Wednesday, June 6, 2012

FT-817 Instability on 144MHz

I bought my FT-817 shortly after it was launched. It was supplied with a ferrite choke from Yaesu  to fix on the DC power lead to solve instability on 440MHz. This worked fine but I have noticed that mine has a tendency to produce full output on 144MHz when switched to SSB and not speaking suggesting PA instability.

Today I did a search on "FT-817 Instability" and came across a post by KC3VO from 2003 describing a modification to stabilise the FT-817 PA. It looked easy to implement as it basically involved swapping over the centre and braid wires of the input coax to the FT-817 PA module. Ten minutes later the mod was done. Testing it out I could not provoke the same reaction on 144MHz. Problem solved!

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