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Posted by: John / KD6JUH Posted On: 03/05/01 Subject: FT-817 to PK-12 Problem Message Posted: I had an interesting experience this weekend trying to connect my FT-817 to my PK-12 TNC. Every time I connected the interface cable between the radio and the TNC, the audio on my FT-817 would go away. A quick check of the various signals on the cable with a scope verified that I had built the cable correctly and that the FT-817 was putting out all the right signals. I know the TNC is good 'cause I used it earlier that day with another radio. So, what gives? My first clue was that the whole system worked fine when I put my MFJ1278 in place of the PK-12. "Aha!" (I said). "The input impedence for the audio lines on the PK-12 is low, 'cause they expect audio from the low Z speaker line." So, I pulled the schematic on the PK-12 and, as near as I can tell, the input Z is about 50K ohms. The output Z of the FT-817 is spec'ed at 10K ohms - should work just fine, but it doesn't. e-mail to AEA is pending, but I'm not expecting too much. Anyone got any other ideas? |
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