at >3000V at STP, and that's a lot of voltage. The
> center
> >> pin can handle 6A continuously, probably 12A intermittently. 1500W is
> 5.48A
> >> in a 50 Ohm system. 1500W is 273.9V in a 50 Ohm system.
> >>
> >> I don't see the issue. I've used type Ns at 1500W output power on 70cm
> for
> >> eme work, and never had one fail...
> >>
> >
> > There is no problem with correctly assembled N connectors at these power
> > levels; but there is a risk of failure if the centre pin is not mated
> > correctly.
> >
> > This can happen when N connectors with a floating centre pin are used
> > with semi-airspaced cables whose centre conductor is free to move
> > inside the cable. A hanging length of cable, and/or some flexing in a
> > rotator loop, can sometimes pull the centre pin partly out from its
> > socket, causing high resistance (especially at UHF where skin depths are
> > smaller) and failures at high power.
> >
> > The solution is always to use connectors that have a captive centre pin,
> > and to take care when installing cables that have a floating centre
> > conductor.
> >
> >
> >
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 6
Date: Wed, 19 Apr 2006 20:01:35 -0400
From: <donovanf at starpower.net>
Subject: Re: [TowerTalk] Power limitation for N-Connectors
To: towertalk at contesting.com
Message-ID: <7122e6dd.aba8c8c7.82a2e00 at ms06.lnh.mail.rcn.net>
Content-Type: text/plain; charset=us-ascii
Ron,
I've been running full legal power into N connectors on the HF
bands for many years with no failures. Correct assembly is
essential to reliability, the relatively new RC connectors
eliminate the most common failure (improperly aligned center
pin).
73!
Frank
W3LPL
------------------------------
Message: 7
Date: Wed, 19 Apr 2006 21:51:24 EDT
From: WarrenWolff at aol.com
Subject: [TowerTalk] Call Book
To: towertalk at contesting.com
Message-ID: <33e.31eabb0.3178431c at aol.com>
Content-Type: text/plain; charset="US-ASCII"
Anyone on here have an old call book, circa 1962-1964?
Please contact me at _WarrenWolff at aol.com_ (mailto:WarrenWolff at aol.com) .
Warren, W7WY
------------------------------
Message: 8
Date: Thu, 20 Apr 2006 00:27:23 -0400
From: "bernard knight" <kn8bk at 1st.net>
Subject: Re: [TowerTalk] Power limitation for N-Connectors
To: "Steve Katz" <stevek at jmr.com>, <ron.stordahl at digikey.com>, "Ian
White GM3SEK" <gm3sek at ifwtech.co.uk>
Cc: towertalk at contesting.com
Message-ID: <20060420003082.SM03084 at yourf78bf48ce2>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
----- Original Message -----
From: "Steve Katz" <stevek at jmr.com>
To: <ron.stordahl at digikey.com>; "Ian White GM3SEK" <gm3sek at ifwtech.co.uk>
Cc: <towertalk at contesting.com>
Sent: Wednesday, April 19, 2006 4:30 PM
Subject: Re: [TowerTalk] Power limitation for N-Connectors
> Ron, the Andrew N connectors for LDF5-50 do have captive center pins, they
> don't make them any other way. The problem discussed doesn't occur with
> Heliax, it occurs with flex cables that use connectors having separate
> center pins. You can always use captive pin type Ns on the RG-213/U or
> whatever flex cable you'll be using. Just buy them that way. They're
> available from many sources including Amphenol, Delta, Kings, Trompeter,
> et
> al.
>
> -WB2WIK/6
>
> -----Original Message-----
> From: Ron Stordahl [mailto:ron.stordahl at digikey.com]
> Sent: Wednesday, April 19, 2006 1:31 PM
> To: Ian White GM3SEK
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] Power limitation for N-Connectors
>
>
> The consensus is that N connectors are fine at 1500 watts up to 30 MHz
> (and probably beyond but my use is 30 MHz or lower). My problem with
> N-connectors in the past, and it's a distant past, is in assembly..maybe
> I had some bad ones. And I am from the old school...like to use
> solder. But if the compression connection for the shield is good enough
> and long lasting..apparently it must be..then fine.
>
> The cable will be LDF5-50A which is foam.
>
> Is there a certain connector which has a 'captive center pin' as you
> mention?
>
> My plan would be to use female connectors on the heliax, then male
> connectors on the more flexible jumpers at the ends, probably short
> length of 213.
>
> Am I on the right path?
>
> Ron Stordahl, N5IN
>
> Ian White GM3SEK wrote:
>> Steve Katz wrote:
>>
>>> I'd say they're wrong.
>>>
>>> Type Ns flashover at >3000V at STP, and that's a lot of voltage. The
> center
>>> pin can handle 6A continuously, probably 12A intermittently. 1500W is
> 5.48A
>>> in a 50 Ohm system. 1500W is 273.9V in a 50 Ohm system.
>>>
>>> I don't see the issue. I've used type Ns at 1500W output power on 70cm
> for
>>> eme work, and never had one fail...
>>>
>>
>> There is no problem with correctly assembled N connectors at these power
>> levels; but there is a risk of failure if the centre pin is not mated
>> correctly.
>>
>> This can happen when N connectors with a floating centre pin are used
>> with semi-airspaced cables whose centre conductor is free to move
>> inside the cable. A hanging length of cable, and/or some flexing in a
>> rotator loop, can sometimes pull the centre pin partly out from its
>> socket, causing high resistance (especially at UHF where skin depths are
>> smaller) and failures at high power.
>>
>> The solution is always to use connectors that have a captive centre pin,
>> and to take care when installing cables that have a floating centre
>> conductor.
>>
>>
>>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
------------------------------
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