Hello every one, i got a Gem Quad a 2 element and i will like to now
what it is the best way to feed the quad,with balun 2:1 or the 1/4 wave
75 ohm`s maching stub`s,also please what are the measurements for the
placement of the plastic tubing on the driver`s at the element`s,i now
that it changes with the feeding system.
Can we use a torroid for the driver`s if so what are the characteristics
of it.
TKS for any help.
73 de Rui.
>From aa7bg@initco.net (AA7BG Matt Trott) Fri Jun 21 04:41:33 1996
From: aa7bg@initco.net (AA7BG Matt Trott) (AA7BG Matt Trott)
Subject: Torque compensation??
Message-ID: <199606210341.VAA09435@zeus.initco.net>
Am I missing something or do these two authors seem to disagree somewhat on
the issue of mast torque compensation?
Leeson (PHYSICAL DESIGN OF YAGI ANTENNAS; p. 6-22):
It is possible to use a comination of element relocation,
element area variation, and compensation to achieve torque
compensation.
Devoldere (LOW-BAND DXING; p. 13-12):
The wind area of the elements and their placement on the
boom do NOT play any role in the mast torque.....
-------------
Brought to you by SPARE (Society for the Preservation of Antenna Rotating
Equipment)
----------------------------------------------------------------------
AA7BG aa7bg@3rivers.net Matt Trott
----------------------------------------------------------------------
>From 0005543629@mcimail.com (David & Barbara Leeson) Fri Jun 21 06:44:00 1996
From: 0005543629@mcimail.com (David & Barbara Leeson) (David & Barbara Leeson)
Subject: Torque comp.
Message-ID: <32960621054423/0005543629DC1EM@MCIMAIL.COM>
Matt, AA7BG, asks whether ON4UN and I disagree about antenna torques.
You're right, we don't agree 100% on this one. The question is how reliable
is a model of a complex aerodynamic situation. The standard for towers when
I wrote my book was EIA's RS-222-C, which was subsequently updated to 222-D
and 222-E. NI6W's YS software is based on "C" as well. "E" (and also ASCE
74) treats wind statistics and force on cylindrical elements more physically
than "C" and "D", and the difference shows up in the question of forces on
cylinders at an angle to the wind. This affects boom strength and rotating
torques.
K5IU pointed out that "E" is a more physically accurate model, and I agree.
"E" predicts no rotating torque from a symmetrical cylindrical element
mounted on a boom. This is true to first order, but then this doesn't
explain why Yagi's with symmetrical booms (Hy-Gain 205BA, for example)
weathervane. I believe ON4UN is following K5IU's point, but I would guess
John's statment refers to mathematical models, not physical antennas.
I was curious to try this with a poor man's wind tunnel experiment, putting
model Yagi's up into the wind through the sunroof of a moving car. Sure
enough, I was satisfied the "E" model is more accurate (makes more physical
sense, too). But there were still easily observed rotating torques not
predicted by the simple model. I've rewritten my own spreadsheets to use
"E", but the resulting antennas aren't much different (zero difference for
elements, some for booms unless you ignore vertical gusting and wind
vortices). If you read the standards carefully, you find that the
differences in wind gusting statistics and drag factors aren't any big deal,
although they are stated in quite different terms that seem at first glance
to be significant.
But we're not dealing with mathematical models when the wind is roaring
through here at 134 mi/h ("fastest mile of wind" measured last December, the
price of living on a mountain top). Either model results in booms that break
upward in the wind if you ignore vertical gusting. I've had better results
with antennas that are symmetrical (balanced) in both the boom and element
planes, while ON4UN designs for symmetry in the boom plane only. His wind
situation is less extreme, but he puts up physically bigger antennas.
I currently prefer to balance in the element plane by offsetting the element
ensemble to eliminate the need for a torque balancing element, then using a
vane on the now unbalanced boom. I use three-way boom guys. The towers and
antennas I put up after writing the book are still up and working (including
two with 50' booms), but even with two-plane balance the rotators have taken
a beating, and will be replaced with prop pitches.
The bottom line is (a) the model is not the thing and (b) you pays your
money and takes your pick.
73 de Dave, W6QHS
>From n4bp@shadow.net (Bob Patten) Fri Jun 21 07:04:50 1996
From: n4bp@shadow.net (Bob Patten) (Bob Patten)
Subject: Field Day & 10 meters
Message-ID: <Pine.SOL.3.91.960621020321.25470B-100000@hyper>
On Thu, 20 Jun 1996, Steven Nace KN5H wrote:
> 10 has been opening lately. From here (New Mexico) I can work W6, W7 & W0.
> Even heard East Coast guys with my R7. SO, pass the word to all the 10
> meter/Novice Field Day ops to check 10, especially after dark, for good
> openings.
I'll definitely be checking it frequently, and will be on it if it shows
any signs of life...
Bob Patten, N4BP
n4bp@shadow.net
>From merchant@silcom.com (Stephen F Merchant) Fri Jun 21 07:33:52 1996
From: merchant@silcom.com (Stephen F Merchant) (Stephen F Merchant)
Subject: New <Old> Callsign
Message-ID: <Pine.LNX.3.91.960620233112.8844A-100000@beach.silcom.com>
Please update your records to show N4TQO retired by W6EMS. Finally. And
where, dr. B., was Ben F. Waple when we needed him?
Steve W6EMS
merchant@silcom.com
>From w7ni@teleport.com (Stan Griffiths) Fri Jun 21 09:08:22 1996
From: w7ni@teleport.com (Stan Griffiths) (Stan Griffiths)
Subject: KV4AA contest
Message-ID: <199606210808.BAA26002@desiree.teleport.com>
>At 07:35 PM 6/16/96 -0400, W3LPL wrote:
>
>>Some of the seasoned veterans on the reflector may even recall the name of
>>the CONTEST magazine published by Wayne Green in the early 1960s...
>>(I'm sure K1VR remembers!)
>>
>Yes, but can you identify Hashafisti Scratchi?
>73, Pete Smith N4ZR
>n4zr@contesting.com
Yes, he lived in Feenix, Arizona. I remember him well . . .
Stan w7ni@teleport.com
>From w7ni@teleport.com (Stan Griffiths) Fri Jun 21 09:08:30 1996
From: w7ni@teleport.com (Stan Griffiths) (Stan Griffiths)
Subject: FW: Callsigns
Message-ID: <199606210808.BAA26052@desiree.teleport.com>
>Hi Bernie...I worked KZ5OJ on 160m a few hours before the Canal reverted to
>Panama control...then worked him just after as HP1XOJ, giving me TWO new
>ones in one night from the same station! That only happened on one other
>occasion for me ...anyone remember who the other one was?...(and OJ did QSL
>for both...KZ5 of course was quickly on the deleted list)...73/Jon AA1K>
Wasn't the other one Jim Neiger, N6TJ, when he was at KB6 (American Phoenix)
and VR1 (British Phoenix), same place, same shack, same time?
Stan w7ni@teleport.com
|