BIRD THRULINE 43 Series, Instruction Book

Page: 59 / 66

2. The line section has higher power capability and is larger,
being 1-5/8 inch in diameter instead of 15/16 inch as in
the Model 43, but this is not externally visible.
The Theory of Operation, and Maintenance Sections for the Model 43 are all
appropriate to the Model 4305A except for changes mentioned previously.
The Model 4305A Thruline Wattmeter does not have provisions for holding
spare elements in the sides of the housing.
Model 4305A Replacement Parts List
The following part numbers differ from those for the Model 43 Parts List.
Model 4330 Thruline Wattmeter
The Model 4330 is very similar to the Model 43 and all the instructions and
provisions apply except as outlined below:
1. The Model 4330 is a low power indicating device with
full scale direct reading levels of 200 and 800 milliwatts.
2. This model uses special 0.2 and 0.8 watt dual-range ele-
ments that cover frequency ranges from 60 to 2300 MHz.
Standard higher power elements must not be used with
the Model 4330.
With these low power type elements, the discrete frequency band widths are
considerably less than the usual 2.5:1 ratio for standard higher power
elements. These band widths (ratios) vary, but tend to be broad in the middle
frequencies of the overall range and becomes narrow at the ends. Likewise,
the relative response fall off beyond the stated bands will have to be
considered as somewhat greater than depicted on the 10W element curve.
Item Description Part Number
1 Housing assembly 4305A003
2 Cover assembly 4305A002
3 Line section assembly 4305-005
Maintenance
45