Hi Dave and many thanks for your (ground breaking for me!) information. Yes my FT 290 IS a very early model. G0MIX has also confirmed this with me and sent useful pics of the location of that cap.
Kind regards
Peter G0LQU
Dave Thompson wrote:
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Sounds like the small variable cap in the VCV. Use a non metal adjustment tool and see if you can get the audio working. First test LSB and compare to USB.
If there is a big differece then the VCV cap needs to be adjusted. This was a major problem in early FT-980's. My first was bought new in 1983 and later models have a better ceramic variable cap. Everything else looks OK. Good luck.
73 Dave K4JRB
-----Original Message-----
From: <[email protected]>
Sent: Oct 7, 2022 1:35 PM
To: <[email protected]>
Subject: [Yaesu-FT-980] Untunable SSB, CW. but AM is OK
By fiddling with the I.F. width control I can "almost" resolve speeech on SSB but clearly something is wrong, with my money on a drifted oscillator.
I did check the Master Oscillator (30 MHz) and this was slightly low so I corrected this. I then checked the tripler output for 90MHz and it wasn't there - but 30 MHz was!
I thought maybe the 30MHz was bleeding through a weak 90 MHz but cant check this at the mo. as my 100MHz scope has packed up.
I read Mat's description of his similar fault and cure but was not sure of the location/part number of the trimmer cap he mentioned and ultimately replaced. I did locate the transformer he replaced but I havn't check mine yet.
So my question is (mainly for Mat?) "Can you state where I can find that variable cap you replaced? You mention "two tin cans" and I wondered if this was in the VCO enclosure (how do you get the lid off?!!) or is it on the VFO board. Can't quite place you photo.
Kind regards
Peter G0LQU
