Telex hy-gain 25FM User manual

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TELEX COMMUNICATIONS INC.
'9600 Aldridl Ave. So .• Miooeapolis. MN 55420 U.S. A.
ORDER NO. 205S-1
Model25FM
.5-Element, 2·MeterBeam PN801313-2
INSTRUCTION MANUAL I
General Description
This antenna is a 5-element, 2-rneter beam op-
timum spaced on a 7Y boom. It featui, s high
forward gain and an excellent front-to-back ratio.
The antenna is end mounted giving it the ad-
vantage
of no mast decoupling and a broad
frequency response. Thi antenna now u~ tain-
less steel hardware in most locations except for
the U-bolts. Also, this antenna now features a
NEW boom-to-mast bracket that fits up
to a mast
diameter
of 2 1/16 inches.
SWR and Fe •edline
The 25FM antenna has an input impedance of
200 ohms. The supplied balun matches the input
to 50 ohms. If you are using transmission line
with a characteristic impedance other than 50
ohms or 200 ohms., a match'ng device must be
made. Refer to any current Amateur Handbook
for information on constructing a matt:hing
d-vice.
}"f !iij!l!i!~~l!!liiij!l!l~ SpecificatiQns .. . .. .. .
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A0 - oeo 11 -c-001
2 7 8 9
\ \ \
Item
No. Description
2
Tub e, Driven Element, aluminum, 7/16"x1 71/ 4"
6 Tube, Rl , aluminum, 3/16"x 39 5 /8"
7 Tube, D1, aluminum, 3/16"x 36 7/ 8"
8 Tube ,D2,aluminum, 3/16"x353/4"
9 Tub e, D3, aluminum, 3/16"x 35 3/8"
BETA ROD
D3
D2 D1
DE
R I
11
18J 1
~. _ __ 20
14 "
__ ___. ...___ __ 15
1
12" _ I 91 14" J 3'1.' '~ _ _ 16
318" - -
--"• l• ,.__ Blt 2" I
(4. 76cm) (51.43c m) (39. 37 cm) -+7 23 .49 c m) (8 . 25cm) (4 1 59 cm) (21.5 9 c ;;;r\
75 " BO OM
Figure 1
Overall
View and Boom Detail
Tuning
NOTE: The Driven and Parasitic Elements are
adjusted independently in the following manner:
Parasitic Elements: This antenna is pretuned
for maximum gain and best radiation pattern
at
146 MHz . This setting will give optimum
performance over the entire 144-148
MHz
band.
If you wish to optimize the antenna for a
frequency higherthan
146 MHz, cut 1/4" off of
thetotalelementlengthsfor each MHzhigher
than 146.
-2-
Driven Element: SWR can be lowered to less
than 1.2:1
at a desired frequency by carefully
trimming the driven element. Keep The
element symmetrical
by cutting the same
amount from each side. Typical SWR curves
are shown inFigure 2A, and a cutting chart is
shown in Figure 2B. Each installation is
slightly different, so cutthedriven element for
the lowest SWR at your particular location.
Measure the SWR as close to the antenna as
youcanfor accurate results.

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Z,2
z.o
,..
,..
1. 4
1.2
,.o
m ITT ~ - ~ - ~ ~ ~ 00 ~
t ◄ 4 IIIIHI ----- -- fr•---~ M WHt
l ◄ I MHt
MIWH,1- •-·-
Figure2A
VSWR forBothVertical
and Horizontal Polarization
Stacking
This antenna can be easily stacked for ap-
proximately 3
dB more gain each time the
number
of yagi is doubled. Refer to Figure3 for
stacking
and phasing harness cutting informa-
tion.
AO· A-0205 •A- 006
.....
r--
~ 17
~
r--
c
.,
E
.,
.;
..... .....
-
.i 161 /z
i,
--
0
.c
O>
~ 16
144
145 146
147 148
Frequency in MHz
Figure2B
Driven Element Cutting Chart
The two phasing lines coming from the two an-
tennas
to the 'T' connector can be any odd
multiple
of 1/4 wavelength in the 75 ohm trans-
missionline. SeeFigure4.
NOTE: When phasing two antennas, the Driven
Element halves that are connected directly to the
phasing lines should
be on the same side of th e
array.
A0·0205·C - 002
Figure3
StackingTwo (2) Antennas
-3-

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The feedline impedance is for 50 ohms (RG-
213/U). For detailed information on stacking
more than two yagis, please consult a current
Amateur Handbook.
~ ~
PLUG
END
6
NOTE: The boom-to-mast bracket may be
placed between the Driven Element and D1
whenstacking two antennas.
2
A0-0203-A - 006
ANTENNA
END
- ------ - 67° -- ---- - -~
RG - 11 /U OR ANY 75-0HM COAX
5/4
A. = 67"
3/4
A. =40"
7
/4,\=93
1
/2
11
% A. =120
11
Figure4
Phasing Line Cutting Dimensions
Installation
This antenna fits a 2" mast. A 2" O.D. pipe is
recommendedfor a sturdy mast.
Mountthe antenna inthe clear. Surrounding ob-
jects-particuJarlypower lines and otherobjects
of considerable mass or length- aredetrimental
to theperformance
of the antenna.
WARNING
Do not allow any part of the antenna to
touch power lines. This could cause
severe burns
or fatal injuries.
When mounting two dissimilar antennas on the
same mast,
be sure they are separated by at least
three feet
(1 m).
-4-
The antenna can be mounted eithervertically or
horizontallyfor
FM or SSB/CW respectively.
Circular polarization can
be obtained by using
two yagis.
For information aboutwhich polariza-
tion
is best, consult local Amateurs who use the
frequencies you desire.
Step-by-StepAssembly
Remove the parts from the carton and check
themagainst the parts list and the illustrations.
Select the boom-to-mastbackup plate (ItemNo.
5),
the boom-to-mast clamp (ItemNo. 4) and the
four (4) 1/4"-20x
3/4" bolts, lockwashers andnuts
(ItemNos. 16,
26, and 23).

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23 21 26 24
11/J. .
-<t- .
...,.,. . .. . __ ~
,,,.. - - ~ 'I!'" ·
13-~ --.-- --~ -·-- , .____
_____ ,.
~:-
Item
No.
1
4
5
13
15
5
Description
Tube, Boom, aluminum, 11/4" x 75"
Clamp, Boom-to-Mast
Backup Plate, Boom-to-Mast
Caplug, 11/4"
U- Bolt, 5/16"-18 x 3 5/8"
'
I
I I
I I
SEE DETAIL A
~---
Item
No.
16
21
23
24
26
Description
Bolt, hex head, 1/4"-20x 3/4 "
Nut , hex, 5/16''-18
Nut, hex, 1/4"-20
Lockwasher, split,5/16"
Lockwasher, internal, 1/4 "
Figure5
Boom-to-Mast
Clamp Assembly
I
I
I I
II
A0 ·0 205·A·007
Item
No. Description
A0 · 0205· B-009
15
11
3/
11
ELEMENT
U/ 16
1 Tube, Boom, aluminum, 11/4" x 75 "
• //
I I
18 Eyebolt, 5/16", #10-24 x 11/2"
22 Nut, hex, #10-24
25 Lockwasher, internal, #10
27 Half - Washer, aluminum
Figure 5 -DetailA
ParasiticElementAttachment
-5-

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Item
No.
3
10
11
12
14
--
TAPE ( 3 PLACES)--_J
Description
BetaRod,3"
Balun Assembly
Insulator (Driven Element-to-Boom)
Beta Clip
Caplug, 7/16"
A0-0205-8-008
~14
~DRIVEN ELEMENT
3
BRAID
Item
No. Description
17 Bolt, hexhead, #10-24x21/2"
19 Bolt, hexhead, #10-24x11/2"
22 Nut, hex, #10-24
25 Lockwasher, internal,
#10
Figure5-Detail B
Driven Element, Beta Match and BalunAssembly
Place the boom-to-mast clamp on the boom as
shown
in Figure 5. Use the l/4"-20x 3/4" bolts in
the outside holes. Leave the inside holes for the
two U-bolts, which will
be used laterfor mount-
ing the mast. Select either the vertical
or
horizontal mounting position. Adjust the boom
accordingly before tightening the bolts securely.
Select the 3/16" x 39 5/8"
Rl tube (Item No. 6),
use penciltoplacea mark at thecenter of therod
(19 13/16" from either end) and place two more
marks 5/
8" from eachside of the ce nte r mark.
-6-
Placea #10-24x 11/2"eyebolt (ItemNo. 18) into
the
Rl slot as shown in Figure 5, Detail A Slide
the
Rl through the holes and the eyebolt until
theoutertwomarks
on the Rl arevisible on each
side
of the boom. Slip on an aluminum half
washer, a lockwasher and a
#10 nut (ItemNos.
27,25, and22).Tighten
it justenough to holdthe
rodsecurely.
DO NOT OVER TIGHTEN.

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Select the element-to-boom insulator (Item No.
11), two sections of the Driven Element (7/16" x
17 1/4") tubing (Item No. 2) and beta rod (Item
No. 3).
NOTE: If 50 ohm coaxialcableisusedtofeed the
antenna, se lect the supplied balun at this time.
Use
the #10-24x 21/2"bolt (ItemNo. 17) to fas-
ten the element-to-boominsulator to the boom.
Refer to Figure5, DetailB.
Use the two (2) #10-24x 11/4"bolts (Item No.
19) to assemble
the DrivenElementas shown in
Figure 5, Detail B. Payparticularattention to the
connections of the beta rod, balunand feedline.
Waterproof
the connection with neoprene,
Krylon®,
or somesimilarsubstance.
Install caplugs
on the ends of the boom and the
DrivenElement.
Kiylon® isa registered trademarlt of Borden Chemical Co.
-7-
Use the # 10x 3/8" screw (Item No. 20) to fasten
the beta rod shorting clip over the beta rod, as
shown in Figure 5, DetailB.
Select the following rods: Dl (367/8" long) (Item
No. 7),
D2 (353/4
11
long) (ItemNo. 8) andD3 (35
3/8" long)
(Item No.9). Mark the centerpoint on
each rod, then make two more marks 5/8" on
either side of the center mark. Secure the ele-
ments to
the boom as shown in Figure l and
Figure
5, Detail A. Be sure they are oriented as
shown.
Slip
the two (2) U-bolts into the boom-to-mast
bracket and fasten
it to the mast securely. Tape
the coaxfeedline to the boom andto the mast. Be
sure to insulate any connections from the boom
or the mast.This completesyour installation.

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PARTS LIST
Item
No. Part No. Description Qty
1 170386 Tube, Boom, aluminum, 1 1/4" x 75".................................................1
2 175157
Tube, Driven Element, aluminum, 7/16" x 171/4" ..........................2
. 3 160040
Beta Rod, 3" ....................... .. ................................................................1
J 4 385142-1
Clamp, Boom-to-Mast ............................................ .. ..........................l
~ 5 385144-1
Backup Plate,Boom-to-Mast............................................................1
: 6 160036
Tube, Rl , aluminum, 3/16"x 39 5/8"...................................... .. .........1
,. 7 160016
Tube, Dl, aluminum, 3/16"x 36 7/8".................................................1
't 8 160019
Tube, D2, aluminum, 3/16"x 35 3/4".................................................1
• 9 160021
)o
871704 .
;11 465420
Tube, D3, aluminum, 3/16"x 35 3/8".................................................1
Balun Assembly............. .. ....................................................................1
Insulator (Driven Element-to-Boom) ..............................................1
;-
872073-1 Parts Pack 205S-1, Stainless Steel .....................................................1
l2
163266 Beta Clip................................................................ .. ........... .. .............1
.,13 455630 Caplug,
11/4" ........................ .. ..........................................................2
14 475639 Caplug, 7/16" ...................................................................
.. ................2
15 540067 U-Bolt, 5/16"-18x 35/8"..................................................................2
16 505266 Bolt,
hex head, 1/4"-20x 3/4
11
.. . .... ............................... ........... ......... 4
17
500164
.
is 540065
i9 500159
Bolt , hex head, # 10-24x 2 1/2".................................................. .... .1
Eyebolt,5/16",
#10-24 x 11/2" ........................................................4
Bolt, hex head, # 10-24x 11/2" .......................................................2
zo
510670 Screw,
pan head, Type A, # 10x 3/8" ... .... ......................................1
21 555747
Nut, hex, 5/16"-18 .............................................................................4
22 554071
Nut, hex, #10-24 .............................................................................11
23 554099
Nut, hex, 1/4"-20...............................................................................4
24 564792 I..ockwasher, split, 5/16"...................................................................4
25 565697 I..ockwasher, internal,
#10 ............................................................ 12
26 562961 I..ockwasher, internal, 1/4"...............................................................5
27 170376
Half Washer, aluminum ..................................................................4
CoµvertingAmerican Measurements
to Metric 1 inch (l") = 2.54
cm
1 foot (1') = 30 .48 cm
Use this scale to identify lengths of bolts,
diameters of tubes, etc .. The American inch (1")
andJoot (1') can be converted to centimeters in
tliliway.
U.S.A.
Example:
42" x 2.54 = 106.7
cm
0 1 2 3 4 5 6
111,1 l ~,J,~11 ~1!1 ~hi 111 ,,, 1,,,1~ !I ,1t1~1l '11 ii,, 1,+11I 1j,1l,1l,1!111,,1111 l,1 ,,,l,,, ,,,,\ I\ l,1~1,I ~l!~I IAf ,11! 11 ,I
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
METRIC
PRINTED IN U.S.A.
Cop yrightC 1993 by Telex
TELEX COMMUN ICATIONS, INC .
All rights reserved.
I Sept 199 3 -8-