Hello Matt,
I'm a bit curious why you may need the
ICOMs IC-735 Optical Tuning Encoder? Although I do not own a IC-735, I do own a IC-251A 2 meter and a IC551D 6 meter units which both have Optical Tuning Encoders. I went back to my ICOM IC-551D Service Shop Manual and did some reading on the Tuning circuit. The key components are a pair of infrared diodes D1 & D2 and a pair of photo transistors Q1 & Q2 which perform the
Up / Down VFO functions and the Clock
CK Pulse
90 degrees out of phase which feeds
IC1, IC2, IC3 & IC4 and the into the microprocessor IC.
Of course the diodes and transistors feed and receive the infrared light with the use of an Encoder Disc to produce the pulses and waveforms through the integrated circuits. The infrared diodes D1 & D2 are
TLR121 and the photo transistors Q1 & Q2 are
TPS606. Apparently the ICOM engineering team must have felt that none of their mechanical parts would ever fail because they do
not provide any parts lists for these components!
If your Encoder Disc is damaged or broken .... I suppose you would need to contact ICOM Spain:
[email protected] or a local authorized ICOM Amateur Radio Dealer / Repair Center.
For the semiconductors, try the
NTE On-Line Cross Reference web page:
http://www.nteinc.com/
Dan