Bird Technologies 28-88-04B User Manual

Instruction Manual

Vari-Notch

Manual Part Number

YOU'RE HEARD, LOUD AND CLEAR.

® Duplexers (4” Cavities)

7-9176

8625 Industrial Parkway, Angola, NY 14006 Tel: [phone] Fax: [phone] [e-mail] www.bird-technologies.com

Warranty

This warranty applies for one year from shipping date.

TX RX Systems Inc. warrants its products to be free from defect in material and workmanship at the time of shipment.

Our obligation under warranty is limited to replacement or repair, at our option, of any such products that shall have
been defective at the time of manufacture. TX RX Systems Inc. reserves the right to replace with merchandise of
equal performance although not identical in every way to that originally sold. TX RX Systems Inc. is not liable for dam-
age caused by lightning or other natural disasters. No product will be accepted for repair or replacement without our
prior written approval. The purchaser must prepay all shipping charges on returned products. TX RX Systems Inc.
shall in no event be liable for consequential damages, installation costs or expense of any nature resulting from the
purchase or use of products, whether or not they are used in accordance with instructions. This warranty is in lieu of all
other warranties, either expressed or implied, including any implied warranty or merchantability of fitness. No repre­sentative is authorized to assume for TX RX Systems Inc. any other liability or warranty than set forth above in con­nection with our products or services.

TERMS AND CONDITIONS OF SALE

PRICES AND TERMS:

Prices are FOB seller’s plant in Angola, NY domestic packaging only, and are subject to change without notice. Fed­eral, State and local sales or excise taxes are not included in prices. When Net 30 terms are applicable, payment is
due within 30 days of invoice date. All orders are subject to a $100.00 net minimum.

QUOTATIONS:

Only written quotations are valid.

ACCEPTANCE OF ORDERS:

Acceptance of orders is valid only when so acknowledged in writing by the seller.

SHIPPING:

Unless otherwise agreed at the time the order is placed, seller reserves the right to make partial shipments for which
payment shall be made in accordance with seller’s stated terms. Shipments are made with transportation charges col­lect unless otherwise specified by the buyer. Seller’s best judgement will be used in routing, except that buyer’s routing
is used where practicable. The seller is not responsible for selection of most economical or timeliest routing.

CLAIMS:

All claims for damage or loss in transit must be made promptly by the buyer against the carrier. All claims for shortages
must be made within 30 days after date of shipment of material from the seller’s plant.

SPECIFICATION CHANGES OR MODIFICATIONS:

All designs and specifications of seller’s products are subject to change without notice provided the changes or modifi­cations do not affect performance.

RETURN MATERIAL:

Product or material may be returned for credit only after written authorization from the seller, as to which seller shall
have sole discretion. In the event of such authorization, credit given shall not exceed 80 percent of the original pur­chase. In no case will Seller authorize return of material more than 90 days after shipment from Seller’s plant. Credit
for returned material is issued by the Seller only to the original purchaser.

ORDER CANCELLATION OR ALTERATION:

Cancellation or alteration of acknowledged orders by the buyer will be accepted only on terms that protect the seller
against loss.

NON WARRANTY REPAIRS AND RETURN WORK:

Consult seller’s plant for pricing. Buyer must prepay all transportation charges to seller’s plant. Standard shipping pol­icy set forth above shall apply with respect to return shipment from TX RX Systems Inc. to buyer.

DISCLAIMER

Product part numbering in photographs and drawings is accurate at time of printing. Part number labels on TX RX
products supersede part numbers given within this manual. Information is subject to change without notice.

Bird Technologies Group TX RX Systems Inc.

Manual Part Number 7-9176

Copyright © 2004 TX RX Systems, Inc.

First Printing: September 1997

Version Number Version Date

1 09/19/97

2 04/09/98

3 04/26/99

4 06/23/04

Symbols Commonly Used

WARNING

CAUTION or ATTENTION

High Voltage

Use Safety Glasses

ESD Elecrostatic Discharge

Hot Surface

Electrical Shock Hazard

NOTE

Important Information

Bird Technologies Group TX RX Systems Inc.

GENERAL DESCRIPTION

Vari-Notch® duplexers are used to provide simulta­neous operation of a transmitter and receiver (or
two transmitters) which are at different frequencies
while connected to a common antenna. These
duplexers are frequently used in radio repeater
systems. This instruction manual (part# 7-9176-1)
covers the installation, tuning, and maintenance of
Vari-Notch duplexers constructed from 4” diameter
cavities.

Tabl e 1

shows the model numbers and
electrical specifications of the duplexers covered by
this manual. Vari-Notch duplexers are composed of
two groups (or sets) of daisy-chained resonant cav­ity filters, which couple signals to and from the
shared antenna. This creates two signal paths, a

high frequency channel and a low frequency chan­nel. The minimum frequency separation between
the channels, as well as the isolation in dB’s (per
channel and between channels) is listed for each
model in table 1.

The cavity filters used in a transmit channel will
reduce transmitter noise components at the
receive frequency, thus preventing noise desensiti­zation of the receiver. Conversely, the cavity filters
used in a receive channel will isolate the receiver
from the transmitter carrier preventing carrier
desensitization of the receiver.

Model

Number

28-38-03A/D 132 - 174 150 0.5 1.9 80 45

28-37-07A/C 144 - 174 400 3 0.7 85 30

28-37-06A/C 144 - 174 125 1 1.2 75 35

28-37-04A/C 144 - 174 125 0.5 1.8 65 30

28-37-81227-A-R2 144 - 174 125 0.5 2 65 30

28-52-02A 215 - 250 250 1.6 1.2 90 55

28-56C-02A 380 - 420 250 5 0.7 100 50

28-65-07A/B 406 - 430 250 3 1.25 85 60

28-65-02A/B 406 - 430 350 3 0.8 80 30

28-66-02A/B 442 - 450 350 5 0.6 100 46

28-70-09A/B 450 - 470 250 5 1.25 100 70

28-70-02A/B 450 - 470 350 5 0.6 100 46

28-69-06A/B 470 - 512 250 3 1.25 86 60

28-69-02A/B 470 - 512 350 3 0.8 80 30

Frequency

Range

(MHz)

Power

Rating

(Watts)

Min. Freq.

Separation

(MHz)

Insertion

Loss

(dB)

Isolation

(dB)

Per Chan. Bet Chan

28-89-01A/B 806 - 866 125 45 0.8 90 60

28-88-04A/B 890 - 960 125 39 0.8 90 50

28-88-01A/B 890 - 960 125 3.6 1.25 90 40

28-97-01A/B 1215 - 1300 125 12 1 100 50

Tabl e 1 :

TXRX Systems Inc. Manual 7-9176-4 06/23/04 Page 1

Vari-Notch Duplexer electrical specifications.

Resonant cavity filters are the basic building blocks

a

of the system. Also important, are the interconnect
cables between each filter which have cut length's
equivalent to either 1/4 λ or 3/4 λ of that channels
pass frequency. The exception is the antenna cable
that couples each channels final filter to the
antenna port, which is cut to 1/2 λ of the other

(or

remaining) channels pass frequency. This effec­tively places a relatively large impedance in parallel
with the antenna, insuring a good impedance
match between the other

(or remaining) channel
and the antenna. This technique of impedance
matching allows both channels to be connected to
the same antenna with very little loss due to mis­matching. The antenna cables are permanently
soldered and crimped to the antenna junction. The
combination of the antenna junction and the
attached antenna cables is referred to as an
"Antenna Junction Assembly".

Figure 1

shows the functional block diagram of a
typical four-cavity Vari-Notch duplexer system. Six
and eight cavity systems are similar except for the

extra filters in each channel. The photograph
shown in

Figure 2

is the front view of a typical four­cavity Vari-Notch duplexer. Each of the physical
components in the system is labeled with the field
adjustable parts shown in emboldened italics.

UNPACKING

Care should be used when removing the duplexer
from it's shipping container to avoid unnecessary
damage. It is important to visually inspect the
duplexer for any shipping damage as soon as pos­sible after taking delivery. It is the customers

responsibility to file any necessary damage claims
with the carrier.

Vari-Notch duplexers are rugged devices but may
become detuned if jostled or dented during ship­ping. The most easily damaged parts of the
duplexer are the tuning rods. These rods are
marked where they exit from the locking nut with a
dab of red varnish or other color/type of paint. If
this seal appears to be broken it may indicate that
the system has been detuned in transit.

High
Frequency
Equipment

Low
Frequency
Equipment

RG214 or RG142
Double-Shielded Cable
(Supplied by customer)

Rejection notch tuned to low frequency

Rejection notch tuned to high frequency

Interconnect Cable

λ

or 3/4 λ of this)

(1/4
(channels pass freq.)

Vari-

Notch

Filter

Passband tuned to high frequency

Vari-

Notch

Filter

Passband tuned to low frequency

Vari-

Notch

Filter

Vari-

Notch

Filter

Antenna Cable

(1/2 λ of the other)

(channels pass freq.)

Antenna
Junction

To
Antenn

TYPICAL FOUR CAVITY VARI-NOTCH FILTER

Figure 1:

TXRX Systems Inc. Manual 7-9176-4 06/23/04 Page 2

Block diagram of typical four-cavity Vari-Notch Duplexers.