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Old 9th Sep 2020, 7:27 pm   #1
Leon Crampin
Octode
 
Join Date: Nov 2005
Location: Surrey, UK.
Posts: 1,869
Default Improving a stiff tuning drive - FB 10

In cheap sets such as the above, the tuning cord runs around fixed pegs rather than pulleys. In the FB 10, this gives rise to drive friction and hysteresis, making fine tuning difficult. On this set, the whole tuning carriage rocks as the set is tuned, due to friction around the pegs.

A fix is to wrap the pegs with PTFE tape. On the FB 10 it's the pegs at either end of the carriage which give rise to the most friction due to a large wrap angle. The tape need not be applied neatly - the cord will make its own groove in the tape which stops it unravelling.

The improvement in the drive feel and tuning accuracy is considerable, and the pointer now moves for small adjustments as it should.

Leon.
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