a.3.6. SB-102 vs. HW-101
What's the difference between an HW-101 and an SB-102? Well, first off, the obvious is
the physical appearance (front panel and both top and bottom covers).
The HW-101 can only be used with the internal LMO where the SB-102 can use both
internal and external LMOs by the flick of a front panel switch. There are differences
between the SB-100 and SB-101 LMOs themselves and the power source wiring when
compared to the SB-102 LMO and the power source and wiring for the SB-102 LMO.
The HW-101 cannot be operated crystal control where the SB-100/101/102 can. There
is a single crystal socket in the SB-100, SB-101, and SB-102 bandpass board that
accepts a single crystal in the frequency range of the LMO (5.000Mhz to 5.500Mhz) that
allows for crystal control receive and/or transmit depending on the front panel's FREQ
CONTROL setting.
The LMO tuning assembly is entirely different in the HW-101 and the SB-100, 101, and
102. The SB-100/101/102 dials, tuning assembly, and escutcheons cannot be
interchanged with the HW-101 and vice verse. However, the dial assembly in the SB-
100 can be directly interchanged with the SB-102 and vice verse. The SB line of dial
assemblies in the SB line of transmitters, transceivers, and receivers were all the same.
The LMOs are different between the SB-102 and the HW-101. The LMO in the HW-101
is built buy the kit builder where the LMO in the SB-100 and SB-101 were built by TRW.
TRW did not build the LMO for the SB-102. The LMO in the SB-102 is the same LMO
as in the SB-303 ham band only receiver and the SB-313 SWL band receiver. The solid
state LMO is rather accurate at the 100Khz dial settings but not so between 100Khz dial
settings.
The SB-102 has a headphone volume control that the HW-101 does not have. The SB-
100 has a "600 ohm" output socket on the rear where the SB-101 does not. The only
difference between the 2 is the 600 ohm socket on the rear. The rest of the circuit's the
same.
The SB-102 has a CW sidetone volume control on the right rear audio board the HW-
101 does not have. You can modify the HW-101 to have this feature as the audio
boards in all of the HW-100, HW-101, and SB-100, 101, and 102, are the same. Simply
duplicate the circuit in the HW-101 from the SB-100, 101, and 102 schematic.
There are numerous other circuit changes/differences that can be seen by comparing
the two schematics.
HW & SB History revised 12/17/2021 Page 19
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