Heathkit SB100 User Manual (English)

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Optimizing the Heathkit HW-101,

SB100-102 Transceivers

he Heathkit HW/SB series of transceivers were very popular in the late 60's through

70's and are fairly plentiful on the used market even today, nearly 30 years later.

This series of modifications will increase the audio quality of both receive and transmit,

improve operation on CW, enhance strong signal handling of the rigs, and make the units

useable with the low-Z headphones so often used today. All of these changes require no

hole drilling or mechanical changes at all, and the rig can be easily restored to its original

configuration at anytime if desired. The text deals with the HW-101, but the changes are

applicable to the above mentioned SB-series as well.

Conversion to Low-Z Headphones:

These rigs are designed to be used with Hi-Z headphones, but if low-Z phones are used

the outboard speaker will not mute completely with the phones connected. To convert to

low-Z phones, make the following wiring changes referring to (Figure 1) of this

document, and pictorial 8-4 (foldout from page 53), and pictorial 8-5 (foldout from page

67) of the HW-101 manual:

1.) Remove the black wire from terminal strip BA lug 2 and reconnect it to lug 3

(ground).

2.) Remove the green wire and the 100Ω resistor from jack AB (speaker).

3.) Connect the green wire to terminal strip BA lug 2.

4.) Connect the 100Ω resistor removed in step 2 to lugs 2 and 3 of terminal strip BA.

5.) Remove the jumper wire from lugs 1 and 2 of headphone jack L.

6.) Run a NEW wire along the wiring harness from speaker jack AB lug 1 to the

headphone jack lug 2.

Now the external speaker should mute completely when low-Z phones are used.

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Heathkit SB100 Specifications

General