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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 23rd Sep 2020, 11:48 pm   #1
kostas_sv3ora
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Default Yaesu FT-301S restoration, knob problem

Hi, I restore a Yaesu FT-301S transceiver (the one with the analogue dial).
It works fine but the main tuning knob is not smooth and velvet to the turning as it should (I have used other ft-301s too and I know that).

When you turn the main tuning knob you can feel the gears on your finger.

Because of this, when you remove your finger from the knob, many times, the knob steps back or forth a bit by itself, so as to find the next "stable" point in the gear and stay there.
It has quite a few gears inside, two of them double anti-backlash, but before I take a photo I would like to ask, does anyone have experienced this effect in other or this radio, and how did you solve it? I do not know which part of the gear causes this and I have to first find out without ruining the radio.
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Old 24th Sep 2020, 1:33 am   #2
Damien VK3RX
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Default Re: Yaesu FT-301S restoration, knob problem

I had that problem when I bought a well used FT225RD.

The teeth on the gears were worn, I also felt it when dialing, and it would jump in frequency at times when it slipped a tooth.

My solution was to remove the knob and insert a felt gasket, which provided some resistance when tuning and it stopped the frequency jump issue. The trick is to find the right thickness to do the job without making it tedious to tune around.
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Old 24th Sep 2020, 9:03 am   #3
kostas_sv3ora
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Default Re: Yaesu FT-301S restoration, knob problem

Hm...
I cannot notice any serious visual wear in the teeth of the gears, so I do not believe it is that severe as in your case.
If there is bearing inside the main shaft of the tuning knob, it could be from the balls inside this though. I remember once I had the same feeling on the touch, with a capacitor with a bearing shaft. It was like the balls were not placed or rotated nicely inside the bearing. I did not bother to fix this in this capacitor though.

I cannot notice any severe wearing on the gears, that is why I suspect the bearing. Also, I sense this even with tiny movements of the knob. Because of the reduction, the teeth of the gears barely move on tiny knob shaft movements. But I can still feel this. The thing that moves faster is the bearing of the knob shaft, that is why I suspect this.

What do you think?
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Old 24th Sep 2020, 5:55 pm   #4
G6Tanuki
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Default Re: Yaesu FT-301S restoration, knob problem

I don't know the particular radio but quite a few Yaesus from that era used a now-obsolete Jackson Bros. slow-motion drive with a 6mm diameter drive-spindle, which suffered over the years with wear that made tuning imprecise.

The 'quick' answer was to swap the VFO-tuning reduction-drive and the PA-tuning reduction-drive, which were identical - the idea being that you don't exactly need precision tuning on the PA side.
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