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Kenwood Optoisolator

wlgrant6

wlgrant6

AK Subscriber
Subscriber
Hello all you Kenwood folks. I have a Kenwood KR7070 which uses at least 3 of these devices. A couple in the multiplex section, and one in the auto-tune section. Of course the original device is no longer available, and this auto coupler looks like it might possibly work. Just wondering if anyone has tried this. I understand these Kenwood Optoisolators have a high failure rate in the old Kenwoods, and a couple of mine appear to have the internal lamp filaments open. Here is the pdf for the VTL5C9, a possible replacement
 

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wlgrant6 said:
a possible replacement
Click to expand...

Don't have relevant experience as to whether such a replacement would be functionally OK, but wanted to highlight that the contemporary part's light source is an LED instead of the original part's incandescent lamp. The implications are that there would be only one orientation of the LED's connections that will work (i.e., the LED must be forward biased), and that current through the LED must be limited to around 20 mA, perhaps with a resistor in series of around 390 ohms. The resistor's power rating should be 1/2 watt or more.
 
That whole muting system in that unit is very confusing. The isolator on the UA0106 board does appear to have polarity fron D9, D10, and Q11, but whether or not an LED would operate at the 0-9½V is in question. I sense there would be a little bench time involved in configuring the circuit to work, it it's even possible.
 
Thanks for your inputs. I knew it wouldn't be a "drop-in", but thought there might be a chance it was doable. And yes, the muting ckt is also not working, and know one of these units is bad. I ordered 5 of these optocouplers from China, for less than $9, and surprisingly got them in 11 days. Shipping must be getting better. I know these optoisolators are notoriously bad after all these years, and was hoping someone else had already explored this route, and wold have some coments on it. Bill
 
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