1W UHF AMPLIFIER ASSEMBLY
PUB99-92 rev 1: June 19, 2000
92-12
1
W UHF Amplifier
Resistors:
Experience has shown that a spares stock to the 5% spares level (1 spare for each 20 of the
same thing, and 1 of each when less than 20) for each value and size of resistor, is usually sufficient.
Incidentally, when a molded carbon composition resistor (as specified on LARCAN drawings 3R152,
3R77, 3R78, or 3R79) such as those made by Ohmite
™
or Allen-Bradley
™
, is used in an RF circuit, it is
not necessarily good practice to make substitution without knowing exactly what the replacement resistor
is; in the past, certain makes of FILM resistors have been touted as replacements for molded composition,
but unless the resistors are specifically made to be non-inductive, they may be unsuitable because some
film resistors are laser-trimmed on a lathe to final value. The resulting helix has significant inductance
which can make the resistor unsatisfactory for use in VHF circuits.
It is worth the trouble to know exactly what is inside your replacement components. Use an RF bridge if
available, to measure any stray inductance and/or capacitance associated with your replacement
resistors.
Spare Parts:
The list on the following pages began as computer output listings "STS10B, STS50B, etc."
from our database used to compile the parts list data for each Section of the manual, and the computer
has classified recommended spare parts and suggested their quantities, by part number. Because the
manual is written to apply to the entire low powered basic series of transmitters, we have made a
composite suggested spares list by simply combining the computer's Low Band and High Band
recommendations.
We suggest that the parts lists in each Section booklet comprising the manual should be thoroughly and
rigorously scrutinized, with the intention of taking your specific local conditions, and your usual dealers or
suppliers inventories and order turnaround times into account, before commitment to a sizable inventory of
replacement parts.
7.1.3
SPARE PARTS RECOMMENDATIONS:
Although it is our sincere hope that they will never be found necessary, it is recommended that a minimum
spares stock of the following items be kept on hand.
Assembly
No.
Description
40D2180G3
1W UHF AMPLIFIER
------------------------------------------------------------------------------------------------
Where used
Part No.
Description
Quantity
40D2180G3
MDL-1
FUSE 1A, 250VAC, SLOW BLOW
2 EA
21B1324G2
MRF 181
TRANSISTOR RF POWER FET
1 EA
10A1453G7
MHW9182
IC AMP
1 EA
