HEATHKIT hw-101 sb-100 101 102 transceiver optimization sm free download

File name heathkit_hw-101_sb-100_101_102_transceiver_optimization_sm.pdf

Optimizing the Heathkit HW-101, SB100-102 Transceivers T 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 100 resistor from jack AB (speaker). 3.) Connect the green wire to terminal strip BA lug 2. 4.) Connect the 100 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. 1 Downloaded from www.Manualslib.com manuals search engine Figure 1 Improved CW Operation: In the CW mode the rig's relays are energized by the CW sidetone amplifier's sidetone output driving the vox relay amplifier. The audio (sidetone) drive to the vox amp is a bit on the low side for fast relay action, and at speeds approaching 20 wpm the first dot sent is heard in the sidetone but isn't transmitted due to the slow relay response time. Correcting