Vanity, not again...
JPalooka at aol.com
JPalooka at aol.com
Thu Jan 9 05:11:57 EST 1997
Hello, Mario,
In a message dated 97-01-08 16:09:04 EST, s56a at s55tcp.ampr.org (Marijan
Miletic) writes:
<< Subj: Vanity, not again...
<snip>
During my short stay in London I met again (for 25 years) Roger, G3SXW and
he
asked what is happening on this reflector since he resign in the midst of
vanity messages. I guess if that thread reappears again, we can lose more
WW audience. There are enough WWW sites, including ARRL, for that extremely
interesting subject :-)
73 de Mario, S56A, N1YU.
P.S. Fred, how is FT-1000MP behaving?
Well, I rejoined it a short time back and have been pleased with Contest
related
messages. This needs to happen to the DX reflector! It's a great deal
better than
when I left and I hope it stays this way.
73, K8Joe"Palooka"
>From bmaves at msw0.attnet.or.jp (Brian Maves) Thu Jan 9 01:30:24 1997
From: bmaves at msw0.attnet.or.jp (Brian Maves) (Brian Maves)
Date: Wed, 08 Jan 97 17:30:24 PST
Subject: Standard Business Trip Plea--Honolulu
Message-ID: <MAPI.Id.0016.006d6176657320203030303630303036 at MAPI.to.RFC822>
I'll be in Honolulu (Hickam AFB) for a conference from 11-17 January.
Would appreciate any information on DX/Contest club meetings, gatherings,
hamfests, etc. happening during that timeframe. Also, I found out today I
will arrive at 6:25 AM on the 11th--is anybody around that area doing a
multi-op in NAQP SSB and want an extra op for the last half of the contest.
Please reply direct.
Thanks for the bandwidth.
Brian, 7J7ABV/NB9T
bmaves at msw0.attnet.or.jp
>From ON7SS at dma.be (Marc, ON7SS) Thu Jan 9 20:03:04 1997
From: ON7SS at dma.be (Marc, ON7SS) (Marc, ON7SS)
Date: Thu, 9 Jan 1997 21:03:04 +0100
Subject: UBA CONTEST RULES in CQ Magazine
Message-ID: <199701092003.VAA09446 at www.dma.be>
Hello all,
Just received CQ Magazine of january today here in Belgium.
Probably something went wrong in sending the rules to K1AR, because there
are a few mistakes in the publication.
To get the right info, pse send me an email, and I will reply will with the
complete rules.
Do not forget: UBA CONTEST 1997
SSB - 25th January 1997, 13:00 UTC to 26th January, 13:00 UTC.
CW - 22th February 1997, 13:00 UTC to 23th February, 13:00 UTC.
CU IN TEST 73 Marc, ON7SS
*********************************************
* Amateur Radio Station ON7SS *
* Marc Domen UBA HF Contest Manager *
* Ferdinand Coosemansstraat 32 *
* B - 2600 Berchem (Antwerpen) BELGIUM *
* Tel: 03-218.52.60 *
* Packet Home BBS ON7SS @ON1ANR.#AN.BEL.EU *
* Email ON7SS at dma.be *
* (have only limited acces on internet) *
* ( i.e. sending and receiving email ) *
*********************************************
>From rrossi at btv.ibm.com (Ronald D Rossi) Thu Jan 9 20:47:27 1997
From: rrossi at btv.ibm.com (Ronald D Rossi) (Ronald D Rossi)
Date: Thu, 09 Jan 1997 15:47:27 -0500
Subject: NAQP CW Teams - a solicitation...
Message-ID: <9701092047.AA21342 at btv.ibm.com>
Well the Big Blue Contesters are pretty light in the CW department...anyone
want to take on a fair to mediocre op to contribute 10hrs of operation to
their score from Vermont?
--
73 de KK1L ex N1PBT...ron (rrossi at btv.ibm.com) <><
Ron Rossi H/P SRAM Engineering -- IBM Microelectronics
>From w2vjn at rosenet.net (George Cutsogeorge) Fri Jan 10 05:11:13 1997
From: w2vjn at rosenet.net (George Cutsogeorge) (George Cutsogeorge)
Date: Fri, 10 Jan 97 05:11:13 GMT
Subject: Ferrite beads, cheap.
Message-ID: <M.010997.211113.11 at ppp002.rosenet.net>
In catalog #98 from MECI, they listed 2 "split cores". Phone 800-344-4465.
PN380-0071 is 1.12 L x 1.12 OD x 0.53 ID, price = $0.45 ea in quantities of 10.
PN380-0072 is 1.13 L x 0.57 OD x 0.25 ID, price = $0.30 ea in quantities of 10.
Material is not specified.
I bought some of each and checked them out on the network analyzer. They
appear to be similar to type 43 material as they check out almost identical to
the previous tests on the expensive variety. They have a cylindrical shape and
are sawn in two. They are shipped in pairs, taped together and will give good
performance if held tightly together. Two small ty-wraps do a good job.
George
----
George Cutsogeorge, W2VJN
Umpqua, OR.
http://www.qth.com/topten
----
George Cutsogeorge, W2VJN
Umpqua, OR.
http://www.qth.com/topten
>From dave at egh.com (David Clemons) Thu Jan 9 21:18:45 1997
From: dave at egh.com (David Clemons) (David Clemons)
Date: Thu, 9 Jan 1997 16:18:45 -0500 (EST)
Subject: Need a NAQP Team Member?
Message-ID: <Pine.LNX.3.91.970109161640.17792A-100000 at newman.egh.com>
Hi,
If anyone is looking for one more member to fill out a team, I am
currently available on a first-come first-serve basis.
If interested, send e-mail to dave at egh.com.
73, Dave Clemons K1VUT
>From gswanson at arrl.org (Swanson, Glenn, KB1GW) Thu Jan 9 21:23:00 1997
From: gswanson at arrl.org (Swanson, Glenn, KB1GW) (Swanson, Glenn, KB1GW)
Date: Thu, 9 Jan 1997 16:23:00 -0500
Subject: FW: Final Summary - cap for inverted-L
Message-ID: <m0viS0b-0004ohC at mgate.arrl.org>
Greetings,
This is a cross-post from the (160 meter) or "TopBand" reflector.
Perhaps some contesters will enjoy the subject: I hope, anyway.
This is in regards to using a capacitor in series with the 50-ohm feedpoint
of a 'classic' (near 5/16-wavelength) inverted-L, which presents inductive
reactance at its feedpoint. (No need to reply--I have enough information!)
Think I'll try a length of coax as a capacitor for feeding the beast.
73, Glenn, KB1GW
----------
From: Swanson, Glenn, KB1GW
To: 'TopBand - postings'
Subject: TopBand: Final Summary - cap for inverted-L
Date: Thursday, January 09, 1997 12:30PM
----------------------------------------------------
Greetings inverted-L fans,
In regards to the 'proper' capacitor to use at the feedpoint
of a 'full-length' (say, 160 to170' long) inverted-L antenna:
Thank you for, and here is, the wisdom of the reflectorites:
Much appreciated,
73, Glenn, KB1GW
---------------------------------------------------------
My original posting:
>Okay, so I'm thinking about extending my 1/4-wavelength "inverted-L"
>out to 170 feet (+/-) and putting a (air-variable) capacitor at the
feedpoint. I know I'll need something like a 500 to 1000 pF cap.
>However, [at] what voltage rating?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Replies received--sans names and call signs:
"Since the cap is in series with a "current" point on the antenna. HV
ratting is not as important as current ratting. a 2KV cap should be
plenty. In fact If you can build a suitable enclosure then even Air
variables work quite well. I use a 150pf air variable shunted with
several of the old surplus 100pf transmitting micas (the brown ones abt
2" square). For example to 500pf TV style doorknobs wont work because
they cant handle the current (they get warm even with 100 watts) even
though they are rated 15kvto 20kv. At 1KW the current can be on the
order of almost 6 amps (more on peaks). If you plan on using the
antenna on other bands (say with a tuner) then be careful you can end up
at "voltage" node on another band and blow the caps!I that case the
vacuum variable is more likely a better bet. I have had the best luck
finding vacuum variables at HAM fests I have paid anywhere from $35 to
$80 for them.
PS: I have two L's in this configuration--fed in phase... good luck"
"My inverted L is abt 160' long (60' vertical). I used fixed+variable
caps to achieve a reasonable match. My fixed was a 500pf 5kv old bathtub
cap and I used a section of RG213 in parallel with it as my "variable" (you
can trim the length to achieve best match). My bathtub went bad
(heated/leaked) so I was left with abt 12' of RG213 alone (abt 20+ pf/ft).
The match is now abt 1.2:1 at 1840 and rises to 2.1:1 at 1800. 2:1 SWR BW
is just under 80kHz, which seems to indicate a reasonable ground (I have
abt 1500'of many short radials) and it seems to play!! I think RG213 is
good
for a few KV and is a lot cheaper than an air variable. Just a thought.
73 es Happy New Year"
"Something up to about 1000 V should do the trick. This is the same sort of
cap one would use as the output cap in a linear amplifier's pi-network.
Remember: P = E*E/R. If the series resistive part of the antenna's Zant is
approx 50 ohms, then for 1500 W, E = SQRT(1500*50) = 372.8 V rms = 387 V
peak. So, a 1000-V cap should do the trick. 73"
"I'm getting ready to put up an inverted-L here, and I'm thinking of
using a length of coax for the capacitor. It would be pretty long, about
30' ( ~30pf / ft for most coaxes) but cheap and no problem with the voltage
rating (2000 - 4000v, depending on the coax type). In the ARRL Handbook,
they say you need a 1500V variable cap for the 175' inv-L. Not easy to find,
or inexpensive. 73" [See posting above. --KB1GW]
"Glenn, I have an inverted L like you are shooting for (maybe a bit longer)
I use have used some old caps with large spacing but am currently using
the old Heathkit remotely tuned cap. It has rather small spacing but doesn't
arc even at 1400 watts. I am also using an inductor so I really have an
L network. I have also used coax as a cap. I would imagine some RG-8
would work with about 5000v rating. Old 5 kv ceramics can be used as
'padders' if you can not find a large value cap. Actually, I only use about
250 pf to tune mine. Good luck and CU on topband. 73"
How about a roll of coax to tune out the reactance of the inverted L.
I have used pieces of coax to tune antennas for years. The voltage
breakdown is high and it stands up to the environment better than bread
slicers, and is a good bit cheaper. Just trim it to the required length.
I cut the braid back on the end to increase the voltage breakdown.
Then coat it Q dope and/or electrical tape. RG 8/58 is about 30 pf
per foot. You can tune up with a variable and then replace it with a
cable cut by either measuring the variable or estimating the Cap.
If you want to tune different parts of the band, consider switching in
or out different or additional pieces of coax. I had a T antenna on
80 that was tuned with a 5 ft length of RG 8 taped to the bottom end
and running back up the antenna. The shield connected to the
antenna and the center conductor connected to the coax.
Hope this has helped give you a few ideas.
Good luck on topband. 73
[See "Table 1," page 24-17 in the ARRL Antenna Book (17th edition)
for characteristics of commonly used transmission lines. --KB1GW]
-(feedline ctr conductor)->(-coax 'x' pF per ft._)_shield of coax to ant_
"Remember that adding length to the inverted L will help, but most
important is that the vertical portion be as long as possible. All you'll be
doing by adding length to the horizontal portion is making a bigger cap.
hat. Good luck"
[And,]
"I've only been playing with verticals for a short while but have reading
lots of material, therefore, my suggestions are unfortunately not from
experience but theoretical.
An inverted L is really a short vertical with a capacitance hat. The hat
does two things. First, its size will dictate the reactance component at
the feedpoint. Second, it will improve antenna efficiency. By adding to
the horiz. length [of the 1/4-wavelength antenna], you'll be changing the
reactance (hence, necessitating a change in your current LC configuration)
but will slightly improve the antennas efficiency. If you can get the
vertical portion longer you'll then be improving the "low angle"
characteristics.
If you got the time, experiment with many options. Would love to hear
your results. I'll look for you during CQWW at months end. I currently
have a center loaded, 40 foot, vertical that seems to play OK, but it was
my first 160 vertical, so I don't have alot to compare to yet. 73"
>All you'll be doing by adding length to the horiz. portion is making a
bigger cap.<
Not completely true - by adding horizontal length *beyond a quarter-wave*,
the current maximum is moved "up" the vertical section. If the wire was
one-half wavelength long, for example, the current maximum would be at the
wire's midpoint. If the L is exactly one-quarter wavelength long, the
current point is at ground level. Raising the current maximum away from
the ground should reduce ground losses and improve low-angle radiation.
How far the current maximum should be raised depends on how long the
vertical section is. I would model the L with different horizontal
lengths and see how the pattern changes - expecting that adding length
would first improve low-angle radiation and then start to fill in the
high-angle pattern as more current begins to flow in the horizontal
section. I would also expect that there would be a fairly large range of
vertical/horizontal ratios for which the pattern changes very little. 73
-- eof --
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