Is there any secrets of getting the cover off of traps on a tribander. I've
got an old tribander that needs cleaning up. I need to clean up the contacts on
the ends of the coils.
I can only move the outer cover about one inch, before the divots that the mfg
had put on the cover, stops the cover from being removed
Thanks
Herb K2LNS
________________________________
From: "topband-request@contesting.com" <topband-request@contesting.com>
To: topband@contesting.com
Sent: Sunday, July 8, 2012 11:07 AM
Subject: Topband Digest, Vol 115, Issue 15
Send Topband mailing list submissions to
topband@contesting.com
To subscribe or unsubscribe via the World Wide Web, visit
http://lists.contesting.com/mailman/listinfo/topband
or, via email, send a message with subject or body 'help' to
topband-request@contesting.com
You can reach the person managing the list at
topband-owner@contesting.com
When replying, please edit your Subject line so it is more specific
than "Re: Contents of Topband digest..."
Today's Topics:
1. Re: More Amplifier info (Tom W8JI)
2. Re: Lightning makes antennas vanish (Guy Olinger K2AV)
3. Re: More Amplifier info (MIKE DURKIN)
4. Loss comparison between two antennas (Steve Flood)
5. Re: More Amplifier info (W2XJ)
6. Re: Lightning makes antennas vanish (Tom W8JI)
7. Re: Loss comparison between two antennas (Jim Brown)
8. Re: Loss comparison between two antennas (Guy Olinger K2AV)
----------------------------------------------------------------------
Message: 1
Date: Sun, 8 Jul 2012 10:18:27 -0400
From: "Tom W8JI" <w8ji@w8ji.com>
Subject: Re: Topband: More Amplifier info
To: "Larry Molitor" <w7iuv@yahoo.com>, <topband@contesting.com>
Message-ID: <549F4937AA6C41AAAD9219B0CBAC96DA@tom0c1d32a93f0>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Hi Larry,
All of the links and data agree with what I found here in my measurements. I
think the real issue is some very creative marketing is being done, and the
factory data sheets can be a bit confusing. They certainly do not contain
linear data.
Here are the main points:
1.) The "1250 watt device" is actually about a 800 watt PEP maximum device
in linear service. At 800 watts, it is right on the edge of what we are
accustomed to for Ham product IMD.
2.) A major problem is heat. Because all heat is in one small footprint, it
needs a very thick machined copper spreader or liquid cooling, even at just
800 watts PEP.
3.) Like any other device, they will fail with mismatch at high power. They
absolutely will require SWR shutdown and temperature monitoring.
If we read all of the links carefully enough to cut through the marketing
fluff, we will see every reference link listed (where they have actually
tested) agrees with all of this.
I think what has really happened, is many home or first-time builders have
taken the data sheet at face value. They have convinced themselves this is a
1250 watt output device that can be run right into almost any load without
worry. Of course, neither of those things are remotely true.
I understand it is tough to let go of the magic of a single 1250-watt device
that slapped on a heatsink without protection, and can be run into a 65:1
SWR without failing. But this is really a 800 watt PEP linear device that
comes with all the long term baggage of any other similar device, as ALL of
those links also seem to agree with.
At 600 watts it will be pretty clean. At 800 watts about at the lower limit
of what cheap tube amps can do. All of this requiring getting the heat out,
and shutting it off if SWR goes high.
73 Tom
<<<<<Like Tom, I am convinced that it is not possible to run that part at
full power in normal amateur service due to the heat issues. Maybe some
energetic person will build one up for 1.8 MHz using cryogenic cooling and
let us know how that works out...
73,
Larry - W7IUV>>>>
------------------------------
Message: 2
Date: Sun, 8 Jul 2012 10:45:04 -0400
From: Guy Olinger K2AV <olinger@bellsouth.net>
Subject: Re: Topband: Lightning makes antennas vanish
To: mikefurrey@att.net
Cc: topband@contesting.com
Message-ID:
<CANckpc2GiEGqoenM6H05EiXyo5APUyexH-jTug=yRiRyMynz-Q@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
I had an 80 half wave inverted L, up 67 out 70 feet, made of #12,
strung with great difficulty between two tall trees, that really
worked well. The vertical came down to my tractor shed from the
western tree and went through the wall with insulation to an tank
circuit tuner on the inside wall. In a lightning storm all the #12
from the outside of the tractor shed to 3/4 of the way to the eastern
tree just simply evaporated.
There were no obvious char marks anywhere, and the tuning network was unharmed.
If it could to that to #12, doing it to #17 would be easy. Not that
I have any technical explanation for what happened, just that it
happened.
73, Guy.
On Sun, Jul 8, 2012 at 10:11 AM, <mikefurrey@att.net> wrote:
> The feed point of my inverted L was blown apart and the copper inside the
> insulation (both the "L" and horizontal elevated radial) was reduced to a
> black, brittle mess from a lightning strike and an adjacent neighbor's TV
> was reduced to a melted pile of plastic. My antenna is suspended between a
> couple of 80' pine trees on my small lot. There were (still visible) also
> char marks on a tree that was used as a support for the elevated radial. The
> radial was about 6" from the tree.
>
> Mike WA5POK
>
> -----Original Message-----
> From: Eddy Swynar
> Sent: Sunday, July 08, 2012 8:47 AM
> To: Tom W8JI
> Cc: Topband@contesting.com
> Subject: Re: Topband: Lightning makes antennas vanish
>
>
> On 2012-07-08, at 9:34 AM, Tom W8JI wrote:
>
>>
>> Anyone else have this happen? My copperweld #14, that clearly has arc
>> pitting where it passed over other wires, shows no damage other than the
>> arc
>> pits. The cad-steel fence wire must get so hot it just vaporizes. I can't
>> even find any pieces of it.
>>
>> Since the 1960's or 70's, this is the very first time I've seen this
>> happen.
>> Are thunderstorms more violent now, or is wire cheaper? :-)
>>
>
>
> Hi Tom,
>
> Are you sure you weren't the victim of "...copper nappers", possibly...?!
>
> There was a report in a Toronto paper the other day where some cell tower
> used by emergency forces of some kind in that city was knocked off the air
> for several hours---thieves had snipped as much copper & wiring that they
> could see, for re-sale to the scrap metal market...
>
> That answers your last question, i.e. wire is NOT getting any
> "cheaper"---not by that stretch of the imagination! Hi Hi
>
> ~73~ de Eddy VE3CUI - VE3XZ
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
------------------------------
Message: 3
Date: Sun, 8 Jul 2012 07:46:02 -0700
From: MIKE DURKIN <patriot121@msn.com>
Subject: Re: Topband: More Amplifier info
To: <topband@contesting.com>
Message-ID: <COL110-W17623731D43287301BA2EC92EC0@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Im not sure what part this was now ... it seems to be lost to the thread ....
Was it the NXP BLF578XR ? if not has the thought of a HF linear droped because
of harmonics,,,, ECT,??
Mike KC7NOA
> From: w8ji@w8ji.com
> To: w7iuv@yahoo.com; topband@contesting.com
> Date: Sun, 8 Jul 2012 10:18:27 -0400
> Subject: Re: Topband: More Amplifier info
>
> Hi Larry,
>
> All of the links and data agree with what I found here in my measurements. I
> think the real issue is some very creative marketing is being done, and the
> factory data sheets can be a bit confusing. They certainly do not contain
> linear data.
>
> Here are the main points:
>
> 1.) The "1250 watt device" is actually about a 800 watt PEP maximum device
> in linear service. At 800 watts, it is right on the edge of what we are
> accustomed to for Ham product IMD.
>
> 2.) A major problem is heat. Because all heat is in one small footprint, it
> needs a very thick machined copper spreader or liquid cooling, even at just
> 800 watts PEP.
>
> 3.) Like any other device, they will fail with mismatch at high power. They
> absolutely will require SWR shutdown and temperature monitoring.
>
> If we read all of the links carefully enough to cut through the marketing
> fluff, we will see every reference link listed (where they have actually
> tested) agrees with all of this.
>
> I think what has really happened, is many home or first-time builders have
> taken the data sheet at face value. They have convinced themselves this is a
> 1250 watt output device that can be run right into almost any load without
> worry. Of course, neither of those things are remotely true.
>
> I understand it is tough to let go of the magic of a single 1250-watt device
> that slapped on a heatsink without protection, and can be run into a 65:1
> SWR without failing. But this is really a 800 watt PEP linear device that
> comes with all the long term baggage of any other similar device, as ALL of
> those links also seem to agree with.
>
> At 600 watts it will be pretty clean. At 800 watts about at the lower limit
> of what cheap tube amps can do. All of this requiring getting the heat out,
> and shutting it off if SWR goes high.
>
> 73 Tom
>
> <<<<<Like Tom, I am convinced that it is not possible to run that part at
> full power in normal amateur service due to the heat issues. Maybe some
> energetic person will build one up for 1.8 MHz using cryogenic cooling and
> let us know how that works out...
>
> 73,
>
> Larry - W7IUV>>>>
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
------------------------------
Message: 4
Date: Sun, 8 Jul 2012 08:54:36 -0600
From: "Steve Flood" <kk7uv@bresnan.net>
Subject: Topband: Loss comparison between two antennas
To: <topband@contesting.com>
Message-ID: <00a401cd5d19$986f50d0$c94df270$@bresnan.net>
Content-Type: text/plain; charset="us-ascii"
I have a 73.5-ft. wire vertical over a decent field of radials (about 60 or
so, 50 to 120 ft. long).
I have configured this vertical two ways over the past several years and am
wondering if they are equal enough in radiated power that I should just use
the simpler of the two.
The configurations differ only in the topload "T", and the feedpoint
matching.
Configuration 1: 70-ft. flat horizontal topload wire with vertical
attached at center. Feedpoint is 25+j0. Matching is through a 2:1 UNUN
wound as per Sevick on a FT-150K.
Configuration 2: 186-ft. flat horizontal topload wire folded back on itself
to fit in a 60 x 6-ft space. (From the center vertical attachment point,
each topload leg goes out 30 feet, turns 90 degrees for 3 feet, then turns
back on itself another 90 degrees and goes 60 feet. Looks like a
squared-off "S".) This resonates the antenna below 1.8Mhz with a feedpoint
Z of 37 +j245. Matching is through an L-network. My intention was to
increase radiation resistance and efficiency and move the current maxima
away from the feedpoint and to the center of the vertical for lower takeoff
angle.
My question is how much am I losing in each system. Is the UNUN
more/less/same loss as the L-network?
I run 1200 watts and the L-net components are sized adequately. A 1-minute
keydown produces no arcing, and the coil and cap do not get hot.
Thanks,
Steve KK7UV
------------------------------
Message: 5
Date: Sun, 08 Jul 2012 11:01:25 -0400
From: W2XJ <w2xj@nyc.rr.com>
Subject: Re: Topband: More Amplifier info
To: topband@contesting.com
Message-ID: <4FF9A0C5.50006@nyc.rr.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
A while back on another list there was a discussion about a robust amp
can not be built in a table top size. I believe this applies to solid
state amps as well. The key to building a gutsy solid state amp is the
use of multiple devices and distributing the heat over a larger area.
All solid state broadcast transmitters are comprised of multiple
modules. Sometimes multiple fans are used to cool the modules. I am not
aware any amateur linears with a modular design but there is nothing
beyond economics to prevent one from being built.
On 7/8/12 10:18 AM, Tom W8JI wrote:
> Hi Larry,
>
> All of the links and data agree with what I found here in my measurements. I
> think the real issue is some very creative marketing is being done, and the
> factory data sheets can be a bit confusing. They certainly do not contain
> linear data.
>
> Here are the main points:
>
> 1.) The "1250 watt device" is actually about a 800 watt PEP maximum device
> in linear service. At 800 watts, it is right on the edge of what we are
> accustomed to for Ham product IMD.
>
> 2.) A major problem is heat. Because all heat is in one small footprint, it
> needs a very thick machined copper spreader or liquid cooling, even at just
> 800 watts PEP.
>
> 3.) Like any other device, they will fail with mismatch at high power. They
> absolutely will require SWR shutdown and temperature monitoring.
>
> If we read all of the links carefully enough to cut through the marketing
> fluff, we will see every reference link listed (where they have actually
> tested) agrees with all of this.
>
> I think what has really happened, is many home or first-time builders have
> taken the data sheet at face value. They have convinced themselves this is a
> 1250 watt output device that can be run right into almost any load without
> worry. Of course, neither of those things are remotely true.
>
> I understand it is tough to let go of the magic of a single 1250-watt device
> that slapped on a heatsink without protection, and can be run into a 65:1
> SWR without failing. But this is really a 800 watt PEP linear device that
> comes with all the long term baggage of any other similar device, as ALL of
> those links also seem to agree with.
>
> At 600 watts it will be pretty clean. At 800 watts about at the lower limit
> of what cheap tube amps can do. All of this requiring getting the heat out,
> and shutting it off if SWR goes high.
>
> 73 Tom
>
> <<<<<Like Tom, I am convinced that it is not possible to run that part at
> full power in normal amateur service due to the heat issues. Maybe some
> energetic person will build one up for 1.8 MHz using cryogenic cooling and
> let us know how that works out...
>
> 73,
>
> Larry - W7IUV>>>>
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
------------------------------
Message: 6
Date: Sun, 8 Jul 2012 11:01:50 -0400
From: "Tom W8JI" <w8ji@w8ji.com>
Subject: Re: Topband: Lightning makes antennas vanish
To: "Eddy Swynar" <deswynar@xplornet.ca>
Cc: Topband@contesting.com
Message-ID: <46D785ED0EBC465DB0BE1D26F8A82FC1@tom0c1d32a93f0>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
> Are you sure you weren't the victim of "...copper nappers", possibly...?!
No, it was lightning.
Here are pictures from an earlier event:
http://www.w8ji.com/lightning_strikes.htm
Now the problem is making wires vanish for long lengths, hundreds of feet!!!
This problem seems to be getting worse.
73 Tom
------------------------------
Message: 7
Date: Sun, 08 Jul 2012 08:06:33 -0700
From: Jim Brown <jim@audiosystemsgroup.com>
Subject: Re: Topband: Loss comparison between two antennas
To: topband@contesting.com
Message-ID: <4FF9A1F9.8020507@audiosystemsgroup.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 7/8/2012 7:54 AM, Steve Flood wrote:
> This resonates the antenna below 1.8Mhz with a feedpoint
> Z of 37 +j245. Matching is through an L-network. My intention was to
> increase radiation resistance and efficiency and move the current maxima
> away from the feedpoint and to the center of the vertical for lower takeoff
> angle.
About five years ago, I increased the top-loading on my 86 ft Tee
vertical so that the feedpoint impedance was 50 + J xxx, and tuned it
with series capacitance. It works "well," but there's no good way to
compare it to anything, other than, perhaps, a model. Like you, I have
a lot of radials on the ground. A couple of years ago, I added a second
vertical wire, spaced from the first by 6-8 inches, wired in parallel at
both ends. The second conductor increases the SWR bandwidth nicely.
73, Jim K9YC
------------------------------
Message: 8
Date: Sun, 8 Jul 2012 11:07:44 -0400
From: Guy Olinger K2AV <olinger@bellsouth.net>
Subject: Re: Topband: Loss comparison between two antennas
To: Steve Flood <kk7uv@bresnan.net>
Cc: topband@contesting.com
Message-ID:
<CANckpc3OKaS1E=zmTcyTzUBwDJ2epGeQys0UCXj_2kDvf9pZNg@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
The losses in a 160 meter vertical antenna system are almost
completely controlled by what you do for the antenna's counterpole
(radials or counterpoise) and the electrical characteristics of the
dirt under the antenna. So the most important thing, the overwhelming
thing, you have not described at all. What are you connecting the
coax shield to? Describe the counterpoles for your two antennas in
detail.
73, Guy.
On Sun, Jul 8, 2012 at 10:54 AM, Steve Flood <kk7uv@bresnan.net> wrote:
> I have a 73.5-ft. wire vertical over a decent field of radials (about 60 or
> so, 50 to 120 ft. long).
>
> I have configured this vertical two ways over the past several years and am
> wondering if they are equal enough in radiated power that I should just use
> the simpler of the two.
>
> The configurations differ only in the topload "T", and the feedpoint
> matching.
>
>
>
> Configuration 1: 70-ft. flat horizontal topload wire with vertical
> attached at center. Feedpoint is 25+j0. Matching is through a 2:1 UNUN
> wound as per Sevick on a FT-150K.
>
>
>
> Configuration 2: 186-ft. flat horizontal topload wire folded back on itself
> to fit in a 60 x 6-ft space. (From the center vertical attachment point,
> each topload leg goes out 30 feet, turns 90 degrees for 3 feet, then turns
> back on itself another 90 degrees and goes 60 feet. Looks like a
> squared-off "S".) This resonates the antenna below 1.8Mhz with a feedpoint
> Z of 37 +j245. Matching is through an L-network. My intention was to
> increase radiation resistance and efficiency and move the current maxima
> away from the feedpoint and to the center of the vertical for lower takeoff
> angle.
>
>
>
> My question is how much am I losing in each system. Is the UNUN
> more/less/same loss as the L-network?
>
> I run 1200 watts and the L-net components are sized adequately. A 1-minute
> keydown produces no arcing, and the coil and cap do not get hot.
>
>
>
> Thanks,
>
> Steve KK7UV
>
>
>
>
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
------------------------------
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
End of Topband Digest, Vol 115, Issue 15
****************************************
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|