The AM Forum

THE AM BULLETIN BOARD => Technical Forum => Topic started by: wa5ddz on December 19, 2012, 06:30:37 PM



Title: What's up front ?
Post by: wa5ddz on December 19, 2012, 06:30:37 PM
Picked up a Heathkit SB-401 at a very gud buy. Now the bad news.
Turning the large tuning knob (it turns very free) results in no movement
of the dial. I did get the manual an a power cord is on the way. I need advice on how to start this dial repair. Thanks for any and all help.


Title: Re: What's up front ?
Post by: Pete, WA2CWA on December 19, 2012, 08:54:44 PM
Follow the assembly instructions in the manual.


Title: Re: What's up front ?
Post by: KL7OF on December 19, 2012, 09:48:35 PM
You might have to free up the bearings (bushings) and the pulleys with some cleaner and some lube...use penetrating oil sparingly on the moving parts and give it time to soak in.....try not to get any on dial cords  and pulley grooves...some verniers need to be disassembled to be cleaned...Just take your time and good luck.....Steve


Title: Re: What's up front ?
Post by: WQ9E on December 19, 2012, 10:00:07 PM
As Pete said it is covered in the assembly instructions.  If you don't have the manual for the transmitter you should acquire one.  But all of the SB series dials work the same way so if you have the manual for any of the SB era gear (well prior to the SB-104 anyway) it will cover this issue.  The VFO knob can be adjusted up/down after loosening the retaining nut so that it properly engages the 0-100 dial/drive rim.
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands