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Author Topic: T4XB Bandswitch  (Read 7374 times)

K3UOD

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T4XB Bandswitch
« on: February 12, 2001, 04:19:43 PM »

I have a Drake T-4XB with a stiff bandswitch.  

I sprayed it with tuner cleaner and it got worse.  I e-mailed Drake about it and they said that spray tuner cleaner makes the phenolic wafers swell up and get tight. They recommended cleaning the wafers with wood alcohol and a soft brush.  I couldn't find any wood alcohol, so I tried ethanol.  That made it better, but it's still stiff.

Any tips?

The rig works great, by the way, just want to solve the stiff switch problem.

73, Jerry
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WB2WIK

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T4XB Bandswitch
« Reply #1 on: February 13, 2001, 10:58:49 AM »

Prior to cleaning switch wafer contacts, which are rarely the cause of "stiffness," it would have been wiser to clean and lubricate the panel bearing and the switch position bearing mechanism.  Those are metal parts and get stiff from dirt building up and eroding the lubrication.  Now that the hydroscopic wafers have already absorbed the tuner cleaner and are swollen (?), to reverse that process may take a long time.  (Actually, I've never heard of this, but it's possible with the pheonolic material Drake used.)  But cleaning/degreasing and then re-lubricating the metal bearings is not complex.  Use a small, stiff brush and some denatured alcohol on all moving parts and bearing surfaces (the metal plate that is part of the main switch mechanism), followed by a blast of air from a dusting sprayer and a tiny drop of electronic bearing lubricant (GC and others sell this stuff in tiny tubes found at electronic parts stores).  Remember to try to clean the panel bearing as well, if you can access it (this is the thrust bearing mounted to the metal subpanel of the T4XB, through which the bandswitch shaft runs to reach the front panel knob).  Hope it works!
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K3UOD

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T4XB Bandswitch
« Reply #2 on: February 20, 2001, 09:25:03 AM »

Already did that.  I found some wood alcohol at a paint store and tried washing the wafers again.  They got a little better.  The e-mail I received from Drake said that I'd have to do it many times.  

I used silicone gun oil, applied with a toothpick, on the shaft bushings and detent assembly.  

I have the rig back on the air and it sounds great.  Since I don't change bands that often, the switch is not much of a problem.  I'll give it another alcohol treatment every time I open it up for any reason.
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