Bird Technologies 28-69-04A User Manual
Instruction Manual
Vari-Notch
Manual Part Number
YOU'RE HEARD, LOUD AND CLEAR.
® Duplexers (6” Cavities)
7-9177
8625 Industrial Parkway, Angola, NY 14006 Tel: 716-549-4700 Fax: 716-549-4772 sales@birdrf.com 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 7-9177
Copyright © 1997 TX RX Systems, Inc.
First Printing: September 1997
Version Number Version Date
1 09/19/97
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 operating at different
frequencies while connected to a common antenna. These duplexers are frequently used in radio repeater systems. This instruction manual
(part# 7-9177-1) covers the installation, tuning,
and maintenance of Vari-Notch duplexers constructed from 6.625" diameter cavities. Table 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.
Resonant cavity filters are the basic building
blocks of the system. Also important, are the interconnect cables between each filter which have cut
length's equivalent to either 1/4λ or 3/4λ 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 1/2λ of the
(or remaining) channels pass frequency.
other
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 on page 2 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 on page 3 is the
front view of a typical four-cavity Vari-Notch duplexer. Each of the physical components in the
system is labeled with the field adjustable parts
shown in emboldened italics.
Model
Number
28-13-01F 30-40 400 0.3 1.5 90 50
28-14-01F 38-50 400 0.3 1.5 90 50
28-28-02A/G 66-88 400 0.35 1.5 85 50
28-36-02A/G 132-150 400 0.5 1.5 85 50
28-36-11E/G 132-150 400 0.3 2.2 100 50
28-37-02A/G 144-174 400 0.5 1.5 85 50
28-37-11E/G 144-174 400 0.3 2.2 100 50
28-37-08G 144-174 400 0.24 3 100 50
28-65-01A 406-430 350 1.5 1.5 90 50
28-65-05A/G 406-430 350 0.7 2.2 100 50
28-70-01A 450-470 350 1.5 1.5 90 50
28-70-07A/G 450-470 350 0.7 2.2 100 50
28-69-01A 470-512 350 1.5 1.5 90 50
28-69-04A 470-512 350 0.7 2.2 100 50
TX RX Systems Inc. Manual 7-9177-1 09/19/97 Page 1
Frequency Range
(MHz)
Table 1: Vari-Notch Duplexer electrical specifications (for 6.625" diameter cavities).
Power
Rating
(Watts)
Min. Freq.
Separation
(MHz)
Insertion
Loss
(dB)
Isolation
(dB)
Per Chan. Bet Chan.
High
a
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
TYPICAL FOUR CAVITY VARI-NOTCH FILTER
Interconne ct C a b le
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
Figure 1: Block diagram of a typical four-cavity Vari-Notch Duplexer (6.625" diameter cavities).
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 damages 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.
INSTALLATION
Vari-Notch duplexers should be securely installed
in a dry, vibration-free environment. Attachment of
the cavity shells to a grounding bus is recommended in order to maximize lightning protection.
A lightning protection device placed in the antenna
feedline, preceding the duplexer, is also recommended. High quality double shielded coaxial cable terminated with quality connectors (N-type) are
recommended for connecting the transmitter and
receiver to the duplexer, and are available from
TX RX Systems Inc. It is also important to observe
the power handling ratings of cables in transmit
systems.
Mount the duplexer in it's permanent operating position using suitable hardware. Connect the two
transmitters (or transmitter/receiver) and the antenna feedline to the duplexer making sure to connect the correct equipment to the correct port.
Labels are affixed next to each port (port labels) to
help you make the right connections. In addition, a
specification tag will be found in a plastic bag attached to one of the tuning rods. The frequency
that each cavity group is tuned to will appear on
either the port labels or the specification tag. The
duplexer is now ready for normal operation. No
tuning is required if the frequencies (high frequency and low frequency) found on the port
labels/specification tag matches the actual operating frequencies.
MAINTENANCE
No special maintenance is required. Vari-Notch
duplexers are passive devices of rugged electrical
and mechanical design. They are tuned at the factory for the original design requirements and require no further adjustment or maintenance.
These devices will stay properly tuned unless they
have been physically damaged or are tampered
with. Check for loose or corroded connectors on
TX RX Systems Inc. Manual 7-9177-1 09/19/97 Page 2
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